1 // SPDX-License-Identifier: GPL-2.0-only
6  * max31865.c - Maxim MAX31865 RTD-to-Digital Converter sensor driver
43 static const char max31865_show_samp_freq[] = "50 60";
64 	return spi_write_then_read(data->spi, &reg, 1, data->buf, read_size);  in max31865_read()
69 	return spi_write(data->spi, data->buf, len);  in max31865_write()
81 	cfg = data->buf[0];  in enable_bias()
83 	data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;  in enable_bias()
84 	data->buf[1] = cfg | MAX31865_CFG_VBIAS;  in enable_bias()
98 	cfg = data->buf[0];  in disable_bias()
101 	data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;  in disable_bias()
102 	data->buf[1] = cfg;  in disable_bias()
112 	/* Enable BIAS to start the conversion */  in max31865_rtd_read()
124 	reg = data->buf[0];  in max31865_rtd_read()
126 	data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;  in max31865_rtd_read()
127 	data->buf[1] = reg;  in max31865_rtd_read()
133 	if (data->filter_50hz) {  in max31865_rtd_read()
134 		/* 50Hz filter mode requires 62.5ms to complete */  in max31865_rtd_read()
137 		/* 60Hz filter mode requires 52ms to complete */  in max31865_rtd_read()
145 	*val = get_unaligned_be16(&data->buf) >> 1;  in max31865_rtd_read()
159 		mutex_lock(&data->lock);  in max31865_read_raw()
161 		mutex_unlock(&data->lock);  in max31865_read_raw()
171 		return -EINVAL;  in max31865_read_raw()
184 	cfg = data->buf[0];  in max31865_init()
186 	if (data->three_wire)  in max31865_init()
187 		/* 3-wire RTD connection */  in max31865_init()
190 	if (data->filter_50hz)  in max31865_init()
191 		/* 50Hz noise rejection filter */  in max31865_init()
194 	data->buf[0] = MAX31865_CFG_REG | MAX31865_RD_WR_BIT;  in max31865_init()
195 	data->buf[1] = cfg;  in max31865_init()
211 	fault = data->buf[0] & faultbit;  in show_fault()
230 	return sysfs_emit(buf, "%d\n", data->filter_50hz ? 50 : 60);  in show_filter()
249 		data->filter_50hz = true;  in set_filter()
251 	case 60:  in set_filter()
252 		data->filter_50hz = false;  in set_filter()
255 		return -EINVAL;  in set_filter()
258 	mutex_lock(&data->lock);  in set_filter()
260 	mutex_unlock(&data->lock);  in set_filter()
295 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));  in max31865_probe()
297 		return -ENOMEM;  in max31865_probe()
300 	data->spi = spi;  in max31865_probe()
301 	data->filter_50hz = false;  in max31865_probe()
302 	mutex_init(&data->lock);  in max31865_probe()
304 	indio_dev->info = &max31865_info;  in max31865_probe()
305 	indio_dev->name = id->name;  in max31865_probe()
306 	indio_dev->modes = INDIO_DIRECT_MODE;  in max31865_probe()
307 	indio_dev->channels = max31865_channels;  in max31865_probe()
308 	indio_dev->num_channels = ARRAY_SIZE(max31865_channels);  in max31865_probe()
310 	if (device_property_read_bool(&spi->dev, "maxim,3-wire")) {  in max31865_probe()
312 		data->three_wire = 1;  in max31865_probe()
315 		data->three_wire = 0;  in max31865_probe()
320 		dev_err(&spi->dev, "error: Failed to configure max31865\n");  in max31865_probe()
324 	return devm_iio_device_register(&spi->dev, indio_dev);  in max31865_probe()
350 MODULE_DESCRIPTION("Maxim MAX31865 RTD-to-Digital Converter sensor driver");