GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / nvmem / mxs-ocotp.c
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
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
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
133 static void mxs_ocotp_action(void *data)
134 {
135         clk_unprepare(data);
136 }
137
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");