drivers/nvmem/lpc18xx_otp.c

   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 reserved 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
  36 struct lpc18xx_otp {
  37         void __iomem *base;
  38 };
  39
  40 static 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
  58 static 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
  66 static 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
  88 static const struct of_device_id lpc18xx_otp_dt_ids[] = {
  89         { .compatible = "nxp,lpc1850-otp" },
  90         { },
  91 };
  92 MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids);
  93
  94 static 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 };
 101 module_platform_driver(lpc18xx_otp_driver);
 102
 103 MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>");
 104 MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver");
 105 MODULE_LICENSE("GPL v2");