1 // SPDX-License-Identifier: GPL-2.0-or-later
5  * Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de>
15 #include <linux/delay.h>
24 /* gain to pulse and scale conversion */
76 	return -EINVAL;  in hx711_get_scale_to_gain()
89 	 * 2x32-bit channel + 64-bit timestamp
93 	 * delay after a rising edge on SCK until the data is ready DOUT
107 	 * if preempted for more then 60us while PD_SCK is high:  in hx711_cycle()
112 	gpiod_set_value(hx711_data->gpiod_pd_sck, 1);  in hx711_cycle()
119 	ndelay(hx711_data->data_ready_delay_ns);  in hx711_cycle()
122 	 * here we are not waiting for 0.2 us as suggested by the datasheet,  in hx711_cycle()
124 	 * at least 1.15 us for PD_SCK high (T3 in datasheet)  in hx711_cycle()
125 	 * and 0.56 us for PD_SCK low on TI Sitara with 800 MHz  in hx711_cycle()
127 	gpiod_set_value(hx711_data->gpiod_pd_sck, 0);  in hx711_cycle()
134 	ndelay(hx711_data->data_ready_delay_ns);  in hx711_cycle()
137 	return gpiod_get_value(hx711_data->gpiod_dout);  in hx711_cycle()
144 	int val = gpiod_get_value(hx711_data->gpiod_dout);  in hx711_read()
148 		return -EIO;  in hx711_read()
159 	for (i = 0; i < hx711_get_gain_to_pulse(hx711_data->gain_set); i++)  in hx711_read()
175 		val = gpiod_get_value(hx711_data->gpiod_dout);  in hx711_wait_for_ready()
182 		return -EIO;  in hx711_wait_for_ready()
201 		gpiod_set_value(hx711_data->gpiod_pd_sck, 1);  in hx711_reset()
203 		gpiod_set_value(hx711_data->gpiod_pd_sck, 0);  in hx711_reset()
208 		hx711_data->gain_set = HX711_RESET_GAIN;  in hx711_reset()
219 		if (hx711_data->gain_set == 32) {  in hx711_set_gain_for_channel()
220 			hx711_data->gain_set = hx711_data->gain_chan_a;  in hx711_set_gain_for_channel()
231 		if (hx711_data->gain_set != 32) {  in hx711_set_gain_for_channel()
232 			hx711_data->gain_set = 32;  in hx711_set_gain_for_channel()
257 		dev_err(hx711_data->dev, "reset failed!");  in hx711_reset_read()
258 		return -EIO;  in hx711_reset_read()
278 		mutex_lock(&hx711_data->lock);  in hx711_read_raw()
280 		*val = hx711_reset_read(hx711_data, chan->channel);  in hx711_read_raw()
282 		mutex_unlock(&hx711_data->lock);  in hx711_read_raw()
289 		mutex_lock(&hx711_data->lock);  in hx711_read_raw()
291 		*val2 = hx711_get_gain_to_scale(hx711_data->gain_set);  in hx711_read_raw()
293 		mutex_unlock(&hx711_data->lock);  in hx711_read_raw()
297 		return -EINVAL;  in hx711_read_raw()
318 			return -EINVAL;  in hx711_write_raw()
320 		mutex_lock(&hx711_data->lock);  in hx711_write_raw()
324 			mutex_unlock(&hx711_data->lock);  in hx711_write_raw()
328 		if (gain != hx711_data->gain_set) {  in hx711_write_raw()
329 			hx711_data->gain_set = gain;  in hx711_write_raw()
331 				hx711_data->gain_chan_a = gain;  in hx711_write_raw()
335 				mutex_unlock(&hx711_data->lock);  in hx711_write_raw()
340 		mutex_unlock(&hx711_data->lock);  in hx711_write_raw()
343 		return -EINVAL;  in hx711_write_raw()
359 	struct iio_dev *indio_dev = pf->indio_dev;  in hx711_trigger()
363 	mutex_lock(&hx711_data->lock);  in hx711_trigger()
365 	memset(hx711_data->buffer, 0, sizeof(hx711_data->buffer));  in hx711_trigger()
367 	for (i = 0; i < indio_dev->masklength; i++) {  in hx711_trigger()
368 		if (!test_bit(i, indio_dev->active_scan_mask))  in hx711_trigger()
371 		hx711_data->buffer[j] = hx711_reset_read(hx711_data,  in hx711_trigger()
372 					indio_dev->channels[i].channel);  in hx711_trigger()
376 	iio_push_to_buffers_with_timestamp(indio_dev, hx711_data->buffer,  in hx711_trigger()
377 							pf->timestamp);  in hx711_trigger()
379 	mutex_unlock(&hx711_data->lock);  in hx711_trigger()
381 	iio_trigger_notify_done(indio_dev->trig);  in hx711_trigger()
391 	int channel = iio_attr->address;  in hx711_scale_available_show()
461 	struct device *dev = &pdev->dev;  in hx711_probe()
462 	struct device_node *np = dev->of_node;  in hx711_probe()
471 		return -ENOMEM;  in hx711_probe()
475 	hx711_data->dev = dev;  in hx711_probe()
477 	mutex_init(&hx711_data->lock);  in hx711_probe()
483 	hx711_data->gpiod_pd_sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);  in hx711_probe()
484 	if (IS_ERR(hx711_data->gpiod_pd_sck)) {  in hx711_probe()
485 		dev_err(dev, "failed to get sck-gpiod: err=%ld\n",  in hx711_probe()
486 					PTR_ERR(hx711_data->gpiod_pd_sck));  in hx711_probe()
487 		return PTR_ERR(hx711_data->gpiod_pd_sck);  in hx711_probe()
494 	hx711_data->gpiod_dout = devm_gpiod_get(dev, "dout", GPIOD_IN);  in hx711_probe()
495 	if (IS_ERR(hx711_data->gpiod_dout)) {  in hx711_probe()
496 		dev_err(dev, "failed to get dout-gpiod: err=%ld\n",  in hx711_probe()
497 					PTR_ERR(hx711_data->gpiod_dout));  in hx711_probe()
498 		return PTR_ERR(hx711_data->gpiod_dout);  in hx711_probe()
501 	hx711_data->reg_avdd = devm_regulator_get(dev, "avdd");  in hx711_probe()
502 	if (IS_ERR(hx711_data->reg_avdd))  in hx711_probe()
503 		return PTR_ERR(hx711_data->reg_avdd);  in hx711_probe()
505 	ret = regulator_enable(hx711_data->reg_avdd);  in hx711_probe()
517 	 * AVDD is in uV, but we need 10^-9 mV  in hx711_probe()
519 	 * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV]  in hx711_probe()
521 	ret = regulator_get_voltage(hx711_data->reg_avdd);  in hx711_probe()
525 	/* we need 10^-9 mV */  in hx711_probe()
532 	hx711_data->gain_set = 128;  in hx711_probe()
533 	hx711_data->gain_chan_a = 128;  in hx711_probe()
535 	hx711_data->clock_frequency = 400000;  in hx711_probe()
536 	ret = of_property_read_u32(np, "clock-frequency",  in hx711_probe()
537 					&hx711_data->clock_frequency);  in hx711_probe()
543 	if (hx711_data->clock_frequency < 20000) {  in hx711_probe()
544 		dev_warn(dev, "clock-frequency too low - assuming 400 kHz\n");  in hx711_probe()
545 		hx711_data->clock_frequency = 400000;  in hx711_probe()
548 	hx711_data->data_ready_delay_ns =  in hx711_probe()
549 				1000000000 / hx711_data->clock_frequency;  in hx711_probe()
553 	indio_dev->name = "hx711";  in hx711_probe()
554 	indio_dev->info = &hx711_iio_info;  in hx711_probe()
555 	indio_dev->modes = INDIO_DIRECT_MODE;  in hx711_probe()
556 	indio_dev->channels = hx711_chan_spec;  in hx711_probe()
557 	indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);  in hx711_probe()
578 	regulator_disable(hx711_data->reg_avdd);  in hx711_probe()
595 	regulator_disable(hx711_data->reg_avdd);  in hx711_remove()
611 		.name		= "hx711-gpio",
618 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
619 MODULE_DESCRIPTION("HX711 bitbanging driver - ADC for weight cells");
621 MODULE_ALIAS("platform:hx711-gpio");