diff options
Diffstat (limited to 'drivers/hwmon/sht15.c')
-rw-r--r-- | drivers/hwmon/sht15.c | 1062 |
1 files changed, 1062 insertions, 0 deletions
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c new file mode 100644 index 0000000000..32a41fc56f --- /dev/null +++ b/drivers/hwmon/sht15.c @@ -0,0 +1,1062 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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 + * + * For further information, see the Documentation/hwmon/sht15.rst 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_status_show() - 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_status_show(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_status_store() - 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_status_store(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_temp_show() - 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_temp_show(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_humidity_show() - 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_humidity_show(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_RO(temp1_input, sht15_temp, 0); +static SENSOR_DEVICE_ATTR_RO(humidity1_input, sht15_humidity, 0); +static SENSOR_DEVICE_ATTR_RO(temp1_fault, sht15_status, + SHT15_STATUS_LOW_BATTERY); +static SENSOR_DEVICE_ATTR_RO(humidity1_fault, sht15_status, + SHT15_STATUS_LOW_BATTERY); +static SENSOR_DEVICE_ATTR_RW(heater_enable, sht15_status, 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); + int ret; + + hwmon_device_unregister(data->hwmon_dev); + sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group); + + ret = sht15_soft_reset(data); + if (ret) + dev_err(&pdev->dev, "Failed to reset device (%pe)\n", ERR_PTR(ret)); + + if (!IS_ERR(data->reg)) { + regulator_unregister_notifier(data->reg, &data->nb); + regulator_disable(data->reg); + } + + 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"); |