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
coreboot_bus_match(struct device * dev,struct device_driver * drv)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
32 return device->entry.tag == driver->tag;
33 }
34
coreboot_bus_probe(struct device * dev)35 static 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
coreboot_bus_remove(struct device * dev)47 static 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
58 static 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
coreboot_device_release(struct device * dev)65 static void coreboot_device_release(struct device *dev)
66 {
67 struct coreboot_device *device = CB_DEV(dev);
68
69 kfree(device);
70 }
71
coreboot_driver_register(struct coreboot_driver * driver)72 int coreboot_driver_register(struct coreboot_driver *driver)
73 {
74 driver->drv.bus = &coreboot_bus_type;
75
76 return driver_register(&driver->drv);
77 }
78 EXPORT_SYMBOL(coreboot_driver_register);
79
coreboot_driver_unregister(struct coreboot_driver * driver)80 void coreboot_driver_unregister(struct coreboot_driver *driver)
81 {
82 driver_unregister(&driver->drv);
83 }
84 EXPORT_SYMBOL(coreboot_driver_unregister);
85
coreboot_table_populate(struct device * dev,void * ptr)86 static 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
coreboot_table_probe(struct platform_device * pdev)120 static 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
__cb_dev_unregister(struct device * dev,void * dummy)165 static int __cb_dev_unregister(struct device *dev, void *dummy)
166 {
167 device_unregister(dev);
168 return 0;
169 }
170
coreboot_table_remove(struct platform_device * pdev)171 static 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
179 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
180 { "GOOGCB00", 0 },
181 { "BOOT0000", 0 },
182 { }
183 };
184 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
185 #endif
186
187 #ifdef CONFIG_OF
188 static const struct of_device_id coreboot_of_match[] = {
189 { .compatible = "coreboot" },
190 {}
191 };
192 MODULE_DEVICE_TABLE(of, coreboot_of_match);
193 #endif
194
195 static 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 };
204 module_platform_driver(coreboot_table_driver);
205 MODULE_AUTHOR("Google, Inc.");
206 MODULE_LICENSE("GPL");
207