drivers/acpi/pci_mcfg.c

   1 /*
   2  * Copyright (C) 2016 Broadcom
   3  *      Author: Jayachandran C <jchandra@broadcom.com>
   4  * Copyright (C) 2016 Semihalf
   5  *      Author: Tomasz Nowicki <tn@semihalf.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License, version 2, as
   9  * published by the Free Software Foundation (the "GPL").
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License version 2 (GPLv2) for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 (GPLv2) along with this source code.
  18  */
  19
  20 #define pr_fmt(fmt) "ACPI: " fmt
  21
  22 #include <linux/kernel.h>
  23 #include <linux/pci.h>
  24 #include <linux/pci-acpi.h>
  25
  26 /* Structure to hold entries from the MCFG table */
  27 struct mcfg_entry {
  28         struct list_head        list;
  29         phys_addr_t             addr;
  30         u16                     segment;
  31         u8                      bus_start;
  32         u8                      bus_end;
  33 };
  34
  35 /* List to save MCFG entries */
  36 static LIST_HEAD(pci_mcfg_list);
  37
  38 phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
  39 {
  40         struct mcfg_entry *e;
  41
  42         /*
  43          * We expect exact match, unless MCFG entry end bus covers more than
  44          * specified by caller.
  45          */
  46         list_for_each_entry(e, &pci_mcfg_list, list) {
  47                 if (e->segment == seg && e->bus_start == bus_res->start &&
  48                     e->bus_end >= bus_res->end)
  49                         return e->addr;
  50         }
  51
  52         return 0;
  53 }
  54
  55 static __init int pci_mcfg_parse(struct acpi_table_header *header)
  56 {
  57         struct acpi_table_mcfg *mcfg;
  58         struct acpi_mcfg_allocation *mptr;
  59         struct mcfg_entry *e, *arr;
  60         int i, n;
  61
  62         if (header->length < sizeof(struct acpi_table_mcfg))
  63                 return -EINVAL;
  64
  65         n = (header->length - sizeof(struct acpi_table_mcfg)) /
  66                                         sizeof(struct acpi_mcfg_allocation);
  67         mcfg = (struct acpi_table_mcfg *)header;
  68         mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
  69
  70         arr = kcalloc(n, sizeof(*arr), GFP_KERNEL);
  71         if (!arr)
  72                 return -ENOMEM;
  73
  74         for (i = 0, e = arr; i < n; i++, mptr++, e++) {
  75                 e->segment = mptr->pci_segment;
  76                 e->addr =  mptr->address;
  77                 e->bus_start = mptr->start_bus_number;
  78                 e->bus_end = mptr->end_bus_number;
  79                 list_add(&e->list, &pci_mcfg_list);
  80         }
  81
  82         pr_info("MCFG table detected, %d entries\n", n);
  83         return 0;
  84 }
  85
  86 /* Interface called by ACPI - parse and save MCFG table */
  87 void __init pci_mmcfg_late_init(void)
  88 {
  89         int err = acpi_table_parse(ACPI_SIG_MCFG, pci_mcfg_parse);
  90         if (err)
  91                 pr_err("Failed to parse MCFG (%d)\n", err);
  92 }