/*
 * Microchip KSZ series register access through SPI
 *
 * Copyright (C) 2017
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <asm/unaligned.h>

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spi/spi.h>

#include "ksz_priv.h"

/* SPI frame opcodes */
#define KS_SPIOP_RD                     3
#define KS_SPIOP_WR                     2

#define SPI_ADDR_SHIFT                  24
#define SPI_ADDR_MASK                   (BIT(SPI_ADDR_SHIFT) - 1)
#define SPI_TURNAROUND_SHIFT            5

static int ksz_spi_read_reg(struct spi_device *spi, u32 reg, u8 *val,
                            unsigned int len)
{
        u32 txbuf;
        int ret;

        txbuf = reg & SPI_ADDR_MASK;
        txbuf |= KS_SPIOP_RD << SPI_ADDR_SHIFT;
        txbuf <<= SPI_TURNAROUND_SHIFT;
        txbuf = cpu_to_be32(txbuf);

        ret = spi_write_then_read(spi, &txbuf, 4, val, len);
        return ret;
}

static int ksz_spi_read(struct ksz_device *dev, u32 reg, u8 *data,
                        unsigned int len)
{
        struct spi_device *spi = dev->priv;

        return ksz_spi_read_reg(spi, reg, data, len);
}

static int ksz_spi_read8(struct ksz_device *dev, u32 reg, u8 *val)
{
        return ksz_spi_read(dev, reg, val, 1);
}

static int ksz_spi_read16(struct ksz_device *dev, u32 reg, u16 *val)
{
        int ret = ksz_spi_read(dev, reg, (u8 *)val, 2);

        if (!ret)
                *val = be16_to_cpu(*val);

        return ret;
}

static int ksz_spi_read24(struct ksz_device *dev, u32 reg, u32 *val)
{
        int ret;

        *val = 0;
        ret = ksz_spi_read(dev, reg, (u8 *)val, 3);
        if (!ret) {
                *val = be32_to_cpu(*val);
                /* convert to 24bit */
                *val >>= 8;
        }

        return ret;
}

static int ksz_spi_read32(struct ksz_device *dev, u32 reg, u32 *val)
{
        int ret = ksz_spi_read(dev, reg, (u8 *)val, 4);

        if (!ret)
                *val = be32_to_cpu(*val);

        return ret;
}

static int ksz_spi_write_reg(struct spi_device *spi, u32 reg, u8 *val,
                             unsigned int len)
{
        u32 txbuf;
        u8 data[12];
        int i;

        txbuf = reg & SPI_ADDR_MASK;
        txbuf |= (KS_SPIOP_WR << SPI_ADDR_SHIFT);
        txbuf <<= SPI_TURNAROUND_SHIFT;
        txbuf = cpu_to_be32(txbuf);

        data[0] = txbuf & 0xFF;
        data[1] = (txbuf & 0xFF00) >> 8;
        data[2] = (txbuf & 0xFF0000) >> 16;
        data[3] = (txbuf & 0xFF000000) >> 24;
        for (i = 0; i < len; i++)
                data[i + 4] = val[i];

        return spi_write(spi, &data, 4 + len);
}

static int ksz_spi_write8(struct ksz_device *dev, u32 reg, u8 value)
{
        struct spi_device *spi = dev->priv;

        return ksz_spi_write_reg(spi, reg, &value, 1);
}

static int ksz_spi_write16(struct ksz_device *dev, u32 reg, u16 value)
{
        struct spi_device *spi = dev->priv;

        value = cpu_to_be16(value);
        return ksz_spi_write_reg(spi, reg, (u8 *)&value, 2);
}

static int ksz_spi_write24(struct ksz_device *dev, u32 reg, u32 value)
{
        struct spi_device *spi = dev->priv;

        /* make it to big endian 24bit from MSB */
        value <<= 8;
        value = cpu_to_be32(value);
        return ksz_spi_write_reg(spi, reg, (u8 *)&value, 3);
}

static int ksz_spi_write32(struct ksz_device *dev, u32 reg, u32 value)
{
        struct spi_device *spi = dev->priv;

        value = cpu_to_be32(value);
        return ksz_spi_write_reg(spi, reg, (u8 *)&value, 4);
}

static const struct ksz_io_ops ksz_spi_ops = {
        .read8 = ksz_spi_read8,
        .read16 = ksz_spi_read16,
        .read24 = ksz_spi_read24,
        .read32 = ksz_spi_read32,
        .write8 = ksz_spi_write8,
        .write16 = ksz_spi_write16,
        .write24 = ksz_spi_write24,
        .write32 = ksz_spi_write32,
};

static int ksz_spi_probe(struct spi_device *spi)
{
        struct ksz_device *dev;
        int ret;

        dev = ksz_switch_alloc(&spi->dev, &ksz_spi_ops, spi);
        if (!dev)
                return -ENOMEM;

        if (spi->dev.platform_data)
                dev->pdata = spi->dev.platform_data;

        ret = ksz_switch_register(dev);
        if (ret)
                return ret;

        spi_set_drvdata(spi, dev);

        return 0;
}

static int ksz_spi_remove(struct spi_device *spi)
{
        struct ksz_device *dev = spi_get_drvdata(spi);

        if (dev)
                ksz_switch_remove(dev);

        return 0;
}

static const struct of_device_id ksz_dt_ids[] = {
        { .compatible = "microchip,ksz9477" },
        {},
};
MODULE_DEVICE_TABLE(of, ksz_dt_ids);

static struct spi_driver ksz_spi_driver = {
        .driver = {
                .name   = "ksz9477-switch",
                .owner  = THIS_MODULE,
                .of_match_table = of_match_ptr(ksz_dt_ids),
        },
        .probe  = ksz_spi_probe,
        .remove = ksz_spi_remove,
};

module_spi_driver(ksz_spi_driver);

MODULE_AUTHOR("Woojung Huh <Woojung.Huh@microchip.com>");
MODULE_DESCRIPTION("Microchip KSZ Series Switch SPI access Driver");
MODULE_LICENSE("GPL");