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