blob: cfa3b85064dd233a463b1556742274d960e4f47b [file] [log] [blame]
Maxime Ripard3d0b16a2015-07-27 12:17:09 +01001/*
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
31static struct nvmem_config econfig = {
32 .name = "sunxi-sid",
33 .read_only = true,
34 .owner = THIS_MODULE,
35};
36
37struct 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 */
46static 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
57static 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
74static 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
80static 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
87static bool sunxi_sid_writeable_reg(struct device *dev, unsigned int reg)
88{
89 return false;
90}
91
92static 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
99static 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;
Maxime Ripardfb727072015-09-30 13:36:31 +0100106 int ret, i, size;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100107 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);
Maxime Ripardfb727072015-09-30 13:36:31 +0100134 if (!randomness) {
135 ret = -EINVAL;
136 goto err_unreg_nvmem;
137 }
138
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100139 for (i = 0; i < size; i++)
140 randomness[i] = sunxi_sid_read_byte(sid, i);
141
142 add_device_randomness(randomness, size);
143 kfree(randomness);
144
145 platform_set_drvdata(pdev, nvmem);
146
147 return 0;
Maxime Ripardfb727072015-09-30 13:36:31 +0100148
149err_unreg_nvmem:
150 nvmem_unregister(nvmem);
151 return ret;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100152}
153
154static int sunxi_sid_remove(struct platform_device *pdev)
155{
156 struct nvmem_device *nvmem = platform_get_drvdata(pdev);
157
158 return nvmem_unregister(nvmem);
159}
160
161static const struct of_device_id sunxi_sid_of_match[] = {
162 { .compatible = "allwinner,sun4i-a10-sid" },
163 { .compatible = "allwinner,sun7i-a20-sid" },
164 {/* sentinel */},
165};
166MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
167
168static struct platform_driver sunxi_sid_driver = {
169 .probe = sunxi_sid_probe,
170 .remove = sunxi_sid_remove,
171 .driver = {
172 .name = "eeprom-sunxi-sid",
173 .of_match_table = sunxi_sid_of_match,
174 },
175};
176module_platform_driver(sunxi_sid_driver);
177
178MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
179MODULE_DESCRIPTION("Allwinner sunxi security id driver");
180MODULE_LICENSE("GPL");