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 
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 
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 
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 
65 static void coreboot_device_release(struct device *dev)
66 {
67 	struct coreboot_device *device = CB_DEV(dev);
68 
69 	kfree(device);
70 }
71 
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 
80 void coreboot_driver_unregister(struct coreboot_driver *driver)
81 {
82 	driver_unregister(&driver->drv);
83 }
84 EXPORT_SYMBOL(coreboot_driver_unregister);
85 
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 
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 
165 static int __cb_dev_unregister(struct device *dev, void *dummy)
166 {
167 	device_unregister(dev);
168 	return 0;
169 }
170 
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