1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * HX711: analog to digital converter for weight sensor module
5  * Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de>
24 /* gain to pulse and scale conversion */
76 	return -EINVAL;  in hx711_get_scale_to_gain()
88 	 * 2x32-bit channel + 64-bit naturally aligned timestamp
111 	gpiod_set_value(hx711_data->gpiod_pd_sck, 1);  in hx711_cycle()
118 	ndelay(hx711_data->data_ready_delay_ns);  in hx711_cycle()
126 	gpiod_set_value(hx711_data->gpiod_pd_sck, 0);  in hx711_cycle()
130 	 * make it a square wave for addressing cases with capacitance on  in hx711_cycle()
133 	ndelay(hx711_data->data_ready_delay_ns);  in hx711_cycle()
136 	return gpiod_get_value(hx711_data->gpiod_dout);  in hx711_cycle()
143 	int val = gpiod_get_value(hx711_data->gpiod_dout);  in hx711_read()
147 		return -EIO;  in hx711_read()
158 	for (i = 0; i < hx711_get_gain_to_pulse(hx711_data->gain_set); i++)  in hx711_read()
171 	 * Allow up to one second for it  in hx711_wait_for_ready()
174 		val = gpiod_get_value(hx711_data->gpiod_dout);  in hx711_wait_for_ready()
181 		return -EIO;  in hx711_wait_for_ready()
200 		gpiod_set_value(hx711_data->gpiod_pd_sck, 1);  in hx711_reset()
202 		gpiod_set_value(hx711_data->gpiod_pd_sck, 0);  in hx711_reset()
207 		hx711_data->gain_set = HX711_RESET_GAIN;  in hx711_reset()
218 		if (hx711_data->gain_set == 32) {  in hx711_set_gain_for_channel()
219 			hx711_data->gain_set = hx711_data->gain_chan_a;  in hx711_set_gain_for_channel()
230 		if (hx711_data->gain_set != 32) {  in hx711_set_gain_for_channel()
231 			hx711_data->gain_set = 32;  in hx711_set_gain_for_channel()
256 		dev_err(hx711_data->dev, "reset failed!");  in hx711_reset_read()
257 		return -EIO;  in hx711_reset_read()
277 		mutex_lock(&hx711_data->lock);  in hx711_read_raw()
279 		*val = hx711_reset_read(hx711_data, chan->channel);  in hx711_read_raw()
281 		mutex_unlock(&hx711_data->lock);  in hx711_read_raw()
288 		mutex_lock(&hx711_data->lock);  in hx711_read_raw()
290 		*val2 = hx711_get_gain_to_scale(hx711_data->gain_set);  in hx711_read_raw()
292 		mutex_unlock(&hx711_data->lock);  in hx711_read_raw()
296 		return -EINVAL;  in hx711_read_raw()
317 			return -EINVAL;  in hx711_write_raw()
319 		mutex_lock(&hx711_data->lock);  in hx711_write_raw()
323 			mutex_unlock(&hx711_data->lock);  in hx711_write_raw()
327 		if (gain != hx711_data->gain_set) {  in hx711_write_raw()
328 			hx711_data->gain_set = gain;  in hx711_write_raw()
330 				hx711_data->gain_chan_a = gain;  in hx711_write_raw()
334 				mutex_unlock(&hx711_data->lock);  in hx711_write_raw()
339 		mutex_unlock(&hx711_data->lock);  in hx711_write_raw()
342 		return -EINVAL;  in hx711_write_raw()
358 	struct iio_dev *indio_dev = pf->indio_dev;  in hx711_trigger()
362 	mutex_lock(&hx711_data->lock);  in hx711_trigger()
364 	memset(hx711_data->buffer, 0, sizeof(hx711_data->buffer));  in hx711_trigger()
367 		hx711_data->buffer[j] = hx711_reset_read(hx711_data,  in hx711_trigger()
368 					indio_dev->channels[i].channel);  in hx711_trigger()
372 	iio_push_to_buffers_with_timestamp(indio_dev, hx711_data->buffer,  in hx711_trigger()
373 							pf->timestamp);  in hx711_trigger()
375 	mutex_unlock(&hx711_data->lock);  in hx711_trigger()
377 	iio_trigger_notify_done(indio_dev->trig);  in hx711_trigger()
387 	int channel = iio_attr->address;  in hx711_scale_available_show()
457 	struct device *dev = &pdev->dev;  in hx711_probe()
465 		return dev_err_probe(dev, -ENOMEM, "failed to allocate IIO device\n");  in hx711_probe()
468 	hx711_data->dev = dev;  in hx711_probe()
470 	mutex_init(&hx711_data->lock);  in hx711_probe()
476 	hx711_data->gpiod_pd_sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);  in hx711_probe()
477 	if (IS_ERR(hx711_data->gpiod_pd_sck))  in hx711_probe()
478 		return dev_err_probe(dev, PTR_ERR(hx711_data->gpiod_pd_sck),  in hx711_probe()
479 				     "failed to get sck-gpiod\n");  in hx711_probe()
485 	hx711_data->gpiod_dout = devm_gpiod_get(dev, "dout", GPIOD_IN);  in hx711_probe()
486 	if (IS_ERR(hx711_data->gpiod_dout))  in hx711_probe()
487 		return dev_err_probe(dev, PTR_ERR(hx711_data->gpiod_dout),  in hx711_probe()
488 				     "failed to get dout-gpiod\n");  in hx711_probe()
502 	 * AVDD is in uV, but we need 10^-9 mV  in hx711_probe()
503 	 * approximately to fit into a 32 bit number:  in hx711_probe()
504 	 * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV]  in hx711_probe()
507 	/* we need 10^-9 mV */  in hx711_probe()
514 	hx711_data->gain_set = 128;  in hx711_probe()
515 	hx711_data->gain_chan_a = 128;  in hx711_probe()
517 	hx711_data->clock_frequency = 400000;  in hx711_probe()
518 	ret = device_property_read_u32(&pdev->dev, "clock-frequency",  in hx711_probe()
519 					&hx711_data->clock_frequency);  in hx711_probe()
525 	if (hx711_data->clock_frequency < 20000) {  in hx711_probe()
526 		dev_warn(dev, "clock-frequency too low - assuming 400 kHz\n");  in hx711_probe()
527 		hx711_data->clock_frequency = 400000;  in hx711_probe()
530 	hx711_data->data_ready_delay_ns =  in hx711_probe()
531 				1000000000 / hx711_data->clock_frequency;  in hx711_probe()
533 	indio_dev->name = "hx711";  in hx711_probe()
534 	indio_dev->info = &hx711_iio_info;  in hx711_probe()
535 	indio_dev->modes = INDIO_DIRECT_MODE;  in hx711_probe()
536 	indio_dev->channels = hx711_chan_spec;  in hx711_probe()
537 	indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);  in hx711_probe()
563 		.name		= "hx711-gpio",
570 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
571 MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
573 MODULE_ALIAS("platform:hx711-gpio");