diff options
Diffstat (limited to 'drivers/nvmem/lpc18xx_otp.c')
| -rw-r--r-- | drivers/nvmem/lpc18xx_otp.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/drivers/nvmem/lpc18xx_otp.c b/drivers/nvmem/lpc18xx_otp.c new file mode 100644 index 000000000..549b5298a --- /dev/null +++ b/drivers/nvmem/lpc18xx_otp.c @@ -0,0 +1,111 @@ +/* + * NXP LPC18xx/43xx OTP memory NVMEM driver + * + * Copyright (c) 2016 Joachim Eastwood <manabian@gmail.com> + * + * Based on the imx ocotp driver, + * Copyright (c) 2015 Pengutronix, Philipp Zabel <p.zabel@pengutronix.de> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation. + * + * TODO: add support for writing OTP register via API in boot ROM. + */ + +#include <linux/io.h> +#include <linux/module.h> +#include <linux/nvmem-provider.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +/* + * LPC18xx OTP memory contains 4 banks with 4 32-bit words. Bank 0 starts + * at offset 0 from the base. + * + * Bank 0 contains the part ID for Flashless devices and is reseverd for + * devices with Flash. + * Bank 1/2 is generale purpose or AES key storage for secure devices. + * Bank 3 contains control data, USB ID and generale purpose words. + */ +#define LPC18XX_OTP_NUM_BANKS 4 +#define LPC18XX_OTP_WORDS_PER_BANK 4 +#define LPC18XX_OTP_WORD_SIZE sizeof(u32) +#define LPC18XX_OTP_SIZE (LPC18XX_OTP_NUM_BANKS * \ + LPC18XX_OTP_WORDS_PER_BANK * \ + LPC18XX_OTP_WORD_SIZE) + +struct lpc18xx_otp { + void __iomem *base; +}; + +static int lpc18xx_otp_read(void *context, unsigned int offset, + void *val, size_t bytes) +{ + struct lpc18xx_otp *otp = context; + unsigned int count = bytes >> 2; + u32 index = offset >> 2; + u32 *buf = val; + int i; + + if (count > (LPC18XX_OTP_SIZE - index)) + count = LPC18XX_OTP_SIZE - index; + + for (i = index; i < (index + count); i++) + *buf++ = readl(otp->base + i * LPC18XX_OTP_WORD_SIZE); + + return 0; +} + +static struct nvmem_config lpc18xx_otp_nvmem_config = { + .name = "lpc18xx-otp", + .read_only = true, + .word_size = LPC18XX_OTP_WORD_SIZE, + .stride = LPC18XX_OTP_WORD_SIZE, + .reg_read = lpc18xx_otp_read, +}; + +static int lpc18xx_otp_probe(struct platform_device *pdev) +{ + struct nvmem_device *nvmem; + struct lpc18xx_otp *otp; + struct resource *res; + + otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL); + if (!otp) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + otp->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(otp->base)) + return PTR_ERR(otp->base); + + lpc18xx_otp_nvmem_config.size = LPC18XX_OTP_SIZE; + lpc18xx_otp_nvmem_config.dev = &pdev->dev; + lpc18xx_otp_nvmem_config.priv = otp; + + nvmem = devm_nvmem_register(&pdev->dev, &lpc18xx_otp_nvmem_config); + + return PTR_ERR_OR_ZERO(nvmem); +} + +static const struct of_device_id lpc18xx_otp_dt_ids[] = { + { .compatible = "nxp,lpc1850-otp" }, + { }, +}; +MODULE_DEVICE_TABLE(of, lpc18xx_otp_dt_ids); + +static struct platform_driver lpc18xx_otp_driver = { + .probe = lpc18xx_otp_probe, + .driver = { + .name = "lpc18xx_otp", + .of_match_table = lpc18xx_otp_dt_ids, + }, +}; +module_platform_driver(lpc18xx_otp_driver); + +MODULE_AUTHOR("Joachim Eastwoood <manabian@gmail.com>"); +MODULE_DESCRIPTION("NXP LPC18xx OTP NVMEM driver"); +MODULE_LICENSE("GPL v2"); |