/*
 *  Driver for the Conexant CX25821 PCIe bridge
 *
 *  Copyright (C) 2009 Conexant Systems Inc.
 *  Authors  <shu.lin@conexant.com>, <hiep.huynh@conexant.com>
 *      Based on Steven Toth <stoth@linuxtv.org> cx23885 driver
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *
 *  GNU General Public License for more details.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/i2c.h>
#include "cx25821.h"

static unsigned int i2c_debug;
module_param(i2c_debug, int, 0644);
MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");

static unsigned int i2c_scan;
module_param(i2c_scan, int, 0444);
MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");

#define dprintk(level, fmt, arg...)                                     \
do {                                                                    \
        if (i2c_debug >= level)                                         \
                printk(KERN_DEBUG "%s/0: " fmt, dev->name, ##arg);      \
} while (0)

#define I2C_WAIT_DELAY 32
#define I2C_WAIT_RETRY 64

#define I2C_EXTEND  (1 << 3)
#define I2C_NOSTOP  (1 << 4)

static inline int i2c_slave_did_ack(struct i2c_adapter *i2c_adap)
{
        struct cx25821_i2c *bus = i2c_adap->algo_data;
        struct cx25821_dev *dev = bus->dev;
        return cx_read(bus->reg_stat) & 0x01;
}

static inline int i2c_is_busy(struct i2c_adapter *i2c_adap)
{
        struct cx25821_i2c *bus = i2c_adap->algo_data;
        struct cx25821_dev *dev = bus->dev;
        return cx_read(bus->reg_stat) & 0x02 ? 1 : 0;
}

static int i2c_wait_done(struct i2c_adapter *i2c_adap)
{
        int count;

        for (count = 0; count < I2C_WAIT_RETRY; count++) {
                if (!i2c_is_busy(i2c_adap))
                        break;
                udelay(I2C_WAIT_DELAY);
        }

        if (I2C_WAIT_RETRY == count)
                return 0;

        return 1;
}

static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
                         const struct i2c_msg *msg, int joined_rlen)
{
        struct cx25821_i2c *bus = i2c_adap->algo_data;
        struct cx25821_dev *dev = bus->dev;
        u32 wdata, addr, ctrl;
        int retval, cnt;

        if (joined_rlen)
                dprintk(1, "%s(msg->wlen=%d, nextmsg->rlen=%d)\n", __func__,
                        msg->len, joined_rlen);
        else
                dprintk(1, "%s(msg->len=%d)\n", __func__, msg->len);

        /* Deal with i2c probe functions with zero payload */
        if (msg->len == 0) {
                cx_write(bus->reg_addr, msg->addr << 25);
                cx_write(bus->reg_ctrl, bus->i2c_period | (1 << 2));

                if (!i2c_wait_done(i2c_adap))
                        return -EIO;

                if (!i2c_slave_did_ack(i2c_adap))
                        return -EIO;

                dprintk(1, "%s(): returns 0\n", __func__);
                return 0;
        }

        /* dev, reg + first byte */
        addr = (msg->addr << 25) | msg->buf[0];
        wdata = msg->buf[0];

        ctrl = bus->i2c_period | (1 << 12) | (1 << 2);

        if (msg->len > 1)
                ctrl |= I2C_NOSTOP | I2C_EXTEND;
        else if (joined_rlen)
                ctrl |= I2C_NOSTOP;

        cx_write(bus->reg_addr, addr);
        cx_write(bus->reg_wdata, wdata);
        cx_write(bus->reg_ctrl, ctrl);

        retval = i2c_wait_done(i2c_adap);
        if (retval < 0)
                goto err;

        if (retval == 0)
                goto eio;

        if (i2c_debug) {
                if (!(ctrl & I2C_NOSTOP))
                        printk(" >\n");
        }

        for (cnt = 1; cnt < msg->len; cnt++) {
                /* following bytes */
                wdata = msg->buf[cnt];
                ctrl = bus->i2c_period | (1 << 12) | (1 << 2);

                if (cnt < msg->len - 1)
                        ctrl |= I2C_NOSTOP | I2C_EXTEND;
                else if (joined_rlen)
                        ctrl |= I2C_NOSTOP;

                cx_write(bus->reg_addr, addr);
                cx_write(bus->reg_wdata, wdata);
                cx_write(bus->reg_ctrl, ctrl);

                retval = i2c_wait_done(i2c_adap);
                if (retval < 0)
                        goto err;

                if (retval == 0)
                        goto eio;

                if (i2c_debug) {
                        dprintk(1, " %02x", msg->buf[cnt]);
                        if (!(ctrl & I2C_NOSTOP))
                                dprintk(1, " >\n");
                }
        }

        return msg->len;

eio:
        retval = -EIO;
err:
        if (i2c_debug)
                pr_err(" ERR: %d\n", retval);
        return retval;
}

static int i2c_readbytes(struct i2c_adapter *i2c_adap,
                         const struct i2c_msg *msg, int joined)
{
        struct cx25821_i2c *bus = i2c_adap->algo_data;
        struct cx25821_dev *dev = bus->dev;
        u32 ctrl, cnt;
        int retval;

        if (i2c_debug && !joined)
                dprintk(1, "6-%s(msg->len=%d)\n", __func__, msg->len);

        /* Deal with i2c probe functions with zero payload */
        if (msg->len == 0) {
                cx_write(bus->reg_addr, msg->addr << 25);
                cx_write(bus->reg_ctrl, bus->i2c_period | (1 << 2) | 1);
                if (!i2c_wait_done(i2c_adap))
                        return -EIO;
                if (!i2c_slave_did_ack(i2c_adap))
                        return -EIO;

                dprintk(1, "%s(): returns 0\n", __func__);
                return 0;
        }

        if (i2c_debug) {
                if (joined)
                        dprintk(1, " R");
                else
                        dprintk(1, " <R %02x", (msg->addr << 1) + 1);
        }

        for (cnt = 0; cnt < msg->len; cnt++) {

                ctrl = bus->i2c_period | (1 << 12) | (1 << 2) | 1;

                if (cnt < msg->len - 1)
                        ctrl |= I2C_NOSTOP | I2C_EXTEND;

                cx_write(bus->reg_addr, msg->addr << 25);
                cx_write(bus->reg_ctrl, ctrl);

                retval = i2c_wait_done(i2c_adap);
                if (retval < 0)
                        goto err;
                if (retval == 0)
                        goto eio;
                msg->buf[cnt] = cx_read(bus->reg_rdata) & 0xff;

                if (i2c_debug) {
                        dprintk(1, " %02x", msg->buf[cnt]);
                        if (!(ctrl & I2C_NOSTOP))
                                dprintk(1, " >\n");
                }
        }

        return msg->len;
eio:
        retval = -EIO;
err:
        if (i2c_debug)
                pr_err(" ERR: %d\n", retval);
        return retval;
}

static int i2c_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
{
        struct cx25821_i2c *bus = i2c_adap->algo_data;
        struct cx25821_dev *dev = bus->dev;
        int i, retval = 0;

        dprintk(1, "%s(num = %d)\n", __func__, num);

        for (i = 0; i < num; i++) {
                dprintk(1, "%s(num = %d) addr = 0x%02x  len = 0x%x\n",
                        __func__, num, msgs[i].addr, msgs[i].len);

                if (msgs[i].flags & I2C_M_RD) {
                        /* read */
                        retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
                } else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
                           msgs[i].addr == msgs[i + 1].addr) {
                        /* write then read from same address */
                        retval = i2c_sendbytes(i2c_adap, &msgs[i],
                                        msgs[i + 1].len);

                        if (retval < 0)
                                goto err;
                        i++;
                        retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
                } else {
                        /* write */
                        retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
                }

                if (retval < 0)
                        goto err;
        }
        return num;

err:
        return retval;
}


static u32 cx25821_functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C | I2C_FUNC_SMBUS_WORD_DATA |
                I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
}

static const struct i2c_algorithm cx25821_i2c_algo_template = {
        .master_xfer = i2c_xfer,
        .functionality = cx25821_functionality,
#ifdef NEED_ALGO_CONTROL
        .algo_control = dummy_algo_control,
#endif
};

static const struct i2c_adapter cx25821_i2c_adap_template = {
        .name = "cx25821",
        .owner = THIS_MODULE,
        .algo = &cx25821_i2c_algo_template,
};

static const struct i2c_client cx25821_i2c_client_template = {
        .name = "cx25821 internal",
};

/* init + register i2c adapter */
int cx25821_i2c_register(struct cx25821_i2c *bus)
{
        struct cx25821_dev *dev = bus->dev;

        dprintk(1, "%s(bus = %d)\n", __func__, bus->nr);

        bus->i2c_adap = cx25821_i2c_adap_template;
        bus->i2c_client = cx25821_i2c_client_template;
        bus->i2c_adap.dev.parent = &dev->pci->dev;

        strlcpy(bus->i2c_adap.name, bus->dev->name, sizeof(bus->i2c_adap.name));

        bus->i2c_adap.algo_data = bus;
        i2c_set_adapdata(&bus->i2c_adap, &dev->v4l2_dev);
        i2c_add_adapter(&bus->i2c_adap);

        bus->i2c_client.adapter = &bus->i2c_adap;

        /* set up the I2c */
        bus->i2c_client.addr = (0x88 >> 1);

        return bus->i2c_rc;
}

int cx25821_i2c_unregister(struct cx25821_i2c *bus)
{
        i2c_del_adapter(&bus->i2c_adap);
        return 0;
}

#if 0 /* Currently unused */
static void cx25821_av_clk(struct cx25821_dev *dev, int enable)
{
        /* write 0 to bus 2 addr 0x144 via i2x_xfer() */
        char buffer[3];
        struct i2c_msg msg;
        dprintk(1, "%s(enabled = %d)\n", __func__, enable);

        /* Register 0x144 */
        buffer[0] = 0x01;
        buffer[1] = 0x44;
        if (enable == 1)
                buffer[2] = 0x05;
        else
                buffer[2] = 0x00;

        msg.addr = 0x44;
        msg.flags = I2C_M_TEN;
        msg.len = 3;
        msg.buf = buffer;

        i2c_xfer(&dev->i2c_bus[0].i2c_adap, &msg, 1);
}
#endif

int cx25821_i2c_read(struct cx25821_i2c *bus, u16 reg_addr, int *value)
{
        struct i2c_client *client = &bus->i2c_client;
        int v = 0;
        u8 addr[2] = { 0, 0 };
        u8 buf[4] = { 0, 0, 0, 0 };

        struct i2c_msg msgs[2] = {
                {
                        .addr = client->addr,
                        .flags = 0,
                        .len = 2,
                        .buf = addr,
                }, {
                        .addr = client->addr,
                        .flags = I2C_M_RD,
                        .len = 4,
                        .buf = buf,
                }
        };

        addr[0] = (reg_addr >> 8);
        addr[1] = (reg_addr & 0xff);
        msgs[0].addr = 0x44;
        msgs[1].addr = 0x44;

        i2c_xfer(client->adapter, msgs, 2);

        v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
        *value = v;

        return v;
}

int cx25821_i2c_write(struct cx25821_i2c *bus, u16 reg_addr, int value)
{
        struct i2c_client *client = &bus->i2c_client;
        int retval = 0;
        u8 buf[6] = { 0, 0, 0, 0, 0, 0 };

        struct i2c_msg msgs[1] = {
                {
                        .addr = client->addr,
                        .flags = 0,
                        .len = 6,
                        .buf = buf,
                }
        };

        buf[0] = reg_addr >> 8;
        buf[1] = reg_addr & 0xff;
        buf[5] = (value >> 24) & 0xff;
        buf[4] = (value >> 16) & 0xff;
        buf[3] = (value >> 8) & 0xff;
        buf[2] = value & 0xff;
        client->flags = 0;
        msgs[0].addr = 0x44;

        retval = i2c_xfer(client->adapter, msgs, 1);

        return retval;
}