These calls allow to map/unmap PCI config space ranges (which are specified in
MMCFG ACPI table).

Signed-off-by: Tomasz Nowicki <[email protected]>
---
 arch/arm64/Kconfig           |  3 ++
 arch/arm64/kernel/Makefile   |  1 +
 arch/arm64/kernel/mmconfig.c | 69 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+)
 create mode 100644 arch/arm64/kernel/mmconfig.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index aee6a60..f2bcb58 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -186,6 +186,9 @@ config PCI_DOMAINS_GENERIC
 config PCI_SYSCALL
        def_bool PCI
 
+config PCI_MMCONFIG
+       def_bool PCI && ACPI
+
 source "drivers/pci/Kconfig"
 source "drivers/pci/pcie/Kconfig"
 source "drivers/pci/hotplug/Kconfig"
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index f48e3f7..ec576e6 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -32,6 +32,7 @@ arm64-obj-$(CONFIG_KGDB)              += kgdb.o
 arm64-obj-$(CONFIG_EFI)                        += efi.o efi-stub.o efi-entry.o
 arm64-obj-$(CONFIG_PCI)                        += pci.o
 arm64-obj-$(CONFIG_ACPI)               += acpi.o
+arm64-obj-$(CONFIG_PCI_MMCONFIG)               += mmconfig.o
 
 obj-y                                  += $(arm64-obj-y) vdso/
 obj-m                                  += $(arm64-obj-m)
diff --git a/arch/arm64/kernel/mmconfig.c b/arch/arm64/kernel/mmconfig.c
new file mode 100644
index 0000000..b0ca0ec
--- /dev/null
+++ b/arch/arm64/kernel/mmconfig.c
@@ -0,0 +1,69 @@
+/*
+ * mmconfig.c - Low-level direct PCI config space access via MMCONFIG
+ *
+ * This is an ARM64 version that allows the mmconfig space to be mapped.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/mmconfig.h>
+
+#define PREFIX "PCI: "
+
+static void __iomem *mcfg_ioremap(struct pci_mmcfg_region *cfg)
+{
+       void __iomem *addr;
+       u64 start, size;
+       int num_buses;
+
+       start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
+       num_buses = cfg->end_bus - cfg->start_bus + 1;
+       size = PCI_MMCFG_BUS_OFFSET(num_buses);
+       addr = ioremap_nocache(start, size);
+       if (addr)
+               addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
+       return addr;
+}
+
+int __init pci_mmcfg_arch_init(void)
+{
+       struct pci_mmcfg_region *cfg;
+
+       list_for_each_entry(cfg, &pci_mmcfg_list, list)
+               if (pci_mmcfg_arch_map(cfg)) {
+                       pci_mmcfg_arch_free();
+                       return 0;
+               }
+
+       return 1;
+}
+
+void __init pci_mmcfg_arch_free(void)
+{
+       struct pci_mmcfg_region *cfg;
+
+       list_for_each_entry(cfg, &pci_mmcfg_list, list)
+               pci_mmcfg_arch_unmap(cfg);
+}
+
+int pci_mmcfg_arch_map(struct pci_mmcfg_region *cfg)
+{
+       cfg->virt = mcfg_ioremap(cfg);
+       if (!cfg->virt) {
+               pr_err(PREFIX "can't map MMCONFIG at %pR\n", &cfg->res);
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+void pci_mmcfg_arch_unmap(struct pci_mmcfg_region *cfg)
+{
+       if (cfg && cfg->virt) {
+               iounmap(cfg->virt + PCI_MMCFG_BUS_OFFSET(cfg->start_bus));
+               cfg->virt = NULL;
+       }
+}
-- 
1.9.1

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