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