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1// SPDX-License-Identifier: GPL-2.0+2/*3 * ADS8344 16-bit 8-Channel ADC driver4 *5 * Author: Gregory CLEMENT <gregory.clement@bootlin.com>6 *7 * Datasheet: https://www.ti.com/lit/ds/symlink/ads8344.pdf8 */9 10#include <linux/delay.h>11#include <linux/iio/buffer.h>12#include <linux/iio/iio.h>13#include <linux/module.h>14#include <linux/regulator/consumer.h>15#include <linux/spi/spi.h>16 17#define ADS8344_START BIT(7)18#define ADS8344_SINGLE_END BIT(2)19#define ADS8344_CHANNEL(channel) ((channel) << 4)20#define ADS8344_CLOCK_INTERNAL 0x2 /* PD1 = 1 and PD0 = 0 */21 22struct ads8344 {23 struct spi_device *spi;24 struct regulator *reg;25 /*26 * Lock protecting access to adc->tx_buff and rx_buff,27 * especially from concurrent read on sysfs file.28 */29 struct mutex lock;30 31 u8 tx_buf __aligned(IIO_DMA_MINALIGN);32 u8 rx_buf[3];33};34 35#define ADS8344_VOLTAGE_CHANNEL(chan, addr) \36 { \37 .type = IIO_VOLTAGE, \38 .indexed = 1, \39 .channel = chan, \40 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \41 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \42 .address = addr, \43 }44 45#define ADS8344_VOLTAGE_CHANNEL_DIFF(chan1, chan2, addr) \46 { \47 .type = IIO_VOLTAGE, \48 .indexed = 1, \49 .channel = (chan1), \50 .channel2 = (chan2), \51 .differential = 1, \52 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \53 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \54 .address = addr, \55 }56 57static const struct iio_chan_spec ads8344_channels[] = {58 ADS8344_VOLTAGE_CHANNEL(0, 0),59 ADS8344_VOLTAGE_CHANNEL(1, 4),60 ADS8344_VOLTAGE_CHANNEL(2, 1),61 ADS8344_VOLTAGE_CHANNEL(3, 5),62 ADS8344_VOLTAGE_CHANNEL(4, 2),63 ADS8344_VOLTAGE_CHANNEL(5, 6),64 ADS8344_VOLTAGE_CHANNEL(6, 3),65 ADS8344_VOLTAGE_CHANNEL(7, 7),66 ADS8344_VOLTAGE_CHANNEL_DIFF(0, 1, 8),67 ADS8344_VOLTAGE_CHANNEL_DIFF(2, 3, 9),68 ADS8344_VOLTAGE_CHANNEL_DIFF(4, 5, 10),69 ADS8344_VOLTAGE_CHANNEL_DIFF(6, 7, 11),70 ADS8344_VOLTAGE_CHANNEL_DIFF(1, 0, 12),71 ADS8344_VOLTAGE_CHANNEL_DIFF(3, 2, 13),72 ADS8344_VOLTAGE_CHANNEL_DIFF(5, 4, 14),73 ADS8344_VOLTAGE_CHANNEL_DIFF(7, 6, 15),74};75 76static int ads8344_adc_conversion(struct ads8344 *adc, int channel,77 bool differential)78{79 struct spi_device *spi = adc->spi;80 int ret;81 82 adc->tx_buf = ADS8344_START;83 if (!differential)84 adc->tx_buf |= ADS8344_SINGLE_END;85 adc->tx_buf |= ADS8344_CHANNEL(channel);86 adc->tx_buf |= ADS8344_CLOCK_INTERNAL;87 88 ret = spi_write(spi, &adc->tx_buf, 1);89 if (ret)90 return ret;91 92 udelay(9);93 94 ret = spi_read(spi, adc->rx_buf, sizeof(adc->rx_buf));95 if (ret)96 return ret;97 98 return adc->rx_buf[0] << 9 | adc->rx_buf[1] << 1 | adc->rx_buf[2] >> 7;99}100 101static int ads8344_read_raw(struct iio_dev *iio,102 struct iio_chan_spec const *channel, int *value,103 int *shift, long mask)104{105 struct ads8344 *adc = iio_priv(iio);106 107 switch (mask) {108 case IIO_CHAN_INFO_RAW:109 mutex_lock(&adc->lock);110 *value = ads8344_adc_conversion(adc, channel->address,111 channel->differential);112 mutex_unlock(&adc->lock);113 if (*value < 0)114 return *value;115 116 return IIO_VAL_INT;117 case IIO_CHAN_INFO_SCALE:118 *value = regulator_get_voltage(adc->reg);119 if (*value < 0)120 return *value;121 122 /* convert regulator output voltage to mV */123 *value /= 1000;124 *shift = 16;125 126 return IIO_VAL_FRACTIONAL_LOG2;127 default:128 return -EINVAL;129 }130}131 132static const struct iio_info ads8344_info = {133 .read_raw = ads8344_read_raw,134};135 136static void ads8344_reg_disable(void *data)137{138 regulator_disable(data);139}140 141static int ads8344_probe(struct spi_device *spi)142{143 struct iio_dev *indio_dev;144 struct ads8344 *adc;145 int ret;146 147 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));148 if (!indio_dev)149 return -ENOMEM;150 151 adc = iio_priv(indio_dev);152 adc->spi = spi;153 mutex_init(&adc->lock);154 155 indio_dev->name = dev_name(&spi->dev);156 indio_dev->info = &ads8344_info;157 indio_dev->modes = INDIO_DIRECT_MODE;158 indio_dev->channels = ads8344_channels;159 indio_dev->num_channels = ARRAY_SIZE(ads8344_channels);160 161 adc->reg = devm_regulator_get(&spi->dev, "vref");162 if (IS_ERR(adc->reg))163 return PTR_ERR(adc->reg);164 165 ret = regulator_enable(adc->reg);166 if (ret)167 return ret;168 169 ret = devm_add_action_or_reset(&spi->dev, ads8344_reg_disable, adc->reg);170 if (ret)171 return ret;172 173 return devm_iio_device_register(&spi->dev, indio_dev);174}175 176static const struct of_device_id ads8344_of_match[] = {177 { .compatible = "ti,ads8344", },178 { }179};180MODULE_DEVICE_TABLE(of, ads8344_of_match);181 182static struct spi_driver ads8344_driver = {183 .driver = {184 .name = "ads8344",185 .of_match_table = ads8344_of_match,186 },187 .probe = ads8344_probe,188};189module_spi_driver(ads8344_driver);190 191MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@bootlin.com>");192MODULE_DESCRIPTION("ADS8344 driver");193MODULE_LICENSE("GPL");194