[RFC PATCH 3/4] arm64, acpi, pci: Add arch specific functions for mmconfig driver.

[Tomasz Nowicki]

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

Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
---
 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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