1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * ADS8344 16-bit 8-Channel ADC driver 4 * 5 * Author: Gregory CLEMENT <gregory.clement@bootlin.com> 6 * 7 * Datasheet: https://www.ti.com/lit/ds/symlink/ads8344.pdf 8 */ 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 22 struct 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 ____cacheline_aligned; 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 57 static 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 76 static 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 } 100 101 static 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 } 131 132 static const struct iio_info ads8344_info = { 133 .read_raw = ads8344_read_raw, 134 }; 135 136 static void ads8344_reg_disable(void *data) 137 { 138 regulator_disable(data); 139 } 140 141 static 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 } 175 176 static const struct of_device_id ads8344_of_match[] = { 177 { .compatible = "ti,ads8344", }, 178 {} 179 }; 180 MODULE_DEVICE_TABLE(of, ads8344_of_match); 181 182 static struct spi_driver ads8344_driver = { 183 .driver = { 184 .name = "ads8344", 185 .of_match_table = ads8344_of_match, 186 }, 187 .probe = ads8344_probe, 188 }; 189 module_spi_driver(ads8344_driver); 190 191 MODULE_AUTHOR("Gregory CLEMENT <gregory.clement@bootlin.com>"); 192 MODULE_DESCRIPTION("ADS8344 driver"); 193 MODULE_LICENSE("GPL"); 194