summaryrefslogtreecommitdiffstats
path: root/drivers/nvmem/sunxi_sid.c
blob: e26ef1bbf1981ebcc13aca5fef4af9d4b7aac0a0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
// SPDX-License-Identifier: GPL-2.0+
/*
 * Allwinner sunXi SoCs Security ID support.
 *
 * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
 * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/device.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/random.h>

/* Registers and special values for doing register-based SID readout on H3 */
#define SUN8I_SID_PRCTL		0x40
#define SUN8I_SID_RDKEY		0x60

#define SUN8I_SID_OFFSET_MASK	0x1FF
#define SUN8I_SID_OFFSET_SHIFT	16
#define SUN8I_SID_OP_LOCK	(0xAC << 8)
#define SUN8I_SID_READ		BIT(1)

struct sunxi_sid_cfg {
	u32	value_offset;
	u32	size;
	bool	need_register_readout;
};

struct sunxi_sid {
	void __iomem		*base;
	u32			value_offset;
};

static int sunxi_sid_read(void *context, unsigned int offset,
			  void *val, size_t bytes)
{
	struct sunxi_sid *sid = context;

	memcpy_fromio(val, sid->base + sid->value_offset + offset, bytes);

	return 0;
}

static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
				      const unsigned int offset,
				      u32 *out)
{
	u32 reg_val;
	int ret;

	/* Set word, lock access, and set read command */
	reg_val = (offset & SUN8I_SID_OFFSET_MASK)
		  << SUN8I_SID_OFFSET_SHIFT;
	reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ;
	writel(reg_val, sid->base + SUN8I_SID_PRCTL);

	ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val,
				 !(reg_val & SUN8I_SID_READ), 100, 250000);
	if (ret)
		return ret;

	if (out)
		*out = readl(sid->base + SUN8I_SID_RDKEY);

	writel(0, sid->base + SUN8I_SID_PRCTL);

	return 0;
}

/*
 * On Allwinner H3, the value on the 0x200 offset of the SID controller seems
 * to be not reliable at all.
 * Read by the registers instead.
 */
static int sun8i_sid_read_by_reg(void *context, unsigned int offset,
				 void *val, size_t bytes)
{
	struct sunxi_sid *sid = context;
	u32 word;
	int ret;

	/* .stride = 4 so offset is guaranteed to be aligned */
	while (bytes >= 4) {
		ret = sun8i_sid_register_readout(sid, offset, val);
		if (ret)
			return ret;

		val += 4;
		offset += 4;
		bytes -= 4;
	}

	if (!bytes)
		return 0;

	/* Handle any trailing bytes */
	ret = sun8i_sid_register_readout(sid, offset, &word);
	if (ret)
		return ret;

	memcpy(val, &word, bytes);

	return 0;
}

static int sunxi_sid_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct resource *res;
	struct nvmem_config *nvmem_cfg;
	struct nvmem_device *nvmem;
	struct sunxi_sid *sid;
	int size;
	char *randomness;
	const struct sunxi_sid_cfg *cfg;

	sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
	if (!sid)
		return -ENOMEM;

	cfg = of_device_get_match_data(dev);
	if (!cfg)
		return -EINVAL;
	sid->value_offset = cfg->value_offset;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	sid->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(sid->base))
		return PTR_ERR(sid->base);

	size = cfg->size;

	nvmem_cfg = devm_kzalloc(dev, sizeof(*nvmem_cfg), GFP_KERNEL);
	if (!nvmem_cfg)
		return -ENOMEM;

	nvmem_cfg->dev = dev;
	nvmem_cfg->name = "sunxi-sid";
	nvmem_cfg->read_only = true;
	nvmem_cfg->size = cfg->size;
	nvmem_cfg->word_size = 1;
	nvmem_cfg->stride = 4;
	nvmem_cfg->priv = sid;
	if (cfg->need_register_readout)
		nvmem_cfg->reg_read = sun8i_sid_read_by_reg;
	else
		nvmem_cfg->reg_read = sunxi_sid_read;

	nvmem = devm_nvmem_register(dev, nvmem_cfg);
	if (IS_ERR(nvmem))
		return PTR_ERR(nvmem);

	randomness = kzalloc(size, GFP_KERNEL);
	if (!randomness)
		return -ENOMEM;

	nvmem_cfg->reg_read(sid, 0, randomness, size);
	add_device_randomness(randomness, size);
	kfree(randomness);

	platform_set_drvdata(pdev, nvmem);

	return 0;
}

static const struct sunxi_sid_cfg sun4i_a10_cfg = {
	.size = 0x10,
};

static const struct sunxi_sid_cfg sun7i_a20_cfg = {
	.size = 0x200,
};

static const struct sunxi_sid_cfg sun8i_h3_cfg = {
	.value_offset = 0x200,
	.size = 0x100,
	.need_register_readout = true,
};

static const struct sunxi_sid_cfg sun50i_a64_cfg = {
	.value_offset = 0x200,
	.size = 0x100,
	.need_register_readout = true,
};

static const struct sunxi_sid_cfg sun50i_h6_cfg = {
	.value_offset = 0x200,
	.size = 0x200,
};

static const struct of_device_id sunxi_sid_of_match[] = {
	{ .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
	{ .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
	{ .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg },
	{ .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
	{ .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg },
	{ .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg },
	{ .compatible = "allwinner,sun50i-h6-sid", .data = &sun50i_h6_cfg },
	{/* sentinel */},
};
MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);

static struct platform_driver sunxi_sid_driver = {
	.probe = sunxi_sid_probe,
	.driver = {
		.name = "eeprom-sunxi-sid",
		.of_match_table = sunxi_sid_of_match,
	},
};
module_platform_driver(sunxi_sid_driver);

MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
MODULE_DESCRIPTION("Allwinner sunxi security id driver");
MODULE_LICENSE("GPL");