]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - drivers/nvmem/sunxi_sid.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial
[mirror_ubuntu-artful-kernel.git] / drivers / nvmem / sunxi_sid.c
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/slab.h>
25 #include <linux/random.h>
26
27 static struct nvmem_config econfig = {
28 .name = "sunxi-sid",
29 .read_only = true,
30 .stride = 4,
31 .word_size = 1,
32 .owner = THIS_MODULE,
33 };
34
35 struct sunxi_sid {
36 void __iomem *base;
37 };
38
39 /* We read the entire key, due to a 32 bit read alignment requirement. Since we
40 * want to return the requested byte, this results in somewhat slower code and
41 * uses 4 times more reads as needed but keeps code simpler. Since the SID is
42 * only very rarely probed, this is not really an issue.
43 */
44 static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
45 const unsigned int offset)
46 {
47 u32 sid_key;
48
49 sid_key = ioread32be(sid->base + round_down(offset, 4));
50 sid_key >>= (offset % 4) * 8;
51
52 return sid_key; /* Only return the last byte */
53 }
54
55 static int sunxi_sid_read(void *context, unsigned int offset,
56 void *val, size_t bytes)
57 {
58 struct sunxi_sid *sid = context;
59 u8 *buf = val;
60
61 while (bytes--)
62 *buf++ = sunxi_sid_read_byte(sid, offset++);
63
64 return 0;
65 }
66
67 static int sunxi_sid_probe(struct platform_device *pdev)
68 {
69 struct device *dev = &pdev->dev;
70 struct resource *res;
71 struct nvmem_device *nvmem;
72 struct sunxi_sid *sid;
73 int ret, i, size;
74 char *randomness;
75
76 sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
77 if (!sid)
78 return -ENOMEM;
79
80 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
81 sid->base = devm_ioremap_resource(dev, res);
82 if (IS_ERR(sid->base))
83 return PTR_ERR(sid->base);
84
85 size = resource_size(res) - 1;
86 econfig.size = resource_size(res);
87 econfig.dev = dev;
88 econfig.reg_read = sunxi_sid_read;
89 econfig.priv = sid;
90 nvmem = nvmem_register(&econfig);
91 if (IS_ERR(nvmem))
92 return PTR_ERR(nvmem);
93
94 randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL);
95 if (!randomness) {
96 ret = -EINVAL;
97 goto err_unreg_nvmem;
98 }
99
100 for (i = 0; i < size; i++)
101 randomness[i] = sunxi_sid_read_byte(sid, i);
102
103 add_device_randomness(randomness, size);
104 kfree(randomness);
105
106 platform_set_drvdata(pdev, nvmem);
107
108 return 0;
109
110 err_unreg_nvmem:
111 nvmem_unregister(nvmem);
112 return ret;
113 }
114
115 static int sunxi_sid_remove(struct platform_device *pdev)
116 {
117 struct nvmem_device *nvmem = platform_get_drvdata(pdev);
118
119 return nvmem_unregister(nvmem);
120 }
121
122 static const struct of_device_id sunxi_sid_of_match[] = {
123 { .compatible = "allwinner,sun4i-a10-sid" },
124 { .compatible = "allwinner,sun7i-a20-sid" },
125 {/* sentinel */},
126 };
127 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
128
129 static struct platform_driver sunxi_sid_driver = {
130 .probe = sunxi_sid_probe,
131 .remove = sunxi_sid_remove,
132 .driver = {
133 .name = "eeprom-sunxi-sid",
134 .of_match_table = sunxi_sid_of_match,
135 },
136 };
137 module_platform_driver(sunxi_sid_driver);
138
139 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
140 MODULE_DESCRIPTION("Allwinner sunxi security id driver");
141 MODULE_LICENSE("GPL");