// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2005-2006 Micronas USA Inc.
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/unistd.h>
#include <linux/time.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>

#include "go7007-priv.h"

/********************* Driver for on-board I2C adapter *********************/

/* #define GO7007_I2C_DEBUG */

#define SPI_I2C_ADDR_BASE               0x1400
#define STATUS_REG_ADDR                 (SPI_I2C_ADDR_BASE + 0x2)
#define I2C_CTRL_REG_ADDR               (SPI_I2C_ADDR_BASE + 0x6)
#define I2C_DEV_UP_ADDR_REG_ADDR        (SPI_I2C_ADDR_BASE + 0x7)
#define I2C_LO_ADDR_REG_ADDR            (SPI_I2C_ADDR_BASE + 0x8)
#define I2C_DATA_REG_ADDR               (SPI_I2C_ADDR_BASE + 0x9)
#define I2C_CLKFREQ_REG_ADDR            (SPI_I2C_ADDR_BASE + 0xa)

#define I2C_STATE_MASK                  0x0007
#define I2C_READ_READY_MASK             0x0008

/* There is only one I2C port on the TW2804 that feeds all four GO7007 VIPs
 * on the Adlink PCI-MPG24, so access is shared between all of them. */
static DEFINE_MUTEX(adlink_mpg24_i2c_mutex);

static inline void adlink_mpg24_i2c_lock(struct go7007 *go)
{
        /* Bridge the I2C port on this GO7007 to the shared bus */
        mutex_lock(&adlink_mpg24_i2c_mutex);
        go7007_write_addr(go, 0x3c82, 0x0020);
}

static inline void adlink_mpg24_i2c_unlock(struct go7007 *go)
{
        /* Isolate the I2C port on this GO7007 from the shared bus */
        go7007_write_addr(go, 0x3c82, 0x0000);
        mutex_unlock(&adlink_mpg24_i2c_mutex);
}

static int go7007_i2c_xfer(struct go7007 *go, u16 addr, int read,
                u16 command, int flags, u8 *data)
{
        int i, ret = -EIO;
        u16 val;

        if (go->status == STATUS_SHUTDOWN)
                return -ENODEV;

#ifdef GO7007_I2C_DEBUG
        if (read)
                dev_dbg(go->dev, "go7007-i2c: reading 0x%02x on 0x%02x\n",
                        command, addr);
        else
                dev_dbg(go->dev,
                        "go7007-i2c: writing 0x%02x to 0x%02x on 0x%02x\n",
                        *data, command, addr);
#endif

        mutex_lock(&go->hw_lock);

        if (go->board_id == GO7007_BOARDID_ADLINK_MPG24)
                adlink_mpg24_i2c_lock(go);

        /* Wait for I2C adapter to be ready */
        for (i = 0; i < 10; ++i) {
                if (go7007_read_addr(go, STATUS_REG_ADDR, &val) < 0)
                        goto i2c_done;
                if (!(val & I2C_STATE_MASK))
                        break;
                msleep(100);
        }
        if (i == 10) {
                dev_err(go->dev, "go7007-i2c: I2C adapter is hung\n");
                goto i2c_done;
        }

        /* Set target register (command) */
        go7007_write_addr(go, I2C_CTRL_REG_ADDR, flags);
        go7007_write_addr(go, I2C_LO_ADDR_REG_ADDR, command);

        /* If we're writing, send the data and target address and we're done */
        if (!read) {
                go7007_write_addr(go, I2C_DATA_REG_ADDR, *data);
                go7007_write_addr(go, I2C_DEV_UP_ADDR_REG_ADDR,
                                        (addr << 9) | (command >> 8));
                ret = 0;
                goto i2c_done;
        }

        /* Otherwise, we're reading.  First clear i2c_rx_data_rdy. */
        if (go7007_read_addr(go, I2C_DATA_REG_ADDR, &val) < 0)
                goto i2c_done;

        /* Send the target address plus read flag */
        go7007_write_addr(go, I2C_DEV_UP_ADDR_REG_ADDR,
                        (addr << 9) | 0x0100 | (command >> 8));

        /* Wait for i2c_rx_data_rdy */
        for (i = 0; i < 10; ++i) {
                if (go7007_read_addr(go, STATUS_REG_ADDR, &val) < 0)
                        goto i2c_done;
                if (val & I2C_READ_READY_MASK)
                        break;
                msleep(100);
        }
        if (i == 10) {
                dev_err(go->dev, "go7007-i2c: I2C adapter is hung\n");
                goto i2c_done;
        }

        /* Retrieve the read byte */
        if (go7007_read_addr(go, I2C_DATA_REG_ADDR, &val) < 0)
                goto i2c_done;
        *data = val;
        ret = 0;

i2c_done:
        if (go->board_id == GO7007_BOARDID_ADLINK_MPG24)
                adlink_mpg24_i2c_unlock(go);
        mutex_unlock(&go->hw_lock);
        return ret;
}

static int go7007_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
                unsigned short flags, char read_write,
                u8 command, int size, union i2c_smbus_data *data)
{
        struct go7007 *go = i2c_get_adapdata(adapter);

        if (size != I2C_SMBUS_BYTE_DATA)
                return -EIO;
        return go7007_i2c_xfer(go, addr, read_write == I2C_SMBUS_READ, command,
                        flags & I2C_CLIENT_SCCB ? 0x10 : 0x00, &data->byte);
}

/* VERY LIMITED I2C master xfer function -- only needed because the
 * SMBus functions only support 8-bit commands and the SAA7135 uses
 * 16-bit commands.  The I2C interface on the GO7007, as limited as
 * it is, does support this mode. */

static int go7007_i2c_master_xfer(struct i2c_adapter *adapter,
                                        struct i2c_msg msgs[], int num)
{
        struct go7007 *go = i2c_get_adapdata(adapter);
        int i;

        for (i = 0; i < num; ++i) {
                /* We can only do two things here -- write three bytes, or
                 * write two bytes and read one byte. */
                if (msgs[i].len == 2) {
                        if (i + 1 == num || msgs[i].addr != msgs[i + 1].addr ||
                                        (msgs[i].flags & I2C_M_RD) ||
                                        !(msgs[i + 1].flags & I2C_M_RD) ||
                                        msgs[i + 1].len != 1)
                                return -EIO;
                        if (go7007_i2c_xfer(go, msgs[i].addr, 1,
                                        (msgs[i].buf[0] << 8) | msgs[i].buf[1],
                                        0x01, &msgs[i + 1].buf[0]) < 0)
                                return -EIO;
                        ++i;
                } else if (msgs[i].len == 3) {
                        if (msgs[i].flags & I2C_M_RD)
                                return -EIO;
                        if (go7007_i2c_xfer(go, msgs[i].addr, 0,
                                        (msgs[i].buf[0] << 8) | msgs[i].buf[1],
                                        0x01, &msgs[i].buf[2]) < 0)
                                return -EIO;
                } else
                        return -EIO;
        }

        return num;
}

static u32 go7007_functionality(struct i2c_adapter *adapter)
{
        return I2C_FUNC_SMBUS_BYTE_DATA;
}

static const struct i2c_algorithm go7007_algo = {
        .smbus_xfer     = go7007_smbus_xfer,
        .master_xfer    = go7007_i2c_master_xfer,
        .functionality  = go7007_functionality,
};

static struct i2c_adapter go7007_adap_templ = {
        .owner                  = THIS_MODULE,
        .name                   = "WIS GO7007SB",
        .algo                   = &go7007_algo,
};

int go7007_i2c_init(struct go7007 *go)
{
        memcpy(&go->i2c_adapter, &go7007_adap_templ,
                        sizeof(go7007_adap_templ));
        go->i2c_adapter.dev.parent = go->dev;
        i2c_set_adapdata(&go->i2c_adapter, go);
        if (i2c_add_adapter(&go->i2c_adapter) < 0) {
                dev_err(go->dev,
                        "go7007-i2c: error: i2c_add_adapter failed\n");
                return -1;
        }
        return 0;
}