hwmon: (sht15) general code clean-up

Kernel driver sht15

===================

Authors:

  * Wouter Horre

  * Jonathan Cameron

Supported chips:

  * Sensirion SHT10

    Prefix: 'sht10'

  * Sensirion SHT11

    Prefix: 'sht11'

  * Sensirion SHT15

    Prefix: 'sht15'

  * Sensirion SHT71

    Prefix: 'sht71'

  * Sensirion SHT75

    Prefix: 'sht75'

Datasheet: Publicly available at the Sensirion website

http://www.sensirion.ch/en/pdf/product_information/Datasheet-humidity-sensor-SHT1x.pdf

Description

-----------

The SHT10, SHT11, SHT15, SHT71, and SHT75 are humidity and temperature

sensors.

The devices communicate using two GPIO lines and use the default

resolution settings of 14 bits for temperature and 12 bits for humidity.

Note: The regulator supply name is set to "vcc".

Sysfs interface

---------------

* temp1_input:     temperature input

* humidity1_input: humidity input

 * 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

 * For further information, see the Documentation/hwmon/sht15 file.

 */

#include <linux/interrupt.h>

#include <linux/slab.h>

#include <asm/atomic.h>

#define SHT15_MEASURE_TEMP	3

#define SHT15_MEASURE_RH	5

/* Commands */

#define SHT15_MEASURE_TEMP		0x03

#define SHT15_MEASURE_RH		0x05

#define SHT15_READING_NOTHING	0

#define SHT15_READING_TEMP	1

#define SHT15_READING_HUMID	2

/* Min timings */

#define SHT15_TSCKL			100	/* (nsecs) clock low */

#define SHT15_TSCKH			100	/* (nsecs) clock high */

#define SHT15_TSU			150	/* (nsecs) data setup time */

/* Min timings in nsecs */

#define SHT15_TSCKL		100	/* clock low */

#define SHT15_TSCKH		100	/* clock high */

#define SHT15_TSU		150	/* data setup time */

/* Actions the driver may be doing */

enum sht15_state {

	SHT15_READING_NOTHING,

	SHT15_READING_TEMP,

	SHT15_READING_HUMID

};

/**

 * struct sht15_temppair - elements of voltage dependent temp calc

	int d1;

};

/* Table 9 from data sheet - relates temperature calculation

 * to supply voltage.

 */

/* Table 9 from datasheet - relates temperature calculation to supply voltage */

static const struct sht15_temppair temppoints[] = {

	{ 2500000, -39400 },

	{ 3000000, -39600 },

/**

 * 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

 * @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.

 * @state:		state identifying the action the driver is doing.

 * @measurements_valid:	are the current stored measures valid (start condition).

 * @last_measurement:	time of last measure.

 * @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

 * @update_supply_work:	work struct that is used to update the supply_uV.

 * @interrupt_handled:	flag used to indicate a handler has been scheduled.

 */

struct sht15_data {

	struct sht15_platform_data	*pdata;

	wait_queue_head_t		wait_queue;

	uint16_t			val_temp;

	uint16_t			val_humid;

	u8				flag;

	u8				valid;

	unsigned long			last_updat;

	enum sht15_state		state;

	bool				measurements_valid;

	unsigned long			last_measurement;

	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;

	bool				supply_uV_valid;

	struct work_struct		update_supply_work;

	atomic_t			interrupt_handled;

};

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);

	}

}

/**

 * 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);

/**

 * 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_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);

 *

 * 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

 * sht15_measurement() - 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,

 */

static int sht15_measurement(struct sht15_data *data,

			     int command,

			     int timeout_msecs)

{

	int ret;

	ret = sht15_send_cmd(data, command);

	if (ret)

		return ret;

			schedule_work(&data->read_work);

	}

	ret = wait_event_timeout(data->wait_queue,

				 (data->flag == SHT15_READING_NOTHING),

				 (data->state == SHT15_READING_NOTHING),

				 msecs_to_jiffies(timeout_msecs));

	if (ret == 0) {/* timeout occurred */

		disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));

}

/**

 * sht15_update_vals() - get updated readings from device if too old

 * sht15_update_measurements() - get updated measures from device if too old

 * @data:	device state

 **/

static int sht15_update_vals(struct sht15_data *data)

 */

static int sht15_update_measurements(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 (time_after(jiffies, data->last_measurement + timeout)

	    || !data->measurements_valid) {

		data->state = SHT15_READING_HUMID;

		ret = sht15_measurement(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);

		data->state = SHT15_READING_TEMP;

		ret = sht15_measurement(data, SHT15_MEASURE_TEMP, 400);

		if (ret)

			goto error_ret;

		data->valid = 1;

		data->last_updat = jiffies;

		data->measurements_valid = true;

		data->last_measurement = jiffies;

	}

error_ret:

	mutex_unlock(&data->read_lock);

 * @data:	device state

 *

 * As per section 4.3 of the data sheet.

 **/

 */

static inline int sht15_calc_temp(struct sht15_data *data)

{

	int d1 = temppoints[0].d1;

 *

 * This is the temperature compensated version as per section 4.2 of

 * the data sheet.

 **/

 *

 * The sensor is assumed to be V3, which is compatible with V4.

 * Humidity conversion coefficients are shown in table 7 of the datasheet.

 */

static inline int sht15_calc_humid(struct sht15_data *data)

{

	int RHlinear; /* milli percent */

	int rh_linear; /* milli percent */

	int temp = sht15_calc_temp(data);

	const int c1 = -4;

	const int c2 = 40500; /* x 10 ^ -6 */

	const int c3 = -28;   /* x 10 ^ -7 */

	RHlinear = c1*1000

	rh_linear = c1 * 1000

		+ c2 * data->val_humid / 1000

		+ (data->val_humid * data->val_humid * c3) / 10000;

	return (temp - 25000) * (10000 + 80 * data->val_humid)

		/ 1000000 + RHlinear;

		/ 1000000 + rh_linear;

}

/**

 * sht15_show_temp() - show temperature measurement value in sysfs

 * @dev:	device.

 * @attr:	device attribute.

 * @buf:	sysfs buffer where measurement values are written to.

 *

 * Will be called on read access to temp1_input sysfs attribute.

 * Returns number of bytes written into buffer, negative errno on error.

 */

static ssize_t sht15_show_temp(struct device *dev,

			       struct device_attribute *attr,

			       char *buf)

	struct sht15_data *data = dev_get_drvdata(dev);

	/* Technically no need to read humidity as well */

	ret = sht15_update_vals(data);

	ret = sht15_update_measurements(data);

	return ret ? ret : sprintf(buf, "%d\n",

				   sht15_calc_temp(data));

}

/**

 * sht15_show_humidity() - show humidity measurement value in sysfs

 * @dev:	device.

 * @attr:	device attribute.

 * @buf:	sysfs buffer where measurement values are written to.

 *

 * Will be called on read access to humidity1_input sysfs attribute.

 * Returns number of bytes written into buffer, negative errno on error.

 */

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);

	ret = sht15_update_measurements(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)

	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 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,

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)

	if (data->state != SHT15_READING_NOTHING)

		schedule_work(&data->read_work);

	return IRQ_HANDLED;

}

/* Each byte of data is acknowledged by pulling the data line

/**

 * sht15_ack() - Send an ack to the device

 *

 * 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_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);

	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!

		/*

		 * 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));

		    || atomic_read(&data->interrupt_handled))

			return;

	}

	/* Read the data back from the device */

	for (i = 0; i < 16; ++i) {

		val <<= 1;

		if (i == 7)

			sht15_ack(data);

	}

	/* Tell the device we are done */

	sht15_end_transmission(data);

	switch (data->flag) {

	switch (data->state) {

	case SHT15_READING_TEMP:

		data->val_temp = val;

		break;

	case SHT15_READING_HUMID:

		data->val_humid = val;

		break;

	default:

		break;

	}

	data->flag = SHT15_READING_NOTHING;

	data->state = SHT15_READING_NOTHING;

	wake_up(&data->wait_queue);

}

 *

 * 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)

	if (!data) {

		ret = -ENOMEM;

		dev_err(&pdev->dev, "kzalloc failed");

		dev_err(&pdev->dev, "kzalloc failed\n");

		goto error_ret;

	}

	init_waitqueue_head(&data->wait_queue);

	if (pdev->dev.platform_data == NULL) {

		dev_err(&pdev->dev, "no platform data supplied");

		dev_err(&pdev->dev, "no platform data supplied\n");

		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!*/

	/*

	 * If a regulator is available,

	 * query what the supply voltage actually is!

	 */

	data->reg = regulator_get(data->dev, "vcc");

	if (!IS_ERR(data->reg)) {

		int voltage;

			data->supply_uV = voltage;

		regulator_enable(data->reg);

		/* setup a notifier block to update this if another device

		 *  causes the voltage to change */

		/*

		 * 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");

		dev_err(&pdev->dev, "gpio request failed\n");

		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");

		dev_err(&pdev->dev, "gpio request failed\n");

		goto err_release_gpio_sck;

	}

	ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group);

			  "sht15 data",

			  data);

	if (ret) {

		dev_err(&pdev->dev, "failed to get irq for data line");

		dev_err(&pdev->dev, "failed to get irq for data line\n");

		goto err_release_gpio_data;

	}

	disable_irq_nosync(gpio_to_irq(data->pdata->gpio_data));

		ret = PTR_ERR(data->hwmon_dev);

		goto err_release_irq;

	}

	return 0;

err_release_irq:

err_free_data:

	kfree(data);

error_ret:

	return ret;

}

{

	struct sht15_data *data = platform_get_drvdata(pdev);

	/* Make sure any reads from the device are done and

	 * prevent new ones from beginning */

	/*

	 * Make sure any reads from the device are done and

	 * prevent new ones beginning

	 */

	mutex_lock(&data->read_lock);

	hwmon_device_unregister(data->hwmon_dev);

	sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);

	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

	},

};

static int __init sht15_init(void)

{

	int ret;

 * 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.

 *

 * For further information, see the Documentation/hwmon/sht15 file.

 */

/**

 * struct sht15_platform_data - sht15 connectivity info

 * @gpio_data:	no. of gpio to which bidirectional data line is connected

 * @gpio_data:		no. of gpio to which bidirectional data line is

 *			connected.

 * @gpio_sck:		no. of gpio to which the data clock is connected.

 * @supply_mv:	supply voltage in mv. Overridden by regulator if available.

 **/

 * @supply_mv:		supply voltage in mv. Overridden by regulator if

 *			available.

 */

struct sht15_platform_data {

	int gpio_data;

	int gpio_sck;