1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Freescale MXS On-Chip OTP driver
4 *
5 * Copyright (C) 2015 Stefan Wahren <stefan.wahren@i2se.com>
6 *
7 * Based on the driver from Huang Shijie and Christoph G. Baumann
8 */
9 #include <linux/clk.h>
10 #include <linux/delay.h>
11 #include <linux/device.h>
12 #include <linux/err.h>
13 #include <linux/io.h>
14 #include <linux/module.h>
15 #include <linux/nvmem-provider.h>
16 #include <linux/of_device.h>
17 #include <linux/platform_device.h>
18 #include <linux/slab.h>
19 #include <linux/stmp_device.h>
20
21 /* OCOTP registers and bits */
22
23 #define BM_OCOTP_CTRL_RD_BANK_OPEN BIT(12)
24 #define BM_OCOTP_CTRL_ERROR BIT(9)
25 #define BM_OCOTP_CTRL_BUSY BIT(8)
26
27 #define OCOTP_TIMEOUT 10000
28 #define OCOTP_DATA_OFFSET 0x20
29
30 struct mxs_ocotp {
31 struct clk *clk;
32 void __iomem *base;
33 struct nvmem_device *nvmem;
34 };
35
mxs_ocotp_wait(struct mxs_ocotp * otp)36 static int mxs_ocotp_wait(struct mxs_ocotp *otp)
37 {
38 int timeout = OCOTP_TIMEOUT;
39 unsigned int status = 0;
40
41 while (timeout--) {
42 status = readl(otp->base);
43
44 if (!(status & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR)))
45 break;
46
47 cpu_relax();
48 }
49
50 if (status & BM_OCOTP_CTRL_BUSY)
51 return -EBUSY;
52 else if (status & BM_OCOTP_CTRL_ERROR)
53 return -EIO;
54
55 return 0;
56 }
57
mxs_ocotp_read(void * context,unsigned int offset,void * val,size_t bytes)58 static int mxs_ocotp_read(void *context, unsigned int offset,
59 void *val, size_t bytes)
60 {
61 struct mxs_ocotp *otp = context;
62 u32 *buf = val;
63 int ret;
64
65 ret = clk_enable(otp->clk);
66 if (ret)
67 return ret;
68
69 writel(BM_OCOTP_CTRL_ERROR, otp->base + STMP_OFFSET_REG_CLR);
70
71 ret = mxs_ocotp_wait(otp);
72 if (ret)
73 goto disable_clk;
74
75 /* open OCOTP banks for read */
76 writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_SET);
77
78 /* approximately wait 33 hclk cycles */
79 udelay(1);
80
81 ret = mxs_ocotp_wait(otp);
82 if (ret)
83 goto close_banks;
84
85 while (bytes) {
86 if ((offset < OCOTP_DATA_OFFSET) || (offset % 16)) {
87 /* fill up non-data register */
88 *buf++ = 0;
89 } else {
90 *buf++ = readl(otp->base + offset);
91 }
92
93 bytes -= 4;
94 offset += 4;
95 }
96
97 close_banks:
98 /* close banks for power saving */
99 writel(BM_OCOTP_CTRL_RD_BANK_OPEN, otp->base + STMP_OFFSET_REG_CLR);
100
101 disable_clk:
102 clk_disable(otp->clk);
103
104 return ret;
105 }
106
107 static struct nvmem_config ocotp_config = {
108 .name = "mxs-ocotp",
109 .stride = 16,
110 .word_size = 4,
111 .reg_read = mxs_ocotp_read,
112 };
113
114 struct mxs_data {
115 int size;
116 };
117
118 static const struct mxs_data imx23_data = {
119 .size = 0x220,
120 };
121
122 static const struct mxs_data imx28_data = {
123 .size = 0x2a0,
124 };
125
126 static const struct of_device_id mxs_ocotp_match[] = {
127 { .compatible = "fsl,imx23-ocotp", .data = &imx23_data },
128 { .compatible = "fsl,imx28-ocotp", .data = &imx28_data },
129 { /* sentinel */},
130 };
131 MODULE_DEVICE_TABLE(of, mxs_ocotp_match);
132
mxs_ocotp_action(void * data)133 static void mxs_ocotp_action(void *data)
134 {
135 clk_unprepare(data);
136 }
137
mxs_ocotp_probe(struct platform_device * pdev)138 static int mxs_ocotp_probe(struct platform_device *pdev)
139 {
140 struct device *dev = &pdev->dev;
141 const struct mxs_data *data;
142 struct mxs_ocotp *otp;
143 const struct of_device_id *match;
144 int ret;
145
146 match = of_match_device(dev->driver->of_match_table, dev);
147 if (!match || !match->data)
148 return -EINVAL;
149
150 otp = devm_kzalloc(dev, sizeof(*otp), GFP_KERNEL);
151 if (!otp)
152 return -ENOMEM;
153
154 otp->base = devm_platform_ioremap_resource(pdev, 0);
155 if (IS_ERR(otp->base))
156 return PTR_ERR(otp->base);
157
158 otp->clk = devm_clk_get(&pdev->dev, NULL);
159 if (IS_ERR(otp->clk))
160 return PTR_ERR(otp->clk);
161
162 ret = clk_prepare(otp->clk);
163 if (ret < 0) {
164 dev_err(dev, "failed to prepare clk: %d\n", ret);
165 return ret;
166 }
167
168 ret = devm_add_action_or_reset(&pdev->dev, mxs_ocotp_action, otp->clk);
169 if (ret)
170 return ret;
171
172 data = match->data;
173
174 ocotp_config.size = data->size;
175 ocotp_config.priv = otp;
176 ocotp_config.dev = dev;
177 otp->nvmem = devm_nvmem_register(dev, &ocotp_config);
178 if (IS_ERR(otp->nvmem))
179 return PTR_ERR(otp->nvmem);
180
181 platform_set_drvdata(pdev, otp);
182
183 return 0;
184 }
185
186 static struct platform_driver mxs_ocotp_driver = {
187 .probe = mxs_ocotp_probe,
188 .driver = {
189 .name = "mxs-ocotp",
190 .of_match_table = mxs_ocotp_match,
191 },
192 };
193
194 module_platform_driver(mxs_ocotp_driver);
195 MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net");
196 MODULE_DESCRIPTION("driver for OCOTP in i.MX23/i.MX28");
197 MODULE_LICENSE("GPL v2");
198