tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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#include <linux/device.h>
19#include <linux/io.h>
20#include <linux/module.h>
21#include <linux/nvmem-provider.h>
22#include <linux/of.h>
23#include <linux/platform_device.h>
24#include <linux/regmap.h>
25#include <linux/slab.h>
26#include <linux/random.h>
27
28static struct nvmem_config econfig = {
29 .name = "sunxi-sid",
30 .read_only = true,
31 .owner = THIS_MODULE,
32};
33
34struct sunxi_sid {
35 void __iomem *base;
36};
37
38/* We read the entire key, due to a 32 bit read alignment requirement. Since we
39 * want to return the requested byte, this results in somewhat slower code and
40 * uses 4 times more reads as needed but keeps code simpler. Since the SID is
41 * only very rarely probed, this is not really an issue.
42 */
43static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
44 const unsigned int offset)
45{
46 u32 sid_key;
47
48 sid_key = ioread32be(sid->base + round_down(offset, 4));
49 sid_key >>= (offset % 4) * 8;
50
51 return sid_key; /* Only return the last byte */
52}
53
54static int sunxi_sid_read(void *context,
55 const void *reg, size_t reg_size,
56 void *val, size_t val_size)
57{
58 struct sunxi_sid *sid = context;
59 unsigned int offset = *(u32 *)reg;
60 u8 *buf = val;
61
62 while (val_size) {
63 *buf++ = sunxi_sid_read_byte(sid, offset);
64 val_size--;
65 offset++;
66 }
67
68 return 0;
69}
70
71static int sunxi_sid_write(void *context, const void *data, size_t count)
72{
73 /* Unimplemented, dummy to keep regmap core happy */
74 return 0;
75}
76
77static struct regmap_bus sunxi_sid_bus = {
78 .read = sunxi_sid_read,
79 .write = sunxi_sid_write,
80 .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
81 .val_format_endian_default = REGMAP_ENDIAN_NATIVE,
82};
83
84static bool sunxi_sid_writeable_reg(struct device *dev, unsigned int reg)
85{
86 return false;
87}
88
89static struct regmap_config sunxi_sid_regmap_config = {
90 .reg_bits = 32,
91 .val_bits = 8,
92 .reg_stride = 1,
93 .writeable_reg = sunxi_sid_writeable_reg,
94};
95
96static int sunxi_sid_probe(struct platform_device *pdev)
97{
98 struct device *dev = &pdev->dev;
99 struct resource *res;
100 struct nvmem_device *nvmem;
101 struct regmap *regmap;
102 struct sunxi_sid *sid;
103 int ret, i, size;
104 char *randomness;
105
106 sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
107 if (!sid)
108 return -ENOMEM;
109
110 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
111 sid->base = devm_ioremap_resource(dev, res);
112 if (IS_ERR(sid->base))
113 return PTR_ERR(sid->base);
114
115 size = resource_size(res) - 1;
116 sunxi_sid_regmap_config.max_register = size;
117
118 regmap = devm_regmap_init(dev, &sunxi_sid_bus, sid,
119 &sunxi_sid_regmap_config);
120 if (IS_ERR(regmap)) {
121 dev_err(dev, "regmap init failed\n");
122 return PTR_ERR(regmap);
123 }
124
125 econfig.dev = dev;
126 nvmem = nvmem_register(&econfig);
127 if (IS_ERR(nvmem))
128 return PTR_ERR(nvmem);
129
130 randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL);
131 if (!randomness) {
132 ret = -EINVAL;
133 goto err_unreg_nvmem;
134 }
135
136 for (i = 0; i < size; i++)
137 randomness[i] = sunxi_sid_read_byte(sid, i);
138
139 add_device_randomness(randomness, size);
140 kfree(randomness);
141
142 platform_set_drvdata(pdev, nvmem);
143
144 return 0;
145
146err_unreg_nvmem:
147 nvmem_unregister(nvmem);
148 return ret;
149}
150
151static int sunxi_sid_remove(struct platform_device *pdev)
152{
153 struct nvmem_device *nvmem = platform_get_drvdata(pdev);
154
155 return nvmem_unregister(nvmem);
156}
157
158static const struct of_device_id sunxi_sid_of_match[] = {
159 { .compatible = "allwinner,sun4i-a10-sid" },
160 { .compatible = "allwinner,sun7i-a20-sid" },
161 {/* sentinel */},
162};
163MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
164
165static struct platform_driver sunxi_sid_driver = {
166 .probe = sunxi_sid_probe,
167 .remove = sunxi_sid_remove,
168 .driver = {
169 .name = "eeprom-sunxi-sid",
170 .of_match_table = sunxi_sid_of_match,
171 },
172};
173module_platform_driver(sunxi_sid_driver);
174
175MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
176MODULE_DESCRIPTION("Allwinner sunxi security id driver");
177MODULE_LICENSE("GPL");