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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 <[email protected]>
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/ioport.h>
17#include <linux/kernel.h>
18#include <linux/device-id/coreboot.h>
19#include <linux/mm.h>
20#include <linux/module.h>
21#include <linux/of.h>
22#include <linux/platform_device.h>
23#include <linux/slab.h>
24
25#include "coreboot_table.h"
26
27/* Coreboot table header structure */
28struct coreboot_table_header {
29 char signature[4];
30 u32 header_bytes;
31 u32 header_checksum;
32 u32 table_bytes;
33 u32 table_checksum;
34 u32 table_entries;
35};
36
37#define CB_DEV(d) container_of(d, struct coreboot_device, dev)
38#define CB_DRV(d) container_of_const(d, struct coreboot_driver, drv)
39
40static int coreboot_bus_match(struct device *dev, const struct device_driver *drv)
41{
42 struct coreboot_device *device = CB_DEV(dev);
43 const struct coreboot_driver *driver = CB_DRV(drv);
44 const struct coreboot_device_id *id;
45
46 if (!driver->id_table)
47 return 0;
48
49 for (id = driver->id_table; id->tag; id++) {
50 if (device->entry.tag == id->tag)
51 return 1;
52 }
53
54 return 0;
55}
56
57static int coreboot_bus_probe(struct device *dev)
58{
59 int ret = -ENODEV;
60 struct coreboot_device *device = CB_DEV(dev);
61 struct coreboot_driver *driver = CB_DRV(dev->driver);
62
63 if (driver->probe)
64 ret = driver->probe(device);
65
66 return ret;
67}
68
69static void coreboot_bus_remove(struct device *dev)
70{
71 struct coreboot_device *device = CB_DEV(dev);
72 struct coreboot_driver *driver = CB_DRV(dev->driver);
73
74 if (driver->remove)
75 driver->remove(device);
76}
77
78static int coreboot_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
79{
80 struct coreboot_device *device = CB_DEV(dev);
81 u32 tag = device->entry.tag;
82
83 return add_uevent_var(env, "MODALIAS=coreboot:t%08X", tag);
84}
85
86static const struct bus_type coreboot_bus_type = {
87 .name = "coreboot",
88 .match = coreboot_bus_match,
89 .probe = coreboot_bus_probe,
90 .remove = coreboot_bus_remove,
91 .uevent = coreboot_bus_uevent,
92};
93
94static void coreboot_device_release(struct device *dev)
95{
96 struct coreboot_device *device = CB_DEV(dev);
97
98 kfree(device);
99}
100
101int __coreboot_driver_register(struct coreboot_driver *driver,
102 struct module *owner)
103{
104 driver->drv.bus = &coreboot_bus_type;
105 driver->drv.owner = owner;
106
107 return driver_register(&driver->drv);
108}
109EXPORT_SYMBOL(__coreboot_driver_register);
110
111void coreboot_driver_unregister(struct coreboot_driver *driver)
112{
113 driver_unregister(&driver->drv);
114}
115EXPORT_SYMBOL(coreboot_driver_unregister);
116
117static int coreboot_table_populate(struct device *dev, void *ptr, resource_size_t len)
118{
119 int i, ret;
120 void *ptr_entry;
121 struct coreboot_device *device;
122 struct coreboot_table_entry *entry;
123 struct coreboot_table_header *header = ptr;
124 void *ptr_end;
125
126 ptr_end = ptr + len;
127 ptr_entry = ptr + header->header_bytes;
128 for (i = 0; i < header->table_entries; i++, ptr_entry += entry->size) {
129 if (ptr_entry + sizeof(*entry) > ptr_end)
130 return -EINVAL;
131 entry = ptr_entry;
132
133 if (entry->size < sizeof(*entry)) {
134 dev_warn(dev, "coreboot table entry too small!\n");
135 return -EINVAL;
136 }
137
138 if (ptr_entry + entry->size > ptr_end)
139 return -EINVAL;
140
141 device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
142 if (!device)
143 return -ENOMEM;
144
145 device->dev.parent = dev;
146 device->dev.bus = &coreboot_bus_type;
147 device->dev.release = coreboot_device_release;
148 memcpy(device->raw, ptr_entry, entry->size);
149
150 switch (device->entry.tag) {
151 case LB_TAG_CBMEM_ENTRY:
152 /*
153 * Skip entries that are not exclusively System RAM or
154 * Reserved memory.
155 * On ARM64, no-map regions are filtered out as they are
156 * IORESOURCE_MEM (see request_standard_resources() in
157 * arch/arm64/kernel/setup.c).
158 * On x86, CBMEM often resides in standard reserved regions
159 * (IORES_DESC_RESERVED).
160 */
161 if (region_intersects(device->cbmem_entry.address,
162 device->cbmem_entry.entry_size,
163 IORESOURCE_SYSTEM_RAM,
164 IORES_DESC_NONE) != REGION_INTERSECTS &&
165 region_intersects(device->cbmem_entry.address,
166 device->cbmem_entry.entry_size,
167 IORESOURCE_MEM,
168 IORES_DESC_RESERVED) != REGION_INTERSECTS) {
169 kfree(device);
170 continue;
171 }
172 dev_set_name(&device->dev, "cbmem-%08x",
173 device->cbmem_entry.id);
174 break;
175 default:
176 dev_set_name(&device->dev, "coreboot%d", i);
177 break;
178 }
179
180 ret = device_register(&device->dev);
181 if (ret) {
182 dev_warn(dev, "failed to register coreboot device: %d\n", ret);
183 put_device(&device->dev);
184 }
185 }
186
187 return 0;
188}
189
190static int coreboot_table_probe(struct platform_device *pdev)
191{
192 resource_size_t len;
193 resource_size_t table_span;
194 struct coreboot_table_header *header;
195 struct resource *res;
196 struct device *dev = &pdev->dev;
197 void *ptr;
198 int ret;
199
200 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
201 if (!res)
202 return -EINVAL;
203
204 len = resource_size(res);
205 if (!res->start || len < sizeof(*header))
206 return -EINVAL;
207
208 /* Check just the header first to make sure things are sane */
209 header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
210 if (!header)
211 return -ENOMEM;
212
213 ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
214
215 if (!ret &&
216 (header->header_bytes < sizeof(*header) ||
217 check_add_overflow((resource_size_t)header->header_bytes,
218 (resource_size_t)header->table_bytes,
219 &table_span) ||
220 table_span > len))
221 ret = -EINVAL;
222
223 memunmap(header);
224 if (ret) {
225 dev_warn(dev, "coreboot table missing or corrupt!\n");
226 return -ENODEV;
227 }
228
229 ptr = memremap(res->start, table_span, MEMREMAP_WB);
230 if (!ptr)
231 return -ENOMEM;
232
233 ret = coreboot_table_populate(dev, ptr, table_span);
234
235 memunmap(ptr);
236
237 return ret;
238}
239
240static int __cb_dev_unregister(struct device *dev, void *dummy)
241{
242 device_unregister(dev);
243 return 0;
244}
245
246static void coreboot_table_remove(struct platform_device *pdev)
247{
248 bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
249}
250
251#ifdef CONFIG_ACPI
252static const struct acpi_device_id cros_coreboot_acpi_match[] = {
253 { .id = "GOOGCB00" },
254 { .id = "BOOT0000" },
255 { }
256};
257MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
258#endif
259
260#ifdef CONFIG_OF
261static const struct of_device_id coreboot_of_match[] = {
262 { .compatible = "coreboot" },
263 {}
264};
265MODULE_DEVICE_TABLE(of, coreboot_of_match);
266#endif
267
268static struct platform_driver coreboot_table_driver = {
269 .probe = coreboot_table_probe,
270 .remove = coreboot_table_remove,
271 .driver = {
272 .name = "coreboot_table",
273 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
274 .of_match_table = of_match_ptr(coreboot_of_match),
275 },
276};
277
278static int __init coreboot_table_driver_init(void)
279{
280 int ret;
281
282 ret = bus_register(&coreboot_bus_type);
283 if (ret)
284 return ret;
285
286 ret = platform_driver_register(&coreboot_table_driver);
287 if (ret) {
288 bus_unregister(&coreboot_bus_type);
289 return ret;
290 }
291
292 return 0;
293}
294
295static void __exit coreboot_table_driver_exit(void)
296{
297 platform_driver_unregister(&coreboot_table_driver);
298 bus_unregister(&coreboot_bus_type);
299}
300
301subsys_initcall(coreboot_table_driver_init);
302module_exit(coreboot_table_driver_exit);
303
304MODULE_AUTHOR("Google, Inc.");
305MODULE_DESCRIPTION("Module providing coreboot table access");
306MODULE_LICENSE("GPL");