// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2013
 * Dirk Eibach,  Guntermann & Drunck GmbH, dirk.eibach@gdsys.cc
 */

#include <common.h>
#include <i2c.h>
#include <dm.h>
#include <regmap.h>
#include <log.h>
#include <asm/global_data.h>
#include <asm/unaligned.h>
#include <linux/bitops.h>
#include <linux/delay.h>

struct ihs_i2c_priv {
        uint speed;
        struct regmap *map;
};

struct ihs_i2c_regs {
        u16 interrupt_status;
        u16 interrupt_enable_control;
        u16 write_mailbox_ext;
        u16 write_mailbox;
        u16 read_mailbox_ext;
        u16 read_mailbox;
};

#define ihs_i2c_set(map, member, val) \
        regmap_set(map, struct ihs_i2c_regs, member, val)

#define ihs_i2c_get(map, member, valp) \
        regmap_get(map, struct ihs_i2c_regs, member, valp)

enum {
        I2CINT_ERROR_EV = BIT(13),
        I2CINT_TRANSMIT_EV = BIT(14),
        I2CINT_RECEIVE_EV = BIT(15),
};

enum {
        I2CMB_READ = 0 << 10,
        I2CMB_WRITE = 1 << 10,
        I2CMB_1BYTE = 0 << 11,
        I2CMB_2BYTE = 1 << 11,
        I2CMB_DONT_HOLD_BUS = 0 << 13,
        I2CMB_HOLD_BUS = 1 << 13,
        I2CMB_NATIVE = 2 << 14,
};

enum {
        I2COP_WRITE = 0,
        I2COP_READ = 1,
};

static int wait_for_int(struct udevice *dev, int read)
{
        u16 val;
        uint ctr = 0;
        struct ihs_i2c_priv *priv = dev_get_priv(dev);

        ihs_i2c_get(priv->map, interrupt_status, &val);
        /* Wait until error or receive/transmit interrupt was raised */
        while (!(val & (I2CINT_ERROR_EV
               | (read ? I2CINT_RECEIVE_EV : I2CINT_TRANSMIT_EV)))) {
                udelay(10);
                if (ctr++ > 5000) {
                        debug("%s: timed out\n", __func__);
                        return -ETIMEDOUT;
                }
                ihs_i2c_get(priv->map, interrupt_status, &val);
        }

        return (val & I2CINT_ERROR_EV) ? -EIO : 0;
}

static int ihs_i2c_transfer(struct udevice *dev, uchar chip,
                            uchar *buffer, int len, int read, bool is_last)
{
        u16 val;
        u16 data;
        int res;
        struct ihs_i2c_priv *priv = dev_get_priv(dev);

        /* Clear interrupt status */
        data = I2CINT_ERROR_EV | I2CINT_RECEIVE_EV | I2CINT_TRANSMIT_EV;
        ihs_i2c_set(priv->map, interrupt_status, data);
        ihs_i2c_get(priv->map, interrupt_status, &val);

        /* If we want to write and have data, write the bytes to the mailbox */
        if (!read && len) {
                val = buffer[0];

                if (len > 1)
                        val |= buffer[1] << 8;
                ihs_i2c_set(priv->map, write_mailbox_ext, val);
        }

        data = I2CMB_NATIVE
               | (read ? 0 : I2CMB_WRITE)
               | (chip << 1)
               | ((len > 1) ? I2CMB_2BYTE : 0)
               | (is_last ? 0 : I2CMB_HOLD_BUS);

        ihs_i2c_set(priv->map, write_mailbox, data);

        res = wait_for_int(dev, read);
        if (res) {
                if (res == -ETIMEDOUT)
                        debug("%s: time out while waiting for event\n", __func__);

                return res;
        }

        /* If we want to read, get the bytes from the mailbox */
        if (read) {
                ihs_i2c_get(priv->map, read_mailbox_ext, &val);
                buffer[0] = val & 0xff;
                if (len > 1)
                        buffer[1] = val >> 8;
        }

        return 0;
}

static int ihs_i2c_send_buffer(struct udevice *dev, uchar chip, u8 *data, int len, bool hold_bus, int read)
{
        int res;

        while (len) {
                int transfer = min(len, 2);
                bool is_last = len <= transfer;

                res = ihs_i2c_transfer(dev, chip, data, transfer, read,
                                       hold_bus ? false : is_last);
                if (res)
                        return res;

                data += transfer;
                len -= transfer;
        }

        return 0;
}

static int ihs_i2c_address(struct udevice *dev, uchar chip, u8 *addr, int alen,
                           bool hold_bus)
{
        return ihs_i2c_send_buffer(dev, chip, addr, alen, hold_bus, I2COP_WRITE);
}

static int ihs_i2c_access(struct udevice *dev, uchar chip, u8 *addr,
                          int alen, uchar *buffer, int len, int read)
{
        int res;

        /* Don't hold the bus if length of data to send/receive is zero */
        if (len <= 0)
                return -EINVAL;

        res = ihs_i2c_address(dev, chip, addr, alen, len);
        if (res)
                return res;

        return ihs_i2c_send_buffer(dev, chip, buffer, len, false, read);
}

int ihs_i2c_probe(struct udevice *bus)
{
        struct ihs_i2c_priv *priv = dev_get_priv(bus);

        regmap_init_mem(dev_ofnode(bus), &priv->map);

        return 0;
}

static int ihs_i2c_set_bus_speed(struct udevice *bus, uint speed)
{
        struct ihs_i2c_priv *priv = dev_get_priv(bus);

        if (speed != priv->speed && priv->speed != 0)
                return -EINVAL;

        priv->speed = speed;

        return 0;
}

static int ihs_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
{
        struct i2c_msg *dmsg, *omsg, dummy;

        memset(&dummy, 0, sizeof(struct i2c_msg));

        /* We expect either two messages (one with an offset and one with the
         * actucal data) or one message (just data)
         */
        if (nmsgs > 2 || nmsgs == 0) {
                debug("%s: Only one or two messages are supported\n", __func__);
                return -ENOTSUPP;
        }

        omsg = nmsgs == 1 ? &dummy : msg;
        dmsg = nmsgs == 1 ? msg : msg + 1;

        if (dmsg->flags & I2C_M_RD)
                return ihs_i2c_access(bus, dmsg->addr, omsg->buf,
                                      omsg->len, dmsg->buf, dmsg->len,
                                      I2COP_READ);
        else
                return ihs_i2c_access(bus, dmsg->addr, omsg->buf,
                                      omsg->len, dmsg->buf, dmsg->len,
                                      I2COP_WRITE);
}

static int ihs_i2c_probe_chip(struct udevice *bus, u32 chip_addr,
                              u32 chip_flags)
{
        uchar buffer[2];
        int res;

        res = ihs_i2c_transfer(bus, chip_addr, buffer, 0, I2COP_READ, true);
        if (res)
                return res;

        return 0;
}

static const struct dm_i2c_ops ihs_i2c_ops = {
        .xfer           = ihs_i2c_xfer,
        .probe_chip     = ihs_i2c_probe_chip,
        .set_bus_speed  = ihs_i2c_set_bus_speed,
};

static const struct udevice_id ihs_i2c_ids[] = {
        { .compatible = "gdsys,ihs_i2cmaster", },
        { /* sentinel */ }
};

U_BOOT_DRIVER(i2c_ihs) = {
        .name = "i2c_ihs",
        .id = UCLASS_I2C,
        .of_match = ihs_i2c_ids,
        .probe = ihs_i2c_probe,
        .priv_auto      = sizeof(struct ihs_i2c_priv),
        .ops = &ihs_i2c_ops,
};