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-rw-r--r--drivers/hwmon/sht15.c1062
1 files changed, 1062 insertions, 0 deletions
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c
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+++ b/drivers/hwmon/sht15.c
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+// 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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 19:19:48 +0000