i2c-xlr.c

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/*
 * Copyright 2011, Netlogic Microsystems Inc.
 * Copyright 2004, Matt Porter <[email protected]>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/platform_device.h>

/* XLR I2C REGISTERS */
#define XLR_I2C_CFG     0x00
#define XLR_I2C_CLKDIV      0x01
#define XLR_I2C_DEVADDR     0x02
#define XLR_I2C_ADDR        0x03
#define XLR_I2C_DATAOUT     0x04
#define XLR_I2C_DATAIN      0x05
#define XLR_I2C_STATUS      0x06
#define XLR_I2C_STARTXFR    0x07
#define XLR_I2C_BYTECNT     0x08
#define XLR_I2C_HDSTATIM    0x09

/* XLR I2C REGISTERS FLAGS */
#define XLR_I2C_BUS_BUSY    0x01
#define XLR_I2C_SDOEMPTY    0x02
#define XLR_I2C_RXRDY       0x04
#define XLR_I2C_ACK_ERR     0x08
#define XLR_I2C_ARB_STARTERR    0x30

/* Register Values */
#define XLR_I2C_CFG_ADDR    0xF8
#define XLR_I2C_CFG_NOADDR  0xFA
#define XLR_I2C_STARTXFR_ND 0x02    /* No Data */
#define XLR_I2C_STARTXFR_RD 0x01    /* Read */
#define XLR_I2C_STARTXFR_WR 0x00    /* Write */

#define XLR_I2C_TIMEOUT     10  /* timeout per byte in msec */

/*
 * On XLR/XLS, we need to use __raw_ IO to read the I2C registers
 * because they are in the big-endian MMIO area on the SoC.
 *
 * The readl/writel implementation on XLR/XLS byteswaps, because
 * those are for its little-endian PCI space (see arch/mips/Kconfig).
 */
static inline void xlr_i2c_wreg(u32 __iomem *base, unsigned int reg, u32 val)
{
    __raw_writel(val, base + reg);
}

static inline u32 xlr_i2c_rdreg(u32 __iomem *base, unsigned int reg)
{
    return __raw_readl(base + reg);
}

struct xlr_i2c_private {
    struct i2c_adapter adap;
    u32 __iomem *iobase;
};

static int xlr_i2c_tx(struct xlr_i2c_private *priv,  u16 len,
    u8 *buf, u16 addr)
{
    struct i2c_adapter *adap = &priv->adap;
    unsigned long timeout, stoptime, checktime;
    u32 i2c_status;
    int pos, timedout;
    u8 offset, byte;

    offset = buf[0];
    xlr_i2c_wreg(priv->iobase, XLR_I2C_ADDR, offset);
    xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr);
    xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_ADDR);
    xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1);

    timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT);
    stoptime = jiffies + timeout;
    timedout = 0;
    pos = 1;
retry:
    if (len == 1) {
        xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR,
                XLR_I2C_STARTXFR_ND);
    } else {
        xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[pos]);
        xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR,
                XLR_I2C_STARTXFR_WR);
    }

    while (!timedout) {
        checktime = jiffies;
        i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);

        if (i2c_status & XLR_I2C_SDOEMPTY) {
            pos++;
            /* need to do a empty dataout after the last byte */
            byte = (pos < len) ? buf[pos] : 0;
            xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, byte);

            /* reset timeout on successful xmit */
            stoptime = jiffies + timeout;
        }
        timedout = time_after(checktime, stoptime);

        if (i2c_status & XLR_I2C_ARB_STARTERR) {
            if (timedout)
                break;
            goto retry;
        }

        if (i2c_status & XLR_I2C_ACK_ERR)
            return -EIO;

        if ((i2c_status & XLR_I2C_BUS_BUSY) == 0 && pos >= len)
            return 0;
    }
    dev_err(&adap->dev, "I2C transmit timeout\n");
    return -ETIMEDOUT;
}

static int xlr_i2c_rx(struct xlr_i2c_private *priv, u16 len, u8 *buf, u16 addr)
{
    struct i2c_adapter *adap = &priv->adap;
    u32 i2c_status;
    unsigned long timeout, stoptime, checktime;
    int nbytes, timedout;
    u8 byte;

    xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_NOADDR);
    xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len);
    xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr);

    timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT);
    stoptime = jiffies + timeout;
    timedout = 0;
    nbytes = 0;
retry:
    xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, XLR_I2C_STARTXFR_RD);

    while (!timedout) {
        checktime = jiffies;
        i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS);
        if (i2c_status & XLR_I2C_RXRDY) {
            if (nbytes > len)
                return -EIO;    /* should not happen */

            /* we need to do a dummy datain when nbytes == len */
            byte = xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN);
            if (nbytes < len)
                buf[nbytes] = byte;
            nbytes++;

            /* reset timeout on successful read */
            stoptime = jiffies + timeout;
        }

        timedout = time_after(checktime, stoptime);
        if (i2c_status & XLR_I2C_ARB_STARTERR) {
            if (timedout)
                break;
            goto retry;
        }

        if (i2c_status & XLR_I2C_ACK_ERR)
            return -EIO;

        if ((i2c_status & XLR_I2C_BUS_BUSY) == 0)
            return 0;
    }

    dev_err(&adap->dev, "I2C receive timeout\n");
    return -ETIMEDOUT;
}

static int xlr_i2c_xfer(struct i2c_adapter *adap,
    struct i2c_msg *msgs, int num)
{
    struct i2c_msg *msg;
    int i;
    int ret = 0;
    struct xlr_i2c_private *priv = i2c_get_adapdata(adap);

    for (i = 0; ret == 0 && i < num; i++) {
        msg = &msgs[i];
        if (msg->flags & I2C_M_RD)
            ret = xlr_i2c_rx(priv, msg->len, &msg->buf[0],
                    msg->addr);
        else
            ret = xlr_i2c_tx(priv, msg->len, &msg->buf[0],
                    msg->addr);
    }

    return (ret != 0) ? ret : num;
}

static u32 xlr_func(struct i2c_adapter *adap)
{
    /* Emulate SMBUS over I2C */
    return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C;
}

static struct i2c_algorithm xlr_i2c_algo = {
    .master_xfer    = xlr_i2c_xfer,
    .functionality  = xlr_func,
};

static int __devinit xlr_i2c_probe(struct platform_device *pdev)
{
    struct xlr_i2c_private  *priv;
    struct resource *res;
    int ret;

    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    priv->iobase = devm_request_and_ioremap(&pdev->dev, res);
    if (!priv->iobase) {
        dev_err(&pdev->dev, "devm_request_and_ioremap failed\n");
        return -EBUSY;
    }

    priv->adap.dev.parent = &pdev->dev;
    priv->adap.owner    = THIS_MODULE;
    priv->adap.algo_data    = priv;
    priv->adap.algo     = &xlr_i2c_algo;
    priv->adap.nr       = pdev->id;
    priv->adap.class    = I2C_CLASS_HWMON;
    snprintf(priv->adap.name, sizeof(priv->adap.name), "xlr-i2c");

    i2c_set_adapdata(&priv->adap, priv);
    ret = i2c_add_numbered_adapter(&priv->adap);
    if (ret < 0) {
        dev_err(&priv->adap.dev, "Failed to add i2c bus.\n");
        return ret;
    }

    platform_set_drvdata(pdev, priv);
    dev_info(&priv->adap.dev, "Added I2C Bus.\n");
    return 0;
}

static int __devexit xlr_i2c_remove(struct platform_device *pdev)
{
    struct xlr_i2c_private *priv;

    priv = platform_get_drvdata(pdev);
    i2c_del_adapter(&priv->adap);
    platform_set_drvdata(pdev, NULL);
    return 0;
}

static struct platform_driver xlr_i2c_driver = {
    .probe  = xlr_i2c_probe,
    .remove = __devexit_p(xlr_i2c_remove),
    .driver = {
        .name   = "xlr-i2cbus",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(xlr_i2c_driver);

MODULE_AUTHOR("Ganesan Ramalingam <[email protected]>");
MODULE_DESCRIPTION("XLR/XLS SoC I2C Controller driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:xlr-i2cbus");