ACPI 5.0a+ spec defines a generic mode of communication between the OS and a platform such as the BMC. This medium (PCC) is typically used by CPPC (ACPI CPU Performance management), RAS (ACPI reliability protocol) and MPST (ACPI Memory power states).

This patch adds initial support for PCC to be usable by the aforementioned PCC clients.

Signed-off-by: Ashwin Chaugule ashwin.chaugule@linaro.org --- drivers/acpi/Kconfig | 10 +++ drivers/acpi/Makefile | 2 +- drivers/acpi/pcc.c | 192 ++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 203 insertions(+), 1 deletion(-) create mode 100644 drivers/acpi/pcc.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index ff5c83c..8f40e52 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -352,6 +352,16 @@ config ACPI_REDUCED_HARDWARE_ONLY

If you are unsure what to do, do not enable this option.

+config ACPI_PCC + bool "ACPI Platform Communication Channel" + def_bool n + depends on ACPI + help + Enable this option if your platform supports PCC as defined in the + ACPI spec 5.0a+. PCC is a generic mechanism for the OS to communicate + with a platform such as a BMC. PCC is typically used by CPPC, RAS + and MPST. + source "drivers/acpi/apei/Kconfig"

config ACPI_EXTLOG diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index fc133d4..d8aa613 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -74,7 +74,7 @@ obj-$(CONFIG_ACPI_HED) += hed.o obj-$(CONFIG_ACPI_EC_DEBUGFS) += ec_sys.o obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o obj-$(CONFIG_ACPI_BGRT) += bgrt.o - +obj-$(CONFIG_ACPI_PCC) += pcc.o # processor has its own "processor." module_param namespace processor-y := processor_driver.o processor_throttling.o processor-y += processor_idle.o processor_thermal.o diff --git a/drivers/acpi/pcc.c b/drivers/acpi/pcc.c new file mode 100644 index 0000000..328ca93 --- /dev/null +++ b/drivers/acpi/pcc.c @@ -0,0 +1,192 @@ +/* + * Copyright (C) 2014 Linaro Ltd. + * Author: Ashwin Chaugule ashwin.chaugule@linaro.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include <linux/acpi.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/ioctl.h> +#include <linux/vmalloc.h> + +#include <acpi/actbl.h> + +#define MAX_PCC_SUBSPACES 256 +#define PCCS_SS_SIG_MAGIC 0x50434300 +#define PCC_CMD_COMPLETE 0x1 +#define PCC_VERSION "0.1" + +struct pcc_ss_desc { + struct acpi_pcct_subspace *pcc_ss_ptr; + raw_spinlock_t lock; +}; + +/* Array of Type 0 PCC Subspace descriptors */ +struct pcc_ss_desc pcc_ss_arr[MAX_PCC_SUBSPACES]; + +/* Total number of subspaces detected in PCCT. */ +static int total_ss; + +/* + * PCC clients call this function to get a base address of their + * Communication channel + */ +int get_pcc_comm_channel(u32 ss_idx, u64 __iomem *addr, int *len) +{ + struct acpi_pcct_subspace *pcct_subspace = + pcc_ss_arr[ss_idx].pcc_ss_ptr; + + if (pcct_subspace) { + *addr = pcct_subspace->base_address; + *len = pcct_subspace->length; + } else + return -EINVAL; + + return 0; +} + +/* Send PCC cmd on behalf of this (subspace id) PCC client */ +u16 send_pcc_cmd(u8 cmd, u8 sci, u32 ss_idx, u64 __iomem *base_addr) +{ + struct acpi_pcct_subspace *pcct_subspace = + pcc_ss_arr[ss_idx].pcc_ss_ptr; + struct acpi_pcct_shared_memory *generic_comm_base = + (struct acpi_pcct_shared_memory *)base_addr; + struct acpi_generic_address doorbell; + u64 doorbell_preserve; + u64 doorbell_val; + u64 doorbell_write; + /* + * Min time in usec that OSPM is expected to wait + * before sending the next PCC cmd. + */ + u16 cmd_delay = pcct_subspace->min_turnaround_time; + + if (!generic_comm_base) { + pr_err("No Generic Communication Channel provided.\n"); + return -EINVAL; + } + + raw_spin_lock(&pcc_ss_arr[ss_idx].lock); + + /* Get doorbell details for this subspace. */ + doorbell = pcct_subspace->doorbell_register; + doorbell_preserve = pcct_subspace->preserve_mask; + doorbell_write = pcct_subspace->write_mask; + + /* Loop until CMD complete bit is set. For prev cmds. */ + while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE)) + udelay(cmd_delay); + + /* Write to the shared comm region. */ + iowrite16(cmd, &generic_comm_base->command); + + /* Write Subspace MAGIC value so platform can identify destination. */ + iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature); + + /* Flip CMD COMPLETE bit */ + iowrite16(0, &generic_comm_base->status); + + /* Sync notification from OSPM to Platform. */ + acpi_read(&doorbell_val, &doorbell); + acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, + &doorbell); + + /* Wait for Platform to consume. */ + while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE)) + udelay(cmd_delay); + + raw_spin_unlock(&pcc_ss_arr[ss_idx].lock); + + return generic_comm_base->status; +} + +static int parse_pcc_subspace(struct acpi_subtable_header *header, + const unsigned long end) +{ + struct acpi_pcct_subspace *pcct_ss; + + if (total_ss <= MAX_PCC_SUBSPACES) { + pcct_ss = (struct acpi_pcct_subspace *) header; + + if (pcct_ss->header.type != ACPI_PCCT_TYPE_GENERIC_SUBSPACE) { + pr_err("Incorrect PCC Subspace type detected\n"); + return -EINVAL; + } + + pcc_ss_arr[total_ss].pcc_ss_ptr = pcct_ss; + raw_spin_lock_init(&pcc_ss_arr[total_ss].lock); + + total_ss++; + } else { + pr_err("No more space for PCC subspaces.\n"); + return -ENOSPC; + } + + return 0; +} + +static int __init pcc_probe(void) +{ + acpi_status status = AE_OK; + acpi_size pcct_tbl_header_size; + struct acpi_table_pcct *pcct_tbl; + + /* Search for PCCT */ + status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0, + (struct acpi_table_header **)&pcct_tbl, + &pcct_tbl_header_size); + + if (ACPI_SUCCESS(status) && !pcct_tbl) { + pr_warn("PCCT header not found.\n"); + status = AE_NOT_FOUND; + goto out_err; + } + + status = acpi_table_parse_entries(ACPI_SIG_PCCT, + sizeof(struct acpi_table_pcct), + ACPI_PCCT_TYPE_GENERIC_SUBSPACE, + parse_pcc_subspace, MAX_PCC_SUBSPACES); + + if (ACPI_SUCCESS(status)) + pr_err("Error parsing PCC subspaces from PCCT\n"); + + pr_info("Detected %d PCC Subspaces\n", total_ss); + +out_err: + return ACPI_SUCCESS(status) ? 1 : 0; +} + +static int __init pcc_init(void) +{ + int ret; + + if (acpi_disabled) + return -ENODEV; + + /* Check if PCC support is available. */ + ret = pcc_probe(); + + if (ret) { + pr_debug("PCC probe failed.\n"); + return -EINVAL; + } + + return ret; +} + +device_initcall(pcc_init);

Opens a node in /proc/pcc_test.

Echo 0 for PCC read Echo 1 for PCC write Echo 2 for read base addr of PCC channel

Signed-off-by: Ashwin Chaugule ashwin.chaugule@linaro.org --- drivers/acpi/Makefile | 2 +- drivers/acpi/pcc-test.c | 172 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 173 insertions(+), 1 deletion(-) create mode 100644 drivers/acpi/pcc-test.c

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index d8aa613..f7bbbe9 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -74,7 +74,7 @@ obj-$(CONFIG_ACPI_HED) += hed.o obj-$(CONFIG_ACPI_EC_DEBUGFS) += ec_sys.o obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o obj-$(CONFIG_ACPI_BGRT) += bgrt.o -obj-$(CONFIG_ACPI_PCC) += pcc.o +obj-$(CONFIG_ACPI_PCC) += pcc.o pcc-test.o # processor has its own "processor." module_param namespace processor-y := processor_driver.o processor_throttling.o processor-y += processor_idle.o processor_thermal.o diff --git a/drivers/acpi/pcc-test.c b/drivers/acpi/pcc-test.c new file mode 100644 index 0000000..cb6ee10 --- /dev/null +++ b/drivers/acpi/pcc-test.c @@ -0,0 +1,172 @@ +/* + * Copyright (C) 2014 Linaro Ltd. + * Author: Ashwin Chaugule ashwin.chaugule@linaro.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include <linux/acpi.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <asm/uaccess.h> + +#include <acpi/actbl.h> + +static u64 pcc_comm_base_addr; /* Returned by the Subspace structure */ +static u64 *comm_base_addr; /* For use after ioremap */ + +extern int get_pcc_comm_channel(u32 ss_idx, u64* addr, int *len); +extern u16 send_pcc_cmd(u8 cmd, u8 sci, u32 ss_idx, u64 * __iomem base_addr); + +/* XXX: The PCC Subspace id is hard coded here only for test purposes. + * In reality it should be parsed from the PCC package as described + * in the PCC client table. e.g. CPC for CPPC + */ +#define PCC_SUBSPACE_IDX 0 +#define CMD_COMPLETE 1 + +enum ppc_cmds { + CMD_READ, + CMD_WRITE, + RESERVED, +}; + +static u64 reg1, reg2; + +static void run_pcc_test_read(void) +{ + u16 pcc_status; + u64 reg1_addr = comm_base_addr + 8; + u64 reg2_addr = comm_base_addr + 16; + + /* READ part of the test */ + pr_info("Sending PCC read req from Channel base addr: %llx\n", pcc_comm_base_addr); + pcc_status = send_pcc_cmd(CMD_READ, 0, PCC_SUBSPACE_IDX, &pcc_comm_base_addr); + if (pcc_status & CMD_COMPLETE) { + pr_info("Read updated values from Platform.\n"); + reg1 = iorea32(&reg1_addr); + reg2 = ioread32(&reg2_addr); + pr_info("updated value of reg1:%llx\n", reg1); + pr_info("updated value of reg2:%llx\n", reg2); + } else + pr_err("Failed to read PCC parameters\n"); +} + +static void run_pcc_test_write(void) +{ + u16 pcc_status; + u64 reg1_addr = comm_base_addr + 8; + u64 reg2_addr = comm_base_addr + 16; + + /* WRITE part of the test */ + reg1++; + reg2++; + + iowrite32(reg1, &reg1_addr); + iowrite32(reg2, &reg2_addr); + + pr_info("Sending PCC write req from Channel base addr: %p\n", comm_base_addr); + pcc_status = send_pcc_cmd(CMD_WRITE, 0, PCC_SUBSPACE_IDX, comm_base_addr); + if (pcc_status & CMD_COMPLETE) + pr_info("OSPM successfully sent PCC read cmd to platform\n"); + else + pr_err("Failed to write PCC parameters. \n"); +} + +void get_pcc_comm(void) +{ + int ret, len; + + ret = get_pcc_comm_channel(PCC_SUBSPACE_IDX, &pcc_comm_base_addr, &len); + + if (ret) { + pr_err("No PCC Communication channel found\n"); + goto out_err; + } + + comm_base_addr = ioremap_nocache(pcc_comm_base_addr, len); + + if (!comm_base_addr) + pr_err("Could not map PCC communicate channel\n"); + + pr_info("Acquired PCC comm channel base addr: %llx\n", pcc_comm_base_addr); + +out_err: + return; +} + +static ssize_t pcc_test_write(struct file *file, const char __user *buf, + size_t count, loff_t *offs) +{ + char ctl[2]; + + if (count != 2 || *offs) + return -EINVAL; + + if (copy_from_user(ctl, buf, count)) + return -EFAULT; + + switch (ctl[0]) { + case '0': + /* PCC read */ + run_pcc_test_read(); + break; + case '1': + /* PCC write */ + run_pcc_test_write(); + break; + case '2': + /* Get PCC channel */ + get_pcc_comm(); + break; + default: + pr_err("Unknown val\n"); + break; + } + + return count; +} + +static int pcc_test_open(struct inode *inode, struct file *filp) +{ + return 0; +} + +static int pcc_test_release(struct inode *inode, struct file *filp) +{ + return 0; +} + +static const struct file_operations pcc_test_fops = { + .open = pcc_test_open, +// .read = seq_read, + .write = pcc_test_write, + .release = pcc_test_release, +}; + +static int __init pcc_test(void) +{ + struct proc_dir_entry *pe; + + pe = proc_create("pcc_test", 0644, NULL, &pcc_test_fops); + + if (!pe) + return -ENOMEM; + + return 0; +} + +late_initcall(pcc_test);