1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Allwinner sunXi SoCs Security ID support.
4 *
5 * Copyright (c) 2013 Oliver Schinagl <oliver@schinagl.nl>
6 * Copyright (C) 2014 Maxime Ripard <maxime.ripard@free-electrons.com>
7 */
8
9#include <linux/device.h>
10#include <linux/io.h>
11#include <linux/iopoll.h>
12#include <linux/module.h>
13#include <linux/nvmem-provider.h>
14#include <linux/of.h>
15#include <linux/platform_device.h>
16#include <linux/slab.h>
17#include <linux/random.h>
18
19/* Registers and special values for doing register-based SID readout on H3 */
20#define SUN8I_SID_PRCTL		0x40
21#define SUN8I_SID_RDKEY		0x60
22
23#define SUN8I_SID_OFFSET_MASK	0x1FF
24#define SUN8I_SID_OFFSET_SHIFT	16
25#define SUN8I_SID_OP_LOCK	(0xAC << 8)
26#define SUN8I_SID_READ		BIT(1)
27
28struct sunxi_sid_cfg {
29	u32	value_offset;
30	u32	size;
31	bool	need_register_readout;
32};
33
34struct sunxi_sid {
35	void __iomem		*base;
36	u32			value_offset;
37};
38
39static int sunxi_sid_read(void *context, unsigned int offset,
40			  void *val, size_t bytes)
41{
42	struct sunxi_sid *sid = context;
43	u32 word;
44
45	/* .stride = 4 so offset is guaranteed to be aligned */
46	__ioread32_copy(val, sid->base + sid->value_offset + offset, bytes / 4);
47
48	val += round_down(bytes, 4);
49	offset += round_down(bytes, 4);
50	bytes = bytes % 4;
51
52	if (!bytes)
53		return 0;
54
55	/* Handle any trailing bytes */
56	word = readl_relaxed(sid->base + sid->value_offset + offset);
57	memcpy(val, &word, bytes);
58
59	return 0;
60}
61
62static int sun8i_sid_register_readout(const struct sunxi_sid *sid,
63				      const unsigned int offset,
64				      u32 *out)
65{
66	u32 reg_val;
67	int ret;
68
69	/* Set word, lock access, and set read command */
70	reg_val = (offset & SUN8I_SID_OFFSET_MASK)
71		  << SUN8I_SID_OFFSET_SHIFT;
72	reg_val |= SUN8I_SID_OP_LOCK | SUN8I_SID_READ;
73	writel(reg_val, sid->base + SUN8I_SID_PRCTL);
74
75	ret = readl_poll_timeout(sid->base + SUN8I_SID_PRCTL, reg_val,
76				 !(reg_val & SUN8I_SID_READ), 100, 250000);
77	if (ret)
78		return ret;
79
80	if (out)
81		*out = readl(sid->base + SUN8I_SID_RDKEY);
82
83	writel(0, sid->base + SUN8I_SID_PRCTL);
84
85	return 0;
86}
87
88/*
89 * On Allwinner H3, the value on the 0x200 offset of the SID controller seems
90 * to be not reliable at all.
91 * Read by the registers instead.
92 */
93static int sun8i_sid_read_by_reg(void *context, unsigned int offset,
94				 void *val, size_t bytes)
95{
96	struct sunxi_sid *sid = context;
97	u32 word;
98	int ret;
99
100	/* .stride = 4 so offset is guaranteed to be aligned */
101	while (bytes >= 4) {
102		ret = sun8i_sid_register_readout(sid, offset, val);
103		if (ret)
104			return ret;
105
106		val += 4;
107		offset += 4;
108		bytes -= 4;
109	}
110
111	if (!bytes)
112		return 0;
113
114	/* Handle any trailing bytes */
115	ret = sun8i_sid_register_readout(sid, offset, &word);
116	if (ret)
117		return ret;
118
119	memcpy(val, &word, bytes);
120
121	return 0;
122}
123
124static int sunxi_sid_probe(struct platform_device *pdev)
125{
126	struct device *dev = &pdev->dev;
127	struct nvmem_config *nvmem_cfg;
128	struct nvmem_device *nvmem;
129	struct sunxi_sid *sid;
130	int size;
131	char *randomness;
132	const struct sunxi_sid_cfg *cfg;
133
134	sid = devm_kzalloc(dev, sizeof(*sid), GFP_KERNEL);
135	if (!sid)
136		return -ENOMEM;
137
138	cfg = of_device_get_match_data(dev);
139	if (!cfg)
140		return -EINVAL;
141	sid->value_offset = cfg->value_offset;
142
143	sid->base = devm_platform_ioremap_resource(pdev, 0);
144	if (IS_ERR(sid->base))
145		return PTR_ERR(sid->base);
146
147	size = cfg->size;
148
149	nvmem_cfg = devm_kzalloc(dev, sizeof(*nvmem_cfg), GFP_KERNEL);
150	if (!nvmem_cfg)
151		return -ENOMEM;
152
153	nvmem_cfg->dev = dev;
154	nvmem_cfg->name = "sunxi-sid";
155	nvmem_cfg->type = NVMEM_TYPE_OTP;
156	nvmem_cfg->read_only = true;
157	nvmem_cfg->size = cfg->size;
158	nvmem_cfg->word_size = 1;
159	nvmem_cfg->stride = 4;
160	nvmem_cfg->priv = sid;
161	if (cfg->need_register_readout)
162		nvmem_cfg->reg_read = sun8i_sid_read_by_reg;
163	else
164		nvmem_cfg->reg_read = sunxi_sid_read;
165
166	nvmem = devm_nvmem_register(dev, nvmem_cfg);
167	if (IS_ERR(nvmem))
168		return PTR_ERR(nvmem);
169
170	randomness = kzalloc(size, GFP_KERNEL);
171	if (!randomness)
172		return -ENOMEM;
173
174	nvmem_cfg->reg_read(sid, 0, randomness, size);
175	add_device_randomness(randomness, size);
176	kfree(randomness);
177
178	platform_set_drvdata(pdev, nvmem);
179
180	return 0;
181}
182
183static const struct sunxi_sid_cfg sun4i_a10_cfg = {
184	.size = 0x10,
185};
186
187static const struct sunxi_sid_cfg sun7i_a20_cfg = {
188	.size = 0x200,
189};
190
191static const struct sunxi_sid_cfg sun8i_h3_cfg = {
192	.value_offset = 0x200,
193	.size = 0x100,
194	.need_register_readout = true,
195};
196
197static const struct sunxi_sid_cfg sun50i_a64_cfg = {
198	.value_offset = 0x200,
199	.size = 0x100,
200};
201
202static const struct sunxi_sid_cfg sun50i_h6_cfg = {
203	.value_offset = 0x200,
204	.size = 0x200,
205};
206
207static const struct of_device_id sunxi_sid_of_match[] = {
208	{ .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
209	{ .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
210	{ .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg },
211	{ .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
212	{ .compatible = "allwinner,sun20i-d1-sid", .data = &sun50i_a64_cfg },
213	{ .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg },
214	{ .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg },
215	{ .compatible = "allwinner,sun50i-h6-sid", .data = &sun50i_h6_cfg },
216	{/* sentinel */},
217};
218MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
219
220static struct platform_driver sunxi_sid_driver = {
221	.probe = sunxi_sid_probe,
222	.driver = {
223		.name = "eeprom-sunxi-sid",
224		.of_match_table = sunxi_sid_of_match,
225	},
226};
227module_platform_driver(sunxi_sid_driver);
228
229MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
230MODULE_DESCRIPTION("Allwinner sunxi security id driver");
231MODULE_LICENSE("GPL");
232