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/platform_device.h>
18#include <linux/slab.h>
19
20/*
21 * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts
22 * at offset 0 from the base.
23 *
24 * Bank 0 contains the part ID for Flashless devices and is reseverd for
25 * devices with Flash.
26 * Bank 1/2 is generale purpose or AES key storage for secure devices.
27 * Bank 3 contains control data, USB ID and generale purpose words.
28 */
29#define LPC18XX_OTP_NUM_BANKS		4
30#define LPC18XX_OTP_WORDS_PER_BANK	4
31#define LPC18XX_OTP_WORD_SIZE		sizeof(u32)
32#define LPC18XX_OTP_SIZE		(LPC18XX_OTP_NUM_BANKS * \
33					 LPC18XX_OTP_WORDS_PER_BANK * \
34					 LPC18XX_OTP_WORD_SIZE)
35
36struct lpc18xx_otp {
37	void __iomem *base;
38};
39
40static int lpc18xx_otp_read(void *context, unsigned int offset,
41			    void *val, size_t bytes)
42{
43	struct lpc18xx_otp *otp = context;
44	unsigned int count = bytes >> 2;
45	u32 index = offset >> 2;
46	u32 *buf = val;
47	int i;
48
49	if (count > (LPC18XX_OTP_SIZE - index))
50		count = LPC18XX_OTP_SIZE - index;
51
52	for (i = index; i < (index + count); i++)
53		*buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE);
54
55	return 0;
56}
57
58static struct nvmem_config lpc18xx_otp_nvmem_config = {
59	.name = "lpc18xx-otp",
60	.read_only = true,
61	.word_size = LPC18XX_OTP_WORD_SIZE,
62	.stride = LPC18XX_OTP_WORD_SIZE,
63	.reg_read = lpc18xx_otp_read,
64};
65
66static int lpc18xx_otp_probe(struct platform_device *pdev)
67{
68	struct nvmem_device *nvmem;
69	struct lpc18xx_otp *otp;
70
71	otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL);
72	if (!otp)
73		return -ENOMEM;
74
75	otp->base = devm_platform_ioremap_resource(pdev, 0);
76	if (IS_ERR(otp->base))
77		return PTR_ERR(otp->base);
78
79	lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE;
80	lpc18xx_otp_nvmem_config.dev = &pdev->dev;
81	lpc18xx_otp_nvmem_config.priv = otp;
82
83	nvmem = devm_nvmem_register(&pdev->dev, &lpc18xx_otp_nvmem_config);
84
85	return PTR_ERR_OR_ZERO(nvmem);
86}
87
88static const struct of_device_id lpc18xx_otp_dt_ids[] = {
89	{ .compatible = "nxp,lpc1850-otp" },
90	{ },
91};
92MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids);
93
94static struct platform_driver lpc18xx_otp_driver = {
95	.probe	= lpc18xx_otp_probe,
96	.driver = {
97		.name	= "lpc18xx_otp",
98		.of_match_table = lpc18xx_otp_dt_ids,
99	},
100};
101module_platform_driver(lpc18xx_otp_driver);
102
103MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>");
104MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver");
105MODULE_LICENSE("GPL v2");
106