Linux 2.6.34-rc3

[pohmelfs.git] / drivers / hwmon / sht15.c

/*
 * sht15.c - support for the SHT15 Temperature and Humidity Sensor
 *
 * Copyright (c) 2009 Jonathan Cameron
 *
 * Copyright (c) 2007 Wouter Horre
 *
 * 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.
 *
 * Currently ignoring checksum on readings.
 * Default resolution only (14bit temp, 12bit humidity)
 * Ignoring battery status.
 * Heater not enabled.
 * Timings are all conservative.
 *
 * Data sheet available (1/2009) at
 * http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf
 *
 * Regulator supply name = vcc
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/err.h>
#include <linux/sht15.h>
#include <linux/regulator/consumer.h>
#include <asm/atomic.h>

#define SHT15_MEASURE_TEMP      3
#define SHT15_MEASURE_RH        5

#define SHT15_READING_NOTHING   0
#define SHT15_READING_TEMP      1
#define SHT15_READING_HUMID     2

/* Min timings in nsecs */
#define SHT15_TSCKL             100     /* clock low */
#define SHT15_TSCKH             100     /* clock high */
#define SHT15_TSU               150     /* data setup time */

/**
 * struct sht15_temppair - elements of voltage dependant temp calc
 * @vdd:        supply voltage in microvolts
 * @d1:         see data sheet
 */
struct sht15_temppair {
        int vdd; /* microvolts */
        int d1;
};

/* Table 9 from data sheet - relates temperature calculation
 * to supply voltage.
 */
static const struct sht15_temppair temppoints[] = {
        { 2500000, -39400 },
        { 3000000, -39600 },
        { 3500000, -39700 },
        { 4000000, -39800 },
        { 5000000, -40100 },
};

/**
 * struct sht15_data - device instance specific data
 * @pdata:      platform data (gpio's etc)
 * @read_work:  bh of interrupt handler
 * @wait_queue: wait queue for getting values from device
 * @val_temp:   last temperature value read from device
 * @val_humid:  last humidity value read from device
 * @flag:       status flag used to identify what the last request was
 * @valid:      are the current stored values valid (start condition)
 * @last_updat: time of last update
 * @read_lock:  mutex to ensure only one read in progress
 *              at a time.
 * @dev:        associate device structure
 * @hwmon_dev:  device associated with hwmon subsystem
 * @reg:        associated regulator (if specified)
 * @nb:         notifier block to handle notifications of voltage changes
 * @supply_uV:  local copy of supply voltage used to allow
 *              use of regulator consumer if available
 * @supply_uV_valid:   indicates that an updated value has not yet
 *              been obtained from the regulator and so any calculations
 *              based upon it will be invalid.
 * @update_supply_work: work struct that is used to update the supply_uV
 * @interrupt_handled:  flag used to indicate a hander has been scheduled
 */
struct sht15_data {
        struct sht15_platform_data      *pdata;
        struct work_struct              read_work;
        wait_queue_head_t               wait_queue;
        uint16_t                        val_temp;
        uint16_t                        val_humid;
        u8                              flag;
        u8                              valid;
        unsigned long                   last_updat;
        struct mutex                    read_lock;
        struct device                   *dev;
        struct device                   *hwmon_dev;
        struct regulator                *reg;
        struct notifier_block           nb;
        int                             supply_uV;
        int                             supply_uV_valid;
        struct work_struct              update_supply_work;
        atomic_t                        interrupt_handled;
};

/**
 * sht15_connection_reset() - reset the comms interface
 * @data:       sht15 specific data
 *
 * This implements section 3.4 of the data sheet
 */
static void sht15_connection_reset(struct sht15_data *data)
{
        int i;
        gpio_direction_output(data->pdata->gpio_data, 1);
        ndelay(SHT15_TSCKL);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL);
        for (i = 0; i < 9; ++i) {
                gpio_set_value(data->pdata->gpio_sck, 1);
                ndelay(SHT15_TSCKH);
                gpio_set_value(data->pdata->gpio_sck, 0);
                ndelay(SHT15_TSCKL);
        }
}
/**
 * sht15_send_bit() - send an individual bit to the device
 * @data:       device state data
 * @val:        value of bit to be sent
 **/
static inline void sht15_send_bit(struct sht15_data *data, int val)
{

        gpio_set_value(data->pdata->gpio_data, val);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 1);
        ndelay(SHT15_TSCKH);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL); /* clock low time */
}

/**
 * sht15_transmission_start() - specific sequence for new transmission
 *
 * @data:       device state data
 * Timings for this are not documented on the data sheet, so very
 * conservative ones used in implementation. This implements
 * figure 12 on the data sheet.
 **/
static void sht15_transmission_start(struct sht15_data *data)
{
        /* ensure data is high and output */
        gpio_direction_output(data->pdata->gpio_data, 1);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL);
        gpio_set_value(data->pdata->gpio_sck, 1);
        ndelay(SHT15_TSCKH);
        gpio_set_value(data->pdata->gpio_data, 0);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL);
        gpio_set_value(data->pdata->gpio_sck, 1);
        ndelay(SHT15_TSCKH);
        gpio_set_value(data->pdata->gpio_data, 1);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL);
}
/**
 * sht15_send_byte() - send a single byte to the device
 * @data:       device state
 * @byte:       value to be sent
 **/
static void sht15_send_byte(struct sht15_data *data, u8 byte)
{
        int i;
        for (i = 0; i < 8; i++) {
                sht15_send_bit(data, !!(byte & 0x80));
                byte <<= 1;
        }
}
/**
 * sht15_wait_for_response() - checks for ack from device
 * @data:       device state
 **/
static int sht15_wait_for_response(struct sht15_data *data)
{
        gpio_direction_input(data->pdata->gpio_data);
        gpio_set_value(data->pdata->gpio_sck, 1);
        ndelay(SHT15_TSCKH);
        if (gpio_get_value(data->pdata->gpio_data)) {
                gpio_set_value(data->pdata->gpio_sck, 0);
                dev_err(data->dev, "Command not acknowledged\n");
                sht15_connection_reset(data);
                return -EIO;
        }
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL);
        return 0;
}

/**
 * sht15_send_cmd() - Sends a command to the device.
 * @data:       device state
 * @cmd:        command byte to be sent
 *
 * On entry, sck is output low, data is output pull high
 * and the interrupt disabled.
 **/
static int sht15_send_cmd(struct sht15_data *data, u8 cmd)
{
        int ret = 0;
        sht15_transmission_start(data);
        sht15_send_byte(data, cmd);
        ret = sht15_wait_for_response(data);
        return ret;
}
/**
 * sht15_update_single_val() - get a new value from device
 * @data:               device instance specific data
 * @command:            command sent to request value
 * @timeout_msecs:      timeout after which comms are assumed
 *                      to have failed are reset.
 **/
static inline int sht15_update_single_val(struct sht15_data *data,
                                          int command,
                                          int timeout_msecs)
{
        int ret;
        ret = sht15_send_cmd(data, command);
        if (ret)
                return ret;

        gpio_direction_input(data->pdata->gpio_data);
        atomic_set(&data->interrupt_handled, 0);

        enable_irq(gpio_to_irq(data->pdata->gpio_data));
        if (gpio_get_value(data->pdata->gpio_data) == 0) {
                disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
                /* Only relevant if the interrupt hasn't occured. */
                if (!atomic_read(&data->interrupt_handled))
                        schedule_work(&data->read_work);
        }
        ret = wait_event_timeout(data->wait_queue,
                                 (data->flag == SHT15_READING_NOTHING),
                                 msecs_to_jiffies(timeout_msecs));
        if (ret == 0) {/* timeout occurred */
                disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
                sht15_connection_reset(data);
                return -ETIME;
        }
        return 0;
}

/**
 * sht15_update_vals() - get updated readings from device if too old
 * @data:       device state
 **/
static int sht15_update_vals(struct sht15_data *data)
{
        int ret = 0;
        int timeout = HZ;

        mutex_lock(&data->read_lock);
        if (time_after(jiffies, data->last_updat + timeout)
            || !data->valid) {
                data->flag = SHT15_READING_HUMID;
                ret = sht15_update_single_val(data, SHT15_MEASURE_RH, 160);
                if (ret)
                        goto error_ret;
                data->flag = SHT15_READING_TEMP;
                ret = sht15_update_single_val(data, SHT15_MEASURE_TEMP, 400);
                if (ret)
                        goto error_ret;
                data->valid = 1;
                data->last_updat = jiffies;
        }
error_ret:
        mutex_unlock(&data->read_lock);

        return ret;
}

/**
 * sht15_calc_temp() - convert the raw reading to a temperature
 * @data:       device state
 *
 * As per section 4.3 of the data sheet.
 **/
static inline int sht15_calc_temp(struct sht15_data *data)
{
        int d1 = 0;
        int i;

        for (i = 1; i < ARRAY_SIZE(temppoints); i++)
                /* Find pointer to interpolate */
                if (data->supply_uV > temppoints[i - 1].vdd) {
                        d1 = (data->supply_uV/1000 - temppoints[i - 1].vdd)
                                * (temppoints[i].d1 - temppoints[i - 1].d1)
                                / (temppoints[i].vdd - temppoints[i - 1].vdd)
                                + temppoints[i - 1].d1;
                        break;
                }

        return data->val_temp*10 + d1;
}

/**
 * sht15_calc_humid() - using last temperature convert raw to humid
 * @data:       device state
 *
 * This is the temperature compensated version as per section 4.2 of
 * the data sheet.
 **/
static inline int sht15_calc_humid(struct sht15_data *data)
{
        int RHlinear; /* milli percent */
        int temp = sht15_calc_temp(data);

        const int c1 = -4;
        const int c2 = 40500; /* x 10 ^ -6 */
        const int c3 = -2800; /* x10 ^ -9 */

        RHlinear = c1*1000
                + c2 * data->val_humid/1000
                + (data->val_humid * data->val_humid * c3)/1000000;
        return (temp - 25000) * (10000 + 80 * data->val_humid)
                / 1000000 + RHlinear;
}

static ssize_t sht15_show_temp(struct device *dev,
                               struct device_attribute *attr,
                               char *buf)
{
        int ret;
        struct sht15_data *data = dev_get_drvdata(dev);

        /* Technically no need to read humidity as well */
        ret = sht15_update_vals(data);

        return ret ? ret : sprintf(buf, "%d\n",
                                   sht15_calc_temp(data));
}

static ssize_t sht15_show_humidity(struct device *dev,
                                   struct device_attribute *attr,
                                   char *buf)
{
        int ret;
        struct sht15_data *data = dev_get_drvdata(dev);

        ret = sht15_update_vals(data);

        return ret ? ret : sprintf(buf, "%d\n", sht15_calc_humid(data));

};
static ssize_t show_name(struct device *dev,
                         struct device_attribute *attr,
                         char *buf)
{
        struct platform_device *pdev = to_platform_device(dev);
        return sprintf(buf, "%s\n", pdev->name);
}

static SENSOR_DEVICE_ATTR(temp1_input,
                          S_IRUGO, sht15_show_temp,
                          NULL, 0);
static SENSOR_DEVICE_ATTR(humidity1_input,
                          S_IRUGO, sht15_show_humidity,
                          NULL, 0);
static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
static struct attribute *sht15_attrs[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_humidity1_input.dev_attr.attr,
        &dev_attr_name.attr,
        NULL,
};

static const struct attribute_group sht15_attr_group = {
        .attrs = sht15_attrs,
};

static irqreturn_t sht15_interrupt_fired(int irq, void *d)
{
        struct sht15_data *data = d;
        /* First disable the interrupt */
        disable_irq_nosync(irq);
        atomic_inc(&data->interrupt_handled);
        /* Then schedule a reading work struct */
        if (data->flag != SHT15_READING_NOTHING)
                schedule_work(&data->read_work);
        return IRQ_HANDLED;
}

/* Each byte of data is acknowledged by pulling the data line
 * low for one clock pulse.
 */
static void sht15_ack(struct sht15_data *data)
{
        gpio_direction_output(data->pdata->gpio_data, 0);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 1);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_data, 1);

        gpio_direction_input(data->pdata->gpio_data);
}
/**
 * sht15_end_transmission() - notify device of end of transmission
 * @data:       device state
 *
 * This is basically a NAK. (single clock pulse, data high)
 **/
static void sht15_end_transmission(struct sht15_data *data)
{
        gpio_direction_output(data->pdata->gpio_data, 1);
        ndelay(SHT15_TSU);
        gpio_set_value(data->pdata->gpio_sck, 1);
        ndelay(SHT15_TSCKH);
        gpio_set_value(data->pdata->gpio_sck, 0);
        ndelay(SHT15_TSCKL);
}

static void sht15_bh_read_data(struct work_struct *work_s)
{
        int i;
        uint16_t val = 0;
        struct sht15_data *data
                = container_of(work_s, struct sht15_data,
                               read_work);
        /* Firstly, verify the line is low */
        if (gpio_get_value(data->pdata->gpio_data)) {
                /* If not, then start the interrupt again - care
                   here as could have gone low in meantime so verify
                   it hasn't!
                */
                atomic_set(&data->interrupt_handled, 0);
                enable_irq(gpio_to_irq(data->pdata->gpio_data));
                /* If still not occured or another handler has been scheduled */
                if (gpio_get_value(data->pdata->gpio_data)
                    || atomic_read(&data->interrupt_handled))
                        return;
        }
        /* Read the data back from the device */
        for (i = 0; i < 16; ++i) {
                val <<= 1;
                gpio_set_value(data->pdata->gpio_sck, 1);
                ndelay(SHT15_TSCKH);
                val |= !!gpio_get_value(data->pdata->gpio_data);
                gpio_set_value(data->pdata->gpio_sck, 0);
                ndelay(SHT15_TSCKL);
                if (i == 7)
                        sht15_ack(data);
        }
        /* Tell the device we are done */
        sht15_end_transmission(data);

        switch (data->flag) {
        case SHT15_READING_TEMP:
                data->val_temp = val;
                break;
        case SHT15_READING_HUMID:
                data->val_humid = val;
                break;
        }

        data->flag = SHT15_READING_NOTHING;
        wake_up(&data->wait_queue);
}

static void sht15_update_voltage(struct work_struct *work_s)
{
        struct sht15_data *data
                = container_of(work_s, struct sht15_data,
                               update_supply_work);
        data->supply_uV = regulator_get_voltage(data->reg);
}

/**
 * sht15_invalidate_voltage() - mark supply voltage invalid when notified by reg
 * @nb:         associated notification structure
 * @event:      voltage regulator state change event code
 * @ignored:    function parameter - ignored here
 *
 * Note that as the notification code holds the regulator lock, we have
 * to schedule an update of the supply voltage rather than getting it directly.
 **/
static int sht15_invalidate_voltage(struct notifier_block *nb,
                                unsigned long event,
                                void *ignored)
{
        struct sht15_data *data = container_of(nb, struct sht15_data, nb);

        if (event == REGULATOR_EVENT_VOLTAGE_CHANGE)
                data->supply_uV_valid = false;
        schedule_work(&data->update_supply_work);

        return NOTIFY_OK;
}

static int __devinit sht15_probe(struct platform_device *pdev)
{
        int ret = 0;
        struct sht15_data *data = kzalloc(sizeof(*data), GFP_KERNEL);

        if (!data) {
                ret = -ENOMEM;
                dev_err(&pdev->dev, "kzalloc failed");
                goto error_ret;
        }

        INIT_WORK(&data->read_work, sht15_bh_read_data);
        INIT_WORK(&data->update_supply_work, sht15_update_voltage);
        platform_set_drvdata(pdev, data);
        mutex_init(&data->read_lock);
        data->dev = &pdev->dev;
        init_waitqueue_head(&data->wait_queue);

        if (pdev->dev.platform_data == NULL) {
                dev_err(&pdev->dev, "no platform data supplied");
                goto err_free_data;
        }
        data->pdata = pdev->dev.platform_data;
        data->supply_uV = data->pdata->supply_mv*1000;

/* If a regulator is available, query what the supply voltage actually is!*/
        data->reg = regulator_get(data->dev, "vcc");
        if (!IS_ERR(data->reg)) {
                data->supply_uV = regulator_get_voltage(data->reg);
                regulator_enable(data->reg);
                /* setup a notifier block to update this if another device
                 *  causes the voltage to change */
                data->nb.notifier_call = &sht15_invalidate_voltage;
                ret = regulator_register_notifier(data->reg, &data->nb);
        }
/* Try requesting the GPIOs */
        ret = gpio_request(data->pdata->gpio_sck, "SHT15 sck");
        if (ret) {
                dev_err(&pdev->dev, "gpio request failed");
                goto err_free_data;
        }
        gpio_direction_output(data->pdata->gpio_sck, 0);
        ret = gpio_request(data->pdata->gpio_data, "SHT15 data");
        if (ret) {
                dev_err(&pdev->dev, "gpio request failed");
                goto err_release_gpio_sck;
        }
        ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group);
        if (ret) {
                dev_err(&pdev->dev, "sysfs create failed");
                goto err_release_gpio_data;
        }

        ret = request_irq(gpio_to_irq(data->pdata->gpio_data),
                          sht15_interrupt_fired,
                          IRQF_TRIGGER_FALLING,
                          "sht15 data",
                          data);
        if (ret) {
                dev_err(&pdev->dev, "failed to get irq for data line");
                goto err_release_gpio_data;
        }
        disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));
        sht15_connection_reset(data);
        sht15_send_cmd(data, 0x1E);

        data->hwmon_dev = hwmon_device_register(data->dev);
        if (IS_ERR(data->hwmon_dev)) {
                ret = PTR_ERR(data->hwmon_dev);
                goto err_release_irq;
        }
        return 0;

err_release_irq:
        free_irq(gpio_to_irq(data->pdata->gpio_data), data);
err_release_gpio_data:
        gpio_free(data->pdata->gpio_data);
err_release_gpio_sck:
        gpio_free(data->pdata->gpio_sck);
err_free_data:
        kfree(data);
error_ret:

        return ret;
}

static int __devexit sht15_remove(struct platform_device *pdev)
{
        struct sht15_data *data = platform_get_drvdata(pdev);

        /* Make sure any reads from the device are done and
         * prevent new ones beginnning */
        mutex_lock(&data->read_lock);
        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);
        if (!IS_ERR(data->reg)) {
                regulator_unregister_notifier(data->reg, &data->nb);
                regulator_disable(data->reg);
                regulator_put(data->reg);
        }

        free_irq(gpio_to_irq(data->pdata->gpio_data), data);
        gpio_free(data->pdata->gpio_data);
        gpio_free(data->pdata->gpio_sck);
        mutex_unlock(&data->read_lock);
        kfree(data);
        return 0;
}


/*
 * sht_drivers simultaneously refers to __devinit and __devexit function
 * which causes spurious section mismatch warning. So use __refdata to
 * get rid from this.
 */
static struct platform_driver __refdata sht_drivers[] = {
        {
                .driver = {
                        .name = "sht10",
                        .owner = THIS_MODULE,
                },
                .probe = sht15_probe,
                .remove = __devexit_p(sht15_remove),
        }, {
                .driver = {
                        .name = "sht11",
                        .owner = THIS_MODULE,
                },
                .probe = sht15_probe,
                .remove = __devexit_p(sht15_remove),
        }, {
                .driver = {
                        .name = "sht15",
                        .owner = THIS_MODULE,
                },
                .probe = sht15_probe,
                .remove = __devexit_p(sht15_remove),
        }, {
                .driver = {
                        .name = "sht71",
                        .owner = THIS_MODULE,
                },
                .probe = sht15_probe,
                .remove = __devexit_p(sht15_remove),
        }, {
                .driver = {
                        .name = "sht75",
                        .owner = THIS_MODULE,
                },
                .probe = sht15_probe,
                .remove = __devexit_p(sht15_remove),
        },
};


static int __init sht15_init(void)
{
        int ret;
        int i;

        for (i = 0; i < ARRAY_SIZE(sht_drivers); i++) {
                ret = platform_driver_register(&sht_drivers[i]);
                if (ret)
                        goto error_unreg;
        }

        return 0;

error_unreg:
        while (--i >= 0)
                platform_driver_unregister(&sht_drivers[i]);

        return ret;
}
module_init(sht15_init);

static void __exit sht15_exit(void)
{
        int i;
        for (i = ARRAY_SIZE(sht_drivers) - 1; i >= 0; i--)
                platform_driver_unregister(&sht_drivers[i]);
}
module_exit(sht15_exit);

MODULE_LICENSE("GPL");