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linux/drivers/hwmon/sht15.c

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/*
* 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 <linux/slab.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 = temppoints[0].d1;
int i;
for (i = ARRAY_SIZE(temppoints) - 1; i > 0; i--)
/* Find pointer to interpolate */
if (data->supply_uV > temppoints[i - 1].vdd) {
d1 = (data->supply_uV - 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 = -28; /* x 10 ^ -7 */
RHlinear = 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;
}
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)) {
int voltage;
voltage = regulator_get_voltage(data->reg);
if (voltage)
data->supply_uV = voltage;
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 from beginning */
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");
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