// SPDX-License-Identifier: GPL-2.0
/*
 * Nuvoton WPCM450 SoC Identification
 *
 * Copyright (C) 2022 Jonathan Neuschäfer
 */

#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/sys_soc.h>

#define GCR_PDID        0
#define PDID_CHIP(x)    ((x) & 0x00ffffff)
#define CHIP_WPCM450    0x926450
#define PDID_REV(x)     ((x) >> 24)

struct revision {
        u8 number;
        const char *name;
};

static const struct revision revisions[] __initconst = {
        { 0x00, "Z1" },
        { 0x03, "Z2" },
        { 0x04, "Z21" },
        { 0x08, "A1" },
        { 0x09, "A2" },
        { 0x0a, "A3" },
        {}
};

static const char * __init get_revision(unsigned int rev)
{
        int i;

        for (i = 0; revisions[i].name; i++)
                if (revisions[i].number == rev)
                        return revisions[i].name;
        return NULL;
}

static struct soc_device_attribute *wpcm450_attr;
static struct soc_device *wpcm450_soc;

static int __init wpcm450_soc_init(void)
{
        struct soc_device_attribute *attr;
        struct soc_device *soc;
        const char *revision;
        struct regmap *gcr;
        u32 pdid;
        int ret;

        if (!of_machine_is_compatible("nuvoton,wpcm450"))
                return 0;

        gcr = syscon_regmap_lookup_by_compatible("nuvoton,wpcm450-gcr");
        if (IS_ERR(gcr))
                return PTR_ERR(gcr);
        ret = regmap_read(gcr, GCR_PDID, &pdid);
        if (ret)
                return ret;

        if (PDID_CHIP(pdid) != CHIP_WPCM450) {
                pr_warn("Unknown chip ID in GCR.PDID: 0x%06x\n", PDID_CHIP(pdid));
                return -ENODEV;
        }

        revision = get_revision(PDID_REV(pdid));
        if (!revision) {
                pr_warn("Unknown chip revision in GCR.PDID: 0x%02x\n", PDID_REV(pdid));
                return -ENODEV;
        }

        attr = kzalloc_obj(*attr);
        if (!attr)
                return -ENOMEM;

        attr->family = "Nuvoton NPCM";
        attr->soc_id = "WPCM450";
        attr->revision = revision;
        soc = soc_device_register(attr);
        if (IS_ERR(soc)) {
                kfree(attr);
                pr_warn("Could not register SoC device\n");
                return PTR_ERR(soc);
        }

        wpcm450_soc = soc;
        wpcm450_attr = attr;
        return 0;
}
module_init(wpcm450_soc_init);

static void __exit wpcm450_soc_exit(void)
{
        if (wpcm450_soc) {
                soc_device_unregister(wpcm450_soc);
                wpcm450_soc = NULL;
                kfree(wpcm450_attr);
        }
}
module_exit(wpcm450_soc_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jonathan Neuschäfer");
MODULE_DESCRIPTION("Nuvoton WPCM450 SoC Identification driver");