// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
 * Copyright (c) 2017 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
 */

#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

#define IMX6Q_SNVS_HPLR         0x00
#define IMX6Q_SNVS_LPLR         0x34
#define IMX6Q_SNVS_LPGPR        0x68

#define IMX7D_SNVS_HPLR         0x00
#define IMX7D_SNVS_LPLR         0x34
#define IMX7D_SNVS_LPGPR        0x90

#define IMX_GPR_SL              BIT(5)
#define IMX_GPR_HL              BIT(5)

struct snvs_lpgpr_cfg {
        int offset;
        int offset_hplr;
        int offset_lplr;
        int size;
};

struct snvs_lpgpr_priv {
        struct device_d                 *dev;
        struct regmap                   *regmap;
        struct nvmem_config             cfg;
        const struct snvs_lpgpr_cfg     *dcfg;
};

static const struct snvs_lpgpr_cfg snvs_lpgpr_cfg_imx6q = {
        .offset         = IMX6Q_SNVS_LPGPR,
        .offset_hplr    = IMX6Q_SNVS_HPLR,
        .offset_lplr    = IMX6Q_SNVS_LPLR,
        .size           = 4,
};

static const struct snvs_lpgpr_cfg snvs_lpgpr_cfg_imx7d = {
        .offset         = IMX7D_SNVS_LPGPR,
        .offset_hplr    = IMX7D_SNVS_HPLR,
        .offset_lplr    = IMX7D_SNVS_LPLR,
        .size           = 16,
};

static int snvs_lpgpr_write(void *context, unsigned int offset, void *val,
                            size_t bytes)
{
        struct snvs_lpgpr_priv *priv = context;
        const struct snvs_lpgpr_cfg *dcfg = priv->dcfg;
        unsigned int lock_reg;
        int ret;

        ret = regmap_read(priv->regmap, dcfg->offset_hplr, &lock_reg);
        if (ret < 0)
                return ret;

        if (lock_reg & IMX_GPR_SL)
                return -EPERM;

        ret = regmap_read(priv->regmap, dcfg->offset_lplr, &lock_reg);
        if (ret < 0)
                return ret;

        if (lock_reg & IMX_GPR_HL)
                return -EPERM;

        return regmap_bulk_write(priv->regmap, dcfg->offset + offset, val,
                                bytes / 4);
}

static int snvs_lpgpr_read(void *context, unsigned int offset, void *val,
                           size_t bytes)
{
        struct snvs_lpgpr_priv *priv = context;
        const struct snvs_lpgpr_cfg *dcfg = priv->dcfg;

        return regmap_bulk_read(priv->regmap, dcfg->offset + offset,
                               val, bytes / 4);
}

static int snvs_lpgpr_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *node = dev->of_node;
        struct device_node *syscon_node;
        struct snvs_lpgpr_priv *priv;
        struct nvmem_config *cfg;
        struct nvmem_device *nvmem;
        const struct snvs_lpgpr_cfg *dcfg;

        if (!node)
                return -ENOENT;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        dcfg = of_device_get_match_data(dev);
        if (!dcfg)
                return -EINVAL;

        syscon_node = of_get_parent(node);
        if (!syscon_node)
                return -ENODEV;

        priv->regmap = syscon_node_to_regmap(syscon_node);
        of_node_put(syscon_node);
        if (IS_ERR(priv->regmap))
                return PTR_ERR(priv->regmap);

        priv->dcfg = dcfg;

        cfg = &priv->cfg;
        cfg->priv = priv;
        cfg->name = dev_name(dev);
        cfg->dev = dev;
        cfg->stride = 4;
        cfg->word_size = 4;
        cfg->size = dcfg->size;
        cfg->owner = THIS_MODULE;
        cfg->reg_read  = snvs_lpgpr_read;
        cfg->reg_write = snvs_lpgpr_write;

        nvmem = devm_nvmem_register(dev, cfg);

        return PTR_ERR_OR_ZERO(nvmem);
}

static const struct of_device_id snvs_lpgpr_dt_ids[] = {
        { .compatible = "fsl,imx6q-snvs-lpgpr", .data = &snvs_lpgpr_cfg_imx6q },
        { .compatible = "fsl,imx6ul-snvs-lpgpr",
          .data = &snvs_lpgpr_cfg_imx6q },
        { .compatible = "fsl,imx7d-snvs-lpgpr", .data = &snvs_lpgpr_cfg_imx7d },
        { },
};
MODULE_DEVICE_TABLE(of, snvs_lpgpr_dt_ids);

static struct platform_driver snvs_lpgpr_driver = {
        .probe  = snvs_lpgpr_probe,
        .driver = {
                .name   = "snvs_lpgpr",
                .of_match_table = snvs_lpgpr_dt_ids,
        },
};
module_platform_driver(snvs_lpgpr_driver);

MODULE_AUTHOR("Oleksij Rempel <o.rempel@pengutronix.de>");
MODULE_DESCRIPTION("Low Power General Purpose Register in i.MX6 and i.MX7 Secure Non-Volatile Storage");
MODULE_LICENSE("GPL v2");