1 // SPDX-License-Identifier: GPL-2.0
3  * sht15.c - support for the SHT15 Temperature and Humidity Sensor
5  * Portions Copyright (c) 2010-2012 Savoir-faire Linux Inc.
21 #include <linux/hwmon-sysfs.h>
28 #include <linux/regulator/consumer.h>
46 #define SHT15_TSRST			11	/* (msecs) soft reset time */
65  * struct sht15_temppair - elements of voltage dependent temp calc
74 /* Table 9 from datasheet - relates temperature calculation to supply voltage */
76 	{ 2500000, -39400 },
77 	{ 3000000, -39600 },
78 	{ 3500000, -39700 },
79 	{ 4000000, -39800 },
80 	{ 5000000, -40100 },
120  * struct sht15_data - device instance specific data
131  * @measurements_valid:	are the current stored measures valid (start condition).
132  * @status_valid:	is the current stored status valid (start condition).
138  * @reg:		associated regulator (if specified).
142  *                      regulator consumer if available.
144  *			obtained from the regulator and so any calculations
167 	struct regulator		*reg;
176  * sht15_crc8() - compute crc8
187 	u8 crc = bitrev8(data->val_status & 0x0F);  in sht15_crc8()
189 	while (len--) {  in sht15_crc8()
198  * sht15_connection_reset() - reset the comms interface
207 	err = gpiod_direction_output(data->data, 1);  in sht15_connection_reset()
211 	gpiod_set_value(data->sck, 0);  in sht15_connection_reset()
214 		gpiod_set_value(data->sck, 1);  in sht15_connection_reset()
216 		gpiod_set_value(data->sck, 0);  in sht15_connection_reset()
223  * sht15_send_bit() - send an individual bit to the device
229 	gpiod_set_value(data->data, val);  in sht15_send_bit()
231 	gpiod_set_value(data->sck, 1);  in sht15_send_bit()
233 	gpiod_set_value(data->sck, 0);  in sht15_send_bit()
238  * sht15_transmission_start() - specific sequence for new transmission
250 	err = gpiod_direction_output(data->data, 1);  in sht15_transmission_start()
254 	gpiod_set_value(data->sck, 0);  in sht15_transmission_start()
256 	gpiod_set_value(data->sck, 1);  in sht15_transmission_start()
258 	gpiod_set_value(data->data, 0);  in sht15_transmission_start()
260 	gpiod_set_value(data->sck, 0);  in sht15_transmission_start()
262 	gpiod_set_value(data->sck, 1);  in sht15_transmission_start()
264 	gpiod_set_value(data->data, 1);  in sht15_transmission_start()
266 	gpiod_set_value(data->sck, 0);  in sht15_transmission_start()
272  * sht15_send_byte() - send a single byte to the device
287  * sht15_wait_for_response() - checks for ack from device
294 	err = gpiod_direction_input(data->data);  in sht15_wait_for_response()
297 	gpiod_set_value(data->sck, 1);  in sht15_wait_for_response()
299 	if (gpiod_get_value(data->data)) {  in sht15_wait_for_response()
300 		gpiod_set_value(data->sck, 0);  in sht15_wait_for_response()
301 		dev_err(data->dev, "Command not acknowledged\n");  in sht15_wait_for_response()
305 		return -EIO;  in sht15_wait_for_response()
307 	gpiod_set_value(data->sck, 0);  in sht15_wait_for_response()
313  * sht15_send_cmd() - Sends a command to the device.
332  * sht15_soft_reset() - send a soft reset command
346 	data->val_status = 0;  in sht15_soft_reset()
352  * sht15_ack() - send a ack
362 	err = gpiod_direction_output(data->data, 0);  in sht15_ack()
366 	gpiod_set_value(data->sck, 1);  in sht15_ack()
368 	gpiod_set_value(data->sck, 0);  in sht15_ack()
370 	gpiod_set_value(data->data, 1);  in sht15_ack()
372 	return gpiod_direction_input(data->data);  in sht15_ack()
376  * sht15_end_transmission() - notify device of end of transmission
385 	err = gpiod_direction_output(data->data, 1);  in sht15_end_transmission()
389 	gpiod_set_value(data->sck, 1);  in sht15_end_transmission()
391 	gpiod_set_value(data->sck, 0);  in sht15_end_transmission()
397  * sht15_read_byte() - Read a byte back from the device
407 		gpiod_set_value(data->sck, 1);  in sht15_read_byte()
409 		byte |= !!gpiod_get_value(data->data);  in sht15_read_byte()
410 		gpiod_set_value(data->sck, 0);  in sht15_read_byte()
417  * sht15_send_status() - write the status register byte
430 	err = gpiod_direction_output(data->data, 1);  in sht15_send_status()
439 	data->val_status = status;  in sht15_send_status()
444  * sht15_update_status() - get updated status register from device if too old
458 	mutex_lock(&data->read_lock);  in sht15_update_status()
459 	if (time_after(jiffies, data->last_status + timeout)  in sht15_update_status()
460 			|| !data->status_valid) {  in sht15_update_status()
466 		if (data->checksumming) {  in sht15_update_status()
471 			data->checksum_ok = (sht15_crc8(data, checksum_vals, 2)  in sht15_update_status()
482 		 * fails, a soft reset command must be sent to the device.  in sht15_update_status()
484 		if (data->checksumming && !data->checksum_ok) {  in sht15_update_status()
485 			previous_config = data->val_status & 0x07;  in sht15_update_status()
492 					dev_err(data->dev,  in sht15_update_status()
498 			ret = -EAGAIN;  in sht15_update_status()
502 		data->val_status = status;  in sht15_update_status()
503 		data->status_valid = true;  in sht15_update_status()
504 		data->last_status = jiffies;  in sht15_update_status()
508 	mutex_unlock(&data->read_lock);  in sht15_update_status()
513  * sht15_measurement() - get a new value from device
530 	ret = gpiod_direction_input(data->data);  in sht15_measurement()
533 	atomic_set(&data->interrupt_handled, 0);  in sht15_measurement()
535 	enable_irq(gpiod_to_irq(data->data));  in sht15_measurement()
536 	if (gpiod_get_value(data->data) == 0) {  in sht15_measurement()
537 		disable_irq_nosync(gpiod_to_irq(data->data));  in sht15_measurement()
539 		if (!atomic_read(&data->interrupt_handled))  in sht15_measurement()
540 			schedule_work(&data->read_work);  in sht15_measurement()
542 	ret = wait_event_timeout(data->wait_queue,  in sht15_measurement()
543 				 (data->state == SHT15_READING_NOTHING),  in sht15_measurement()
545 	if (data->state != SHT15_READING_NOTHING) { /* I/O error occurred */  in sht15_measurement()
546 		data->state = SHT15_READING_NOTHING;  in sht15_measurement()
547 		return -EIO;  in sht15_measurement()
549 		disable_irq_nosync(gpiod_to_irq(data->data));  in sht15_measurement()
553 		return -ETIME;  in sht15_measurement()
559 	 *  a soft reset command must be sent to the device.  in sht15_measurement()
561 	if (data->checksumming && !data->checksum_ok) {  in sht15_measurement()
562 		previous_config = data->val_status & 0x07;  in sht15_measurement()
569 				dev_err(data->dev,  in sht15_measurement()
575 		return -EAGAIN;  in sht15_measurement()
582  * sht15_update_measurements() - get updated measures from device if too old
590 	mutex_lock(&data->read_lock);  in sht15_update_measurements()
591 	if (time_after(jiffies, data->last_measurement + timeout)  in sht15_update_measurements()
592 	    || !data->measurements_valid) {  in sht15_update_measurements()
593 		data->state = SHT15_READING_HUMID;  in sht15_update_measurements()
597 		data->state = SHT15_READING_TEMP;  in sht15_update_measurements()
601 		data->measurements_valid = true;  in sht15_update_measurements()
602 		data->last_measurement = jiffies;  in sht15_update_measurements()
606 	mutex_unlock(&data->read_lock);  in sht15_update_measurements()
611  * sht15_calc_temp() - convert the raw reading to a temperature
619 	int d2 = (data->val_status & SHT15_STATUS_LOW_RESOLUTION) ? 40 : 10;  in sht15_calc_temp()
622 	for (i = ARRAY_SIZE(temppoints) - 1; i > 0; i--)  in sht15_calc_temp()
624 		if (data->supply_uv > temppoints[i - 1].vdd) {  in sht15_calc_temp()
625 			d1 = (data->supply_uv - temppoints[i - 1].vdd)  in sht15_calc_temp()
626 				* (temppoints[i].d1 - temppoints[i - 1].d1)  in sht15_calc_temp()
627 				/ (temppoints[i].vdd - temppoints[i - 1].vdd)  in sht15_calc_temp()
628 				+ temppoints[i - 1].d1;  in sht15_calc_temp()
632 	return data->val_temp * d2 + d1;  in sht15_calc_temp()
636  * sht15_calc_humid() - using last temperature convert raw to humid
651 	const int c1 = -4;  in sht15_calc_humid()
653 	if (data->val_status & SHT15_STATUS_LOW_RESOLUTION) {  in sht15_calc_humid()
654 		c2 = 648000; /* x 10 ^ -6 */  in sht15_calc_humid()
655 		c3 = -7200;  /* x 10 ^ -7 */  in sht15_calc_humid()
658 		c2 = 40500;  /* x 10 ^ -6 */  in sht15_calc_humid()
659 		c3 = -28;    /* x 10 ^ -7 */  in sht15_calc_humid()
664 		+ c2 * data->val_humid / 1000  in sht15_calc_humid()
665 		+ (data->val_humid * data->val_humid * c3) / 10000;  in sht15_calc_humid()
666 	return (temp - 25000) * (10000 + t2 * data->val_humid)  in sht15_calc_humid()
671  * sht15_show_status() - show status information in sysfs
685 	u8 bit = to_sensor_dev_attr(attr)->index;  in sht15_status_show()
689 	return ret ? ret : sprintf(buf, "%d\n", !!(data->val_status & bit));  in sht15_status_show()
693  * sht15_store_heater() - change heater state via sysfs
712 		return -EINVAL;  in sht15_status_store()
714 	mutex_lock(&data->read_lock);  in sht15_status_store()
715 	status = data->val_status & 0x07;  in sht15_status_store()
722 	mutex_unlock(&data->read_lock);  in sht15_status_store()
728  * sht15_show_temp() - show temperature measurement value in sysfs
750  * sht15_show_humidity() - show humidity measurement value in sysfs
774 	return sprintf(buf, "%s\n", pdev->name);  in name_show()
805 	atomic_inc(&data->interrupt_handled);  in sht15_interrupt_fired()
807 	if (data->state != SHT15_READING_NOTHING)  in sht15_interrupt_fired()
808 		schedule_work(&data->read_work);  in sht15_interrupt_fired()
822 	if (gpiod_get_value(data->data)) {  in sht15_bh_read_data()
824 		 * If not, then start the interrupt again - care here as could  in sht15_bh_read_data()
827 		atomic_set(&data->interrupt_handled, 0);  in sht15_bh_read_data()
828 		enable_irq(gpiod_to_irq(data->data));  in sht15_bh_read_data()
830 		if (gpiod_get_value(data->data)  in sht15_bh_read_data()
831 		    || atomic_read(&data->interrupt_handled))  in sht15_bh_read_data()
842 	if (data->checksumming) {  in sht15_bh_read_data()
850 		checksum_vals[0] = (data->state == SHT15_READING_TEMP) ?  in sht15_bh_read_data()
854 		data->checksum_ok  in sht15_bh_read_data()
862 	switch (data->state) {  in sht15_bh_read_data()
864 		data->val_temp = val;  in sht15_bh_read_data()
867 		data->val_humid = val;  in sht15_bh_read_data()
873 	data->state = SHT15_READING_NOTHING;  in sht15_bh_read_data()
875 	wake_up(&data->wait_queue);  in sht15_bh_read_data()
883 	data->supply_uv = regulator_get_voltage(data->reg);  in sht15_update_voltage()
887  * sht15_invalidate_voltage() - mark supply voltage invalid when notified by reg
889  * @event:	voltage regulator state change event code
890  * @ignored:	function parameter - ignored here
892  * Note that as the notification code holds the regulator lock, we have
902 		data->supply_uv_valid = false;  in sht15_invalidate_voltage()
903 	schedule_work(&data->update_supply_work);  in sht15_invalidate_voltage()
921 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);  in sht15_probe()
923 		return -ENOMEM;  in sht15_probe()
925 	INIT_WORK(&data->read_work, sht15_bh_read_data);  in sht15_probe()
926 	INIT_WORK(&data->update_supply_work, sht15_update_voltage);  in sht15_probe()
928 	mutex_init(&data->read_lock);  in sht15_probe()
929 	data->dev = &pdev->dev;  in sht15_probe()
930 	init_waitqueue_head(&data->wait_queue);  in sht15_probe()
933 	 * If a regulator is available,  in sht15_probe()
936 	data->reg = devm_regulator_get_optional(data->dev, "vcc");  in sht15_probe()
937 	if (!IS_ERR(data->reg)) {  in sht15_probe()
940 		voltage = regulator_get_voltage(data->reg);  in sht15_probe()
942 			data->supply_uv = voltage;  in sht15_probe()
944 		ret = regulator_enable(data->reg);  in sht15_probe()
946 			dev_err(&pdev->dev,  in sht15_probe()
947 				"failed to enable regulator: %d\n", ret);  in sht15_probe()
955 		data->nb.notifier_call = &sht15_invalidate_voltage;  in sht15_probe()
956 		ret = regulator_register_notifier(data->reg, &data->nb);  in sht15_probe()
958 			dev_err(&pdev->dev,  in sht15_probe()
959 				"regulator notifier request failed\n");  in sht15_probe()
960 			regulator_disable(data->reg);  in sht15_probe()
966 	data->sck = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_LOW);  in sht15_probe()
967 	if (IS_ERR(data->sck)) {  in sht15_probe()
968 		ret = PTR_ERR(data->sck);  in sht15_probe()
969 		dev_err(&pdev->dev, "clock line GPIO request failed\n");  in sht15_probe()
972 	data->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);  in sht15_probe()
973 	if (IS_ERR(data->data)) {  in sht15_probe()
974 		ret = PTR_ERR(data->data);  in sht15_probe()
975 		dev_err(&pdev->dev, "data line GPIO request failed\n");  in sht15_probe()
979 	ret = devm_request_irq(&pdev->dev, gpiod_to_irq(data->data),  in sht15_probe()
985 		dev_err(&pdev->dev, "failed to get irq for data line\n");  in sht15_probe()
988 	disable_irq_nosync(gpiod_to_irq(data->data));  in sht15_probe()
996 	ret = sysfs_create_group(&pdev->dev.kobj, &sht15_attr_group);  in sht15_probe()
998 		dev_err(&pdev->dev, "sysfs create failed\n");  in sht15_probe()
1002 	data->hwmon_dev = hwmon_device_register(data->dev);  in sht15_probe()
1003 	if (IS_ERR(data->hwmon_dev)) {  in sht15_probe()
1004 		ret = PTR_ERR(data->hwmon_dev);  in sht15_probe()
1011 	sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);  in sht15_probe()
1013 	if (!IS_ERR(data->reg)) {  in sht15_probe()
1014 		regulator_unregister_notifier(data->reg, &data->nb);  in sht15_probe()
1015 		regulator_disable(data->reg);  in sht15_probe()
1028 	mutex_lock(&data->read_lock);  in sht15_remove()
1030 		mutex_unlock(&data->read_lock);  in sht15_remove()
1031 		return -EFAULT;  in sht15_remove()
1033 	hwmon_device_unregister(data->hwmon_dev);  in sht15_remove()
1034 	sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group);  in sht15_remove()
1035 	if (!IS_ERR(data->reg)) {  in sht15_remove()
1036 		regulator_unregister_notifier(data->reg, &data->nb);  in sht15_remove()
1037 		regulator_disable(data->reg);  in sht15_remove()
1040 	mutex_unlock(&data->read_lock);  in sht15_remove()