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/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
  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
  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");