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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.
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010016 */
17
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010018#include <linux/device.h>
19#include <linux/io.h>
Icenowy Zheng1a963642017-03-31 13:44:48 +010020#include <linux/iopoll.h>
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010021#include <linux/module.h>
22#include <linux/nvmem-provider.h>
23#include <linux/of.h>
Icenowy Zheng4a72cda2017-03-31 13:44:47 +010024#include <linux/of_device.h>
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010025#include <linux/platform_device.h>
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010026#include <linux/slab.h>
27#include <linux/random.h>
28
Icenowy Zheng1a963642017-03-31 13:44:48 +010029/* Registers and special values for doing register-based SID readout on H3 */
30#define SUN8I_SID_PRCTL 0x40
31#define SUN8I_SID_RDKEY 0x60
32
33#define SUN8I_SID_OFFSET_MASK 0x1FF
34#define SUN8I_SID_OFFSET_SHIFT 16
35#define SUN8I_SID_OP_LOCK (0xAC << 8)
36#define SUN8I_SID_READ BIT(1)
37
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010038static struct nvmem_config econfig = {
39 .name = "sunxi-sid",
40 .read_only = true,
Srinivas Kandagatla9c7b16e2016-04-24 20:28:10 +010041 .stride = 4,
42 .word_size = 1,
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010043 .owner = THIS_MODULE,
44};
45
Icenowy Zheng4a72cda2017-03-31 13:44:47 +010046struct sunxi_sid_cfg {
Icenowy Zheng1a963642017-03-31 13:44:48 +010047 u32 value_offset;
Icenowy Zheng4a72cda2017-03-31 13:44:47 +010048 u32 size;
Icenowy Zheng1a963642017-03-31 13:44:48 +010049 bool need_register_readout;
Icenowy Zheng4a72cda2017-03-31 13:44:47 +010050};
51
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010052struct sunxi_sid {
53 void __iomem *base;
Icenowy Zheng1a963642017-03-31 13:44:48 +010054 u32 value_offset;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010055};
56
57/* We read the entire key, due to a 32 bit read alignment requirement. Since we
58 * want to return the requested byte, this results in somewhat slower code and
59 * uses 4 times more reads as needed but keeps code simpler. Since the SID is
60 * only very rarely probed, this is not really an issue.
61 */
62static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
63 const unsigned int offset)
64{
65 u32 sid_key;
66
67 sid_key = ioread32be(sid->base + round_down(offset, 4));
68 sid_key >>= (offset % 4) * 8;
69
70 return sid_key; /* Only return the last byte */
71}
72
Srinivas Kandagatla9c7b16e2016-04-24 20:28:10 +010073static int sunxi_sid_read(void *context, unsigned int offset,
74 void *val, size_t bytes)
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010075{
76 struct sunxi_sid *sid = context;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010077 u8 *buf = val;
78
Icenowy Zheng1a963642017-03-31 13:44:48 +010079 /* Offset the read operation to the real position of SID */
80 offset += sid->value_offset;
81
Srinivas Kandagatla9c7b16e2016-04-24 20:28:10 +010082 while (bytes--)
83 *buf++ = sunxi_sid_read_byte(sid, offset++);
Maxime Ripard3d0b16a2015-07-27 12:17:09 +010084
85 return 0;
86}
87
Icenowy Zheng1a963642017-03-31 13:44:48 +010088static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
89 const unsigned int word)
90{
91 u32 reg_val;
92 int ret;
93
94 /* Set word, lock access, and set read command */
95 reg_val = (word & SUN8I_SID_OFFSET_MASK)
96 << SUN8I_SID_OFFSET_SHIFT;
97 reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ;
98 writel(reg_val, sid->base + SUN8I_SID_PRCTL);
99
100 ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val,
101 !(reg_val & SUN8I_SID_READ), 100, 250000);
102 if (ret)
103 return ret;
104
105 writel(0, sid->base + SUN8I_SID_PRCTL);
106 return 0;
107}
108
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100109static int sunxi_sid_probe(struct platform_device *pdev)
110{
111 struct device *dev = &pdev->dev;
112 struct resource *res;
113 struct nvmem_device *nvmem;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100114 struct sunxi_sid *sid;
Maxime Ripardfb727072015-09-30 13:36:31 +0100115 int ret, i, size;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100116 char *randomness;
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100117 const struct sunxi_sid_cfg *cfg;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100118
119 sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
120 if (!sid)
121 return -ENOMEM;
122
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100123 cfg = of_device_get_match_data(dev);
124 if (!cfg)
125 return -EINVAL;
Icenowy Zheng1a963642017-03-31 13:44:48 +0100126 sid->value_offset = cfg->value_offset;
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100127
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100128 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
129 sid->base = devm_ioremap_resource(dev, res);
130 if (IS_ERR(sid->base))
131 return PTR_ERR(sid->base);
132
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100133 size = cfg->size;
134
Icenowy Zheng1a963642017-03-31 13:44:48 +0100135 if (cfg->need_register_readout) {
136 /*
137 * H3's SID controller have a bug that the value at 0x200
138 * offset is not the correct value when the hardware is reseted.
139 * However, after doing a register-based read operation, the
140 * value become right.
141 * Do a full read operation here, but ignore its value
142 * (as it's more fast to read by direct MMIO value than
143 * with registers)
144 */
145 for (i = 0; i < (size >> 2); i++) {
146 ret = sun8i_sid_register_readout(sid, i);
147 if (ret)
148 return ret;
149 }
150 }
151
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100152 econfig.size = size;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100153 econfig.dev = dev;
Srinivas Kandagatla9c7b16e2016-04-24 20:28:10 +0100154 econfig.reg_read = sunxi_sid_read;
155 econfig.priv = sid;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100156 nvmem = nvmem_register(&econfig);
157 if (IS_ERR(nvmem))
158 return PTR_ERR(nvmem);
159
Caesar Wangd16abd32015-12-14 09:43:21 +0000160 randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL);
Maxime Ripardfb727072015-09-30 13:36:31 +0100161 if (!randomness) {
162 ret = -EINVAL;
163 goto err_unreg_nvmem;
164 }
165
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100166 for (i = 0; i < size; i++)
167 randomness[i] = sunxi_sid_read_byte(sid, i);
168
169 add_device_randomness(randomness, size);
170 kfree(randomness);
171
172 platform_set_drvdata(pdev, nvmem);
173
174 return 0;
Maxime Ripardfb727072015-09-30 13:36:31 +0100175
176err_unreg_nvmem:
177 nvmem_unregister(nvmem);
178 return ret;
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100179}
180
181static int sunxi_sid_remove(struct platform_device *pdev)
182{
183 struct nvmem_device *nvmem = platform_get_drvdata(pdev);
184
185 return nvmem_unregister(nvmem);
186}
187
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100188static const struct sunxi_sid_cfg sun4i_a10_cfg = {
189 .size = 0x10,
190};
191
192static const struct sunxi_sid_cfg sun7i_a20_cfg = {
193 .size = 0x200,
194};
195
Icenowy Zheng1a963642017-03-31 13:44:48 +0100196static const struct sunxi_sid_cfg sun8i_h3_cfg = {
197 .value_offset = 0x200,
198 .size = 0x100,
199 .need_register_readout = true,
200};
201
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100202static const struct of_device_id sunxi_sid_of_match[] = {
Icenowy Zheng4a72cda2017-03-31 13:44:47 +0100203 { .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
204 { .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
Icenowy Zheng1a963642017-03-31 13:44:48 +0100205 { .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
Maxime Ripard3d0b16a2015-07-27 12:17:09 +0100206 {/* sentinel */},
207};
208MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
209
210static struct platform_driver sunxi_sid_driver = {
211 .probe = sunxi_sid_probe,
212 .remove = sunxi_sid_remove,
213 .driver = {
214 .name = "eeprom-sunxi-sid",
215 .of_match_table = sunxi_sid_of_match,
216 },
217};
218module_platform_driver(sunxi_sid_driver);
219
220MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
221MODULE_DESCRIPTION("Allwinner sunxi security id driver");
222MODULE_LICENSE("GPL");