1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * coreboot_table.c
  4 *
  5 * Module providing coreboot table access.
  6 *
  7 * Copyright 2017 Google Inc.
  8 * Copyright 2017 Samuel Holland <samuel@sholland.org>
  9 */
 10
 11#include <linux/acpi.h>
 12#include <linux/device.h>
 13#include <linux/err.h>
 14#include <linux/init.h>
 15#include <linux/io.h>
 16#include <linux/kernel.h>
 17#include <linux/module.h>
 18#include <linux/of.h>
 19#include <linux/platform_device.h>
 20#include <linux/slab.h>
 21
 22#include "coreboot_table.h"
 23
 24#define CB_DEV(d) container_of(d, struct coreboot_device, dev)
 25#define CB_DRV(d) container_of(d, struct coreboot_driver, drv)
 26
 27static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
 28{
 29	struct coreboot_device *device = CB_DEV(dev);
 30	struct coreboot_driver *driver = CB_DRV(drv);
 31
 32	return device->entry.tag == driver->tag;
 33}
 34
 35static int coreboot_bus_probe(struct device *dev)
 36{
 37	int ret = -ENODEV;
 38	struct coreboot_device *device = CB_DEV(dev);
 39	struct coreboot_driver *driver = CB_DRV(dev->driver);
 40
 41	if (driver->probe)
 42		ret = driver->probe(device);
 43
 44	return ret;
 45}
 46
 47static int coreboot_bus_remove(struct device *dev)
 48{
 49	struct coreboot_device *device = CB_DEV(dev);
 50	struct coreboot_driver *driver = CB_DRV(dev->driver);
 51
 52	if (driver->remove)
 53		driver->remove(device);
 54
 55	return 0;
 56}
 57
 58static struct bus_type coreboot_bus_type = {
 59	.name		= "coreboot",
 60	.match		= coreboot_bus_match,
 61	.probe		= coreboot_bus_probe,
 62	.remove		= coreboot_bus_remove,
 63};
 64
 65static void coreboot_device_release(struct device *dev)
 66{
 67	struct coreboot_device *device = CB_DEV(dev);
 68
 69	kfree(device);
 70}
 71
 72int coreboot_driver_register(struct coreboot_driver *driver)
 73{
 74	driver->drv.bus = &coreboot_bus_type;
 75
 76	return driver_register(&driver->drv);
 77}
 78EXPORT_SYMBOL(coreboot_driver_register);
 79
 80void coreboot_driver_unregister(struct coreboot_driver *driver)
 81{
 82	driver_unregister(&driver->drv);
 83}
 84EXPORT_SYMBOL(coreboot_driver_unregister);
 85
 86static int coreboot_table_populate(struct device *dev, void *ptr)
 87{
 88	int i, ret;
 89	void *ptr_entry;
 90	struct coreboot_device *device;
 91	struct coreboot_table_entry *entry;
 92	struct coreboot_table_header *header = ptr;
 93
 94	ptr_entry = ptr + header->header_bytes;
 95	for (i = 0; i < header->table_entries; i++) {
 96		entry = ptr_entry;
 97
 98		device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
 99		if (!device)
100			return -ENOMEM;
101
102		dev_set_name(&device->dev, "coreboot%d", i);
103		device->dev.parent = dev;
104		device->dev.bus = &coreboot_bus_type;
105		device->dev.release = coreboot_device_release;
106		memcpy(&device->entry, ptr_entry, entry->size);
107
108		ret = device_register(&device->dev);
109		if (ret) {
110			put_device(&device->dev);
111			return ret;
112		}
113
114		ptr_entry += entry->size;
115	}
116
117	return 0;
118}
119
120static int coreboot_table_probe(struct platform_device *pdev)
121{
122	resource_size_t len;
123	struct coreboot_table_header *header;
124	struct resource *res;
125	struct device *dev = &pdev->dev;
126	void *ptr;
127	int ret;
128
129	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
130	if (!res)
131		return -EINVAL;
132
133	len = resource_size(res);
134	if (!res->start || !len)
135		return -EINVAL;
136
137	/* Check just the header first to make sure things are sane */
138	header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
139	if (!header)
140		return -ENOMEM;
141
142	len = header->header_bytes + header->table_bytes;
143	ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
144	memunmap(header);
145	if (ret) {
146		dev_warn(dev, "coreboot table missing or corrupt!\n");
147		return -ENODEV;
148	}
149
150	ptr = memremap(res->start, len, MEMREMAP_WB);
151	if (!ptr)
152		return -ENOMEM;
153
154	ret = bus_register(&coreboot_bus_type);
155	if (!ret) {
156		ret = coreboot_table_populate(dev, ptr);
157		if (ret)
158			bus_unregister(&coreboot_bus_type);
159	}
160	memunmap(ptr);
161
162	return ret;
163}
164
165static int __cb_dev_unregister(struct device *dev, void *dummy)
166{
167	device_unregister(dev);
168	return 0;
169}
170
171static int coreboot_table_remove(struct platform_device *pdev)
172{
173	bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
174	bus_unregister(&coreboot_bus_type);
175	return 0;
176}
177
178#ifdef CONFIG_ACPI
179static const struct acpi_device_id cros_coreboot_acpi_match[] = {
180	{ "GOOGCB00", 0 },
181	{ "BOOT0000", 0 },
182	{ }
183};
184MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
185#endif
186
187#ifdef CONFIG_OF
188static const struct of_device_id coreboot_of_match[] = {
189	{ .compatible = "coreboot" },
190	{}
191};
192MODULE_DEVICE_TABLE(of, coreboot_of_match);
193#endif
194
195static struct platform_driver coreboot_table_driver = {
196	.probe = coreboot_table_probe,
197	.remove = coreboot_table_remove,
198	.driver = {
199		.name = "coreboot_table",
200		.acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
201		.of_match_table = of_match_ptr(coreboot_of_match),
202	},
203};
204module_platform_driver(coreboot_table_driver);
205MODULE_AUTHOR("Google, Inc.");
206MODULE_LICENSE("GPL");