Commit 935c760e authored by Tomasz Nowicki's avatar Tomasz Nowicki Committed by Bjorn Helgaas

PCI/ACPI: Add generic MCFG table handling

On ACPI systems that support memory-mapped config space access, i.e., ECAM,
the PCI Firmware Specification says the OS can learn where the ECAM space
is from either:

  - the static MCFG table (for non-hotpluggable bridges), or
  - the _CBA method (for hotpluggable bridges)

The current MCFG table handling code cannot be easily generalized owing to
x86-specific quirks, which makes it hard to reuse on other architectures.

Implement generic MCFG handling from scratch, including:

  - Simple MCFG table parsing (via pci_mmcfg_late_init() as in current x86)
  - MCFG region lookup for a (domain, bus_start, bus_end) tuple

[bhelgaas: changelog]
Signed-off-by: default avatarTomasz Nowicki <>
Signed-off-by: default avatarJayachandran C <>
Signed-off-by: default avatarBjorn Helgaas <>
Reviewed-by: default avatarLorenzo Pieralisi <>
parent 0a70abb3
......@@ -217,6 +217,9 @@ config ACPI_PROCESSOR_IDLE
select CPU_IDLE
config ACPI_MCFG
......@@ -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_MCFG) += pci_mcfg.o
acpi-y += acpi_lpss.o acpi_apd.o
acpi-y += acpi_platform.o
acpi-y += acpi_pnp.o
* Copyright (C) 2016 Broadcom
* Author: Jayachandran C <>
* Copyright (C) 2016 Semihalf
* Author: Tomasz Nowicki <>
* 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
* 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.
#define pr_fmt(fmt) "ACPI: " fmt
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/pci-acpi.h>
/* Structure to hold entries from the MCFG table */
struct mcfg_entry {
struct list_head list;
phys_addr_t addr;
u16 segment;
u8 bus_start;
u8 bus_end;
/* List to save MCFG entries */
static LIST_HEAD(pci_mcfg_list);
phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
struct mcfg_entry *e;
* We expect exact match, unless MCFG entry end bus covers more than
* specified by caller.
list_for_each_entry(e, &pci_mcfg_list, list) {
if (e->segment == seg && e->bus_start == bus_res->start &&
e->bus_end >= bus_res->end)
return e->addr;
return 0;
static __init int pci_mcfg_parse(struct acpi_table_header *header)
struct acpi_table_mcfg *mcfg;
struct acpi_mcfg_allocation *mptr;
struct mcfg_entry *e, *arr;
int i, n;
if (header->length < sizeof(struct acpi_table_mcfg))
return -EINVAL;
n = (header->length - sizeof(struct acpi_table_mcfg)) /
sizeof(struct acpi_mcfg_allocation);
mcfg = (struct acpi_table_mcfg *)header;
mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
arr = kcalloc(n, sizeof(*arr), GFP_KERNEL);
if (!arr)
return -ENOMEM;
for (i = 0, e = arr; i < n; i++, mptr++, e++) {
e->segment = mptr->pci_segment;
e->addr = mptr->address;
e->bus_start = mptr->start_bus_number;
e->bus_end = mptr->end_bus_number;
list_add(&e->list, &pci_mcfg_list);
pr_info("MCFG table detected, %d entries\n", n);
return 0;
/* Interface called by ACPI - parse and save MCFG table */
void __init pci_mmcfg_late_init(void)
int err = acpi_table_parse(ACPI_SIG_MCFG, pci_mcfg_parse);
if (err)
pr_err("Failed to parse MCFG (%d)\n", err);
......@@ -24,6 +24,8 @@ static inline acpi_status pci_acpi_remove_pm_notifier(struct acpi_device *dev)
extern phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle);
extern phys_addr_t pci_mcfg_lookup(u16 domain, struct resource *bus_res);
static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
struct pci_bus *pbus = pdev->bus;
......@@ -1723,7 +1723,7 @@ void pcibios_free_irq(struct pci_dev *dev);
extern struct dev_pm_ops pcibios_pm_ops;
void __init pci_mmcfg_early_init(void);
void __init pci_mmcfg_late_init(void);
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment