// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018, Nuvoton Corporation.
 * Copyright (c) 2018, Intel Corporation.
 */

#define pr_fmt(fmt) "nuvoton-kcs-bmc: " fmt

#include <linux/atomic.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#include "kcs_bmc_device.h"

#define DEVICE_NAME     "npcm-kcs-bmc"
#define KCS_CHANNEL_MAX 3

#define KCS1ST          0x0C
#define KCS2ST          0x1E
#define KCS3ST          0x30

#define KCS1DO          0x0E
#define KCS2DO          0x20
#define KCS3DO          0x32

#define KCS1DI          0x10
#define KCS2DI          0x22
#define KCS3DI          0x34

#define KCS1CTL         0x18
#define KCS2CTL         0x2A
#define KCS3CTL         0x3C
#define    KCS_CTL_IBFIE        BIT(0)
#define    KCS_CTL_OBEIE        BIT(1)

#define KCS1IE          0x1C
#define KCS2IE          0x2E
#define KCS3IE          0x40
#define    KCS_IE_IRQE          BIT(0)
#define    KCS_IE_HIRQE         BIT(3)

/*
 * 7.2.4 Core KCS Registers
 * Registers in this module are 8 bits. An 8-bit register must be accessed
 * by an 8-bit read or write.
 *
 * sts: KCS Channel n Status Register (KCSnST).
 * dob: KCS Channel n Data Out Buffer Register (KCSnDO).
 * dib: KCS Channel n Data In Buffer Register (KCSnDI).
 * ctl: KCS Channel n Control Register (KCSnCTL).
 * ie : KCS Channel n  Interrupt Enable Register (KCSnIE).
 */
struct npcm7xx_kcs_reg {
        u32 sts;
        u32 dob;
        u32 dib;
        u32 ctl;
        u32 ie;
};

struct npcm7xx_kcs_bmc {
        struct kcs_bmc_device kcs_bmc;

        struct regmap *map;

        const struct npcm7xx_kcs_reg *reg;
};

static const struct npcm7xx_kcs_reg npcm7xx_kcs_reg_tbl[KCS_CHANNEL_MAX] = {
        { .sts = KCS1ST, .dob = KCS1DO, .dib = KCS1DI, .ctl = KCS1CTL, .ie = KCS1IE },
        { .sts = KCS2ST, .dob = KCS2DO, .dib = KCS2DI, .ctl = KCS2CTL, .ie = KCS2IE },
        { .sts = KCS3ST, .dob = KCS3DO, .dib = KCS3DI, .ctl = KCS3CTL, .ie = KCS3IE },
};

static inline struct npcm7xx_kcs_bmc *to_npcm7xx_kcs_bmc(struct kcs_bmc_device *kcs_bmc)
{
        return container_of(kcs_bmc, struct npcm7xx_kcs_bmc, kcs_bmc);
}

static u8 npcm7xx_kcs_inb(struct kcs_bmc_device *kcs_bmc, u32 reg)
{
        struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
        u32 val = 0;
        int rc;

        rc = regmap_read(priv->map, reg, &val);
        WARN(rc != 0, "regmap_read() failed: %d\n", rc);

        return rc == 0 ? (u8)val : 0;
}

static void npcm7xx_kcs_outb(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 data)
{
        struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
        int rc;

        rc = regmap_write(priv->map, reg, data);
        WARN(rc != 0, "regmap_write() failed: %d\n", rc);
}

static void npcm7xx_kcs_updateb(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 mask, u8 data)
{
        struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
        int rc;

        rc = regmap_update_bits(priv->map, reg, mask, data);
        WARN(rc != 0, "regmap_update_bits() failed: %d\n", rc);
}

static void npcm7xx_kcs_enable_channel(struct kcs_bmc_device *kcs_bmc, bool enable)
{
        struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);

        regmap_update_bits(priv->map, priv->reg->ie, KCS_IE_IRQE | KCS_IE_HIRQE,
                           enable ? KCS_IE_IRQE | KCS_IE_HIRQE : 0);
}

static void npcm7xx_kcs_irq_mask_update(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 state)
{
        struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);

        if (mask & KCS_BMC_EVENT_TYPE_OBE)
                regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_OBEIE,
                                   !!(state & KCS_BMC_EVENT_TYPE_OBE) * KCS_CTL_OBEIE);

        if (mask & KCS_BMC_EVENT_TYPE_IBF)
                regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_IBFIE,
                                   !!(state & KCS_BMC_EVENT_TYPE_IBF) * KCS_CTL_IBFIE);
}

static irqreturn_t npcm7xx_kcs_irq(int irq, void *arg)
{
        struct kcs_bmc_device *kcs_bmc = arg;

        return kcs_bmc_handle_event(kcs_bmc);
}

static int npcm7xx_kcs_config_irq(struct kcs_bmc_device *kcs_bmc,
                                  struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int irq;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        return devm_request_irq(dev, irq, npcm7xx_kcs_irq, IRQF_SHARED,
                                dev_name(dev), kcs_bmc);
}

static const struct kcs_bmc_device_ops npcm7xx_kcs_ops = {
        .irq_mask_update = npcm7xx_kcs_irq_mask_update,
        .io_inputb = npcm7xx_kcs_inb,
        .io_outputb = npcm7xx_kcs_outb,
        .io_updateb = npcm7xx_kcs_updateb,
};

static int npcm7xx_kcs_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct npcm7xx_kcs_bmc *priv;
        struct kcs_bmc_device *kcs_bmc;
        u32 chan;
        int rc;

        rc = of_property_read_u32(dev->of_node, "kcs_chan", &chan);
        if (rc != 0 || chan == 0 || chan > KCS_CHANNEL_MAX) {
                dev_err(dev, "no valid 'kcs_chan' configured\n");
                return -ENODEV;
        }

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

        priv->map = syscon_node_to_regmap(dev->parent->of_node);
        if (IS_ERR(priv->map)) {
                dev_err(dev, "Couldn't get regmap\n");
                return -ENODEV;
        }
        priv->reg = &npcm7xx_kcs_reg_tbl[chan - 1];

        kcs_bmc = &priv->kcs_bmc;
        kcs_bmc->dev = &pdev->dev;
        kcs_bmc->channel = chan;
        kcs_bmc->ioreg.idr = priv->reg->dib;
        kcs_bmc->ioreg.odr = priv->reg->dob;
        kcs_bmc->ioreg.str = priv->reg->sts;
        kcs_bmc->ops = &npcm7xx_kcs_ops;

        platform_set_drvdata(pdev, priv);

        rc = npcm7xx_kcs_config_irq(kcs_bmc, pdev);
        if (rc)
                return rc;

        npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
        npcm7xx_kcs_enable_channel(kcs_bmc, true);

        rc = kcs_bmc_add_device(kcs_bmc);
        if (rc) {
                dev_warn(&pdev->dev, "Failed to register channel %d: %d\n", kcs_bmc->channel, rc);
                return rc;
        }

        pr_info("channel=%u idr=0x%x odr=0x%x str=0x%x\n",
                chan,
                kcs_bmc->ioreg.idr, kcs_bmc->ioreg.odr, kcs_bmc->ioreg.str);

        return 0;
}

static void npcm7xx_kcs_remove(struct platform_device *pdev)
{
        struct npcm7xx_kcs_bmc *priv = platform_get_drvdata(pdev);
        struct kcs_bmc_device *kcs_bmc = &priv->kcs_bmc;

        kcs_bmc_remove_device(kcs_bmc);

        npcm7xx_kcs_enable_channel(kcs_bmc, false);
        npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
}

static const struct of_device_id npcm_kcs_bmc_match[] = {
        { .compatible = "nuvoton,npcm750-kcs-bmc" },
        { }
};
MODULE_DEVICE_TABLE(of, npcm_kcs_bmc_match);

static struct platform_driver npcm_kcs_bmc_driver = {
        .driver = {
                .name           = DEVICE_NAME,
                .of_match_table = npcm_kcs_bmc_match,
        },
        .probe  = npcm7xx_kcs_probe,
        .remove = npcm7xx_kcs_remove,
};
module_platform_driver(npcm_kcs_bmc_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Avi Fishman <avifishman70@gmail.com>");
MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
MODULE_DESCRIPTION("NPCM7xx device interface to the KCS BMC device");