/*
 * I2C driver for PKUnity-v3 SoC
 * Code specific to PKUnity SoC and UniCore ISA
 *
 *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
 *      Copyright (C) 2001-2010 Guan Xuetao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <mach/hardware.h>

/*
 * Poll the i2c status register until the specified bit is set.
 * Returns 0 if timed out (100 msec).
 */
static short poll_status(unsigned long bit)
{
        int loop_cntr = 1000;

        if (bit & I2C_STATUS_TFNF) {
                do {
                        udelay(10);
                } while (!(readl(I2C_STATUS) & bit) && (--loop_cntr > 0));
        } else {
                /* RXRDY handler */
                do {
                        if (readl(I2C_TAR) == I2C_TAR_EEPROM)
                                msleep(20);
                        else
                                udelay(10);
                } while (!(readl(I2C_RXFLR) & 0xf) && (--loop_cntr > 0));
        }

        return (loop_cntr > 0);
}

static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
{
        int i2c_reg = *buf;

        /* Read data */
        while (length--) {
                if (!poll_status(I2C_STATUS_TFNF)) {
                        dev_dbg(&adap->dev, "Tx FIFO Not Full timeout\n");
                        return -ETIMEDOUT;
                }

                /* send addr */
                writel(i2c_reg | I2C_DATACMD_WRITE, I2C_DATACMD);

                /* get ready to next write */
                i2c_reg++;

                /* send read CMD */
                writel(I2C_DATACMD_READ, I2C_DATACMD);

                /* wait until the Rx FIFO have available */
                if (!poll_status(I2C_STATUS_RFNE)) {
                        dev_dbg(&adap->dev, "RXRDY timeout\n");
                        return -ETIMEDOUT;
                }

                /* read the data to buf */
                *buf = (readl(I2C_DATACMD) & I2C_DATACMD_DAT_MASK);
                buf++;
        }

        return 0;
}

static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length)
{
        int i2c_reg = *buf;

        /* Do nothing but storing the reg_num to a static variable */
        if (i2c_reg == -1) {
                printk(KERN_WARNING "Error i2c reg\n");
                return -ETIMEDOUT;
        }

        if (length == 1)
                return 0;

        buf++;
        length--;
        while (length--) {
                /* send addr */
                writel(i2c_reg | I2C_DATACMD_WRITE, I2C_DATACMD);

                /* send write CMD */
                writel(*buf | I2C_DATACMD_WRITE, I2C_DATACMD);

                /* wait until the Rx FIFO have available */
                msleep(20);

                /* read the data to buf */
                i2c_reg++;
                buf++;
        }

        return 0;
}

/*
 * Generic i2c master transfer entrypoint.
 *
 */
static int puv3_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg,
                int num)
{
        int i, ret;
        unsigned char swap;

        /* Disable i2c */
        writel(I2C_ENABLE_DISABLE, I2C_ENABLE);

        /* Set the work mode and speed*/
        writel(I2C_CON_MASTER | I2C_CON_SPEED_STD | I2C_CON_SLAVEDISABLE, I2C_CON);

        writel(pmsg->addr, I2C_TAR);

        /* Enable i2c */
        writel(I2C_ENABLE_ENABLE, I2C_ENABLE);

        dev_dbg(&adap->dev, "puv3_i2c_xfer: processing %d messages:\n", num);

        for (i = 0; i < num; i++) {
                dev_dbg(&adap->dev, " #%d: %sing %d byte%s %s 0x%02x\n", i,
                        pmsg->flags & I2C_M_RD ? "read" : "writ",
                        pmsg->len, pmsg->len > 1 ? "s" : "",
                        pmsg->flags & I2C_M_RD ? "from" : "to", pmsg->addr);

                if (pmsg->len && pmsg->buf) {   /* sanity check */
                        if (pmsg->flags & I2C_M_RD)
                                ret = xfer_read(adap, pmsg->buf, pmsg->len);
                        else
                                ret = xfer_write(adap, pmsg->buf, pmsg->len);

                        if (ret)
                                return ret;

                }
                dev_dbg(&adap->dev, "transfer complete\n");
                pmsg++;         /* next message */
        }

        /* XXX: fixup be16_to_cpu in bq27x00_battery.c */
        if (pmsg->addr == I2C_TAR_PWIC) {
                swap = pmsg->buf[0];
                pmsg->buf[0] = pmsg->buf[1];
                pmsg->buf[1] = swap;
        }

        return i;
}

/*
 * Return list of supported functionality.
 */
static u32 puv3_i2c_func(struct i2c_adapter *adapter)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static struct i2c_algorithm puv3_i2c_algorithm = {
        .master_xfer    = puv3_i2c_xfer,
        .functionality  = puv3_i2c_func,
};

/*
 * Main initialization routine.
 */
static int puv3_i2c_probe(struct platform_device *pdev)
{
        struct i2c_adapter *adapter;
        struct resource *mem;
        int rc;

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!mem)
                return -ENODEV;

        if (!request_mem_region(mem->start, resource_size(mem), "puv3_i2c"))
                return -EBUSY;

        adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
        if (adapter == NULL) {
                dev_err(&pdev->dev, "can't allocate interface!\n");
                rc = -ENOMEM;
                goto fail_nomem;
        }
        snprintf(adapter->name, sizeof(adapter->name), "PUV3-I2C at 0x%08x",
                        mem->start);
        adapter->algo = &puv3_i2c_algorithm;
        adapter->class = I2C_CLASS_HWMON;
        adapter->dev.parent = &pdev->dev;

        platform_set_drvdata(pdev, adapter);

        adapter->nr = pdev->id;
        rc = i2c_add_numbered_adapter(adapter);
        if (rc) {
                dev_err(&pdev->dev, "Adapter '%s' registration failed\n",
                                adapter->name);
                goto fail_add_adapter;
        }

        dev_info(&pdev->dev, "PKUnity v3 i2c bus adapter.\n");
        return 0;

fail_add_adapter:
        kfree(adapter);
fail_nomem:
        release_mem_region(mem->start, resource_size(mem));

        return rc;
}

static int puv3_i2c_remove(struct platform_device *pdev)
{
        struct i2c_adapter *adapter = platform_get_drvdata(pdev);
        struct resource *mem;

        i2c_del_adapter(adapter);

        put_device(&pdev->dev);

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        release_mem_region(mem->start, resource_size(mem));

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int puv3_i2c_suspend(struct device *dev)
{
        int poll_count;
        /* Disable the IIC */
        writel(I2C_ENABLE_DISABLE, I2C_ENABLE);
        for (poll_count = 0; poll_count < 50; poll_count++) {
                if (readl(I2C_ENSTATUS) & I2C_ENSTATUS_ENABLE)
                        udelay(25);
        }

        return 0;
}

static SIMPLE_DEV_PM_OPS(puv3_i2c_pm, puv3_i2c_suspend, NULL);
#define PUV3_I2C_PM     (&puv3_i2c_pm)

#else
#define PUV3_I2C_PM     NULL
#endif

static struct platform_driver puv3_i2c_driver = {
        .probe          = puv3_i2c_probe,
        .remove         = puv3_i2c_remove,
        .driver         = {
                .name   = "PKUnity-v3-I2C",
                .pm     = PUV3_I2C_PM,
        }
};

module_platform_driver(puv3_i2c_driver);

MODULE_DESCRIPTION("PKUnity v3 I2C driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:puv3_i2c");