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