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 
28 struct sunxi_sid_cfg {
29 	u32	value_offset;
30 	u32	size;
31 	bool	need_register_readout;
32 };
33 
34 struct sunxi_sid {
35 	void __iomem		*base;
36 	u32			value_offset;
37 };
38 
sunxi_sid_read(void * context,unsigned int offset,void * val,size_t bytes)39 static 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 
sun8i_sid_register_readout(const struct sunxi_sid * sid,const unsigned int offset,u32 * out)62 static 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  */
sun8i_sid_read_by_reg(void * context,unsigned int offset,void * val,size_t bytes)93 static 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 
sunxi_sid_probe(struct platform_device * pdev)124 static 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->add_legacy_fixed_of_cells = true;
157 	nvmem_cfg->read_only = true;
158 	nvmem_cfg->size = cfg->size;
159 	nvmem_cfg->word_size = 1;
160 	nvmem_cfg->stride = 4;
161 	nvmem_cfg->priv = sid;
162 	if (cfg->need_register_readout)
163 		nvmem_cfg->reg_read = sun8i_sid_read_by_reg;
164 	else
165 		nvmem_cfg->reg_read = sunxi_sid_read;
166 
167 	nvmem = devm_nvmem_register(dev, nvmem_cfg);
168 	if (IS_ERR(nvmem))
169 		return PTR_ERR(nvmem);
170 
171 	randomness = kzalloc(size, GFP_KERNEL);
172 	if (!randomness)
173 		return -ENOMEM;
174 
175 	nvmem_cfg->reg_read(sid, 0, randomness, size);
176 	add_device_randomness(randomness, size);
177 	kfree(randomness);
178 
179 	platform_set_drvdata(pdev, nvmem);
180 
181 	return 0;
182 }
183 
184 static const struct sunxi_sid_cfg sun4i_a10_cfg = {
185 	.size = 0x10,
186 };
187 
188 static const struct sunxi_sid_cfg sun7i_a20_cfg = {
189 	.size = 0x200,
190 };
191 
192 static const struct sunxi_sid_cfg sun8i_h3_cfg = {
193 	.value_offset = 0x200,
194 	.size = 0x100,
195 	.need_register_readout = true,
196 };
197 
198 static const struct sunxi_sid_cfg sun50i_a64_cfg = {
199 	.value_offset = 0x200,
200 	.size = 0x100,
201 };
202 
203 static const struct sunxi_sid_cfg sun50i_h6_cfg = {
204 	.value_offset = 0x200,
205 	.size = 0x200,
206 };
207 
208 static const struct of_device_id sunxi_sid_of_match[] = {
209 	{ .compatible = "allwinner,sun4i-a10-sid", .data = &sun4i_a10_cfg },
210 	{ .compatible = "allwinner,sun7i-a20-sid", .data = &sun7i_a20_cfg },
211 	{ .compatible = "allwinner,sun8i-a83t-sid", .data = &sun50i_a64_cfg },
212 	{ .compatible = "allwinner,sun8i-h3-sid", .data = &sun8i_h3_cfg },
213 	{ .compatible = "allwinner,sun20i-d1-sid", .data = &sun50i_a64_cfg },
214 	{ .compatible = "allwinner,sun50i-a64-sid", .data = &sun50i_a64_cfg },
215 	{ .compatible = "allwinner,sun50i-h5-sid", .data = &sun50i_a64_cfg },
216 	{ .compatible = "allwinner,sun50i-h6-sid", .data = &sun50i_h6_cfg },
217 	{/* sentinel */},
218 };
219 MODULE_DEVICE_TABLE(of, sunxi_sid_of_match);
220 
221 static struct platform_driver sunxi_sid_driver = {
222 	.probe = sunxi_sid_probe,
223 	.driver = {
224 		.name = "eeprom-sunxi-sid",
225 		.of_match_table = sunxi_sid_of_match,
226 	},
227 };
228 module_platform_driver(sunxi_sid_driver);
229 
230 MODULE_AUTHOR("Oliver Schinagl <oliver@schinagl.nl>");
231 MODULE_DESCRIPTION("Allwinner sunxi security id driver");
232 MODULE_LICENSE("GPL");
233