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: 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>
diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
new file mode 100644
index 0000000..b5b376e
--- /dev/null
+++ b/drivers/acpi/pci_mcfg.c
@@ -0,0 +1,92 @@
+/*
+ * 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.
+ */
+
+#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);
+}