From: Graeme Gregory graeme.gregory@linaro.org

Now with the base changes to the arm memory mapping it is safe to convert to using ioremap to map in the tables after acpi_gbl_permanent_mmap is set.

CC: Rafael J Wysocki rjw@rjwysocki.net Tested-by: Robert Richter rrichter@cavium.com Tested-by: Timur Tabi timur@codeaurora.org Acked-by: Robert Richter rrichter@cavium.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Grant Likely grant.likely@linaro.org Signed-off-by: Al Stone al.stone@linaro.org Signed-off-by: Graeme Gregory graeme.gregory@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- drivers/acpi/osl.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index f9eeae8..39748bb 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -336,11 +336,11 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size) return NULL; }

-#ifndef CONFIG_IA64 -#define should_use_kmap(pfn) page_is_ram(pfn) -#else +#if defined(CONFIG_IA64) || defined(CONFIG_ARM64) /* ioremap will take care of cache attributes */ #define should_use_kmap(pfn) 0 +#else +#define should_use_kmap(pfn) page_is_ram(pfn) #endif

static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz)

From: Mark Salter msalter@redhat.com

Commit 0e63ea48b4d8 (arm64/efi: add missing call to early_ioremap_reset()) added a missing call to early_ioremap_reset(). This triggers a BUG if code tries using early_ioremap() after the early_ioremap_reset(). This is a problem for some ACPI code which needs short-lived temporary mappings after paging_init() but before acpi_early_init() in start_kernel(). This patch adds definitions for the __late_set_fixmap() and __late_clear_fixmap() which avoids the BUG by allowing later use of early_ioremap().

CC: Leif Lindholm leif.lindholm@linaro.org CC: Ard Biesheuvel ard.biesheuvel@linaro.org Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Robert Richter rrichter@cavium.com Tested-by: Timur Tabi timur@codeaurora.org Acked-by: Robert Richter rrichter@cavium.com Reviewed-by: Grant Likely grant.likely@linaro.org Signed-off-by: Mark Salter msalter@redhat.com Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/include/asm/fixmap.h | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h index defa0ff9..f196e40 100644 --- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -62,6 +62,9 @@ void __init early_fixmap_init(void);

#define __early_set_fixmap __set_fixmap

+#define __late_set_fixmap __set_fixmap +#define __late_clear_fixmap(idx) __set_fixmap((idx), 0, FIXMAP_PAGE_CLEAR) + extern void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot);

#include <asm-generic/fixmap.h>

From: Al Stone al.stone@linaro.org

As we want to get ACPI tables to parse and then use the information for system initialization, we should get the RSDP (Root System Description Pointer) first, it then locates Extended Root Description Table (XSDT) which contains all the 64-bit physical address that pointer to other boot-time tables.

Introduce acpi.c and its related head file in this patch to provide fundamental needs of extern variables and functions for ACPI core, and then get boot-time tables as needed. - asm/acenv.h for arch specific ACPICA environments and implementation, It is needed unconditionally by ACPI core; - asm/acpi.h for arch specific variables and functions needed by ACPI driver core; - acpi.c for ARM64 related ACPI implementation for ACPI driver core;

acpi_boot_table_init() is introduced to get RSDP and boot-time tables, it will be called in setup_arch() before paging_init(), so we should use eary_memremap() mechanism here to get the RSDP and all the table pointers.

FADT Major.Minor version was introduced in ACPI 5.1, it is the same as ACPI version.

In ACPI 5.1, some major gaps are fixed for ARM, such as updates in MADT table for GIC and SMP init, without those updates, we can not get the MPIDR for SMP init, and GICv2/3 related init information, so we can't boot arm64 ACPI properly with table versions predating 5.1.

If firmware provides ACPI tables with ACPI version less than 5.1, OS has no way to retrieve the configuration data that is necessary to init SMP boot protocol and the GIC properly, so disable ACPI if we get an FADT table with version less that 5.1 when acpi_boot_table_init() called.

CC: Catalin Marinas catalin.marinas@arm.com CC: Will Deacon will.deacon@arm.com CC: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Yijing Wang wangyijing@huawei.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Timur Tabi timur@codeaurora.org Tested-by: Robert Richter rrichter@cavium.com Acked-by: Robert Richter rrichter@cavium.com Acked-by: Olof Johansson olof@lixom.net Acked-by: Grant Likely grant.likely@linaro.org Signed-off-by: Al Stone al.stone@linaro.org Signed-off-by: Graeme Gregory graeme.gregory@linaro.org Signed-off-by: Tomasz Nowicki tomasz.nowicki@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/include/asm/acenv.h | 18 ++++++++ arch/arm64/include/asm/acpi.h | 45 ++++++++++++++++++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/acpi.c | 101 +++++++++++++++++++++++++++++++++++++++++ arch/arm64/kernel/setup.c | 5 ++ 5 files changed, 170 insertions(+) create mode 100644 arch/arm64/include/asm/acenv.h create mode 100644 arch/arm64/include/asm/acpi.h create mode 100644 arch/arm64/kernel/acpi.c

diff --git a/arch/arm64/include/asm/acenv.h b/arch/arm64/include/asm/acenv.h new file mode 100644 index 0000000..b49166f --- /dev/null +++ b/arch/arm64/include/asm/acenv.h @@ -0,0 +1,18 @@ +/* + * ARM64 specific ACPICA environments and implementation + * + * Copyright (C) 2014, Linaro Ltd. + * Author: Hanjun Guo hanjun.guo@linaro.org + * Author: Graeme Gregory graeme.gregory@linaro.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#ifndef _ASM_ACENV_H +#define _ASM_ACENV_H + +/* It is required unconditionally by ACPI core, update it when needed. */ + +#endif /* _ASM_ACENV_H */ diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h new file mode 100644 index 0000000..8b837ab --- /dev/null +++ b/arch/arm64/include/asm/acpi.h @@ -0,0 +1,45 @@ +/* + * Copyright (C) 2013-2014, Linaro Ltd. + * Author: Al Stone al.stone@linaro.org + * Author: Graeme Gregory graeme.gregory@linaro.org + * Author: Hanjun Guo hanjun.guo@linaro.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation; + */ + +#ifndef _ASM_ACPI_H +#define _ASM_ACPI_H + +/* Basic configuration for ACPI */ +#ifdef CONFIG_ACPI +#define acpi_strict 1 /* No out-of-spec workarounds on ARM64 */ +extern int acpi_disabled; +extern int acpi_noirq; +extern int acpi_pci_disabled; + +static inline void disable_acpi(void) +{ + acpi_disabled = 1; + acpi_pci_disabled = 1; + acpi_noirq = 1; +} + +/* + * It's used from ACPI core in kdump to boot UP system with SMP kernel, + * with this check the ACPI core will not override the CPU index + * obtained from GICC with 0 and not print some error message as well. + * Since MADT must provide at least one GICC structure for GIC + * initialization, CPU will be always available in MADT on ARM64. + */ +static inline bool acpi_has_cpu_in_madt(void) +{ + return true; +} + +static inline void arch_fix_phys_package_id(int num, u32 slot) { } + +#endif /* CONFIG_ACPI */ + +#endif /*_ASM_ACPI_H*/ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 5ee07ee..fdc7877 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -35,6 +35,7 @@ arm64-obj-$(CONFIG_KGDB) += kgdb.o arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o arm64-obj-$(CONFIG_PCI) += pci.o arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o +arm64-obj-$(CONFIG_ACPI) += acpi.o

obj-y += $(arm64-obj-y) vdso/ obj-m += $(arm64-obj-m) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c new file mode 100644 index 0000000..7abac24 --- /dev/null +++ b/arch/arm64/kernel/acpi.c @@ -0,0 +1,101 @@ +/* + * ARM64 Specific Low-Level ACPI Boot Support + * + * Copyright (C) 2013-2014, Linaro Ltd. + * Author: Al Stone al.stone@linaro.org + * Author: Graeme Gregory graeme.gregory@linaro.org + * Author: Hanjun Guo hanjun.guo@linaro.org + * Author: Tomasz Nowicki tomasz.nowicki@linaro.org + * Author: Naresh Bhat naresh.bhat@linaro.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#define pr_fmt(fmt) "ACPI: " fmt + +#include <linux/acpi.h> +#include <linux/bootmem.h> +#include <linux/cpumask.h> +#include <linux/init.h> +#include <linux/irq.h> +#include <linux/irqdomain.h> +#include <linux/memblock.h> +#include <linux/smp.h> + +int acpi_noirq; /* skip ACPI IRQ initialization */ +int acpi_disabled; +EXPORT_SYMBOL(acpi_disabled); + +int acpi_pci_disabled; /* skip ACPI PCI scan and IRQ initialization */ +EXPORT_SYMBOL(acpi_pci_disabled); + +/* + * __acpi_map_table() will be called before page_init(), so early_ioremap() + * or early_memremap() should be called here to for ACPI table mapping. + */ +char *__init __acpi_map_table(unsigned long phys, unsigned long size) +{ + if (!size) + return NULL; + + return early_memremap(phys, size); +} + +void __init __acpi_unmap_table(char *map, unsigned long size) +{ + if (!map || !size) + return; + + early_memunmap(map, size); +} + +static int __init acpi_parse_fadt(struct acpi_table_header *table) +{ + struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table; + + /* + * Revision in table header is the FADT Major revision, and there + * is a minor revision of FADT which was introduced by ACPI 5.1, + * we only deal with ACPI 5.1 or newer revision to get GIC and SMP + * boot protocol configuration data, or we will disable ACPI. + */ + if (table->revision > 5 || + (table->revision == 5 && fadt->minor_revision >= 1)) + return 0; + + pr_warn("Unsupported FADT revision %d.%d, should be 5.1+, will disable ACPI\n", + table->revision, fadt->minor_revision); + disable_acpi(); + + return -EINVAL; +} + +/* + * acpi_boot_table_init() called from setup_arch(), always. + * 1. find RSDP and get its address, and then find XSDT + * 2. extract all tables and checksums them all + * 3. check ACPI FADT revision + * + * We can parse ACPI boot-time tables such as MADT after + * this function is called. + */ +void __init acpi_boot_table_init(void) +{ + /* If acpi_disabled, bail out */ + if (acpi_disabled) + return; + + /* Initialize the ACPI boot-time table parser. */ + if (acpi_table_init()) { + disable_acpi(); + return; + } + + if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) { + /* disable ACPI if no FADT is found */ + disable_acpi(); + pr_err("Can't find FADT\n"); + } +} diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index e8420f6..4f1a014 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -17,6 +17,7 @@ * along with this program. If not, see http://www.gnu.org/licenses/. */

+#include <linux/acpi.h> #include <linux/export.h> #include <linux/kernel.h> #include <linux/stddef.h> @@ -46,6 +47,7 @@ #include <linux/efi.h> #include <linux/personality.h>

+#include <asm/acpi.h> #include <asm/fixmap.h> #include <asm/cpu.h> #include <asm/cputype.h> @@ -380,6 +382,9 @@ void __init setup_arch(char **cmdline_p) efi_init(); arm64_memblock_init();

+ /* Parse the ACPI tables for possible boot-time configuration */ + acpi_boot_table_init(); + paging_init(); request_standard_resources();

From: Mark Salter msalter@redhat.com

The acpi_os_ioremap() function may be used to map normal RAM or IO regions. The current implementation simply uses ioremap_cache(). This will work for some architectures, but arm64 ioremap_cache() cannot be used to map IO regions which don't support caching. So for arm64, use ioremap() for non-RAM regions.

CC: Rafael J Wysocki rjw@rjwysocki.net CC: Catalin Marinas catalin.marinas@arm.com Tested-by: Robert Richter rrichter@cavium.com Tested-by: Timur Tabi timur@codeaurora.org Acked-by: Robert Richter rrichter@cavium.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Grant Likely grant.likely@linaro.org Signed-off-by: Mark Salter msalter@redhat.com Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/include/asm/acpi.h | 13 +++++++++++++ include/acpi/acpi_io.h | 4 ++++ 2 files changed, 17 insertions(+)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index 8b837ab..40e0924 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -12,8 +12,21 @@ #ifndef _ASM_ACPI_H #define _ASM_ACPI_H

+#include <linux/mm.h> + /* Basic configuration for ACPI */ #ifdef CONFIG_ACPI +/* ACPI table mapping after acpi_gbl_permanent_mmap is set */ +static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys, + acpi_size size) +{ + if (!page_is_ram(phys >> PAGE_SHIFT)) + return ioremap(phys, size); + + return ioremap_cache(phys, size); +} +#define acpi_os_ioremap acpi_os_ioremap + #define acpi_strict 1 /* No out-of-spec workarounds on ARM64 */ extern int acpi_disabled; extern int acpi_noirq; diff --git a/include/acpi/acpi_io.h b/include/acpi/acpi_io.h index 444671e..dd86c5f 100644 --- a/include/acpi/acpi_io.h +++ b/include/acpi/acpi_io.h @@ -3,11 +3,15 @@

#include <linux/io.h>

+#include <asm/acpi.h> + +#ifndef acpi_os_ioremap static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) { return ioremap_cache(phys, size); } +#endif

void __iomem *__init_refok acpi_os_map_iomem(acpi_physical_address phys, acpi_size size);

From: Graeme Gregory graeme.gregory@linaro.org

ACPI 5.1 does not currently support S states for ARM64 hardware but ACPI code will call acpi_target_system_state() and acpi_sleep_init() for device power management, so introduce CONFIG_ACPI_SYSTEM_POWER_STATES_SUPPORT and select it for x86 and ia64 only to make sleep functions available, and also introduce stub function to allow other drivers to function until S states are defined for ARM64.

It will be no functional change for x86 and IA64.

Suggested-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Acked-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Graeme Gregory graeme.gregory@linaro.org Signed-off-by: Tomasz Nowicki tomasz.nowicki@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/ia64/Kconfig | 1 + arch/x86/Kconfig | 1 + drivers/acpi/Kconfig | 4 ++++ drivers/acpi/Makefile | 2 +- drivers/acpi/internal.h | 4 ++++ 5 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 074e52b..cc3414f 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -10,6 +10,7 @@ config IA64 select ARCH_MIGHT_HAVE_PC_SERIO select PCI if (!IA64_HP_SIM) select ACPI if (!IA64_HP_SIM) + select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI select HAVE_UNSTABLE_SCHED_CLOCK select HAVE_IDE diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b7d31ca..c3ea9f9 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -22,6 +22,7 @@ config X86_64 ### Arch settings config X86 def_bool y + select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS select ARCH_HAS_FAST_MULTIPLIER diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index e6c3ddd..a726381 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -48,9 +48,13 @@ config ACPI_LEGACY_TABLES_LOOKUP config ARCH_MIGHT_HAVE_ACPI_PDC bool

+config ACPI_SYSTEM_POWER_STATES_SUPPORT + bool + config ACPI_SLEEP bool depends on SUSPEND || HIBERNATION + depends on ACPI_SYSTEM_POWER_STATES_SUPPORT default y

config ACPI_PROCFS_POWER diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 623b117..db153c6 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -23,7 +23,7 @@ acpi-y += nvs.o

# Power management related files acpi-y += wakeup.o -acpi-y += sleep.o +acpi-$(CONFIG_ACPI_SYSTEM_POWER_STATES_SUPPORT) += sleep.o acpi-y += device_pm.o acpi-$(CONFIG_ACPI_SLEEP) += proc.o

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h index 56b321a..ba4a61e 100644 --- a/drivers/acpi/internal.h +++ b/drivers/acpi/internal.h @@ -161,7 +161,11 @@ void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit); /*-------------------------------------------------------------------------- Suspend/Resume -------------------------------------------------------------------------- */ +#ifdef CONFIG_ACPI_SYSTEM_POWER_STATES_SUPPORT extern int acpi_sleep_init(void); +#else +static inline int acpi_sleep_init(void) { return -ENXIO; } +#endif

#ifdef CONFIG_ACPI_SLEEP int acpi_sleep_proc_init(void);

From: Graeme Gregory graeme.gregory@linaro.org

There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set, the former signals to the OS that the firmware is PSCI compliant. The latter selects the appropriate conduit for PSCI calls by toggling between Hypervisor Calls (HVC) and Secure Monitor Calls (SMC).

FADT table contains such information in ACPI 5.1, FADT table was parsed in ACPI table init and copy to struct acpi_gbl_FADT, so use the flags in struct acpi_gbl_FADT for PSCI init.

Since ACPI 5.1 doesn't support self defined PSCI function IDs, which means that only PSCI 0.2+ is supported in ACPI.

CC: Lorenzo Pieralisi lorenzo.pieralisi@arm.com CC: Catalin Marinas catalin.marinas@arm.com CC: Will Deacon will.deacon@arm.com Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Yijing Wang wangyijing@huawei.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Timur Tabi timur@codeaurora.org Tested-by: Robert Richter rrichter@cavium.com Acked-by: Robert Richter rrichter@cavium.com Acked-by: Olof Johansson olof@lixom.net Acked-by: Grant Likely grant.likely@linaro.org Signed-off-by: Graeme Gregory graeme.gregory@linaro.org Signed-off-by: Tomasz Nowicki tomasz.nowicki@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/include/asm/acpi.h | 15 +++++++++ arch/arm64/include/asm/psci.h | 3 +- arch/arm64/kernel/psci.c | 78 ++++++++++++++++++++++++++++++------------- arch/arm64/kernel/setup.c | 8 +++-- 4 files changed, 76 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index c5a9b97..9ea650c 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -32,6 +32,18 @@ extern int acpi_disabled; extern int acpi_noirq; extern int acpi_pci_disabled;

+/* 1 to indicate PSCI 0.2+ is implemented */ +static inline bool acpi_psci_present(void) +{ + return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT; +} + +/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */ +static inline bool acpi_psci_use_hvc(void) +{ + return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC; +} + static inline void disable_acpi(void) { acpi_disabled = 1; @@ -60,6 +72,9 @@ static inline bool acpi_has_cpu_in_madt(void)

static inline void arch_fix_phys_package_id(int num, u32 slot) { }

+#else +static inline bool acpi_psci_present(void) { return false; } +static inline bool acpi_psci_use_hvc(void) { return false; } #endif /* CONFIG_ACPI */

#endif /*_ASM_ACPI_H*/ diff --git a/arch/arm64/include/asm/psci.h b/arch/arm64/include/asm/psci.h index e5312ea..2454bc5 100644 --- a/arch/arm64/include/asm/psci.h +++ b/arch/arm64/include/asm/psci.h @@ -14,6 +14,7 @@ #ifndef __ASM_PSCI_H #define __ASM_PSCI_H

-int psci_init(void); +int psci_dt_init(void); +int psci_acpi_init(void);

#endif /* __ASM_PSCI_H */ diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c index 9b8a70a..d3c52ce 100644 --- a/arch/arm64/kernel/psci.c +++ b/arch/arm64/kernel/psci.c @@ -15,6 +15,7 @@

#define pr_fmt(fmt) "psci: " fmt

+#include <linux/acpi.h> #include <linux/init.h> #include <linux/of.h> #include <linux/smp.h> @@ -24,6 +25,7 @@ #include <linux/slab.h> #include <uapi/linux/psci.h>

+#include <asm/acpi.h> #include <asm/compiler.h> #include <asm/cpu_ops.h> #include <asm/errno.h> @@ -273,6 +275,33 @@ static void psci_sys_poweroff(void) invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0); }

+static void __init psci_0_2_set_functions(void) +{ + pr_info("Using standard PSCI v0.2 function IDs\n"); + psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN64_CPU_SUSPEND; + psci_ops.cpu_suspend = psci_cpu_suspend; + + psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF; + psci_ops.cpu_off = psci_cpu_off; + + psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN64_CPU_ON; + psci_ops.cpu_on = psci_cpu_on; + + psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN64_MIGRATE; + psci_ops.migrate = psci_migrate; + + psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_0_2_FN64_AFFINITY_INFO; + psci_ops.affinity_info = psci_affinity_info; + + psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] = + PSCI_0_2_FN_MIGRATE_INFO_TYPE; + psci_ops.migrate_info_type = psci_migrate_info_type; + + arm_pm_restart = psci_sys_reset; + + pm_power_off = psci_sys_poweroff; +} + /* * PSCI Function IDs for v0.2+ are well defined so use * standard values. @@ -306,29 +335,7 @@ static int __init psci_0_2_init(struct device_node *np) } }

- pr_info("Using standard PSCI v0.2 function IDs\n"); - psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN64_CPU_SUSPEND; - psci_ops.cpu_suspend = psci_cpu_suspend; - - psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF; - psci_ops.cpu_off = psci_cpu_off; - - psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN64_CPU_ON; - psci_ops.cpu_on = psci_cpu_on; - - psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN64_MIGRATE; - psci_ops.migrate = psci_migrate; - - psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_0_2_FN64_AFFINITY_INFO; - psci_ops.affinity_info = psci_affinity_info; - - psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] = - PSCI_0_2_FN_MIGRATE_INFO_TYPE; - psci_ops.migrate_info_type = psci_migrate_info_type; - - arm_pm_restart = psci_sys_reset; - - pm_power_off = psci_sys_poweroff; + psci_0_2_set_functions();

out_put_node: of_node_put(np); @@ -381,7 +388,7 @@ static const struct of_device_id psci_of_match[] __initconst = { {}, };

-int __init psci_init(void) +int __init psci_dt_init(void) { struct device_node *np; const struct of_device_id *matched_np; @@ -396,6 +403,29 @@ int __init psci_init(void) return init_fn(np); }

+/* + * We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's + * explicitly clarified in SBBR + */ +int __init psci_acpi_init(void) +{ + if (!acpi_psci_present()) { + pr_info("is not implemented in ACPI.\n"); + return -EOPNOTSUPP; + } + + pr_info("probing for conduit method from ACPI.\n"); + + if (acpi_psci_use_hvc()) + invoke_psci_fn = __invoke_psci_fn_hvc; + else + invoke_psci_fn = __invoke_psci_fn_smc; + + psci_0_2_set_functions(); + + return 0; +} + #ifdef CONFIG_SMP

static int __init cpu_psci_cpu_init(struct device_node *dn, unsigned int cpu) diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index e8c7000..97fa7f3 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -390,10 +390,12 @@ void __init setup_arch(char **cmdline_p)

early_ioremap_reset();

- if (acpi_disabled) + if (acpi_disabled) { unflatten_device_tree(); - - psci_init(); + psci_dt_init(); + } else { + psci_acpi_init(); + }

cpu_read_bootcpu_ops(); #ifdef CONFIG_SMP

When MADT is parsed, print GIC information as debug message:

ACPI: GICC (acpi_id[0x0000] address[00000000e112f000] MPIDR[0x0] enabled) ACPI: GICC (acpi_id[0x0001] address[00000000e112f000] MPIDR[0x1] enabled) ... ACPI: GICC (acpi_id[0x0201] address[00000000e112f000] MPIDR[0x201] enabled)

This debug information will be very helpful to bring up early systems to see if acpi_id and MPIDR are matched or not as spec defined.

CC: Rafael J. Wysocki rjw@rjwysocki.net Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Yijing Wang wangyijing@huawei.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Timur Tabi timur@codeaurora.org Tested-by: Robert Richter rrichter@cavium.com Acked-by: Robert Richter rrichter@cavium.com Acked-by: Sudeep Holla sudeep.holla@arm.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Acked-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Acked-by: Grant Likely grant.likely@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org Signed-off-by: Tomasz Nowicki tomasz.nowicki@linaro.org --- drivers/acpi/tables.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index f4e5b88..2e19189 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -185,6 +185,28 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header) } break;

+ case ACPI_MADT_TYPE_GENERIC_INTERRUPT: + { + struct acpi_madt_generic_interrupt *p = + (struct acpi_madt_generic_interrupt *)header; + pr_debug("GICC (acpi_id[0x%04x] address[%llx] MPIDR[0x%llx] %s)\n", + p->uid, p->base_address, + p->arm_mpidr, + (p->flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled"); + + } + break; + + case ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR: + { + struct acpi_madt_generic_distributor *p = + (struct acpi_madt_generic_distributor *)header; + pr_debug("GIC Distributor (gic_id[0x%04x] address[%llx] gsi_base[%d])\n", + p->gic_id, p->base_address, + p->global_irq_base); + } + break; + default: pr_warn("Found unsupported MADT entry (type = 0x%x)\n", header->type);

Introduce a new function map_gicc_mpidr() to allow MPIDRs to be obtained from the GICC Structure introduced by ACPI 5.1, since MPIDR for ARM64 is 64-bit, so typedef u64 for phys_cpuid_t.

The ARM architecture defines the MPIDR register as the CPU hardware identifier. This patch adds the code infrastructure to retrieve the MPIDR values from the ARM ACPI GICC structure in order to look-up the kernel CPU hardware ids required by the ACPI core code to identify CPUs.

CC: Rafael J. Wysocki rjw@rjwysocki.net CC: Catalin Marinas catalin.marinas@arm.com CC: Will Deacon will.deacon@arm.com Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Yijing Wang wangyijing@huawei.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Timur Tabi timur@codeaurora.org Tested-by: Robert Richter rrichter@cavium.com Acked-by: Robert Richter rrichter@cavium.com Acked-by: Lorenzo Pieralisi lorenzo.pieralisi@arm.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Grant Likely grant.likely@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/include/asm/acpi.h | 12 ++++++++++++ drivers/acpi/processor_core.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index 9719921..eea0bc3 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -13,6 +13,8 @@ #define _ASM_ACPI_H

#include <linux/mm.h> +#include <asm/cputype.h> +#include <asm/smp_plat.h>

/* Basic configuration for ACPI */ #ifdef CONFIG_ACPI @@ -27,6 +29,9 @@ static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys, } #define acpi_os_ioremap acpi_os_ioremap

+typedef u64 phys_cpuid_t; +#define PHYS_CPUID_INVALID INVALID_HWID + #define acpi_strict 1 /* No out-of-spec workarounds on ARM64 */ extern int acpi_disabled; extern int acpi_noirq; @@ -59,6 +64,13 @@ static inline void enable_acpi(void) }

/* + * The ACPI processor driver for ACPI core code needs this macro + * to find out this cpu was already mapped (mapping from CPU hardware + * ID to CPU logical ID) or not. + */ +#define cpu_physical_id(cpu) cpu_logical_map(cpu) + +/* * It's used from ACPI core in kdump to boot UP system with SMP kernel, * with this check the ACPI core will not override the CPU index * obtained from GICC with 0 and not print some error message as well. diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c index 51cc299..b1ec78b 100644 --- a/drivers/acpi/processor_core.c +++ b/drivers/acpi/processor_core.c @@ -83,6 +83,31 @@ static int map_lsapic_id(struct acpi_subtable_header *entry, return 0; }

+/* + * Retrieve the ARM CPU physical identifier (MPIDR) + */ +static int map_gicc_mpidr(struct acpi_subtable_header *entry, + int device_declaration, u32 acpi_id, phys_cpuid_t *mpidr) +{ + struct acpi_madt_generic_interrupt *gicc = + container_of(entry, struct acpi_madt_generic_interrupt, header); + + if (!(gicc->flags & ACPI_MADT_ENABLED)) + return -ENODEV; + + /* device_declaration means Device object in DSDT, in the + * GIC interrupt model, logical processors are required to + * have a Processor Device object in the DSDT, so we should + * check device_declaration here + */ + if (device_declaration && (gicc->uid == acpi_id)) { + *mpidr = gicc->arm_mpidr; + return 0; + } + + return -EINVAL; +} + static phys_cpuid_t map_madt_entry(int type, u32 acpi_id) { unsigned long madt_end, entry; @@ -111,6 +136,9 @@ static phys_cpuid_t map_madt_entry(int type, u32 acpi_id) } else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) { if (!map_lsapic_id(header, type, acpi_id, &phys_id)) break; + } else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) { + if (!map_gicc_mpidr(header, type, acpi_id, &phys_id)) + break; } entry += header->length; } @@ -143,6 +171,8 @@ static phys_cpuid_t map_mat_entry(acpi_handle handle, int type, u32 acpi_id) map_lsapic_id(header, type, acpi_id, &phys_id); else if (header->type == ACPI_MADT_TYPE_LOCAL_X2APIC) map_x2apic_id(header, type, acpi_id, &phys_id); + else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) + map_gicc_mpidr(header, type, acpi_id, &phys_id);

exit: kfree(buffer.pointer);

Introduce ACPI_IRQ_MODEL_GIC which is needed for ARM64 as GIC is used, and then register device's gsi with the core IRQ subsystem.

acpi_register_gsi() is similar to DT based irq_of_parse_and_map(), since gsi is unique in the system, so use hwirq number directly for the mapping.

We are going to implement stacked domains when GICv2m, GICv3, ITS support are added.

CC: Marc Zyngier marc.zyngier@arm.com Originally-by: Amit Daniel Kachhap amit.daniel@samsung.com Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Yijing Wang wangyijing@huawei.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Timur Tabi timur@codeaurora.org Tested-by: Robert Richter rrichter@cavium.com Acked-by: Robert Richter rrichter@cavium.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Grant Likely grant.likely@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/kernel/acpi.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++ drivers/acpi/bus.c | 3 ++ include/linux/acpi.h | 1 + 3 files changed, 77 insertions(+)

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index c9203c0..dec6f8a 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -76,6 +76,12 @@ static int __init dt_scan_depth1_nodes(unsigned long node, }

/* + * Since we're on ARM, the default interrupt routing model + * clearly has to be GIC. + */ +enum acpi_irq_model_id acpi_irq_model = ACPI_IRQ_MODEL_GIC; + +/* * __acpi_map_table() will be called before page_init(), so early_ioremap() * or early_memremap() should be called here to for ACPI table mapping. */ @@ -218,6 +224,73 @@ void __init acpi_init_cpus(void) pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus); }

+int acpi_gsi_to_irq(u32 gsi, unsigned int *irq) +{ + *irq = irq_find_mapping(NULL, gsi); + + return 0; +} +EXPORT_SYMBOL_GPL(acpi_gsi_to_irq); + +/* + * success: return IRQ number (>0) + * failure: return =< 0 + */ +int acpi_register_gsi(struct device *dev, u32 gsi, int trigger, int polarity) +{ + unsigned int irq; + unsigned int irq_type; + + /* + * ACPI have no bindings to indicate SPI or PPI, so we + * use different mappings from DT in ACPI. + * + * For FDT + * PPI interrupt: in the range [0, 15]; + * SPI interrupt: in the range [0, 987]; + * + * For ACPI, GSI should be unique so using + * the hwirq directly for the mapping: + * PPI interrupt: in the range [16, 31]; + * SPI interrupt: in the range [32, 1019]; + */ + + if (trigger == ACPI_EDGE_SENSITIVE && + polarity == ACPI_ACTIVE_LOW) + irq_type = IRQ_TYPE_EDGE_FALLING; + else if (trigger == ACPI_EDGE_SENSITIVE && + polarity == ACPI_ACTIVE_HIGH) + irq_type = IRQ_TYPE_EDGE_RISING; + else if (trigger == ACPI_LEVEL_SENSITIVE && + polarity == ACPI_ACTIVE_LOW) + irq_type = IRQ_TYPE_LEVEL_LOW; + else if (trigger == ACPI_LEVEL_SENSITIVE && + polarity == ACPI_ACTIVE_HIGH) + irq_type = IRQ_TYPE_LEVEL_HIGH; + else + irq_type = IRQ_TYPE_NONE; + + /* + * Since only one GIC is supported in ACPI 5.0, we can + * create mapping refer to the default domain + */ + irq = irq_create_mapping(NULL, gsi); + if (!irq) + return irq; + + /* Set irq type if specified and different than the current one */ + if (irq_type != IRQ_TYPE_NONE && + irq_type != irq_get_trigger_type(irq)) + irq_set_irq_type(irq, irq_type); + return irq; +} +EXPORT_SYMBOL_GPL(acpi_register_gsi); + +void acpi_unregister_gsi(u32 gsi) +{ +} +EXPORT_SYMBOL_GPL(acpi_unregister_gsi); + static int __init acpi_parse_fadt(struct acpi_table_header *table) { struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table; diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index 8b67bd0..c412fdb 100644 --- a/drivers/acpi/bus.c +++ b/drivers/acpi/bus.c @@ -448,6 +448,9 @@ static int __init acpi_bus_init_irq(void) case ACPI_IRQ_MODEL_IOSAPIC: message = "IOSAPIC"; break; + case ACPI_IRQ_MODEL_GIC: + message = "GIC"; + break; case ACPI_IRQ_MODEL_PLATFORM: message = "platform specific model"; break; diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 6ec33c5..de4e86f 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -73,6 +73,7 @@ enum acpi_irq_model_id { ACPI_IRQ_MODEL_IOAPIC, ACPI_IRQ_MODEL_IOSAPIC, ACPI_IRQ_MODEL_PLATFORM, + ACPI_IRQ_MODEL_GIC, ACPI_IRQ_MODEL_COUNT };

From: Graeme Gregory graeme.gregory@linaro.org

Add Kconfigs to build ACPI on ARM64, and make ACPI available on ARM64.

acpi_idle driver is x86/IA64 dependent now, so make CONFIG_ACPI_PROCESSOR depend on X86 || IA64, and implement it on ARM64 in the future.

CC: Rafael J. Wysocki rjw@rjwysocki.net CC: Catalin Marinas catalin.marinas@arm.com CC: Will Deacon will.deacon@arm.com Reviewed-by: Grant Likely grant.likely@linaro.org Tested-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Tested-by: Yijing Wang wangyijing@huawei.com Tested-by: Mark Langsdorf mlangsdo@redhat.com Tested-by: Jon Masters jcm@redhat.com Tested-by: Timur Tabi timur@codeaurora.org Tested-by: Robert Richter rrichter@cavium.com Acked-by: Robert Richter rrichter@cavium.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Graeme Gregory graeme.gregory@linaro.org Signed-off-by: Al Stone al.stone@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- arch/arm64/Kconfig | 2 ++ drivers/acpi/Kconfig | 3 ++- 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index d00ab9a..e5aa081 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -713,6 +713,8 @@ source "drivers/Kconfig"

source "drivers/firmware/Kconfig"

+source "drivers/acpi/Kconfig" + source "fs/Kconfig"

source "arch/arm64/kvm/Kconfig" diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index a726381..a8f531e2 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -5,7 +5,7 @@ menuconfig ACPI bool "ACPI (Advanced Configuration and Power Interface) Support" depends on !IA64_HP_SIM - depends on IA64 || X86 + depends on IA64 || X86 || (ARM64 && EXPERT) depends on PCI select PNP default y @@ -167,6 +167,7 @@ config ACPI_PROCESSOR tristate "Processor" select THERMAL select CPU_IDLE + depends on X86 || IA64 default y help This driver installs ACPI as the idle handler for Linux and uses

From: Graeme Gregory graeme.gregory@linaro.org

Add documentation for the guidelines of how to use ACPI on ARM64.

Reviewed-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com Reviewed-by: Yi Li phoenix.liyi@huawei.com Reviewed-by: Mark Langsdorf mlangsdo@redhat.com Reviewed-by: Ashwin Chaugule ashwinc@codeaurora.org Acked-by: Robert Richter rrichter@cavium.com Signed-off-by: Graeme Gregory graeme.gregory@linaro.org Signed-off-by: Al Stone al.stone@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- Documentation/arm64/arm-acpi.txt | 505 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 505 insertions(+) create mode 100644 Documentation/arm64/arm-acpi.txt

diff --git a/Documentation/arm64/arm-acpi.txt b/Documentation/arm64/arm-acpi.txt new file mode 100644 index 0000000..7d6e636 --- /dev/null +++ b/Documentation/arm64/arm-acpi.txt @@ -0,0 +1,505 @@ +ACPI on ARMv8 Servers +--------------------- +ACPI can be used for ARMv8 general purpose servers designed to follow +the ARM SBSA (Server Base System Architecture) [0] and SBBR (Server +Base Boot Requirements) [1] specifications. Please note that the SBBR +can be retrieved simply by visiting [1], but the SBSA is currently only +available to those with an ARM login due to ARM IP licensing concerns. + +The ARMv8 kernel implements the reduced hardware model of ACPI version +5.1 or later. Links to the specification and all external documents +it refers to are managed by the UEFI Forum. The specification is +available at http://www.uefi.org/specifications and documents referenced +by the specification can be found via http://www.uefi.org/acpi. + +If an ARMv8 system does not meet the requirements of the SBSA and SBBR, +or cannot be described using the mechanisms defined in the required ACPI +specifications, then ACPI may not be a good fit for the hardware. + +While the documents mentioned above set out the requirements for building +industry-standard ARMv8 servers, they also apply to more than one operating +system. The purpose of this document is to describe the interaction between +ACPI and Linux only, on an ARMv8 system -- that is, what Linux expects of +ACPI and what ACPI can expect of Linux. + + +Why ACPI on ARM? +---------------- +Before examining the details of the interface between ACPI and Linux, it is +useful to understand why ACPI is being used. Several technologies already +exist in Linux for describing non-enumerable hardware, after all. In this +section we summarize a blog post [2] from Grant Likely that outlines the +reasoning behind ACPI on ARMv8 servers. Actually, we snitch a good portion +of the summary text almost directly, to be honest. + +The short form of the rationale for ACPI on ARM is: + +-- ACPI’s bytecode (AML) allows the platform to encode hardware behavior, + while DT explicitly does not support this. For hardware vendors, being + able to encode behavior is a key tool used in supporting operating + system releases on new hardware. + +-- ACPI’s OSPM defines a power management model that constrains what the + platform is allowed to do into a specific model, while still providing + flexibility in hardware design. + +-- In the enterprise server environment, ACPI has established bindings (such + as for RAS) which are currently used in production systems. DT does not. + Such bindings could be defined in DT at some point, but doing so means ARM + and x86 would end up using completely different code paths in both firmware + and the kernel. + +-- Choosing a single interface to describe the abstraction between a platform + and an OS is important. Hardware vendors would not be required to implement + both DT and ACPI if they want to support multiple operating systems. And, + agreeing on a single interface instead of being fragmented into per OS + interfaces makes for better interoperability overall. + +-- The new ACPI governance process works well and Linux is now at the same + table as hardware vendors and other OS vendors. In fact, there is no + longer any reason to feel that ACPI is only belongs to Windows or that + Linux is in any way secondary to Microsoft in this arena. The move of + ACPI governance into the UEFI forum has significantly opened up the + specification development process, and currently, a large portion of the + changes being made to ACPI is being driven by Linux. + +Key to the use of ACPI is the support model. For servers in general, the +responsibility for hardware behaviour cannot solely be the domain of the +kernel, but rather must be split between the platform and the kernel, in +order to allow for orderly change over time. ACPI frees the OS from needing +to understand all the minute details of the hardware so that the OS doesn’t +need to be ported to each and every device individually. It allows the +hardware vendors to take responsibility for power management behaviour without +depending on an OS release cycle which is not under their control. + +ACPI is also important because hardware and OS vendors have already worked +out the mechanisms for supporting a general purpose computing ecosystem. The +infrastructure is in place, the bindings are in place, and the processes are +in place. DT does exactly what Linux needs it to when working with vertically +integrated devices, but there are no good processes for supporting what the +server vendors need. Linux could potentially get there with DT, but doing so +really just duplicates something that already works. ACPI already does what +the hardware vendors need, Microsoft won’t collaborate on DT, and hardware +vendors would still end up providing two completely separate firmware +interfaces -- one for Linux and one for Windows. + + +Kernel Compatibility +-------------------- +One of the primary motivations for ACPI is standardization, and using that +to provide backward compatibility for Linux kernels. In the server market, +software and hardware are often used for long periods. ACPI allows the +kernel and firmware to agree on a consistent abstraction that can be +maintained over time, even as hardware or software change. As long as the +abstraction is supported, systems can be updated without necessarily having +to replace the kernel. + +When a Linux driver or subsystem is first implemented using ACPI, it by +definition ends up requiring a specific version of the ACPI specification +-- it's baseline. ACPI firmware must continue to work, even though it may +not be optimal, with the earliest kernel version that first provides support +for that baseline version of ACPI. There may be a need for additional drivers, +but adding new functionality (e.g., CPU power management) should not break +older kernel versions. Further, ACPI firmware must also work with the most +recent version of the kernel. + + +Relationship with Device Tree +----------------------------- +ACPI support in drivers and subsystems for ARMv8 should never be mutually +exclusive with DT support at compile time. + +At boot time the kernel will only use one description method depending on +parameters passed from the bootloader (including kernel bootargs). + +Regardless of whether DT or ACPI is used, the kernel must always be capable +of booting with either scheme (in kernels with both schemes enabled at compile +time). + + +Booting using ACPI tables +------------------------- +The only defined method for passing ACPI tables to the kernel on ARMv8 +is via the UEFI system configuration table. Just so it is explicit, this +means that ACPI is only supported on platforms that boot via UEFI. + +When an ARMv8 system boots, it can either have DT information, ACPI tables, +or in some very unusual cases, both. If no command line parameters are used, +the kernel will try to use DT for device enumeration; if there is no DT +present, the kernel will try to use ACPI tables, but only if they are present. +In neither is available, the kernel will not boot. If acpi=force is used +on the command line, the kernel will attempt to use ACPI tables first, but +fall back to DT if there are no ACPI tables present. The basic idea is that +the kernel will not fail to boot unless it absolutely has no other choice. + +Processing of ACPI tables may be disabled by passing acpi=off on the kernel +command line; this is the default behavior. + +In order for the kernel to load and use ACPI tables, the UEFI implementation +MUST set the ACPI_20_TABLE_GUID to point to the RSDP table (the table with +the ACPI signature "RSD PTR "). If this pointer is incorrect and acpi=force +is used, the kernel will disable ACPI and try to use DT to boot instead; the +kernel has, in effect, determined that ACPI tables are not present at that +point. + +If the pointer to the RSDP table is correct, the table will be mapped into +the kernel by the ACPI core, using the address provided by UEFI. + +The ACPI core will then locate and map in all other ACPI tables provided by +using the addresses in the RSDP table to find the XSDT (eXtended System +Description Table). The XSDT in turn provides the addresses to all other +ACPI tables provided by the system firmware; the ACPI core will then traverse +this table and map in the tables listed. + +The ACPI core will ignore any provided RSDT (Root System Description Table). +RSDTs have been deprecated and are ignored on arm64 since they only allow +for 32-bit addresses. + +Further, the ACPI core will only use the 64-bit address fields in the FADT +(Fixed ACPI Description Table). Any 32-bit address fields in the FADT will +be ignored on arm64. + +Hardware reduced mode (see Section 4.1 of the ACPI 5.1 specification) will +be enforced by the ACPI core on arm64. Doing so allows the ACPI core to +run less complex code since it no longer has to provide support for legacy +hardware from other architectures. Any fields that are not to be used for +hardware reduced mode must be set to zero. + +For the ACPI core to operate properly, and in turn provide the information +the kernel needs to configure devices, it expects to find the following +tables (all section numbers refer to the ACPI 5.1 specfication): + + -- RSDP (Root System Description Pointer), section 5.2.5 + + -- XSDT (eXtended System Description Table), section 5.2.8 + + -- FADT (Fixed ACPI Description Table), section 5.2.9 + + -- DSDT (Differentiated System Description Table), section + 5.2.11.1 + + -- MADT (Multiple APIC Description Table), section 5.2.12 + + -- GTDT (Generic Timer Description Table), section 5.2.24 + + -- If PCI is supported, the MCFG (Memory mapped ConFiGuration + Table), section 5.2.6, specifically Table 5-31. + +If the above tables are not all present, the kernel may or may not be +able to boot properly since it may not be able to configure all of the +devices available. + + +ACPI Detection +-------------- +Drivers should determine their probe() type by checking for a null +value for ACPI_HANDLE, or checking .of_node, or other information in +the device structure. This is detailed further in the "Driver +Recommendations" section. + +In non-driver code, if the presence of ACPI needs to be detected at +runtime, then check the value of acpi_disabled. If CONFIG_ACPI is not +set, acpi_disabled will always be 1. + + +Device Enumeration +------------------ +Device descriptions in ACPI should use standard recognized ACPI interfaces. +These may contain less information than is typically provided via a Device +Tree description for the same device. This is also one of the reasons that +ACPI can be useful -- the driver takes into account that it may have less +detailed information about the device and uses sensible defaults instead. +If done properly in the driver, the hardware can change and improve over +time without the driver having to change at all. + +Clocks provide an excellent example. In DT, clocks need to be specified +and the drivers need to take them into account. In ACPI, the assumption +is that UEFI will leave the device in a reasonable default state, including +any clock settings. If for some reason the driver needs to change a clock +value, this can be done in an ACPI method; all the driver needs to do is +invoke the method and not concern itself with what the method needs to do +to change the clock. Changing the hardware can then take place over time +by changing what the ACPI method does, and not the driver. + +In DT, the parameters needed by the driver to set up clocks as in the example +above are known as "bindings"; in ACPI, these are known as "Device Properties" +and provided to a driver via the _DSD object. + +ACPI tables are described with a formal language called ASL, the ACPI +Source Language (section 19 of the specification). This means that there +are always multiple ways to describe the same thing -- including device +properties. For example, device properties could use an ASL construct +that looks like this: Name(KEY0, "value0"). An ACPI device driver would +then retrieve the value of the property by evaluating the KEY0 object. +However, using Name() this way has multiple problems: (1) ACPI limits +names ("KEY0") to four characters unlike DT; (2) there is no industry +wide registry that maintains a list of names, minimzing re-use; (3) +there is also no registry for the definition of property values ("value0"), +again making re-use difficult; and (4) how does one maintain backward +compatibility as new hardware comes out? The _DSD method was created +to solve precisely these sorts of problems; Linux drivers should ALWAYS +use the _DSD method for device properties and nothing else. + +The _DSM object (ACPI Section 9.14.1) could also be used for conveying +device properties to a driver. Linux drivers should only expect it to +be used if _DSD cannot represent the data required, and there is no way +to create a new UUID for the _DSD object. Note that there is even less +regulation of the use of _DSM than there is of _DSD. Drivers that depend +on the contents of _DSM objects will be more difficult to maintain over +time because of this; as of this writing, the use of _DSM is the cause +of quite a few firmware problems and is not recommended. + +Drivers should look for device properties in the _DSD object ONLY; the _DSD +object is described in the ACPI specification section 6.2.5, but this only +describes how to define the structure of an object returned via _DSD, and +how specific data structures are defined by specific UUIDs. Linux should +only use the _DSD Device Properties UUID [5]: + + -- UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301 + + -- http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUI... + +The UEFI Forum provides a mechanism for registering device properties [4] +so that they may be used across all operating systems supporting ACPI. +Device properties that have not been registered with the UEFI Forum should +not be used. + +Before creating new device properties, check to be sure that they have not +been defined before and either registered in the Linux kernel documentation +as DT bindings, or the UEFI Forum as device properties. While we do not want +to simply move all DT bindings into ACPI device properties, we can learn from +what has been previously defined. + +If it is necessary to define a new device property, or if it makes sense to +synthesize the definition of a binding so it can be used in any firmware, +both DT bindings and ACPI device properties for device drivers have review +processes. Use them both. When the driver itself is submitted for review +to the Linux mailing lists, the device property definitions needed must be +submitted at the same time. A driver that supports ACPI and uses device +properties will not be considered complete without their definitions. Once +the device property has been accepted by the Linux community, it must be +registered with the UEFI Forum [4], which will review it again for consistency +within the registry. This may require iteration. The UEFI Forum, though, +will always be the canonical site for device property definitions. + +It may make sense to provide notice to the UEFI Forum that there is the +intent to register a previously unused device property name as a means of +reserving the name for later use. Other operating system vendors will +also be submitting registration requests and this may help smooth the +process. + +Once registration and review have been completed, the kernel provides an +interface for looking up device properties in a manner independent of +whether DT or ACPI is being used. This API should be used [6]; it can +eliminate some duplication of code paths in driver probing functions and +discourage divergence between DT bindings and ACPI device properties. + + +Programmable Power Control Resources +------------------------------------ +Programmable power control resources include such resources as voltage/current +providers (regulators) and clock sources. + +With ACPI, the kernel clock and regulator framework is not expected to be used +at all. + +The kernel assumes that power control of these resources is represented with +Power Resource Objects (ACPI section 7.1). The ACPI core will then handle +correctly enabling and disabling resources as they are needed. In order to +get that to work, ACPI assumes each device has defined D-states and that these +can be controlled through the optional ACPI methods _PS0, _PS1, _PS2, and _PS3; +in ACPI, _PS0 is the method to invoke to turn a device full on, and _PS3 is for +turning a device full off. + +There are two options for using those Power Resources. They can: + + -- be managed in a _PSx method which gets called on entry to power + state Dx. + + -- be declared separately as power resources with their own _ON and _OFF + methods. They are then tied back to D-states for a particular device + via _PRx which specifies which power resources a device needs to be on + while in Dx. Kernel then tracks number of devices using a power resource + and calls _ON/_OFF as needed. + +The kernel ACPI code will also assume that the _PSx methods follow the normal +ACPI rules for such methods: + + -- If either _PS0 or _PS3 is implemented, then the other method must also + be implemented. + + -- If a device requires usage or setup of a power resource when on, the ASL + should organize that it is allocated/enabled using the _PS0 method. + + -- Resources allocated or enabled in the _PS0 method should be disabled + or de-allocated in the _PS3 method. + + -- Firmware will leave the resources in a reasonable state before handing + over control to the kernel. + +Such code in _PSx methods will of course be very platform specific. But, +this allows the driver to abstract out the interface for operating the device +and avoid having to read special non-standard values from ACPI tables. Further, +abstracting the use of these resources allows the hardware to change over time +without requiring updates to the driver. + + +Clocks +------ +ACPI makes the assumption that clocks are initialized by the firmware -- +UEFI, in this case -- to some working value before control is handed over +to the kernel. This has implications for devices such as UARTs, or SoC-driven +LCD displays, for example. + +When the kernel boots, the clocks are assumed to be set to reasonable +working values. If for some reason the frequency needs to change -- e.g., +throttling for power management -- the device driver should expect that +process to be abstracted out into some ACPI method that can be invoked +(please see the ACPI specification for further recommendations on standard +methods to be expected). The only exceptions to this are CPU clocks where +CPPC provides a much richer interface than ACPI methods. If the clocks +are not set, there is no direct way for Linux to control them. + +If an SoC vendor wants to provide fine-grained control of the system clocks, +they could do so by providing ACPI methods that could be invoked by Linux +drivers. However, this is NOT recommended and Linux drivers should NOT use +such methods, even if they are provided. Such methods are not currently +standardized in the ACPI specification, and using them could tie a kernel +to a very specific SoC, or tie an SoC to a very specific version of the +kernel, both of which we are trying to avoid. + + +Driver Recommendations +---------------------- +DO NOT remove any DT handling when adding ACPI support for a driver. The +same device may be used on many different systems. + +DO try to structure the driver so that it is data-driven. That is, set up +a struct containing internal per-device state based on defaults and whatever +else must be discovered by the driver probe function. Then, have the rest +of the driver operate off of the contents of that struct. Doing so should +allow most divergence between ACPI and DT functionality to be kept local to +the probe function instead of being scattered throughout the driver. For +example: + +static int device_probe_dt(struct platform_device *pdev) +{ + /* DT specific functionality */ + ... +} + +static int device_probe_acpi(struct platform_device *pdev) +{ + /* ACPI specific functionality */ + ... +} + +static int device_probe(struct platform_device *pdev) +{ + ... + struct device_node node = pdev->dev.of_node; + ... + + if (node) + ret = device_probe_dt(pdev); + else if (ACPI_HANDLE(&pdev->dev)) + ret = device_probe_acpi(pdev); + else + /* other initialization */ + ... + /* Continue with any generic probe operations */ + ... +} + +DO keep the MODULE_DEVICE_TABLE entries together in the driver to make it +clear the different names the driver is probed for, both from DT and from +ACPI: + +static struct of_device_id virtio_mmio_match[] = { + { .compatible = "virtio,mmio", }, + { } +}; +MODULE_DEVICE_TABLE(of, virtio_mmio_match); + +static const struct acpi_device_id virtio_mmio_acpi_match[] = { + { "LNRO0005", }, + { } +}; +MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match); + + +ASWG +---- +The ACPI specification changes regularly. During the year 2014, for instance, +version 5.1 was released and version 6.0 substantially completed, with most of +the changes being driven by ARM-specific requirements. Proposed changes are +presented and discussed in the ASWG (ACPI Specification Working Group) which +is a part of the UEFI Forum. + +Participation in this group is open to all UEFI members. Please see +http://www.uefi.org/workinggroup for details on group membership. + +It is the intent of the ARMv8 ACPI kernel code to follow the ACPI specification +as closely as possible, and to only implement functionality that complies with +the released standards from UEFI ASWG. As a practical matter, there will be +vendors that provide bad ACPI tables or violate the standards in some way. +If this is because of errors, quirks and fixups may be necessary, but will +be avoided if possible. If there are features missing from ACPI that preclude +it from being used on a platform, ECRs (Engineering Change Requests) should be +submitted to ASWG and go through the normal approval process; for those that +are not UEFI members, many other members of the Linux community are and would +likely be willing to assist in submitting ECRs. + + +Linux Code +---------- +Individual items specific to Linux on ARM, contained in the the Linux +source code, are in the list that follows: + +ACPI_OS_NAME This macro defines the string to be returned when + an ACPI method invokes the _OS method. On ARM64 + systems, this macro will be "Linux" by default. + The command line parameter acpi_os=<string> + can be used to set it to some other value. The + default value for other architectures is "Microsoft + Windows NT", for example. + +ACPI Objects +------------ +Detailed expectations for ACPI tables and object are listed in the file +Documentation/arm64/acpi_object_usage.txt. + + +References +---------- +[0] http://silver.arm.com -- document ARM-DEN-0029, or newer + "Server Base System Architecture", version 2.3, dated 27 Mar 2014 + +[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_R... + Document ARM-DEN-0044A, or newer: "Server Base Boot Requirements, System + Software on ARM Platforms", dated 16 Aug 2014 + +[2] http://www.secretlab.ca/archives/151, 10 Jan 2015, Copyright (c) 2015, + Linaro Ltd., written by Grant Likely. A copy of the verbatim text (apart + from formatting) is also in Documentation/arm64/why_use_acpi.txt. + +[3] AMD ACPI for Seattle platform documentation: + http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Seattle_ACPI_... + +[4] http://www.uefi.org/acpi -- please see the link for the "ACPI _DSD Device + Property Registry Instructions" + +[5] http://www.uefi.org/acpi -- please see the link for the "_DSD (Device + Specific Data) Implementation Guide" + +[6] Kernel code for the unified device property interface can be found in + include/linux/property.h and drivers/base/property.c. + + +Authors +------- +Al Stone al.stone@linaro.org +Graeme Gregory graeme.gregory@linaro.org +Hanjun Guo hanjun.guo@linaro.org + +Grant Likely grant.likely@linaro.org, for the "Why ACPI on ARM?" section

From: Al Stone al.stone@linaro.org

One more documentation file are also being added:

A section by section review of the ACPI spec (acpi_object_usage.txt) to note recommendations and prohibitions on the use of the numerous ACPI tables and objects. This sets out the current expectations of the firmware by Linux very explicitly (or as explicitly as I can, for now).

CC: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com CC: Yi Li phoenix.liyi@huawei.com CC: Mark Langsdorf mlangsdo@redhat.com CC: Ashwin Chaugule ashwinc@codeaurora.org Acked-by: Robert Richter rrichter@cavium.com Signed-off-by: Al Stone al.stone@linaro.org Signed-off-by: Hanjun Guo hanjun.guo@linaro.org --- Documentation/arm64/acpi_object_usage.txt | 593 ++++++++++++++++++++++++++++++ 1 file changed, 593 insertions(+) create mode 100644 Documentation/arm64/acpi_object_usage.txt

diff --git a/Documentation/arm64/acpi_object_usage.txt b/Documentation/arm64/acpi_object_usage.txt new file mode 100644 index 0000000..96e2273 --- /dev/null +++ b/Documentation/arm64/acpi_object_usage.txt @@ -0,0 +1,593 @@ +ACPI Tables +----------- +The expectations of individual ACPI tables are discussed in the list that +follows. + +If a section number is used, it refers to a section number in the ACPI +specification where the object is defined. If "Signature Reserved" is used, +the table signature (the first four bytes of the table) is the only portion +of the table recognized by the specification, and the actual table is defined +outside of the UEFI Forum (see Section 5.2.6 of the specification). + +For ACPI on arm64, tables also fall into the following categories: + + -- Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT + + -- Recommended: BERT, EINJ, ERST, HEST, SSDT + + -- Optional: BGRT, CPEP, CSRT, DRTM, ECDT, FACS, FPDT, MCHI, MPST, + MSCT, RASF, SBST, SLIT, SPMI, SRAT, TCPA, TPM2, UEFI + + -- Not supported: BOOT, DBG2, DBGP, DMAR, ETDT, HPET, IBFT, IVRS, + LPIT, MSDM, RSDT, SLIC, WAET, WDAT, WDRT, WPBT + + +Table Usage for ARMv8 Linux +----- ---------------------------------------------------------------- +BERT Section 18.3 (signature == "BERT") + == Boot Error Record Table == + Must be supplied if RAS support is provided by the platform. It + is recommended this table be supplied. + +BOOT Signature Reserved (signature == "BOOT") + == simple BOOT flag table == + Microsoft only table, will not be supported. + +BGRT Section 5.2.22 (signature == "BGRT") + == Boot Graphics Resource Table == + Optional, not currently supported, with no real use-case for an + ARM server. + +CPEP Section 5.2.18 (signature == "CPEP") + == Corrected Platform Error Polling table == + Optional, not currently supported, and not recommended until such + time as ARM-compatible hardware is available, and the specification + suitably modified. + +CSRT Signature Reserved (signature == "CSRT") + == Core System Resources Table == + Optional, not currently supported. + +DBG2 Signature Reserved (signature == "DBG2") + == DeBuG port table 2 == + Microsoft only table, will not be supported. + +DBGP Signature Reserved (signature == "DBGP") + == DeBuG Port table == + Microsoft only table, will not be supported. + +DSDT Section 5.2.11.1 (signature == "DSDT") + == Differentiated System Description Table == + A DSDT is required; see also SSDT. + + ACPI tables contain only one DSDT but can contain one or more SSDTs, + which are optional. Each SSDT can only add to the ACPI namespace, + but cannot modify or replace anything in the DSDT. + +DMAR Signature Reserved (signature == "DMAR") + == DMA Remapping table == + x86 only table, will not be supported. + +DRTM Signature Reserved (signature == "DRTM") + == Dynamic Root of Trust for Measurement table == + Optional, not currently supported. + +ECDT Section 5.2.16 (signature == "ECDT") + == Embedded Controller Description Table == + Optional, not currently supported, but could be used on ARM if and + only if one uses the GPE_BIT field to represent an IRQ number, since + there are no GPE blocks defined in hardware reduced mode. This would + need to be modified in the ACPI specification. + +EINJ Section 18.6 (signature == "EINJ") + == Error Injection table == + This table is very useful for testing platform response to error + conditions; it allows one to inject an error into the system as + if it had actually occurred. However, this table should not be + shipped with a production system; it should be dynamically loaded + and executed with the ACPICA tools only during testing. + +ERST Section 18.5 (signature == "ERST") + == Error Record Serialization Table == + On a platform supports RAS, this table must be supplied if it is not + UEFI-based; if it is UEFI-based, this table may be supplied. When this + table is not present, UEFI run time service will be utilized to save + and retrieve hardware error information to and from a persistent store. + +ETDT Signature Reserved (signature == "ETDT") + == Event Timer Description Table == + Obsolete table, will not be supported. + +FACS Section 5.2.10 (signature == "FACS") + == Firmware ACPI Control Structure == + It is unlikely that this table will be terribly useful. If it is + provided, the Global Lock will NOT be used since it is not part of + the hardware reduced profile, and only 64-bit address fields will + be considered valid. + +FADT Section 5.2.9 (signature == "FACP") + == Fixed ACPI Description Table == + Required for arm64. + + The HW_REDUCED_ACPI flag must be set. All of the fields that are + to be ignored when HW_REDUCED_ACPI is set are expected to be set to + zero. + + If an FACS table is provided, the X_FIRMWARE_CTRL field is to be + used, not FIRMWARE_CTRL. + + If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is + filled in properly -- that the PSCI_COMPLIANT flag is set and that + PSCI_USE_HVC is set or unset as needed (see table 5-37). + + For the DSDT that is also required, the X_DSDT field is to be used, + not the DSDT field. + +FPDT Section 5.2.23 (signature == "FPDT") + == Firmware Performance Data Table == + Optional, not currently supported. + +GTDT Section 5.2.24 (signature == "GTDT") + == Generic Timer Description Table == + Required for arm64. + +HEST Section 18.3.2 (signature == "HEST") + == Hardware Error Source Table == + Until further error source types are defined, use only types 6 (AER + Root Port), 7 (AER Endpoint), 8 (AER Bridge), or 9 (Generic Hardware + Error Source). Firmware first error handling is possible if and only + if Trusted Firmware is being used on arm64. + + Must be supplied if RAS support is provided by the platform. It + is recommended this table be supplied. + +HPET Signature Reserved (signature == "HPET") + == High Precision Event timer Table == + x86 only table, will not be supported. + +IBFT Signature Reserved (signature == "IBFT") + == iSCSI Boot Firmware Table == + Microsoft defined table, support TBD. + +IVRS Signature Reserved (signature == "IVRS") + == I/O Virtualization Reporting Structure == + x86_64 (AMD) only table, will not be supported. + +LPIT Signature Reserved (signature == "LPIT") + == Low Power Idle Table == + x86 only table as of ACPI 5.1; future versions have been adapted for + use with ARM and will be recommended in order to support ACPI power + management. + +MADT Section 5.2.12 (signature == "APIC") + == Multiple APIC Description Table == + Required for arm64. Only the GIC interrupt controller structures + should be used (types 0xA - 0xE). + +MCFG Signature Reserved (signature == "MCFG") + == Memory-mapped ConFiGuration space == + If the platform supports PCI/PCIe, an MCFG table is required. + +MCHI Signature Reserved (signature == "MCHI") + == Management Controller Host Interface table == + Optional, not currently supported. + +MPST Section 5.2.21 (signature == "MPST") + == Memory Power State Table == + Optional, not currently supported. + +MSDM Signature Reserved (signature == "MSDM") + == Microsoft Data Management table == + Microsoft only table, will not be supported. + +MSCT Section 5.2.19 (signature == "MSCT") + == Maximum System Characteristic Table == + Optional, not currently supported. + +RASF Section 5.2.20 (signature == "RASF") + == RAS Feature table == + Optional, not currently supported. + +RSDP Section 5.2.5 (signature == "RSD PTR") + == Root System Description PoinTeR == + Required for arm64. + +RSDT Section 5.2.7 (signature == "RSDT") + == Root System Description Table == + Since this table can only provide 32-bit addresses, it is deprecated + on arm64, and will not be used. + +SBST Section 5.2.14 (signature == "SBST") + == Smart Battery Subsystem Table == + Optional, not currently supported. + +SLIC Signature Reserved (signature == "SLIC") + == Software LIcensing table == + Microsoft only table, will not be supported. + +SLIT Section 5.2.17 (signature == "SLIT") + == System Locality distance Information Table == + Optional in general, but required for NUMA systems. + +SPCR Signature Reserved (signature == "SPCR") + == Serial Port Console Redirection table == + Required for arm64. + +SPMI Signature Reserved (signature == "SPMI") + == Server Platform Management Interface table == + Optional, not currently supported. + +SRAT Section 5.2.16 (signature == "SRAT") + == System Resource Affinity Table == + Optional, but if used, only the GICC Affinity structures are read. + To support NUMA, this table is required. + +SSDT Section 5.2.11.2 (signature == "SSDT") + == Secondary System Description Table == + These tables are a continuation of the DSDT; these are recommended + for use with devices that can be added to a running system, but can + also serve the purpose of dividing up device descriptions into more + manageable pieces. + + An SSDT can only ADD to the ACPI namespace. It cannot modify or + replace existing device descriptions already in the namespace. + + These tables are optional, however. ACPI tables should contain only + one DSDT but can contain many SSDTs. + +TCPA Signature Reserved (signature == "TCPA") + == Trusted Computing Platform Alliance table == + Optional, not currently supported, and may need changes to fully + interoperate with arm64. + +TPM2 Signature Reserved (signature == "TPM2") + == Trusted Platform Module 2 table == + Optional, not currently supported, and may need changes to fully + interoperate with arm64. + +UEFI Signature Reserved (signature == "UEFI") + == UEFI ACPI data table == + Optional, not currently supported. No known use case for arm64, + at present. + +WAET Signature Reserved (signature == "WAET") + == Windows ACPI Emulated devices Table == + Microsoft only table, will not be supported. + +WDAT Signature Reserved (signature == "WDAT") + == Watch Dog Action Table == + Microsoft only table, will not be supported. + +WDRT Signature Reserved (signature == "WDRT") + == Watch Dog Resource Table == + Microsoft only table, will not be supported. + +WPBT Signature Reserved (signature == "WPBT") + == Windows Platform Binary Table == + Microsoft only table, will not be supported. + +XSDT Section 5.2.8 (signature == "XSDT") + == eXtended System Description Table == + Required for arm64. + + +ACPI Objects +------------ +The expectations on individual ACPI objects are discussed in the list that +follows: + +Name Section Usage for ARMv8 Linux +---- ------------ ------------------------------------------------- +_ADR 6.1.1 Use as needed. + +_BBN 6.5.5 Use as needed; PCI-specific. + +_BDN 6.5.3 Optional; not likely to be used on arm64. + +_CCA 6.2.17 This method should be defined for all bus masters + on arm64. While cache coherency is assumed, making + it explicit ensures the kernel will set up DMA as + it should. + +_CDM 6.2.1 Optional, to be used only for processor devices. + +_CID 6.1.2 Use as needed. + +_CLS 6.1.3 Use as needed. + +_CRS 6.2.2 Required on arm64. + +_DCK 6.5.2 Optional; not likely to be used on arm64. + +_DDN 6.1.4 This field can be used for a device name. However, + it is meant for DOS device names (e.g., COM1), so be + careful of its use across OSes. + +_DEP 6.5.8 Use as needed. + +_DIS 6.2.3 Optional, for power management use. + +_DLM 5.7.5 Optional. + +_DMA 6.2.4 Optional. + +_DSD 6.2.5 To be used with caution. If this object is used, try + to use it within the constraints already defined by the + Device Properties UUID. Only in rare circumstances + should it be necessary to create a new _DSD UUID. + + In either case, submit the _DSD definition along with + any driver patches for discussion, especially when + device properties are used. A driver will not be + considered complete without a corresponding _DSD + description. Once approved by kernel maintainers, + the UUID or device properties must then be registered + with the UEFI Forum; this may cause some iteration as + more than one OS will be registering entries. + +_DSM Do not use this method. It is not standardized, the + return values are not well documented, and it is + currently a frequent source of error. + +_DSW 7.2.1 Use as needed; power management specific. + +_EDL 6.3.1 Optional. + +_EJD 6.3.2 Optional. + +_EJx 6.3.3 Optional. + +_FIX 6.2.7 x86 specific, not used on arm64. + +_GL 5.7.1 This object is not to be used in hardware reduced + mode, and therefore should not be used on arm64. + +_GLK 6.5.7 This object requires a global lock be defined; there + is no global lock on arm64 since it runs in hardware + reduced mode. Hence, do not use this object on arm64. + +_GPE 5.3.1 This namespace is for x86 use only. Do not use it + on arm64. + +_GSB 6.2.7 Optional. + +_HID 6.1.5 Use as needed. This is the primary object to use in + device probing, though _CID and _CLS may also be used. + +_HPP 6.2.8 Optional, PCI specific. + +_HPX 6.2.9 Optional, PCI specific. + +_HRV 6.1.6 Optional, use as needed to clarify device behavior; in + some cases, this may be easier to use than _DSD. + +_INI 6.5.1 Not required, but can be useful in setting up devices + when UEFI leaves them in a state that may not be what + the driver expects before it starts probing. + +_IRC 7.2.15 Use as needed; power management specific. + +_LCK 6.3.4 Optional. + +_MAT 6.2.10 Optional; see also the MADT. + +_MLS 6.1.7 Optional, but highly recommended for use in + internationalization. + +_OFF 7.1.2 It is recommended to define this method for any device + that can be turned on or off. + +_ON 7.1.3 It is recommended to define this method for any device + that can be turned on or off. + +_OS 5.7.3 This method will return "Linux" by default (this is + the value of the macro ACPI_OS_NAME on Linux). The + command line parameter acpi_os=<string> can be used + to set it to some other value. + +_OSC 6.2.11 This method can be a global method in ACPI (i.e., + _SB._OSC), or it may be associated with a specific + device (e.g., _SB.DEV0._OSC), or both. When used + as a global method, only capabilities published in + the ACPI specification are allowed. When used as + a device-specific method, the process described for + using _DSD MUST be used to create an _OSC definition; + out-of-process use of _OSC is not allowed. That is, + submit the device-specific _OSC usage description as + part of the kernel driver submission, get it approved + by the kernel community, then register it with the + UEFI Forum. + +_OSI 5.7.2 Deprecated on ARM64. Any invocation of this method + will print a warning on the console and return false. + That is, as far as ACPI firmware is concerned, _OSI + cannot be used to determine what sort of system is + being used or what functionality is provided. The + _OSC method is to be used instead. + +_OST 6.3.5 Optional. + +_PDC 8.4.1 Deprecated, do not use on arm64. + +_PIC 5.8.1 The method should not be used. On arm64, the only + interrupt model available is GIC. + +_PLD 6.1.8 Optional. + +_PR 5.3.1 This namespace is for x86 use only on legacy systems. + Do not use it on arm64. + +_PRS 6.2.12 Optional. + +_PRT 6.2.13 Required as part of the definition of all PCI root + devices. + +_PRW 7.2.13 Use as needed; power management specific. + +_PRx 7.2.8-11 Use as needed; power management specific. If _PR0 is + defined, _PR3 must also be defined. + +_PSC 7.2.6 Use as needed; power management specific. + +_PSE 7.2.7 Use as needed; power management specific. + +_PSW 7.2.14 Use as needed; power management specific. + +_PSx 7.2.2-5 Use as needed; power management specific. If _PS0 is + defined, _PS3 must also be defined. If clocks or + regulators need adjusting to be consistent with power + usage, change them in these methods. + +_PTS 7.3.1 Use as needed; power management specific. + +_PXM 6.2.14 Optional. + +_REG 6.5.4 Use as needed. + +_REV 5.7.4 Always returns the latest version of ACPI supported. + +_RMV 6.3.6 Optional. + +_SB 5.3.1 Required on arm64; all devices must be defined in this + namespace. + +_SEG 6.5.6 Use as needed; PCI-specific. + +_SI 5.3.1, Optional. + 9.1 + +_SLI 6.2.15 Optional; recommended when SLIT table is in use. + +_STA 6.3.7, It is recommended to define this method for any device + 7.1.4 that can be turned on or off. + +_SRS 6.2.16 Optional; see also _PRS. + +_STR 6.1.10 Recommended for conveying device names to end users; + this is preferred over using _DDN. + +_SUB 6.1.9 Use as needed; _HID or _CID are preferred. + +_SUN 6.1.11 Optional. + +_Sx 7.3.2 Use as needed; power management specific. + +_SxD 7.2.16-19 Use as needed; power management specific. + +_SxW 7.2.20-24 Use as needed; power management specific. + +_SWS 7.3.3 Use as needed; power management specific; this may + require specification changes for use on arm64. + +_TTS 7.3.4 Use as needed; power management specific. + +_TZ 5.3.1 Optional. + +_UID 6.1.12 Recommended for distinguishing devices of the same + class; define it if at all possible. + +_WAK 7.3.5 Use as needed; power management specific. + + +ACPI Event Model +---------------- +Do not use GPE block devices; these are not supported in the hardware reduced +profile used by arm64. Since there are no GPE blocks defined for use on ARM +platforms, GPIO-signaled interrupts should be used for creating system events. + + +ACPI Processor Control +---------------------- +Section 8 of the ACPI specification is currently undergoing change that +should be completed in the 6.0 version of the specification. Processor +performance control will be handled differently for arm64 at that point +in time. Processor aggregator devices (section 8.5) will not be used, +for example, but another similar mechanism instead. + +While UEFI constrains what we can say until the release of 6.0, it is +recommended that CPPC (8.4.5) be used as the primary model. This will +still be useful into the future. C-states and P-states will still be +provided, but most of the current design work appears to favor CPPC. + +Further, it is essential that the ARMv8 SoC provide a fully functional +implementation of PSCI; this will be the only mechanism supported by ACPI +to control CPU power state (including secondary CPU booting). + +More details will be provided on the release of the ACPI 6.0 specification. + + +ACPI System Address Map Interfaces +---------------------------------- +In Section 15 of the ACPI specification, several methods are mentioned as +possible mechanisms for conveying memory resource information to the kernel. +For arm64, we will only support UEFI for booting with ACPI, hence the UEFI +GetMemoryMap() boot service is the only mechanism that will be used. + + +ACPI Platform Error Interfaces (APEI) +------------------------------------- +The APEI tables supported are described above. + +APEI requires the equivalent of an SCI and an NMI on ARMv8. The SCI is used +to notify the OSPM of errors that have occurred but can be corrected and the +system can continue correct operation, even if possibly degraded. The NMI is +used to indicate fatal errors that cannot be corrected, and require immediate +attention. + +Since there is no direct equivalent of the x86 SCI or NMI, arm64 handles +these slightly differently. The SCI is handled as a normal GPIO-signaled +interrupt; given that these are corrected (or correctable) errors being +reported, this is sufficient. The NMI is emulated as the highest priority +GPIO-signaled interrupt possible. This implies some caution must be used +since there could be interrupts at higher privilege levels or even interrupts +at the same priority as the emulated NMI. In Linux, this should not be the +case but one should be aware it could happen. + + +ACPI Objects Not Supported on ARM64 +----------------------------------- +While this may change in the future, there are several classes of objects +that can be defined, but are not currently of general interest to ARM servers. + +These are not supported: + + -- Section 9.2: ambient light sensor devices + + -- Section 9.3: battery devices + + -- Section 9.4: lids (e.g., laptop lids) + + -- Section 9.8.2: IDE controllers + + -- Section 9.9: floppy controllers + + -- Section 9.10: GPE block devices + + -- Section 9.15: PC/AT RTC/CMOS devices + + -- Section 9.16: user presence detection devices + + -- Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT + + -- Section 9.18: time and alarm devices (see 9.15) + + +ACPI Objects Not Yet Implemented +-------------------------------- +While these objects have x86 equivalents, and they do make some sense in ARM +servers, there is either no hardware available at present, or in some cases +there may not yet be a non-ARM implementation. Hence, they are currently not +implemented though that may change in the future. + +Not yet implemented are: + + -- Section 10: power source and power meter devices + + -- Section 11: thermal management + + -- Section 12: embedded controllers interface + + -- Section 13: SMBus interfaces + + -- Section 17: NUMA support (prototypes have been submitted for + review)