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3d0b16a6 MR |
1 | /* |
2 | * Allwinner sunXi SoCs Security ID support. | |
3 | * | |
4 | * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl> | |
5 | * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | */ | |
18 | ||
19 | ||
20 | #include <linux/device.h> | |
21 | #include <linux/io.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/nvmem-provider.h> | |
24 | #include <linux/of.h> | |
25 | #include <linux/platform_device.h> | |
26 | #include <linux/regmap.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/random.h> | |
29 | ||
30 | ||
31 | static struct nvmem_config econfig = { | |
32 | .name = "sunxi-sid", | |
33 | .read_only = true, | |
34 | .owner = THIS_MODULE, | |
35 | }; | |
36 | ||
37 | struct sunxi_sid { | |
38 | void __iomem *base; | |
39 | }; | |
40 | ||
41 | /* We read the entire key, due to a 32 bit read alignment requirement. Since we | |
42 | * want to return the requested byte, this results in somewhat slower code and | |
43 | * uses 4 times more reads as needed but keeps code simpler. Since the SID is | |
44 | * only very rarely probed, this is not really an issue. | |
45 | */ | |
46 | static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid, | |
47 | const unsigned int offset) | |
48 | { | |
49 | u32 sid_key; | |
50 | ||
51 | sid_key = ioread32be(sid->base + round_down(offset, 4)); | |
52 | sid_key >>= (offset % 4) * 8; | |
53 | ||
54 | return sid_key; /* Only return the last byte */ | |
55 | } | |
56 | ||
57 | static int sunxi_sid_read(void *context, | |
58 | const void *reg, size_t reg_size, | |
59 | void *val, size_t val_size) | |
60 | { | |
61 | struct sunxi_sid *sid = context; | |
62 | unsigned int offset = *(u32 *)reg; | |
63 | u8 *buf = val; | |
64 | ||
65 | while (val_size) { | |
66 | *buf++ = sunxi_sid_read_byte(sid, offset); | |
67 | val_size--; | |
68 | offset++; | |
69 | } | |
70 | ||
71 | return 0; | |
72 | } | |
73 | ||
74 | static int sunxi_sid_write(void *context, const void *data, size_t count) | |
75 | { | |
76 | /* Unimplemented, dummy to keep regmap core happy */ | |
77 | return 0; | |
78 | } | |
79 | ||
80 | static struct regmap_bus sunxi_sid_bus = { | |
81 | .read = sunxi_sid_read, | |
82 | .write = sunxi_sid_write, | |
83 | .reg_format_endian_default = REGMAP_ENDIAN_NATIVE, | |
84 | .val_format_endian_default = REGMAP_ENDIAN_NATIVE, | |
85 | }; | |
86 | ||
87 | static bool sunxi_sid_writeable_reg(struct device *dev, unsigned int reg) | |
88 | { | |
89 | return false; | |
90 | } | |
91 | ||
92 | static struct regmap_config sunxi_sid_regmap_config = { | |
93 | .reg_bits = 32, | |
94 | .val_bits = 8, | |
95 | .reg_stride = 1, | |
96 | .writeable_reg = sunxi_sid_writeable_reg, | |
97 | }; | |
98 | ||
99 | static int sunxi_sid_probe(struct platform_device *pdev) | |
100 | { | |
101 | struct device *dev = &pdev->dev; | |
102 | struct resource *res; | |
103 | struct nvmem_device *nvmem; | |
104 | struct regmap *regmap; | |
105 | struct sunxi_sid *sid; | |
106 | int i, size; | |
107 | char *randomness; | |
108 | ||
109 | sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL); | |
110 | if (!sid) | |
111 | return -ENOMEM; | |
112 | ||
113 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
114 | sid->base = devm_ioremap_resource(dev, res); | |
115 | if (IS_ERR(sid->base)) | |
116 | return PTR_ERR(sid->base); | |
117 | ||
118 | size = resource_size(res) - 1; | |
119 | sunxi_sid_regmap_config.max_register = size; | |
120 | ||
121 | regmap = devm_regmap_init(dev, &sunxi_sid_bus, sid, | |
122 | &sunxi_sid_regmap_config); | |
123 | if (IS_ERR(regmap)) { | |
124 | dev_err(dev, "regmap init failed\n"); | |
125 | return PTR_ERR(regmap); | |
126 | } | |
127 | ||
128 | econfig.dev = dev; | |
129 | nvmem = nvmem_register(&econfig); | |
130 | if (IS_ERR(nvmem)) | |
131 | return PTR_ERR(nvmem); | |
132 | ||
133 | randomness = kzalloc(sizeof(u8) * size, GFP_KERNEL); | |
134 | for (i = 0; i < size; i++) | |
135 | randomness[i] = sunxi_sid_read_byte(sid, i); | |
136 | ||
137 | add_device_randomness(randomness, size); | |
138 | kfree(randomness); | |
139 | ||
140 | platform_set_drvdata(pdev, nvmem); | |
141 | ||
142 | return 0; | |
143 | } | |
144 | ||
145 | static int sunxi_sid_remove(struct platform_device *pdev) | |
146 | { | |
147 | struct nvmem_device *nvmem = platform_get_drvdata(pdev); | |
148 | ||
149 | return nvmem_unregister(nvmem); | |
150 | } | |
151 | ||
152 | static const struct of_device_id sunxi_sid_of_match[] = { | |
153 | { .compatible = "allwinner,sun4i-a10-sid" }, | |
154 | { .compatible = "allwinner,sun7i-a20-sid" }, | |
155 | {/* sentinel */}, | |
156 | }; | |
157 | MODULE_DEVICE_TABLE(of, sunxi_sid_of_match); | |
158 | ||
159 | static struct platform_driver sunxi_sid_driver = { | |
160 | .probe = sunxi_sid_probe, | |
161 | .remove = sunxi_sid_remove, | |
162 | .driver = { | |
163 | .name = "eeprom-sunxi-sid", | |
164 | .of_match_table = sunxi_sid_of_match, | |
165 | }, | |
166 | }; | |
167 | module_platform_driver(sunxi_sid_driver); | |
168 | ||
169 | MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>"); | |
170 | MODULE_DESCRIPTION("Allwinner sunxi security id driver"); | |
171 | MODULE_LICENSE("GPL"); |