i2c-puv3.c

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/*
 * I2C driver for PKUnity-v3 SoC
 * Code specific to PKUnity SoC and UniCore ISA
 *
 *  Maintained by GUAN Xue-tao <[email protected]>
 *  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/init.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 __devinit 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 inteface!\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:
    platform_set_drvdata(pdev, NULL);
    kfree(adapter);
fail_nomem:
    release_mem_region(mem->start, resource_size(mem));

    return rc;
}

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

    rc = i2c_del_adapter(adapter);
    if (rc) {
        dev_err(&pdev->dev, "Adapter '%s' delete fail\n",
                adapter->name);
        return rc;
    }

    put_device(&pdev->dev);
    platform_set_drvdata(pdev, NULL);

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

    return rc;
}

#ifdef CONFIG_PM
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     = __devexit_p(puv3_i2c_remove),
    .driver     = {
        .name   = "PKUnity-v3-I2C",
        .owner  = THIS_MODULE,
        .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");