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[linux.git] / drivers / firmware / google / coreboot_table.c
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/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
27 static 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         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
44 static 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
56 static 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
65 static 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
73 static 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
81 static void coreboot_device_release(struct device *dev)
82 {
83         struct coreboot_device *device = CB_DEV(dev);
84
85         kfree(device);
86 }
87
88 int coreboot_driver_register(struct coreboot_driver *driver)
89 {
90         driver->drv.bus = &coreboot_bus_type;
91
92         return driver_register(&driver->drv);
93 }
94 EXPORT_SYMBOL(coreboot_driver_register);
95
96 void coreboot_driver_unregister(struct coreboot_driver *driver)
97 {
98         driver_unregister(&driver->drv);
99 }
100 EXPORT_SYMBOL(coreboot_driver_unregister);
101
102 static int coreboot_table_populate(struct device *dev, void *ptr)
103 {
104         int i, ret;
105         void *ptr_entry;
106         struct coreboot_device *device;
107         struct coreboot_table_entry *entry;
108         struct coreboot_table_header *header = ptr;
109
110         ptr_entry = ptr + header->header_bytes;
111         for (i = 0; i < header->table_entries; i++) {
112                 entry = ptr_entry;
113
114                 if (entry->size < sizeof(*entry)) {
115                         dev_warn(dev, "coreboot table entry too small!\n");
116                         return -EINVAL;
117                 }
118
119                 device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
120                 if (!device)
121                         return -ENOMEM;
122
123                 device->dev.parent = dev;
124                 device->dev.bus = &coreboot_bus_type;
125                 device->dev.release = coreboot_device_release;
126                 memcpy(device->raw, ptr_entry, entry->size);
127
128                 switch (device->entry.tag) {
129                 case LB_TAG_CBMEM_ENTRY:
130                         dev_set_name(&device->dev, "cbmem-%08x",
131                                      device->cbmem_entry.id);
132                         break;
133                 default:
134                         dev_set_name(&device->dev, "coreboot%d", i);
135                         break;
136                 }
137
138                 ret = device_register(&device->dev);
139                 if (ret) {
140                         put_device(&device->dev);
141                         return ret;
142                 }
143
144                 ptr_entry += entry->size;
145         }
146
147         return 0;
148 }
149
150 static int coreboot_table_probe(struct platform_device *pdev)
151 {
152         resource_size_t len;
153         struct coreboot_table_header *header;
154         struct resource *res;
155         struct device *dev = &pdev->dev;
156         void *ptr;
157         int ret;
158
159         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
160         if (!res)
161                 return -EINVAL;
162
163         len = resource_size(res);
164         if (!res->start || !len)
165                 return -EINVAL;
166
167         /* Check just the header first to make sure things are sane */
168         header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
169         if (!header)
170                 return -ENOMEM;
171
172         len = header->header_bytes + header->table_bytes;
173         ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
174         memunmap(header);
175         if (ret) {
176                 dev_warn(dev, "coreboot table missing or corrupt!\n");
177                 return -ENODEV;
178         }
179
180         ptr = memremap(res->start, len, MEMREMAP_WB);
181         if (!ptr)
182                 return -ENOMEM;
183
184         ret = coreboot_table_populate(dev, ptr);
185
186         memunmap(ptr);
187
188         return ret;
189 }
190
191 static int __cb_dev_unregister(struct device *dev, void *dummy)
192 {
193         device_unregister(dev);
194         return 0;
195 }
196
197 static void coreboot_table_remove(struct platform_device *pdev)
198 {
199         bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
200 }
201
202 #ifdef CONFIG_ACPI
203 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
204         { "GOOGCB00", 0 },
205         { "BOOT0000", 0 },
206         { }
207 };
208 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
209 #endif
210
211 #ifdef CONFIG_OF
212 static const struct of_device_id coreboot_of_match[] = {
213         { .compatible = "coreboot" },
214         {}
215 };
216 MODULE_DEVICE_TABLE(of, coreboot_of_match);
217 #endif
218
219 static struct platform_driver coreboot_table_driver = {
220         .probe = coreboot_table_probe,
221         .remove_new = coreboot_table_remove,
222         .driver = {
223                 .name = "coreboot_table",
224                 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
225                 .of_match_table = of_match_ptr(coreboot_of_match),
226         },
227 };
228
229 static int __init coreboot_table_driver_init(void)
230 {
231         int ret;
232
233         ret = bus_register(&coreboot_bus_type);
234         if (ret)
235                 return ret;
236
237         ret = platform_driver_register(&coreboot_table_driver);
238         if (ret) {
239                 bus_unregister(&coreboot_bus_type);
240                 return ret;
241         }
242
243         return 0;
244 }
245
246 static void __exit coreboot_table_driver_exit(void)
247 {
248         platform_driver_unregister(&coreboot_table_driver);
249         bus_unregister(&coreboot_bus_type);
250 }
251
252 module_init(coreboot_table_driver_init);
253 module_exit(coreboot_table_driver_exit);
254
255 MODULE_AUTHOR("Google, Inc.");
256 MODULE_LICENSE("GPL");
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