Re: [Linaro-acpi] [PATCH V7 08/11] pci, acpi: Support for ACPI based generic PCI host controller

On 10/05/16 17:19, Tomasz Nowicki wrote:

This patch is going to implement generic PCI host controller for ACPI world, similar to what pci-host-generic.c driver does for DT world.

All such drivers, which we have seen so far, were implemented within arch/ directory since they had some arch assumptions (x86 and ia64). However, they all are doing similar thing, so it makes sense to find some common code and abstract it into the generic driver.

In order to handle PCI config space regions properly, we define new MCFG interface which does sanity checks on MCFG table and keeps its root pointer. User is able to lookup MCFG regions based on that root pointer and specified domain:bus_start:bus_end touple. We are using pci_mmcfg_late_init old prototype to avoid another function name.

The implementation of pci_acpi_scan_root() looks up the MCFG entries and sets up a new mapping (regions are not mapped until host controller ask for it). Generic PCI functions are used for accessing config space. Driver selects PCI_ECAM and uses functions from drivers/pci/ecam.h to create and access ECAM mappings.

As mentioned in Kconfig help section, ACPI_PCI_HOST_GENERIC choice should be made on a per-architecture basis.

Signed-off-by: Tomasz Nowicki tn@semihalf.com Signed-off-by: Jayachandran C jchandra@broadcom.com

---

drivers/acpi/Kconfig | 8 +++ drivers/acpi/Makefile | 1 + drivers/acpi/pci_mcfg.c | 97 ++++++++++++++++++++++++++ drivers/acpi/pci_root_generic.c | 149 ++++++++++++++++++++++++++++++++++++++++ drivers/pci/ecam.h | 5 ++ include/linux/pci-acpi.h | 5 ++ include/linux/pci.h | 5 +- 7 files changed, 269 insertions(+), 1 deletion(-) create mode 100644 drivers/acpi/pci_mcfg.c create mode 100644 drivers/acpi/pci_root_generic.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 183ffa3..44afc76 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -346,6 +346,14 @@ config ACPI_PCI_SLOT i.e., segment/bus/device/function tuples, with physical slots in the system. If you are unsure, say N.

+config ACPI_PCI_HOST_GENERIC

• bool
• select PCI_ECAM
• help

•  Select this config option from the architecture Kconfig,
  

•  if it is preferred to enable ACPI PCI host controller driver which
  

•  has no arch-specific assumptions.
  

• config X86_PM_TIMER bool "Power Management Timer Support" if EXPERT depends on X86

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 81e5cbc..627a2b7 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -40,6 +40,7 @@ acpi-$(CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC) += processor_pdc.o acpi-y += ec.o acpi-$(CONFIG_ACPI_DOCK) += dock.o acpi-y += pci_root.o pci_link.o pci_irq.o +obj-$(CONFIG_ACPI_PCI_HOST_GENERIC) += pci_root_generic.o pci_mcfg.o acpi-y += acpi_lpss.o acpi_apd.o acpi-y += acpi_platform.o acpi-y += acpi_pnp.o diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c new file mode 100644 index 0000000..373d079 --- /dev/null +++ b/drivers/acpi/pci_mcfg.c @@ -0,0 +1,97 @@ +/*

• • Copyright (C) 2016 Broadcom
• • Author: Jayachandran C jchandra@broadcom.com
• • Copyright (C) 2016 Semihalf
• • Author: Tomasz Nowicki tn@semihalf.com
• • 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 (the "GPL").
• • 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 version 2 (GPLv2) for more details.
• • You should have received a copy of the GNU General Public License
• • version 2 (GPLv2) along with this source code.
• */

+#include <linux/kernel.h> +#include <linux/pci.h> +#include <linux/pci-acpi.h>

+#define PREFIX "ACPI: "

+/* Root pointer to the mapped MCFG table */ +static struct acpi_table_mcfg *mcfg_table;

+#define MCFG_ENTRIES(mcfg_ptr) (((mcfg_ptr)->header.length - \

• 		sizeof(struct acpi_table_mcfg)) /	\
  

• 		sizeof(struct acpi_mcfg_allocation))
  

+static phys_addr_t pci_mcfg_lookup_static(u16 seg, u8 bus_start, u8 bus_end) +{

• struct acpi_mcfg_allocation *mptr;
• int i;
• if (!mcfg_table) {

• pr_err(PREFIX "MCFG table not available, lookup failed\n");
  

• return -ENXIO;
  

• }
• mptr = (struct acpi_mcfg_allocation *) &mcfg_table[1];
• /*

• * We expect exact match, unless MCFG entry end bus covers more than
  

• * specified by caller.
  

• */
  

• for (i = 0; i < MCFG_ENTRIES(mcfg_table); i++, mptr++) {

• if (mptr->pci_segment == seg &&
  

•     mptr->start_bus_number == bus_start &&
  

•     mptr->end_bus_number >= bus_end) {
  

• 	return mptr->address;
  

• }
  

• }
• return -ENXIO;

+}

+phys_addr_t pci_mcfg_lookup(struct acpi_device *device, u16 seg,

• 	    struct resource *bus_res)
  

+{

• phys_addr_t addr;
• addr = acpi_pci_root_get_mcfg_addr(device->handle);
• if (addr)

• return addr;
  

• return pci_mcfg_lookup_static(seg, bus_res->start, bus_res->end);

+}

+static __init int pci_mcfg_parse(struct acpi_table_header *header) +{

• struct acpi_table_mcfg *mcfg;
• int n;
• if (!header)

• return -EINVAL;
  

Maybe that's bike shedding, but acpi_table_parse already checks that the table passed to the handler exists, so this is redundant.

Regards, Matthias