hwmon: (sht15) general code clean-up
* 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>
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c
index f4e617a..080af75 100644
--- a/drivers/hwmon/sht15.c
+++ b/drivers/hwmon/sht15.c
@@ -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 @@
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 @@
/**
* 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 @@
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 @@
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 @@
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 @@
/**
* 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 @@
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 @@
*
* 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 @@
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 @@
}
/**
- * 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 @@
* @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 @@
break;
}
- return data->val_temp*10 + d1;
+ return data->val_temp * 10 + d1;
}
/**
@@ -325,23 +325,35 @@
*
* 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 @@
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 @@
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 @@
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 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 @@
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 @@
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 @@
|| 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 @@
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 @@
*
* 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 @@
if (!data) {
ret = -ENOMEM;
- dev_err(&pdev->dev, "kzalloc failed");
+ dev_err(&pdev->dev, "kzalloc failed\n");
goto error_ret;
}
@@ -533,13 +563,16 @@
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 @@
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 @@
"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 @@
ret = PTR_ERR(data->hwmon_dev);
goto err_release_irq;
}
+
return 0;
err_release_irq:
@@ -601,7 +639,6 @@
err_free_data:
kfree(data);
error_ret:
-
return ret;
}
@@ -609,8 +646,10 @@
{
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 @@
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 int __init sht15_init(void)
{
int ret;