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 void 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 
56 static struct bus_type coreboot_bus_type = {
57 	.name		= "coreboot",
58 	.match		= coreboot_bus_match,
59 	.probe		= coreboot_bus_probe,
60 	.remove		= coreboot_bus_remove,
61 };
62 
63 static void coreboot_device_release(struct device *dev)
64 {
65 	struct coreboot_device *device = CB_DEV(dev);
66 
67 	kfree(device);
68 }
69 
70 int coreboot_driver_register(struct coreboot_driver *driver)
71 {
72 	driver->drv.bus = &coreboot_bus_type;
73 
74 	return driver_register(&driver->drv);
75 }
76 EXPORT_SYMBOL(coreboot_driver_register);
77 
78 void coreboot_driver_unregister(struct coreboot_driver *driver)
79 {
80 	driver_unregister(&driver->drv);
81 }
82 EXPORT_SYMBOL(coreboot_driver_unregister);
83 
84 static int coreboot_table_populate(struct device *dev, void *ptr)
85 {
86 	int i, ret;
87 	void *ptr_entry;
88 	struct coreboot_device *device;
89 	struct coreboot_table_entry *entry;
90 	struct coreboot_table_header *header = ptr;
91 
92 	ptr_entry = ptr + header->header_bytes;
93 	for (i = 0; i < header->table_entries; i++) {
94 		entry = ptr_entry;
95 
96 		device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
97 		if (!device)
98 			return -ENOMEM;
99 
100 		dev_set_name(&device->dev, "coreboot%d", i);
101 		device->dev.parent = dev;
102 		device->dev.bus = &coreboot_bus_type;
103 		device->dev.release = coreboot_device_release;
104 		memcpy(&device->entry, ptr_entry, entry->size);
105 
106 		ret = device_register(&device->dev);
107 		if (ret) {
108 			put_device(&device->dev);
109 			return ret;
110 		}
111 
112 		ptr_entry += entry->size;
113 	}
114 
115 	return 0;
116 }
117 
118 static int coreboot_table_probe(struct platform_device *pdev)
119 {
120 	resource_size_t len;
121 	struct coreboot_table_header *header;
122 	struct resource *res;
123 	struct device *dev = &pdev->dev;
124 	void *ptr;
125 	int ret;
126 
127 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
128 	if (!res)
129 		return -EINVAL;
130 
131 	len = resource_size(res);
132 	if (!res->start || !len)
133 		return -EINVAL;
134 
135 	/* Check just the header first to make sure things are sane */
136 	header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
137 	if (!header)
138 		return -ENOMEM;
139 
140 	len = header->header_bytes + header->table_bytes;
141 	ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
142 	memunmap(header);
143 	if (ret) {
144 		dev_warn(dev, "coreboot table missing or corrupt!\n");
145 		return -ENODEV;
146 	}
147 
148 	ptr = memremap(res->start, len, MEMREMAP_WB);
149 	if (!ptr)
150 		return -ENOMEM;
151 
152 	ret = bus_register(&coreboot_bus_type);
153 	if (!ret) {
154 		ret = coreboot_table_populate(dev, ptr);
155 		if (ret)
156 			bus_unregister(&coreboot_bus_type);
157 	}
158 	memunmap(ptr);
159 
160 	return ret;
161 }
162 
163 static int __cb_dev_unregister(struct device *dev, void *dummy)
164 {
165 	device_unregister(dev);
166 	return 0;
167 }
168 
169 static int coreboot_table_remove(struct platform_device *pdev)
170 {
171 	bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
172 	bus_unregister(&coreboot_bus_type);
173 	return 0;
174 }
175 
176 #ifdef CONFIG_ACPI
177 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
178 	{ "GOOGCB00", 0 },
179 	{ "BOOT0000", 0 },
180 	{ }
181 };
182 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
183 #endif
184 
185 #ifdef CONFIG_OF
186 static const struct of_device_id coreboot_of_match[] = {
187 	{ .compatible = "coreboot" },
188 	{}
189 };
190 MODULE_DEVICE_TABLE(of, coreboot_of_match);
191 #endif
192 
193 static struct platform_driver coreboot_table_driver = {
194 	.probe = coreboot_table_probe,
195 	.remove = coreboot_table_remove,
196 	.driver = {
197 		.name = "coreboot_table",
198 		.acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
199 		.of_match_table = of_match_ptr(coreboot_of_match),
200 	},
201 };
202 module_platform_driver(coreboot_table_driver);
203 MODULE_AUTHOR("Google, Inc.");
204 MODULE_LICENSE("GPL");
205