1 files changed, 306 insertions, 0 deletions
diff --git a/drivers/firmware/coreboot/coreboot_table.c b/drivers/firmware/coreboot/coreboot_table.c
new file mode 100644
index 000000000000..2c8c928fbb33
--- /dev/null
+++ b/drivers/firmware/coreboot/coreboot_table.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * coreboot_table.c
+ *
+ * Module providing coreboot table access.
+ *
+ * Copyright 2017 Google Inc.
+ * Copyright 2017 Samuel Holland <samuel@sholland.org>
+ */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/device-id/coreboot.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "coreboot_table.h"
+
+/* Coreboot table header structure */
+struct coreboot_table_header {
+	char signature[4];
+	u32 header_bytes;
+	u32 header_checksum;
+	u32 table_bytes;
+	u32 table_checksum;
+	u32 table_entries;
+};
+
+#define CB_DEV(d) container_of(d, struct coreboot_device, dev)
+#define CB_DRV(d) container_of_const(d, struct coreboot_driver, drv)
+
+static int coreboot_bus_match(struct device *dev, const struct device_driver *drv)
+{
+	struct coreboot_device *device = CB_DEV(dev);
+	const struct coreboot_driver *driver = CB_DRV(drv);
+	const struct coreboot_device_id *id;
+
+	if (!driver->id_table)
+		return 0;
+
+	for (id = driver->id_table; id->tag; id++) {
+		if (device->entry.tag == id->tag)
+			return 1;
+	}
+
+	return 0;
+}
+
+static int coreboot_bus_probe(struct device *dev)
+{
+	int ret = -ENODEV;
+	struct coreboot_device *device = CB_DEV(dev);
+	struct coreboot_driver *driver = CB_DRV(dev->driver);
+
+	if (driver->probe)
+		ret = driver->probe(device);
+
+	return ret;
+}
+
+static void coreboot_bus_remove(struct device *dev)
+{
+	struct coreboot_device *device = CB_DEV(dev);
+	struct coreboot_driver *driver = CB_DRV(dev->driver);
+
+	if (driver->remove)
+		driver->remove(device);
+}
+
+static int coreboot_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	struct coreboot_device *device = CB_DEV(dev);
+	u32 tag = device->entry.tag;
+
+	return add_uevent_var(env, "MODALIAS=coreboot:t%08X", tag);
+}
+
+static const struct bus_type coreboot_bus_type = {
+	.name		= "coreboot",
+	.match		= coreboot_bus_match,
+	.probe		= coreboot_bus_probe,
+	.remove		= coreboot_bus_remove,
+	.uevent		= coreboot_bus_uevent,
+};
+
+static void coreboot_device_release(struct device *dev)
+{
+	struct coreboot_device *device = CB_DEV(dev);
+
+	kfree(device);
+}
+
+int __coreboot_driver_register(struct coreboot_driver *driver,
+			       struct module *owner)
+{
+	driver->drv.bus = &coreboot_bus_type;
+	driver->drv.owner = owner;
+
+	return driver_register(&driver->drv);
+}
+EXPORT_SYMBOL(__coreboot_driver_register);
+
+void coreboot_driver_unregister(struct coreboot_driver *driver)
+{
+	driver_unregister(&driver->drv);
+}
+EXPORT_SYMBOL(coreboot_driver_unregister);
+
+static int coreboot_table_populate(struct device *dev, void *ptr, resource_size_t len)
+{
+	int i, ret;
+	void *ptr_entry;
+	struct coreboot_device *device;
+	struct coreboot_table_entry *entry;
+	struct coreboot_table_header *header = ptr;
+	void *ptr_end;
+
+	ptr_end = ptr + len;
+	ptr_entry = ptr + header->header_bytes;
+	for (i = 0; i < header->table_entries; i++, ptr_entry += entry->size) {
+		if (ptr_entry + sizeof(*entry) > ptr_end)
+			return -EINVAL;
+		entry = ptr_entry;
+
+		if (entry->size < sizeof(*entry)) {
+			dev_warn(dev, "coreboot table entry too small!\n");
+			return -EINVAL;
+		}
+
+		if (ptr_entry + entry->size > ptr_end)
+			return -EINVAL;
+
+		device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
+		if (!device)
+			return -ENOMEM;
+
+		device->dev.parent = dev;
+		device->dev.bus = &coreboot_bus_type;
+		device->dev.release = coreboot_device_release;
+		memcpy(device->raw, ptr_entry, entry->size);
+
+		switch (device->entry.tag) {
+		case LB_TAG_CBMEM_ENTRY:
+			/*
+			 * Skip entries that are not exclusively System RAM or
+			 * Reserved memory.
+			 * On ARM64, no-map regions are filtered out as they are
+			 * IORESOURCE_MEM (see request_standard_resources() in
+			 * arch/arm64/kernel/setup.c).
+			 * On x86, CBMEM often resides in standard reserved regions
+			 * (IORES_DESC_RESERVED).
+			 */
+			if (region_intersects(device->cbmem_entry.address,
+					      device->cbmem_entry.entry_size,
+					      IORESOURCE_SYSTEM_RAM,
+					      IORES_DESC_NONE) != REGION_INTERSECTS &&
+			    region_intersects(device->cbmem_entry.address,
+					      device->cbmem_entry.entry_size,
+					      IORESOURCE_MEM,
+					      IORES_DESC_RESERVED) != REGION_INTERSECTS) {
+				kfree(device);
+				continue;
+			}
+			dev_set_name(&device->dev, "cbmem-%08x",
+				     device->cbmem_entry.id);
+			break;
+		default:
+			dev_set_name(&device->dev, "coreboot%d", i);
+			break;
+		}
+
+		ret = device_register(&device->dev);
+		if (ret) {
+			dev_warn(dev, "failed to register coreboot device: %d\n", ret);
+			put_device(&device->dev);
+		}
+	}
+
+	return 0;
+}
+
+static int coreboot_table_probe(struct platform_device *pdev)
+{
+	resource_size_t len;
+	resource_size_t table_span;
+	struct coreboot_table_header *header;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	void *ptr;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	len = resource_size(res);
+	if (!res->start || len < sizeof(*header))
+		return -EINVAL;
+
+	/* Check just the header first to make sure things are sane */
+	header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
+	if (!header)
+		return -ENOMEM;
+
+	ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
+
+	if (!ret &&
+	    (header->header_bytes < sizeof(*header) ||
+	     check_add_overflow((resource_size_t)header->header_bytes,
+				(resource_size_t)header->table_bytes,
+				&table_span) ||
+	     table_span > len))
+		ret = -EINVAL;
+
+	memunmap(header);
+	if (ret) {
+		dev_warn(dev, "coreboot table missing or corrupt!\n");
+		return -ENODEV;
+	}
+
+	ptr = memremap(res->start, table_span, MEMREMAP_WB);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = coreboot_table_populate(dev, ptr, table_span);
+
+	memunmap(ptr);
+
+	return ret;
+}
+
+static int __cb_dev_unregister(struct device *dev, void *dummy)
+{
+	device_unregister(dev);
+	return 0;
+}
+
+static void coreboot_table_remove(struct platform_device *pdev)
+{
+	bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
+}
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id cros_coreboot_acpi_match[] = {
+	{ .id = "GOOGCB00" },
+	{ .id = "BOOT0000" },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
+#endif
+
+#ifdef CONFIG_OF
+static const struct of_device_id coreboot_of_match[] = {
+	{ .compatible = "coreboot" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, coreboot_of_match);
+#endif
+
+static struct platform_driver coreboot_table_driver = {
+	.probe = coreboot_table_probe,
+	.remove = coreboot_table_remove,
+	.driver = {
+		.name = "coreboot_table",
+		.acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
+		.of_match_table = of_match_ptr(coreboot_of_match),
+	},
+};
+
+static int __init coreboot_table_driver_init(void)
+{
+	int ret;
+
+	ret = bus_register(&coreboot_bus_type);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&coreboot_table_driver);
+	if (ret) {
+		bus_unregister(&coreboot_bus_type);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit coreboot_table_driver_exit(void)
+{
+	platform_driver_unregister(&coreboot_table_driver);
+	bus_unregister(&coreboot_bus_type);
+}
+
+subsys_initcall(coreboot_table_driver_init);
+module_exit(coreboot_table_driver_exit);
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_DESCRIPTION("Module providing coreboot table access");
+MODULE_LICENSE("GPL");