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WSL2-Linux-Kernel/drivers/hwmon/sht15.c

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28 KiB
C
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/*
* sht15.c - support for the SHT15 Temperature and Humidity Sensor
*
* Portions Copyright (c) 2010-2012 Savoir-faire Linux Inc.
* Jerome Oufella <jerome.oufella@savoirfairelinux.com>
* Vivien Didelot <vivien.didelot@savoirfairelinux.com>
*
* 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.
*
* For further information, see the Documentation/hwmon/sht15 file.
*/
#include <linux/interrupt.h>
#include <linux/irq.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/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <linux/bitrev.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
/* Commands */
#define SHT15_MEASURE_TEMP 0x03
#define SHT15_MEASURE_RH 0x05
#define SHT15_WRITE_STATUS 0x06
#define SHT15_READ_STATUS 0x07
#define SHT15_SOFT_RESET 0x1E
/* Min timings */
#define SHT15_TSCKL 100 /* (nsecs) clock low */
#define SHT15_TSCKH 100 /* (nsecs) clock high */
#define SHT15_TSU 150 /* (nsecs) data setup time */
#define SHT15_TSRST 11 /* (msecs) soft reset time */
/* Status Register Bits */
#define SHT15_STATUS_LOW_RESOLUTION 0x01
#define SHT15_STATUS_NO_OTP_RELOAD 0x02
#define SHT15_STATUS_HEATER 0x04
#define SHT15_STATUS_LOW_BATTERY 0x40
/* List of supported chips */
enum sht15_chips { sht10, sht11, sht15, sht71, sht75 };
/* 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
* @vdd: supply voltage in microvolts
* @d1: see data sheet
*/
struct sht15_temppair {
int vdd; /* microvolts */
int d1;
};
/* Table 9 from datasheet - relates temperature calculation to supply voltage */
static const struct sht15_temppair temppoints[] = {
{ 2500000, -39400 },
{ 3000000, -39600 },
{ 3500000, -39700 },
{ 4000000, -39800 },
{ 5000000, -40100 },
};
/* Table from CRC datasheet, section 2.4 */
static const u8 sht15_crc8_table[] = {
0, 49, 98, 83, 196, 245, 166, 151,
185, 136, 219, 234, 125, 76, 31, 46,
67, 114, 33, 16, 135, 182, 229, 212,
250, 203, 152, 169, 62, 15, 92, 109,
134, 183, 228, 213, 66, 115, 32, 17,
63, 14, 93, 108, 251, 202, 153, 168,
197, 244, 167, 150, 1, 48, 99, 82,
124, 77, 30, 47, 184, 137, 218, 235,
61, 12, 95, 110, 249, 200, 155, 170,
132, 181, 230, 215, 64, 113, 34, 19,
126, 79, 28, 45, 186, 139, 216, 233,
199, 246, 165, 148, 3, 50, 97, 80,
187, 138, 217, 232, 127, 78, 29, 44,
2, 51, 96, 81, 198, 247, 164, 149,
248, 201, 154, 171, 60, 13, 94, 111,
65, 112, 35, 18, 133, 180, 231, 214,
122, 75, 24, 41, 190, 143, 220, 237,
195, 242, 161, 144, 7, 54, 101, 84,
57, 8, 91, 106, 253, 204, 159, 174,
128, 177, 226, 211, 68, 117, 38, 23,
252, 205, 158, 175, 56, 9, 90, 107,
69, 116, 39, 22, 129, 176, 227, 210,
191, 142, 221, 236, 123, 74, 25, 40,
6, 55, 100, 85, 194, 243, 160, 145,
71, 118, 37, 20, 131, 178, 225, 208,
254, 207, 156, 173, 58, 11, 88, 105,
4, 53, 102, 87, 192, 241, 162, 147,
189, 140, 223, 238, 121, 72, 27, 42,
193, 240, 163, 146, 5, 52, 103, 86,
120, 73, 26, 43, 188, 141, 222, 239,
130, 179, 224, 209, 70, 119, 36, 21,
59, 10, 89, 104, 255, 206, 157, 172
};
/**
* struct sht15_data - device instance specific data
* @sck: clock GPIO line
* @data: data GPIO line
* @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.
* @val_status: last status register value read from device.
* @checksum_ok: last value read from the device passed CRC validation.
* @checksumming: flag used to enable the data validation with CRC.
* @state: state identifying the action the driver is doing.
* @measurements_valid: are the current stored measures valid (start condition).
* @status_valid: is the current stored status valid (start condition).
* @last_measurement: time of last measure.
* @last_status: time of last status reading.
* @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 gpio_desc *sck;
struct gpio_desc *data;
struct work_struct read_work;
wait_queue_head_t wait_queue;
uint16_t val_temp;
uint16_t val_humid;
u8 val_status;
bool checksum_ok;
bool checksumming;
enum sht15_state state;
bool measurements_valid;
bool status_valid;
unsigned long last_measurement;
unsigned long last_status;
struct mutex read_lock;
struct device *dev;
struct device *hwmon_dev;
struct regulator *reg;
struct notifier_block nb;
int supply_uv;
bool supply_uv_valid;
struct work_struct update_supply_work;
atomic_t interrupt_handled;
};
/**
* sht15_crc8() - compute crc8
* @data: sht15 specific data.
* @value: sht15 retrieved data.
* @len: Length of retrieved data
*
* This implements section 2 of the CRC datasheet.
*/
static u8 sht15_crc8(struct sht15_data *data,
const u8 *value,
int len)
{
u8 crc = bitrev8(data->val_status & 0x0F);
while (len--) {
crc = sht15_crc8_table[*value ^ crc];
value++;
}
return crc;
}
/**
* sht15_connection_reset() - reset the comms interface
* @data: sht15 specific data
*
* This implements section 3.4 of the data sheet
*/
static int sht15_connection_reset(struct sht15_data *data)
{
int i, err;
err = gpiod_direction_output(data->data, 1);
if (err)
return err;
ndelay(SHT15_TSCKL);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
for (i = 0; i < 9; ++i) {
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
}
return 0;
}
/**
* 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)
{
gpiod_set_value(data->data, val);
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
gpiod_set_value(data->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 int sht15_transmission_start(struct sht15_data *data)
{
int err;
/* ensure data is high and output */
err = gpiod_direction_output(data->data, 1);
if (err)
return err;
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
gpiod_set_value(data->data, 0);
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
gpiod_set_value(data->data, 1);
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
return 0;
}
/**
* 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)
{
int err;
err = gpiod_direction_input(data->data);
if (err)
return err;
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
if (gpiod_get_value(data->data)) {
gpiod_set_value(data->sck, 0);
dev_err(data->dev, "Command not acknowledged\n");
err = sht15_connection_reset(data);
if (err)
return err;
return -EIO;
}
gpiod_set_value(data->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 err;
err = sht15_transmission_start(data);
if (err)
return err;
sht15_send_byte(data, cmd);
return sht15_wait_for_response(data);
}
/**
* sht15_soft_reset() - send a soft reset command
* @data: sht15 specific data.
*
* As described in section 3.2 of the datasheet.
*/
static int sht15_soft_reset(struct sht15_data *data)
{
int ret;
ret = sht15_send_cmd(data, SHT15_SOFT_RESET);
if (ret)
return ret;
msleep(SHT15_TSRST);
/* device resets default hardware status register value */
data->val_status = 0;
return ret;
}
/**
* sht15_ack() - send a ack
* @data: sht15 specific data.
*
* Each byte of data is acknowledged by pulling the data line
* low for one clock pulse.
*/
static int sht15_ack(struct sht15_data *data)
{
int err;
err = gpiod_direction_output(data->data, 0);
if (err)
return err;
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSU);
gpiod_set_value(data->data, 1);
return gpiod_direction_input(data->data);
}
/**
* sht15_end_transmission() - notify device of end of transmission
* @data: device state.
*
* This is basically a NAK (single clock pulse, data high).
*/
static int sht15_end_transmission(struct sht15_data *data)
{
int err;
err = gpiod_direction_output(data->data, 1);
if (err)
return err;
ndelay(SHT15_TSU);
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
return 0;
}
/**
* sht15_read_byte() - Read a byte back from the device
* @data: device state.
*/
static u8 sht15_read_byte(struct sht15_data *data)
{
int i;
u8 byte = 0;
for (i = 0; i < 8; ++i) {
byte <<= 1;
gpiod_set_value(data->sck, 1);
ndelay(SHT15_TSCKH);
byte |= !!gpiod_get_value(data->data);
gpiod_set_value(data->sck, 0);
ndelay(SHT15_TSCKL);
}
return byte;
}
/**
* sht15_send_status() - write the status register byte
* @data: sht15 specific data.
* @status: the byte to set the status register with.
*
* As described in figure 14 and table 5 of the datasheet.
*/
static int sht15_send_status(struct sht15_data *data, u8 status)
{
int err;
err = sht15_send_cmd(data, SHT15_WRITE_STATUS);
if (err)
return err;
err = gpiod_direction_output(data->data, 1);
if (err)
return err;
ndelay(SHT15_TSU);
sht15_send_byte(data, status);
err = sht15_wait_for_response(data);
if (err)
return err;
data->val_status = status;
return 0;
}
/**
* sht15_update_status() - get updated status register from device if too old
* @data: device instance specific data.
*
* As described in figure 15 and table 5 of the datasheet.
*/
static int sht15_update_status(struct sht15_data *data)
{
int ret = 0;
u8 status;
u8 previous_config;
u8 dev_checksum = 0;
u8 checksum_vals[2];
int timeout = HZ;
mutex_lock(&data->read_lock);
if (time_after(jiffies, data->last_status + timeout)
|| !data->status_valid) {
ret = sht15_send_cmd(data, SHT15_READ_STATUS);
if (ret)
goto unlock;
status = sht15_read_byte(data);
if (data->checksumming) {
sht15_ack(data);
dev_checksum = bitrev8(sht15_read_byte(data));
checksum_vals[0] = SHT15_READ_STATUS;
checksum_vals[1] = status;
data->checksum_ok = (sht15_crc8(data, checksum_vals, 2)
== dev_checksum);
}
ret = sht15_end_transmission(data);
if (ret)
goto unlock;
/*
* Perform checksum validation on the received data.
* Specification mentions that in case a checksum verification
* fails, a soft reset command must be sent to the device.
*/
if (data->checksumming && !data->checksum_ok) {
previous_config = data->val_status & 0x07;
ret = sht15_soft_reset(data);
if (ret)
goto unlock;
if (previous_config) {
ret = sht15_send_status(data, previous_config);
if (ret) {
dev_err(data->dev,
"CRC validation failed, unable "
"to restore device settings\n");
goto unlock;
}
}
ret = -EAGAIN;
goto unlock;
}
data->val_status = status;
data->status_valid = true;
data->last_status = jiffies;
}
unlock:
mutex_unlock(&data->read_lock);
return ret;
}
/**
* 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 int sht15_measurement(struct sht15_data *data,
int command,
int timeout_msecs)
{
int ret;
u8 previous_config;
ret = sht15_send_cmd(data, command);
if (ret)
return ret;
ret = gpiod_direction_input(data->data);
if (ret)
return ret;
atomic_set(&data->interrupt_handled, 0);
enable_irq(gpiod_to_irq(data->data));
if (gpiod_get_value(data->data) == 0) {
disable_irq_nosync(gpiod_to_irq(data->data));
/* Only relevant if the interrupt hasn't occurred. */
if (!atomic_read(&data->interrupt_handled))
schedule_work(&data->read_work);
}
ret = wait_event_timeout(data->wait_queue,
(data->state == SHT15_READING_NOTHING),
msecs_to_jiffies(timeout_msecs));
if (data->state != SHT15_READING_NOTHING) { /* I/O error occurred */
data->state = SHT15_READING_NOTHING;
return -EIO;
} else if (ret == 0) { /* timeout occurred */
disable_irq_nosync(gpiod_to_irq(data->data));
ret = sht15_connection_reset(data);
if (ret)
return ret;
return -ETIME;
}
/*
* Perform checksum validation on the received data.
* Specification mentions that in case a checksum verification fails,
* a soft reset command must be sent to the device.
*/
if (data->checksumming && !data->checksum_ok) {
previous_config = data->val_status & 0x07;
ret = sht15_soft_reset(data);
if (ret)
return ret;
if (previous_config) {
ret = sht15_send_status(data, previous_config);
if (ret) {
dev_err(data->dev,
"CRC validation failed, unable "
"to restore device settings\n");
return ret;
}
}
return -EAGAIN;
}
return 0;
}
/**
* sht15_update_measurements() - get updated measures from device if too old
* @data: device state
*/
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_measurement + timeout)
|| !data->measurements_valid) {
data->state = SHT15_READING_HUMID;
ret = sht15_measurement(data, SHT15_MEASURE_RH, 160);
if (ret)
goto unlock;
data->state = SHT15_READING_TEMP;
ret = sht15_measurement(data, SHT15_MEASURE_TEMP, 400);
if (ret)
goto unlock;
data->measurements_valid = true;
data->last_measurement = jiffies;
}
unlock:
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 d2 = (data->val_status & SHT15_STATUS_LOW_RESOLUTION) ? 40 : 10;
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 * d2 + 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.
*
* 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 rh_linear; /* milli percent */
int temp = sht15_calc_temp(data);
int c2, c3;
int t2;
const int c1 = -4;
if (data->val_status & SHT15_STATUS_LOW_RESOLUTION) {
c2 = 648000; /* x 10 ^ -6 */
c3 = -7200; /* x 10 ^ -7 */
t2 = 1280;
} else {
c2 = 40500; /* x 10 ^ -6 */
c3 = -28; /* x 10 ^ -7 */
t2 = 80;
}
rh_linear = c1 * 1000
+ c2 * data->val_humid / 1000
+ (data->val_humid * data->val_humid * c3) / 10000;
return (temp - 25000) * (10000 + t2 * data->val_humid)
/ 1000000 + rh_linear;
}
/**
* sht15_show_status() - show status information in sysfs
* @dev: device.
* @attr: device attribute.
* @buf: sysfs buffer where information is written to.
*
* Will be called on read access to temp1_fault, humidity1_fault
* and heater_enable sysfs attributes.
* Returns number of bytes written into buffer, negative errno on error.
*/
static ssize_t sht15_show_status(struct device *dev,
struct device_attribute *attr,
char *buf)
{
int ret;
struct sht15_data *data = dev_get_drvdata(dev);
u8 bit = to_sensor_dev_attr(attr)->index;
ret = sht15_update_status(data);
return ret ? ret : sprintf(buf, "%d\n", !!(data->val_status & bit));
}
/**
* sht15_store_heater() - change heater state via sysfs
* @dev: device.
* @attr: device attribute.
* @buf: sysfs buffer to read the new heater state from.
* @count: length of the data.
*
* Will be called on write access to heater_enable sysfs attribute.
* Returns number of bytes actually decoded, negative errno on error.
*/
static ssize_t sht15_store_heater(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
int ret;
struct sht15_data *data = dev_get_drvdata(dev);
long value;
u8 status;
if (kstrtol(buf, 10, &value))
return -EINVAL;
mutex_lock(&data->read_lock);
status = data->val_status & 0x07;
if (!!value)
status |= SHT15_STATUS_HEATER;
else
status &= ~SHT15_STATUS_HEATER;
ret = sht15_send_status(data, status);
mutex_unlock(&data->read_lock);
return ret ? ret : count;
}
/**
* 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)
{
int ret;
struct sht15_data *data = dev_get_drvdata(dev);
/* Technically no need to read humidity as well */
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_measurements(data);
return ret ? ret : sprintf(buf, "%d\n", sht15_calc_humid(data));
}
static ssize_t name_show(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 SENSOR_DEVICE_ATTR(temp1_fault, S_IRUGO, sht15_show_status, NULL,
SHT15_STATUS_LOW_BATTERY);
static SENSOR_DEVICE_ATTR(humidity1_fault, S_IRUGO, sht15_show_status, NULL,
SHT15_STATUS_LOW_BATTERY);
static SENSOR_DEVICE_ATTR(heater_enable, S_IRUGO | S_IWUSR, sht15_show_status,
sht15_store_heater, SHT15_STATUS_HEATER);
static DEVICE_ATTR_RO(name);
static struct attribute *sht15_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
&sensor_dev_attr_humidity1_input.dev_attr.attr,
&sensor_dev_attr_temp1_fault.dev_attr.attr,
&sensor_dev_attr_humidity1_fault.dev_attr.attr,
&sensor_dev_attr_heater_enable.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->state != SHT15_READING_NOTHING)
schedule_work(&data->read_work);
return IRQ_HANDLED;
}
static void sht15_bh_read_data(struct work_struct *work_s)
{
uint16_t val = 0;
u8 dev_checksum = 0;
u8 checksum_vals[3];
struct sht15_data *data
= container_of(work_s, struct sht15_data,
read_work);
/* Firstly, verify the line is low */
if (gpiod_get_value(data->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(gpiod_to_irq(data->data));
/* If still not occurred or another handler was scheduled */
if (gpiod_get_value(data->data)
|| atomic_read(&data->interrupt_handled))
return;
}
/* Read the data back from the device */
val = sht15_read_byte(data);
val <<= 8;
if (sht15_ack(data))
goto wakeup;
val |= sht15_read_byte(data);
if (data->checksumming) {
/*
* Ask the device for a checksum and read it back.
* Note: the device sends the checksum byte reversed.
*/
if (sht15_ack(data))
goto wakeup;
dev_checksum = bitrev8(sht15_read_byte(data));
checksum_vals[0] = (data->state == SHT15_READING_TEMP) ?
SHT15_MEASURE_TEMP : SHT15_MEASURE_RH;
checksum_vals[1] = (u8) (val >> 8);
checksum_vals[2] = (u8) val;
data->checksum_ok
= (sht15_crc8(data, checksum_vals, 3) == dev_checksum);
}
/* Tell the device we are done */
if (sht15_end_transmission(data))
goto wakeup;
switch (data->state) {
case SHT15_READING_TEMP:
data->val_temp = val;
break;
case SHT15_READING_HUMID:
data->val_humid = val;
break;
default:
break;
}
data->state = SHT15_READING_NOTHING;
wakeup:
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;
}
#ifdef CONFIG_OF
static const struct of_device_id sht15_dt_match[] = {
{ .compatible = "sensirion,sht15" },
{ },
};
MODULE_DEVICE_TABLE(of, sht15_dt_match);
#endif
static int sht15_probe(struct platform_device *pdev)
{
int ret;
struct sht15_data *data;
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
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 a regulator is available,
* query what the supply voltage actually is!
*/
data->reg = devm_regulator_get_optional(data->dev, "vcc");
if (!IS_ERR(data->reg)) {
int voltage;
voltage = regulator_get_voltage(data->reg);
if (voltage)
data->supply_uv = voltage;
ret = regulator_enable(data->reg);
if (ret != 0) {
dev_err(&pdev->dev,
"failed to enable regulator: %d\n", ret);
return ret;
}
/*
* 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);
if (ret) {
dev_err(&pdev->dev,
"regulator notifier request failed\n");
regulator_disable(data->reg);
return ret;
}
}
/* Try requesting the GPIOs */
data->sck = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_LOW);
if (IS_ERR(data->sck)) {
ret = PTR_ERR(data->sck);
dev_err(&pdev->dev, "clock line GPIO request failed\n");
goto err_release_reg;
}
data->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
if (IS_ERR(data->data)) {
ret = PTR_ERR(data->data);
dev_err(&pdev->dev, "data line GPIO request failed\n");
goto err_release_reg;
}
ret = devm_request_irq(&pdev->dev, gpiod_to_irq(data->data),
sht15_interrupt_fired,
IRQF_TRIGGER_FALLING,
"sht15 data",
data);
if (ret) {
dev_err(&pdev->dev, "failed to get irq for data line\n");
goto err_release_reg;
}
disable_irq_nosync(gpiod_to_irq(data->data));
ret = sht15_connection_reset(data);
if (ret)
goto err_release_reg;
ret = sht15_soft_reset(data);
if (ret)
goto err_release_reg;
ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group);
if (ret) {
dev_err(&pdev->dev, "sysfs create failed\n");
goto err_release_reg;
}
data->hwmon_dev = hwmon_device_register(data->dev);
if (IS_ERR(data->hwmon_dev)) {
ret = PTR_ERR(data->hwmon_dev);
goto err_release_sysfs_group;
}
return 0;
err_release_sysfs_group:
sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);
err_release_reg:
if (!IS_ERR(data->reg)) {
regulator_unregister_notifier(data->reg, &data->nb);
regulator_disable(data->reg);
}
return ret;
}
static int 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 beginning
*/
mutex_lock(&data->read_lock);
if (sht15_soft_reset(data)) {
mutex_unlock(&data->read_lock);
return -EFAULT;
}
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);
}
mutex_unlock(&data->read_lock);
return 0;
}
static const struct platform_device_id sht15_device_ids[] = {
{ "sht10", sht10 },
{ "sht11", sht11 },
{ "sht15", sht15 },
{ "sht71", sht71 },
{ "sht75", sht75 },
{ }
};
MODULE_DEVICE_TABLE(platform, sht15_device_ids);
static struct platform_driver sht15_driver = {
.driver = {
.name = "sht15",
.of_match_table = of_match_ptr(sht15_dt_match),
},
.probe = sht15_probe,
.remove = sht15_remove,
.id_table = sht15_device_ids,
};
module_platform_driver(sht15_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Sensirion SHT15 temperature and humidity sensor driver");
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