console: Replace #if 0 with atomic var 'ignore_console_lock_warning'

[linux/fpc-iii.git] / drivers / w1 / masters / omap_hdq.c

/*
 * drivers/w1/masters/omap_hdq.c
 *
 * Copyright (C) 2007,2012 Texas Instruments, Inc.
 *
 * 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/platform_device.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/sched.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>

#include <linux/w1.h>

#define MOD_NAME        "OMAP_HDQ:"

#define OMAP_HDQ_REVISION                       0x00
#define OMAP_HDQ_TX_DATA                        0x04
#define OMAP_HDQ_RX_DATA                        0x08
#define OMAP_HDQ_CTRL_STATUS                    0x0c
#define OMAP_HDQ_CTRL_STATUS_SINGLE             BIT(7)
#define OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK      BIT(6)
#define OMAP_HDQ_CTRL_STATUS_CLOCKENABLE        BIT(5)
#define OMAP_HDQ_CTRL_STATUS_GO                 BIT(4)
#define OMAP_HDQ_CTRL_STATUS_PRESENCE           BIT(3)
#define OMAP_HDQ_CTRL_STATUS_INITIALIZATION     BIT(2)
#define OMAP_HDQ_CTRL_STATUS_DIR                BIT(1)
#define OMAP_HDQ_INT_STATUS                     0x10
#define OMAP_HDQ_INT_STATUS_TXCOMPLETE          BIT(2)
#define OMAP_HDQ_INT_STATUS_RXCOMPLETE          BIT(1)
#define OMAP_HDQ_INT_STATUS_TIMEOUT             BIT(0)
#define OMAP_HDQ_SYSCONFIG                      0x14
#define OMAP_HDQ_SYSCONFIG_SOFTRESET            BIT(1)
#define OMAP_HDQ_SYSCONFIG_AUTOIDLE             BIT(0)
#define OMAP_HDQ_SYSCONFIG_NOIDLE               0x0
#define OMAP_HDQ_SYSSTATUS                      0x18
#define OMAP_HDQ_SYSSTATUS_RESETDONE            BIT(0)

#define OMAP_HDQ_FLAG_CLEAR                     0
#define OMAP_HDQ_FLAG_SET                       1
#define OMAP_HDQ_TIMEOUT                        (HZ/5)

#define OMAP_HDQ_MAX_USER                       4

static DECLARE_WAIT_QUEUE_HEAD(hdq_wait_queue);

static int w1_id;
module_param(w1_id, int, S_IRUSR);
MODULE_PARM_DESC(w1_id, "1-wire id for the slave detection in HDQ mode");

struct hdq_data {
        struct device           *dev;
        void __iomem            *hdq_base;
        /* lock status update */
        struct  mutex           hdq_mutex;
        int                     hdq_usecount;
        u8                      hdq_irqstatus;
        /* device lock */
        spinlock_t              hdq_spinlock;
        /*
         * Used to control the call to omap_hdq_get and omap_hdq_put.
         * HDQ Protocol: Write the CMD|REG_address first, followed by
         * the data wrire or read.
         */
        int                     init_trans;
        int                     rrw;
        /* mode: 0-HDQ 1-W1 */
        int                     mode;

};

/* HDQ register I/O routines */
static inline u8 hdq_reg_in(struct hdq_data *hdq_data, u32 offset)
{
        return __raw_readl(hdq_data->hdq_base + offset);
}

static inline void hdq_reg_out(struct hdq_data *hdq_data, u32 offset, u8 val)
{
        __raw_writel(val, hdq_data->hdq_base + offset);
}

static inline u8 hdq_reg_merge(struct hdq_data *hdq_data, u32 offset,
                        u8 val, u8 mask)
{
        u8 new_val = (__raw_readl(hdq_data->hdq_base + offset) & ~mask)
                        | (val & mask);
        __raw_writel(new_val, hdq_data->hdq_base + offset);

        return new_val;
}

static void hdq_disable_interrupt(struct hdq_data *hdq_data, u32 offset,
                                  u32 mask)
{
        u32 ie;

        ie = readl(hdq_data->hdq_base + offset);
        writel(ie & mask, hdq_data->hdq_base + offset);
}

/*
 * Wait for one or more bits in flag change.
 * HDQ_FLAG_SET: wait until any bit in the flag is set.
 * HDQ_FLAG_CLEAR: wait until all bits in the flag are cleared.
 * return 0 on success and -ETIMEDOUT in the case of timeout.
 */
static int hdq_wait_for_flag(struct hdq_data *hdq_data, u32 offset,
                u8 flag, u8 flag_set, u8 *status)
{
        int ret = 0;
        unsigned long timeout = jiffies + OMAP_HDQ_TIMEOUT;

        if (flag_set == OMAP_HDQ_FLAG_CLEAR) {
                /* wait for the flag clear */
                while (((*status = hdq_reg_in(hdq_data, offset)) & flag)
                        && time_before(jiffies, timeout)) {
                        schedule_timeout_uninterruptible(1);
                }
                if (*status & flag)
                        ret = -ETIMEDOUT;
        } else if (flag_set == OMAP_HDQ_FLAG_SET) {
                /* wait for the flag set */
                while (!((*status = hdq_reg_in(hdq_data, offset)) & flag)
                        && time_before(jiffies, timeout)) {
                        schedule_timeout_uninterruptible(1);
                }
                if (!(*status & flag))
                        ret = -ETIMEDOUT;
        } else
                return -EINVAL;

        return ret;
}

/* write out a byte and fill *status with HDQ_INT_STATUS */
static int hdq_write_byte(struct hdq_data *hdq_data, u8 val, u8 *status)
{
        int ret;
        u8 tmp_status;
        unsigned long irqflags;

        *status = 0;

        spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
        /* clear interrupt flags via a dummy read */
        hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
        /* ISR loads it with new INT_STATUS */
        hdq_data->hdq_irqstatus = 0;
        spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);

        hdq_reg_out(hdq_data, OMAP_HDQ_TX_DATA, val);

        /* set the GO bit */
        hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, OMAP_HDQ_CTRL_STATUS_GO,
                OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO);
        /* wait for the TXCOMPLETE bit */
        ret = wait_event_timeout(hdq_wait_queue,
                hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
        if (ret == 0) {
                dev_dbg(hdq_data->dev, "TX wait elapsed\n");
                ret = -ETIMEDOUT;
                goto out;
        }

        *status = hdq_data->hdq_irqstatus;
        /* check irqstatus */
        if (!(*status & OMAP_HDQ_INT_STATUS_TXCOMPLETE)) {
                dev_dbg(hdq_data->dev, "timeout waiting for"
                        " TXCOMPLETE/RXCOMPLETE, %x", *status);
                ret = -ETIMEDOUT;
                goto out;
        }

        /* wait for the GO bit return to zero */
        ret = hdq_wait_for_flag(hdq_data, OMAP_HDQ_CTRL_STATUS,
                        OMAP_HDQ_CTRL_STATUS_GO,
                        OMAP_HDQ_FLAG_CLEAR, &tmp_status);
        if (ret) {
                dev_dbg(hdq_data->dev, "timeout waiting GO bit"
                        " return to zero, %x", tmp_status);
        }

out:
        return ret;
}

/* HDQ Interrupt service routine */
static irqreturn_t hdq_isr(int irq, void *_hdq)
{
        struct hdq_data *hdq_data = _hdq;
        unsigned long irqflags;

        spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
        hdq_data->hdq_irqstatus = hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
        spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);
        dev_dbg(hdq_data->dev, "hdq_isr: %x", hdq_data->hdq_irqstatus);

        if (hdq_data->hdq_irqstatus &
                (OMAP_HDQ_INT_STATUS_TXCOMPLETE | OMAP_HDQ_INT_STATUS_RXCOMPLETE
                | OMAP_HDQ_INT_STATUS_TIMEOUT)) {
                /* wake up sleeping process */
                wake_up(&hdq_wait_queue);
        }

        return IRQ_HANDLED;
}

/* W1 search callback function  in HDQ mode */
static void omap_w1_search_bus(void *_hdq, struct w1_master *master_dev,
                u8 search_type, w1_slave_found_callback slave_found)
{
        u64 module_id, rn_le, cs, id;

        if (w1_id)
                module_id = w1_id;
        else
                module_id = 0x1;

        rn_le = cpu_to_le64(module_id);
        /*
         * HDQ might not obey truly the 1-wire spec.
         * So calculate CRC based on module parameter.
         */
        cs = w1_calc_crc8((u8 *)&rn_le, 7);
        id = (cs << 56) | module_id;

        slave_found(master_dev, id);
}

static int _omap_hdq_reset(struct hdq_data *hdq_data)
{
        int ret;
        u8 tmp_status;

        hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
                    OMAP_HDQ_SYSCONFIG_SOFTRESET);
        /*
         * Select HDQ/1W mode & enable clocks.
         * It is observed that INT flags can't be cleared via a read and GO/INIT
         * won't return to zero if interrupt is disabled. So we always enable
         * interrupt.
         */
        hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
                OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
                OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);

        /* wait for reset to complete */
        ret = hdq_wait_for_flag(hdq_data, OMAP_HDQ_SYSSTATUS,
                OMAP_HDQ_SYSSTATUS_RESETDONE, OMAP_HDQ_FLAG_SET, &tmp_status);
        if (ret)
                dev_dbg(hdq_data->dev, "timeout waiting HDQ reset, %x",
                                tmp_status);
        else {
                hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
                        OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
                        OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK |
                        hdq_data->mode);
                hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
                        OMAP_HDQ_SYSCONFIG_AUTOIDLE);
        }

        return ret;
}

/* Issue break pulse to the device */
static int omap_hdq_break(struct hdq_data *hdq_data)
{
        int ret = 0;
        u8 tmp_status;
        unsigned long irqflags;

        ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
        if (ret < 0) {
                dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
                ret = -EINTR;
                goto rtn;
        }

        spin_lock_irqsave(&hdq_data->hdq_spinlock, irqflags);
        /* clear interrupt flags via a dummy read */
        hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
        /* ISR loads it with new INT_STATUS */
        hdq_data->hdq_irqstatus = 0;
        spin_unlock_irqrestore(&hdq_data->hdq_spinlock, irqflags);

        /* set the INIT and GO bit */
        hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS,
                OMAP_HDQ_CTRL_STATUS_INITIALIZATION | OMAP_HDQ_CTRL_STATUS_GO,
                OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_INITIALIZATION |
                OMAP_HDQ_CTRL_STATUS_GO);

        /* wait for the TIMEOUT bit */
        ret = wait_event_timeout(hdq_wait_queue,
                hdq_data->hdq_irqstatus, OMAP_HDQ_TIMEOUT);
        if (ret == 0) {
                dev_dbg(hdq_data->dev, "break wait elapsed\n");
                ret = -EINTR;
                goto out;
        }

        tmp_status = hdq_data->hdq_irqstatus;
        /* check irqstatus */
        if (!(tmp_status & OMAP_HDQ_INT_STATUS_TIMEOUT)) {
                dev_dbg(hdq_data->dev, "timeout waiting for TIMEOUT, %x",
                                tmp_status);
                ret = -ETIMEDOUT;
                goto out;
        }

        /*
         * check for the presence detect bit to get
         * set to show that the slave is responding
         */
        if (!(hdq_reg_in(hdq_data, OMAP_HDQ_CTRL_STATUS) &
                        OMAP_HDQ_CTRL_STATUS_PRESENCE)) {
                dev_dbg(hdq_data->dev, "Presence bit not set\n");
                ret = -ETIMEDOUT;
                goto out;
        }

        /*
         * wait for both INIT and GO bits rerurn to zero.
         * zero wait time expected for interrupt mode.
         */
        ret = hdq_wait_for_flag(hdq_data, OMAP_HDQ_CTRL_STATUS,
                        OMAP_HDQ_CTRL_STATUS_INITIALIZATION |
                        OMAP_HDQ_CTRL_STATUS_GO, OMAP_HDQ_FLAG_CLEAR,
                        &tmp_status);
        if (ret)
                dev_dbg(hdq_data->dev, "timeout waiting INIT&GO bits"
                        " return to zero, %x", tmp_status);

out:
        mutex_unlock(&hdq_data->hdq_mutex);
rtn:
        return ret;
}

static int hdq_read_byte(struct hdq_data *hdq_data, u8 *val)
{
        int ret = 0;
        u8 status;

        ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
        if (ret < 0) {
                ret = -EINTR;
                goto rtn;
        }

        if (!hdq_data->hdq_usecount) {
                ret = -EINVAL;
                goto out;
        }

        if (!(hdq_data->hdq_irqstatus & OMAP_HDQ_INT_STATUS_RXCOMPLETE)) {
                hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS,
                        OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO,
                        OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO);
                /*
                 * The RX comes immediately after TX.
                 */
                wait_event_timeout(hdq_wait_queue,
                                   (hdq_data->hdq_irqstatus
                                    & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
                                   OMAP_HDQ_TIMEOUT);

                hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, 0,
                        OMAP_HDQ_CTRL_STATUS_DIR);
                status = hdq_data->hdq_irqstatus;
                /* check irqstatus */
                if (!(status & OMAP_HDQ_INT_STATUS_RXCOMPLETE)) {
                        dev_dbg(hdq_data->dev, "timeout waiting for"
                                " RXCOMPLETE, %x", status);
                        ret = -ETIMEDOUT;
                        goto out;
                }
        }
        /* the data is ready. Read it in! */
        *val = hdq_reg_in(hdq_data, OMAP_HDQ_RX_DATA);
out:
        mutex_unlock(&hdq_data->hdq_mutex);
rtn:
        return ret;

}

/* Enable clocks and set the controller to HDQ/1W mode */
static int omap_hdq_get(struct hdq_data *hdq_data)
{
        int ret = 0;

        ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
        if (ret < 0) {
                ret = -EINTR;
                goto rtn;
        }

        if (OMAP_HDQ_MAX_USER == hdq_data->hdq_usecount) {
                dev_dbg(hdq_data->dev, "attempt to exceed the max use count");
                ret = -EINVAL;
                goto out;
        } else {
                hdq_data->hdq_usecount++;
                try_module_get(THIS_MODULE);
                if (1 == hdq_data->hdq_usecount) {

                        pm_runtime_get_sync(hdq_data->dev);

                        /* make sure HDQ/1W is out of reset */
                        if (!(hdq_reg_in(hdq_data, OMAP_HDQ_SYSSTATUS) &
                                OMAP_HDQ_SYSSTATUS_RESETDONE)) {
                                ret = _omap_hdq_reset(hdq_data);
                                if (ret)
                                        /* back up the count */
                                        hdq_data->hdq_usecount--;
                        } else {
                                /* select HDQ/1W mode & enable clocks */
                                hdq_reg_out(hdq_data, OMAP_HDQ_CTRL_STATUS,
                                        OMAP_HDQ_CTRL_STATUS_CLOCKENABLE |
                                        OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK |
                                        hdq_data->mode);
                                hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
                                        OMAP_HDQ_SYSCONFIG_NOIDLE);
                                hdq_reg_in(hdq_data, OMAP_HDQ_INT_STATUS);
                        }
                }
        }

out:
        mutex_unlock(&hdq_data->hdq_mutex);
rtn:
        return ret;
}

/* Disable clocks to the module */
static int omap_hdq_put(struct hdq_data *hdq_data)
{
        int ret = 0;

        ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
        if (ret < 0)
                return -EINTR;

        hdq_reg_out(hdq_data, OMAP_HDQ_SYSCONFIG,
                    OMAP_HDQ_SYSCONFIG_AUTOIDLE);
        if (0 == hdq_data->hdq_usecount) {
                dev_dbg(hdq_data->dev, "attempt to decrement use count"
                        " when it is zero");
                ret = -EINVAL;
        } else {
                hdq_data->hdq_usecount--;
                module_put(THIS_MODULE);
                if (0 == hdq_data->hdq_usecount)
                        pm_runtime_put_sync(hdq_data->dev);
        }
        mutex_unlock(&hdq_data->hdq_mutex);

        return ret;
}

/*
 * W1 triplet callback function - used for searching ROM addresses.
 * Registered only when controller is in 1-wire mode.
 */
static u8 omap_w1_triplet(void *_hdq, u8 bdir)
{
        u8 id_bit, comp_bit;
        int err;
        u8 ret = 0x3; /* no slaves responded */
        struct hdq_data *hdq_data = _hdq;
        u8 ctrl = OMAP_HDQ_CTRL_STATUS_SINGLE | OMAP_HDQ_CTRL_STATUS_GO |
                  OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK;
        u8 mask = ctrl | OMAP_HDQ_CTRL_STATUS_DIR;

        omap_hdq_get(_hdq);

        err = mutex_lock_interruptible(&hdq_data->hdq_mutex);
        if (err < 0) {
                dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
                goto rtn;
        }

        hdq_data->hdq_irqstatus = 0;
        /* read id_bit */
        hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS,
                      ctrl | OMAP_HDQ_CTRL_STATUS_DIR, mask);
        err = wait_event_timeout(hdq_wait_queue,
                                 (hdq_data->hdq_irqstatus
                                  & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
                                 OMAP_HDQ_TIMEOUT);
        if (err == 0) {
                dev_dbg(hdq_data->dev, "RX wait elapsed\n");
                goto out;
        }
        id_bit = (hdq_reg_in(_hdq, OMAP_HDQ_RX_DATA) & 0x01);

        hdq_data->hdq_irqstatus = 0;
        /* read comp_bit */
        hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS,
                      ctrl | OMAP_HDQ_CTRL_STATUS_DIR, mask);
        err = wait_event_timeout(hdq_wait_queue,
                                 (hdq_data->hdq_irqstatus
                                  & OMAP_HDQ_INT_STATUS_RXCOMPLETE),
                                 OMAP_HDQ_TIMEOUT);
        if (err == 0) {
                dev_dbg(hdq_data->dev, "RX wait elapsed\n");
                goto out;
        }
        comp_bit = (hdq_reg_in(_hdq, OMAP_HDQ_RX_DATA) & 0x01);

        if (id_bit && comp_bit) {
                ret = 0x03;  /* no slaves responded */
                goto out;
        }
        if (!id_bit && !comp_bit) {
                /* Both bits are valid, take the direction given */
                ret = bdir ? 0x04 : 0;
        } else {
                /* Only one bit is valid, take that direction */
                bdir = id_bit;
                ret = id_bit ? 0x05 : 0x02;
        }

        /* write bdir bit */
        hdq_reg_out(_hdq, OMAP_HDQ_TX_DATA, bdir);
        hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS, ctrl, mask);
        err = wait_event_timeout(hdq_wait_queue,
                                 (hdq_data->hdq_irqstatus
                                  & OMAP_HDQ_INT_STATUS_TXCOMPLETE),
                                 OMAP_HDQ_TIMEOUT);
        if (err == 0) {
                dev_dbg(hdq_data->dev, "TX wait elapsed\n");
                goto out;
        }

        hdq_reg_merge(_hdq, OMAP_HDQ_CTRL_STATUS, 0,
                      OMAP_HDQ_CTRL_STATUS_SINGLE);

out:
        mutex_unlock(&hdq_data->hdq_mutex);
rtn:
        omap_hdq_put(_hdq);
        return ret;
}

/* reset callback */
static u8 omap_w1_reset_bus(void *_hdq)
{
        omap_hdq_get(_hdq);
        omap_hdq_break(_hdq);
        omap_hdq_put(_hdq);
        return 0;
}

/* Read a byte of data from the device */
static u8 omap_w1_read_byte(void *_hdq)
{
        struct hdq_data *hdq_data = _hdq;
        u8 val = 0;
        int ret;

        /* First write to initialize the transfer */
        if (hdq_data->init_trans == 0)
                omap_hdq_get(hdq_data);

        ret = hdq_read_byte(hdq_data, &val);
        if (ret) {
                ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
                if (ret < 0) {
                        dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
                        return -EINTR;
                }
                hdq_data->init_trans = 0;
                mutex_unlock(&hdq_data->hdq_mutex);
                omap_hdq_put(hdq_data);
                return -1;
        }

        hdq_disable_interrupt(hdq_data, OMAP_HDQ_CTRL_STATUS,
                              ~OMAP_HDQ_CTRL_STATUS_INTERRUPTMASK);

        /* Write followed by a read, release the module */
        if (hdq_data->init_trans) {
                ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
                if (ret < 0) {
                        dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
                        return -EINTR;
                }
                hdq_data->init_trans = 0;
                mutex_unlock(&hdq_data->hdq_mutex);
                omap_hdq_put(hdq_data);
        }

        return val;
}

/* Write a byte of data to the device */
static void omap_w1_write_byte(void *_hdq, u8 byte)
{
        struct hdq_data *hdq_data = _hdq;
        int ret;
        u8 status;

        /* First write to initialize the transfer */
        if (hdq_data->init_trans == 0)
                omap_hdq_get(hdq_data);

        /*
         * We need to reset the slave before
         * issuing the SKIP ROM command, else
         * the slave will not work.
         */
        if (byte == W1_SKIP_ROM)
                omap_hdq_break(hdq_data);

        ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
        if (ret < 0) {
                dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
                return;
        }
        hdq_data->init_trans++;
        mutex_unlock(&hdq_data->hdq_mutex);

        ret = hdq_write_byte(hdq_data, byte, &status);
        if (ret < 0) {
                dev_dbg(hdq_data->dev, "TX failure:Ctrl status %x\n", status);
                return;
        }

        /* Second write, data transferred. Release the module */
        if (hdq_data->init_trans > 1) {
                omap_hdq_put(hdq_data);
                ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
                if (ret < 0) {
                        dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
                        return;
                }
                hdq_data->init_trans = 0;
                mutex_unlock(&hdq_data->hdq_mutex);
        }
}

static struct w1_bus_master omap_w1_master = {
        .read_byte      = omap_w1_read_byte,
        .write_byte     = omap_w1_write_byte,
        .reset_bus      = omap_w1_reset_bus,
};

static int omap_hdq_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct hdq_data *hdq_data;
        struct resource *res;
        int ret, irq;
        u8 rev;
        const char *mode;

        hdq_data = devm_kzalloc(dev, sizeof(*hdq_data), GFP_KERNEL);
        if (!hdq_data) {
                dev_dbg(&pdev->dev, "unable to allocate memory\n");
                return -ENOMEM;
        }

        hdq_data->dev = dev;
        platform_set_drvdata(pdev, hdq_data);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        hdq_data->hdq_base = devm_ioremap_resource(dev, res);
        if (IS_ERR(hdq_data->hdq_base))
                return PTR_ERR(hdq_data->hdq_base);

        hdq_data->hdq_usecount = 0;
        hdq_data->rrw = 0;
        mutex_init(&hdq_data->hdq_mutex);

        pm_runtime_enable(&pdev->dev);
        ret = pm_runtime_get_sync(&pdev->dev);
        if (ret < 0) {
                dev_dbg(&pdev->dev, "pm_runtime_get_sync failed\n");
                goto err_w1;
        }

        ret = _omap_hdq_reset(hdq_data);
        if (ret) {
                dev_dbg(&pdev->dev, "reset failed\n");
                goto err_irq;
        }

        rev = hdq_reg_in(hdq_data, OMAP_HDQ_REVISION);
        dev_info(&pdev->dev, "OMAP HDQ Hardware Rev %c.%c. Driver in %s mode\n",
                (rev >> 4) + '0', (rev & 0x0f) + '0', "Interrupt");

        spin_lock_init(&hdq_data->hdq_spinlock);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_dbg(&pdev->dev, "Failed to get IRQ: %d\n", irq);
                ret = irq;
                goto err_irq;
        }

        ret = devm_request_irq(dev, irq, hdq_isr, 0, "omap_hdq", hdq_data);
        if (ret < 0) {
                dev_dbg(&pdev->dev, "could not request irq\n");
                goto err_irq;
        }

        omap_hdq_break(hdq_data);

        pm_runtime_put_sync(&pdev->dev);

        ret = of_property_read_string(pdev->dev.of_node, "ti,mode", &mode);
        if (ret < 0 || !strcmp(mode, "hdq")) {
                hdq_data->mode = 0;
                omap_w1_master.search = omap_w1_search_bus;
        } else {
                hdq_data->mode = 1;
                omap_w1_master.triplet = omap_w1_triplet;
        }

        omap_w1_master.data = hdq_data;

        ret = w1_add_master_device(&omap_w1_master);
        if (ret) {
                dev_dbg(&pdev->dev, "Failure in registering w1 master\n");
                goto err_w1;
        }

        return 0;

err_irq:
        pm_runtime_put_sync(&pdev->dev);
err_w1:
        pm_runtime_disable(&pdev->dev);

        return ret;
}

static int omap_hdq_remove(struct platform_device *pdev)
{
        struct hdq_data *hdq_data = platform_get_drvdata(pdev);

        mutex_lock(&hdq_data->hdq_mutex);

        if (hdq_data->hdq_usecount) {
                dev_dbg(&pdev->dev, "removed when use count is not zero\n");
                mutex_unlock(&hdq_data->hdq_mutex);
                return -EBUSY;
        }

        mutex_unlock(&hdq_data->hdq_mutex);

        /* remove module dependency */
        pm_runtime_disable(&pdev->dev);

        return 0;
}

static const struct of_device_id omap_hdq_dt_ids[] = {
        { .compatible = "ti,omap3-1w" },
        { .compatible = "ti,am4372-hdq" },
        {}
};
MODULE_DEVICE_TABLE(of, omap_hdq_dt_ids);

static struct platform_driver omap_hdq_driver = {
        .probe = omap_hdq_probe,
        .remove = omap_hdq_remove,
        .driver = {
                .name = "omap_hdq",
                .of_match_table = omap_hdq_dt_ids,
        },
};
module_platform_driver(omap_hdq_driver);

MODULE_AUTHOR("Texas Instruments");
MODULE_DESCRIPTION("HDQ-1W driver Library");
MODULE_LICENSE("GPL");