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https://github.com/edk2-porting/linux-next.git
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935c760ec8
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: Tomasz Nowicki <tn@semihalf.com> Signed-off-by: Jayachandran C <jchandra@broadcom.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
93 lines
2.4 KiB
C
93 lines
2.4 KiB
C
/*
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* Copyright (C) 2016 Broadcom
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* Author: Jayachandran C <jchandra@broadcom.com>
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* Copyright (C) 2016 Semihalf
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* Author: Tomasz Nowicki <tn@semihalf.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation (the "GPL").
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License version 2 (GPLv2) for more details.
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*
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* You should have received a copy of the GNU General Public License
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* version 2 (GPLv2) along with this source code.
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*/
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#define pr_fmt(fmt) "ACPI: " fmt
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#include <linux/kernel.h>
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#include <linux/pci.h>
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#include <linux/pci-acpi.h>
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/* Structure to hold entries from the MCFG table */
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struct mcfg_entry {
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struct list_head list;
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phys_addr_t addr;
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u16 segment;
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u8 bus_start;
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u8 bus_end;
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};
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/* List to save MCFG entries */
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static LIST_HEAD(pci_mcfg_list);
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phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
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{
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struct mcfg_entry *e;
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/*
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* We expect exact match, unless MCFG entry end bus covers more than
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* specified by caller.
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*/
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list_for_each_entry(e, &pci_mcfg_list, list) {
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if (e->segment == seg && e->bus_start == bus_res->start &&
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e->bus_end >= bus_res->end)
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return e->addr;
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}
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return 0;
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}
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static __init int pci_mcfg_parse(struct acpi_table_header *header)
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{
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struct acpi_table_mcfg *mcfg;
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struct acpi_mcfg_allocation *mptr;
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struct mcfg_entry *e, *arr;
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int i, n;
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if (header->length < sizeof(struct acpi_table_mcfg))
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return -EINVAL;
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n = (header->length - sizeof(struct acpi_table_mcfg)) /
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sizeof(struct acpi_mcfg_allocation);
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mcfg = (struct acpi_table_mcfg *)header;
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mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
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arr = kcalloc(n, sizeof(*arr), GFP_KERNEL);
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if (!arr)
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return -ENOMEM;
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for (i = 0, e = arr; i < n; i++, mptr++, e++) {
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e->segment = mptr->pci_segment;
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e->addr = mptr->address;
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e->bus_start = mptr->start_bus_number;
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e->bus_end = mptr->end_bus_number;
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list_add(&e->list, &pci_mcfg_list);
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}
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pr_info("MCFG table detected, %d entries\n", n);
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return 0;
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}
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/* Interface called by ACPI - parse and save MCFG table */
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void __init pci_mmcfg_late_init(void)
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{
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int err = acpi_table_parse(ACPI_SIG_MCFG, pci_mcfg_parse);
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if (err)
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pr_err("Failed to parse MCFG (%d)\n", err);
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}
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