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_const(d, struct coreboot_driver, drv)
 26
 27static int coreboot_bus_match(struct device *dev, const struct device_driver *drv)
 28{
 29	struct coreboot_device *device = CB_DEV(dev);
 30	const struct coreboot_driver *driver = CB_DRV(drv);
 31	const struct coreboot_device_id *id;
 32
 33	if (!driver->id_table)
 34		return 0;
 35
 36	for (id = driver->id_table; id->tag; id++) {
 37		if (device->entry.tag == id->tag)
 38			return 1;
 39	}
 40
 41	return 0;
 42}
 43
 44static int coreboot_bus_probe(struct device *dev)
 45{
 46	int ret = -ENODEV;
 47	struct coreboot_device *device = CB_DEV(dev);
 48	struct coreboot_driver *driver = CB_DRV(dev->driver);
 49
 50	if (driver->probe)
 51		ret = driver->probe(device);
 52
 53	return ret;
 54}
 55
 56static void coreboot_bus_remove(struct device *dev)
 57{
 58	struct coreboot_device *device = CB_DEV(dev);
 59	struct coreboot_driver *driver = CB_DRV(dev->driver);
 60
 61	if (driver->remove)
 62		driver->remove(device);
 63}
 64
 65static int coreboot_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
 66{
 67	struct coreboot_device *device = CB_DEV(dev);
 68	u32 tag = device->entry.tag;
 69
 70	return add_uevent_var(env, "MODALIAS=coreboot:t%08X", tag);
 71}
 72
 73static const struct bus_type coreboot_bus_type = {
 74	.name		= "coreboot",
 75	.match		= coreboot_bus_match,
 76	.probe		= coreboot_bus_probe,
 77	.remove		= coreboot_bus_remove,
 78	.uevent		= coreboot_bus_uevent,
 79};
 80
 81static void coreboot_device_release(struct device *dev)
 82{
 83	struct coreboot_device *device = CB_DEV(dev);
 84
 85	kfree(device);
 86}
 87
 88int __coreboot_driver_register(struct coreboot_driver *driver,
 89			       struct module *owner)
 90{
 91	driver->drv.bus = &coreboot_bus_type;
 92	driver->drv.owner = owner;
 93
 94	return driver_register(&driver->drv);
 95}
 96EXPORT_SYMBOL(__coreboot_driver_register);
 97
 98void coreboot_driver_unregister(struct coreboot_driver *driver)
 99{
100	driver_unregister(&driver->drv);
101}
102EXPORT_SYMBOL(coreboot_driver_unregister);
103
104static int coreboot_table_populate(struct device *dev, void *ptr)
105{
106	int i, ret;
107	void *ptr_entry;
108	struct coreboot_device *device;
109	struct coreboot_table_entry *entry;
110	struct coreboot_table_header *header = ptr;
111
112	ptr_entry = ptr + header->header_bytes;
113	for (i = 0; i < header->table_entries; i++) {
114		entry = ptr_entry;
115
116		if (entry->size < sizeof(*entry)) {
117			dev_warn(dev, "coreboot table entry too small!\n");
118			return -EINVAL;
119		}
120
121		device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
122		if (!device)
123			return -ENOMEM;
124
125		device->dev.parent = dev;
126		device->dev.bus = &coreboot_bus_type;
127		device->dev.release = coreboot_device_release;
128		memcpy(device->raw, ptr_entry, entry->size);
129
130		switch (device->entry.tag) {
131		case LB_TAG_CBMEM_ENTRY:
132			dev_set_name(&device->dev, "cbmem-%08x",
133				     device->cbmem_entry.id);
134			break;
135		default:
136			dev_set_name(&device->dev, "coreboot%d", i);
137			break;
138		}
139
140		ret = device_register(&device->dev);
141		if (ret) {
142			put_device(&device->dev);
143			return ret;
144		}
145
146		ptr_entry += entry->size;
147	}
148
149	return 0;
150}
151
152static int coreboot_table_probe(struct platform_device *pdev)
153{
154	resource_size_t len;
155	struct coreboot_table_header *header;
156	struct resource *res;
157	struct device *dev = &pdev->dev;
158	void *ptr;
159	int ret;
160
161	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
162	if (!res)
163		return -EINVAL;
164
165	len = resource_size(res);
166	if (!res->start || !len)
167		return -EINVAL;
168
169	/* Check just the header first to make sure things are sane */
170	header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
171	if (!header)
172		return -ENOMEM;
173
174	len = header->header_bytes + header->table_bytes;
175	ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
176	memunmap(header);
177	if (ret) {
178		dev_warn(dev, "coreboot table missing or corrupt!\n");
179		return -ENODEV;
180	}
181
182	ptr = memremap(res->start, len, MEMREMAP_WB);
183	if (!ptr)
184		return -ENOMEM;
185
186	ret = coreboot_table_populate(dev, ptr);
187
188	memunmap(ptr);
189
190	return ret;
191}
192
193static int __cb_dev_unregister(struct device *dev, void *dummy)
194{
195	device_unregister(dev);
196	return 0;
197}
198
199static void coreboot_table_remove(struct platform_device *pdev)
200{
201	bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
202}
203
204#ifdef CONFIG_ACPI
205static const struct acpi_device_id cros_coreboot_acpi_match[] = {
206	{ "GOOGCB00", 0 },
207	{ "BOOT0000", 0 },
208	{ }
209};
210MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
211#endif
212
213#ifdef CONFIG_OF
214static const struct of_device_id coreboot_of_match[] = {
215	{ .compatible = "coreboot" },
216	{}
217};
218MODULE_DEVICE_TABLE(of, coreboot_of_match);
219#endif
220
221static struct platform_driver coreboot_table_driver = {
222	.probe = coreboot_table_probe,
223	.remove = coreboot_table_remove,
224	.driver = {
225		.name = "coreboot_table",
226		.acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
227		.of_match_table = of_match_ptr(coreboot_of_match),
228	},
229};
230
231static int __init coreboot_table_driver_init(void)
232{
233	int ret;
234
235	ret = bus_register(&coreboot_bus_type);
236	if (ret)
237		return ret;
238
239	ret = platform_driver_register(&coreboot_table_driver);
240	if (ret) {
241		bus_unregister(&coreboot_bus_type);
242		return ret;
243	}
244
245	return 0;
246}
247
248static void __exit coreboot_table_driver_exit(void)
249{
250	platform_driver_unregister(&coreboot_table_driver);
251	bus_unregister(&coreboot_bus_type);
252}
253
254module_init(coreboot_table_driver_init);
255module_exit(coreboot_table_driver_exit);
256
257MODULE_AUTHOR("Google, Inc.");
258MODULE_DESCRIPTION("Module providing coreboot table access");
259MODULE_LICENSE("GPL");