1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * NXP LPC18xx/43xx OTP memory NVMEM driver
4 *
5 * Copyright (c) 2016 Joachim Eastwood <manabian@gmail.com>
6 *
7 * Based on the imx ocotp driver,
8 * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de>
9 *
10 * TODO: add support for writing OTP register via API in boot ROM.
11 */
12
13 #include <linux/io.h>
14 #include <linux/module.h>
15 #include <linux/nvmem-provider.h>
16 #include <linux/of.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/slab.h>
20
21 /*
22 * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts
23 * at offset 0 from the base.
24 *
25 * Bank 0 contains the part ID for Flashless devices and is reseverd for
26 * devices with Flash.
27 * Bank 1/2 is generale purpose or AES key storage for secure devices.
28 * Bank 3 contains control data, USB ID and generale purpose words.
29 */
30 #define LPC18XX_OTP_NUM_BANKS 4
31 #define LPC18XX_OTP_WORDS_PER_BANK 4
32 #define LPC18XX_OTP_WORD_SIZE sizeof(u32)
33 #define LPC18XX_OTP_SIZE (LPC18XX_OTP_NUM_BANKS * \
34 LPC18XX_OTP_WORDS_PER_BANK * \
35 LPC18XX_OTP_WORD_SIZE)
36
37 struct lpc18xx_otp {
38 void __iomem *base;
39 };
40
lpc18xx_otp_read(void * context,unsigned int offset,void * val,size_t bytes)41 static int lpc18xx_otp_read(void *context, unsigned int offset,
42 void *val, size_t bytes)
43 {
44 struct lpc18xx_otp *otp = context;
45 unsigned int count = bytes >> 2;
46 u32 index = offset >> 2;
47 u32 *buf = val;
48 int i;
49
50 if (count > (LPC18XX_OTP_SIZE - index))
51 count = LPC18XX_OTP_SIZE - index;
52
53 for (i = index; i < (index + count); i++)
54 *buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE);
55
56 return 0;
57 }
58
59 static struct nvmem_config lpc18xx_otp_nvmem_config = {
60 .name = "lpc18xx-otp",
61 .read_only = true,
62 .word_size = LPC18XX_OTP_WORD_SIZE,
63 .stride = LPC18XX_OTP_WORD_SIZE,
64 .reg_read = lpc18xx_otp_read,
65 };
66
lpc18xx_otp_probe(struct platform_device * pdev)67 static int lpc18xx_otp_probe(struct platform_device *pdev)
68 {
69 struct nvmem_device *nvmem;
70 struct lpc18xx_otp *otp;
71 struct resource *res;
72
73 otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL);
74 if (!otp)
75 return -ENOMEM;
76
77 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
78 otp->base = devm_ioremap_resource(&pdev->dev, res);
79 if (IS_ERR(otp->base))
80 return PTR_ERR(otp->base);
81
82 lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE;
83 lpc18xx_otp_nvmem_config.dev = &pdev->dev;
84 lpc18xx_otp_nvmem_config.priv = otp;
85
86 nvmem = devm_nvmem_register(&pdev->dev, &lpc18xx_otp_nvmem_config);
87
88 return PTR_ERR_OR_ZERO(nvmem);
89 }
90
91 static const struct of_device_id lpc18xx_otp_dt_ids[] = {
92 { .compatible = "nxp,lpc1850-otp" },
93 { },
94 };
95 MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids);
96
97 static struct platform_driver lpc18xx_otp_driver = {
98 .probe = lpc18xx_otp_probe,
99 .driver = {
100 .name = "lpc18xx_otp",
101 .of_match_table = lpc18xx_otp_dt_ids,
102 },
103 };
104 module_platform_driver(lpc18xx_otp_driver);
105
106 MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>");
107 MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver");
108 MODULE_LICENSE("GPL v2");
109