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hwmon: (sht15) general code clean-up

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* Add a documentation file for the device.
* Respect a bit more the kernel-doc syntax.
* Rename some variables for clarity.
* Use bool type for flags.
* Use an enum for states (actions being done).

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
This commit is contained in:
Vivien Didelot 2011-04-12 15:34:36 -04:00 committed by Guenter Roeck
parent 83bffbce74
commit 99a0378de9
3 changed files with 203 additions and 119 deletions
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42
Documentation/hwmon/sht15 Normal file
View File

@ -0,0 +1,42 @@
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

268
drivers/hwmon/sht15.c
View File

@ -9,16 +9,7 @@
* 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>
@ -39,17 +30,21 @@
#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
@ -61,9 +56,7 @@ struct sht15_temppair {
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 },
@ -74,27 +67,27 @@ static const struct sht15_temppair temppoints[] = {
/**
* 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
* @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 handler has been scheduled.
*/
struct sht15_data {
struct sht15_platform_data *pdata;
@ -102,16 +95,16 @@ struct sht15_data {
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;
};
@ -125,6 +118,7 @@ struct sht15_data {
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);
@ -136,14 +130,14 @@ static void sht15_connection_reset(struct sht15_data *data)
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);
@ -154,12 +148,12 @@ static inline void sht15_send_bit(struct sht15_data *data, int val)
/**
* 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 */
@ -180,23 +174,26 @@ static void sht15_transmission_start(struct sht15_data *data)
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);
@ -220,27 +217,30 @@ static int sht15_wait_for_response(struct sht15_data *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,
int command,
int timeout_msecs)
*/
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;
@ -256,7 +256,7 @@ static inline int sht15_update_single_val(struct sht15_data *data,
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));
@ -267,27 +267,27 @@ static inline int sht15_update_single_val(struct sht15_data *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);
@ -300,7 +300,7 @@ static int sht15_update_vals(struct sht15_data *data)
* @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;
@ -316,7 +316,7 @@ static inline int sht15_calc_temp(struct sht15_data *data)
break;
}
return data->val_temp*10 + d1;
return data->val_temp * 10 + d1;
}
/**
@ -325,23 +325,35 @@ static inline int sht15_calc_temp(struct sht15_data *data)
*
* 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 */
const int c3 = -28; /* x 10 ^ -7 */
RHlinear = c1*1000
+ c2 * data->val_humid/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)
@ -350,12 +362,21 @@ static ssize_t sht15_show_temp(struct device *dev,
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)
@ -363,11 +384,12 @@ static ssize_t sht15_show_humidity(struct device *dev,
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)
@ -376,12 +398,10 @@ static ssize_t show_name(struct 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 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,
@ -397,16 +417,20 @@ static const struct attribute_group sht15_attr_group = {
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)
@ -421,12 +445,13 @@ 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);
@ -444,12 +469,13 @@ static void sht15_bh_read_data(struct work_struct *work_s)
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));
/* If still not occurred or another handler has been scheduled */
@ -457,6 +483,7 @@ static void sht15_bh_read_data(struct work_struct *work_s)
|| atomic_read(&data->interrupt_handled))
return;
}
/* Read the data back from the device */
for (i = 0; i < 16; ++i) {
val <<= 1;
@ -468,19 +495,22 @@ static void sht15_bh_read_data(struct work_struct *work_s)
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);
}
@ -500,10 +530,10 @@ static void sht15_update_voltage(struct work_struct *work_s)
*
* 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)
unsigned long event,
void *ignored)
{
struct sht15_data *data = container_of(nb, struct sht15_data, nb);
@ -521,7 +551,7 @@ static int __devinit sht15_probe(struct platform_device *pdev)
if (!data) {
ret = -ENOMEM;
dev_err(&pdev->dev, "kzalloc failed");
dev_err(&pdev->dev, "kzalloc failed\n");
goto error_ret;
}
@ -533,13 +563,16 @@ static int __devinit sht15_probe(struct platform_device *pdev)
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;
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;
@ -549,21 +582,25 @@ static int __devinit sht15_probe(struct platform_device *pdev)
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 */
/* 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);
@ -578,7 +615,7 @@ static int __devinit sht15_probe(struct platform_device *pdev)
"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));
@ -590,6 +627,7 @@ static int __devinit sht15_probe(struct platform_device *pdev)
ret = PTR_ERR(data->hwmon_dev);
goto err_release_irq;
}
return 0;
err_release_irq:
@ -601,7 +639,6 @@ static int __devinit sht15_probe(struct platform_device *pdev)
err_free_data:
kfree(data);
error_ret:
return ret;
}
@ -609,8 +646,10 @@ 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 */
/*
* 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);
@ -625,10 +664,10 @@ static int __devexit sht15_remove(struct platform_device *pdev)
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
@ -673,7 +712,6 @@ static struct platform_driver __refdata sht_drivers[] = {
},
};
static int __init sht15_init(void)
{
int ret;

12
include/linux/sht15.h
View File

@ -8,14 +8,18 @@
* 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_sck: no. of gpio to which the data clock is connected.
* @supply_mv: supply voltage in mv. Overridden by regulator if available.
**/
* @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.
*/
struct sht15_platform_data {
int gpio_data;
int gpio_sck;