// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 *
 * 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/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 reserved 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;

        otp = devm_kzalloc(&pdev->dev, sizeof(*otp), GFP_KERNEL);
        if (!otp)
                return -ENOMEM;

        otp->base = devm_platform_ioremap_resource(pdev, 0);
        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");