1 // SPDX-License-Identifier: GPL-2.0-only
3  * MAX1241 low-power, 12-bit serial ADC
5  * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
8 #include <linux/delay.h>
13 #include <linux/spi/spi.h>
23 	struct spi_device *spi;  member
46 		 * tconv us.  in max1241_read()
50 			.delay.value = 8,  in max1241_read()
51 			.delay.unit = SPI_DELAY_UNIT_USECS,  in max1241_read()
54 		 * Then read two bytes of data in our RX buffer.  in max1241_read()
57 			.rx_buf = &adc->data,  in max1241_read()
62 	return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));  in max1241_read()
74 		mutex_lock(&adc->lock);  in max1241_read_raw()
76 		if (adc->shutdown) {  in max1241_read_raw()
77 			gpiod_set_value(adc->shutdown, 0);  in max1241_read_raw()
80 			gpiod_set_value(adc->shutdown, 1);  in max1241_read_raw()
85 			mutex_unlock(&adc->lock);  in max1241_read_raw()
89 		*val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;  in max1241_read_raw()
91 		mutex_unlock(&adc->lock);  in max1241_read_raw()
94 		vref_uV = regulator_get_voltage(adc->vref);  in max1241_read_raw()
104 		return -EINVAL;  in max1241_read_raw()
115 	struct device *dev = &adc->spi->dev;  in max1241_disable_vref_action()
118 	err = regulator_disable(adc->vref);  in max1241_disable_vref_action()
123 static int max1241_probe(struct spi_device *spi)  in max1241_probe()  argument
125 	struct device *dev = &spi->dev;  in max1241_probe()
132 		return -ENOMEM;  in max1241_probe()
135 	adc->spi = spi;  in max1241_probe()
136 	mutex_init(&adc->lock);  in max1241_probe()
143 	adc->vref = devm_regulator_get(dev, "vref");  in max1241_probe()
144 	if (IS_ERR(adc->vref))  in max1241_probe()
145 		return dev_err_probe(dev, PTR_ERR(adc->vref),  in max1241_probe()
148 	ret = regulator_enable(adc->vref);  in max1241_probe()
158 	adc->shutdown = devm_gpiod_get_optional(dev, "shutdown",  in max1241_probe()
160 	if (IS_ERR(adc->shutdown))  in max1241_probe()
161 		return dev_err_probe(dev, PTR_ERR(adc->shutdown),  in max1241_probe()
164 	if (adc->shutdown)  in max1241_probe()
165 		dev_dbg(dev, "shutdown pin passed, low-power mode enabled");  in max1241_probe()
167 		dev_dbg(dev, "no shutdown pin passed, low-power mode disabled");  in max1241_probe()
169 	indio_dev->name = spi_get_device_id(spi)->name;  in max1241_probe()
170 	indio_dev->info = &max1241_info;  in max1241_probe()
171 	indio_dev->modes = INDIO_DIRECT_MODE;  in max1241_probe()
172 	indio_dev->channels = max1241_channels;  in max1241_probe()
173 	indio_dev->num_channels = ARRAY_SIZE(max1241_channels);  in max1241_probe()