1 /* 2 * Copyright (C) 2014 Angelo Compagnucci <angelo.compagnucci@gmail.com> 3 * 4 * Driver for Texas Instruments' ADC128S052 ADC chip. 5 * Datasheet can be found here: 6 * http://www.ti.com/lit/ds/symlink/adc128s052.pdf 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <linux/err.h> 14 #include <linux/spi/spi.h> 15 #include <linux/module.h> 16 #include <linux/iio/iio.h> 17 #include <linux/regulator/consumer.h> 18 19 struct adc128 { 20 struct spi_device *spi; 21 22 struct regulator *reg; 23 struct mutex lock; 24 25 u8 buffer[2] ____cacheline_aligned; 26 }; 27 28 static int adc128_adc_conversion(struct adc128 *adc, u8 channel) 29 { 30 int ret; 31 32 mutex_lock(&adc->lock); 33 34 adc->buffer[0] = channel << 3; 35 adc->buffer[1] = 0; 36 37 ret = spi_write(adc->spi, &adc->buffer, 2); 38 if (ret < 0) { 39 mutex_unlock(&adc->lock); 40 return ret; 41 } 42 43 ret = spi_read(adc->spi, &adc->buffer, 2); 44 45 mutex_unlock(&adc->lock); 46 47 if (ret < 0) 48 return ret; 49 50 return ((adc->buffer[0] << 8 | adc->buffer[1]) & 0xFFF); 51 } 52 53 static int adc128_read_raw(struct iio_dev *indio_dev, 54 struct iio_chan_spec const *channel, int *val, 55 int *val2, long mask) 56 { 57 struct adc128 *adc = iio_priv(indio_dev); 58 int ret; 59 60 switch (mask) { 61 case IIO_CHAN_INFO_RAW: 62 63 ret = adc128_adc_conversion(adc, channel->channel); 64 if (ret < 0) 65 return ret; 66 67 *val = ret; 68 return IIO_VAL_INT; 69 70 case IIO_CHAN_INFO_SCALE: 71 72 ret = regulator_get_voltage(adc->reg); 73 if (ret < 0) 74 return ret; 75 76 *val = ret / 1000; 77 *val2 = 12; 78 return IIO_VAL_FRACTIONAL_LOG2; 79 80 default: 81 return -EINVAL; 82 } 83 84 } 85 86 #define ADC128_VOLTAGE_CHANNEL(num) \ 87 { \ 88 .type = IIO_VOLTAGE, \ 89 .indexed = 1, \ 90 .channel = (num), \ 91 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 92 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \ 93 } 94 95 static const struct iio_chan_spec adc128_channels[] = { 96 ADC128_VOLTAGE_CHANNEL(0), 97 ADC128_VOLTAGE_CHANNEL(1), 98 ADC128_VOLTAGE_CHANNEL(2), 99 ADC128_VOLTAGE_CHANNEL(3), 100 ADC128_VOLTAGE_CHANNEL(4), 101 ADC128_VOLTAGE_CHANNEL(5), 102 ADC128_VOLTAGE_CHANNEL(6), 103 ADC128_VOLTAGE_CHANNEL(7), 104 }; 105 106 static const struct iio_info adc128_info = { 107 .read_raw = adc128_read_raw, 108 .driver_module = THIS_MODULE, 109 }; 110 111 static int adc128_probe(struct spi_device *spi) 112 { 113 struct iio_dev *indio_dev; 114 struct adc128 *adc; 115 int ret; 116 117 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); 118 if (!indio_dev) 119 return -ENOMEM; 120 121 adc = iio_priv(indio_dev); 122 adc->spi = spi; 123 124 spi_set_drvdata(spi, indio_dev); 125 126 indio_dev->dev.parent = &spi->dev; 127 indio_dev->name = spi_get_device_id(spi)->name; 128 indio_dev->modes = INDIO_DIRECT_MODE; 129 indio_dev->info = &adc128_info; 130 131 indio_dev->channels = adc128_channels; 132 indio_dev->num_channels = ARRAY_SIZE(adc128_channels); 133 134 adc->reg = devm_regulator_get(&spi->dev, "vref"); 135 if (IS_ERR(adc->reg)) 136 return PTR_ERR(adc->reg); 137 138 ret = regulator_enable(adc->reg); 139 if (ret < 0) 140 return ret; 141 142 mutex_init(&adc->lock); 143 144 ret = iio_device_register(indio_dev); 145 146 return ret; 147 } 148 149 static int adc128_remove(struct spi_device *spi) 150 { 151 struct iio_dev *indio_dev = spi_get_drvdata(spi); 152 struct adc128 *adc = iio_priv(indio_dev); 153 154 iio_device_unregister(indio_dev); 155 regulator_disable(adc->reg); 156 157 return 0; 158 } 159 160 static const struct spi_device_id adc128_id[] = { 161 { "adc128s052", 0}, 162 { } 163 }; 164 MODULE_DEVICE_TABLE(spi, adc128_id); 165 166 static struct spi_driver adc128_driver = { 167 .driver = { 168 .name = "adc128s052", 169 .owner = THIS_MODULE, 170 }, 171 .probe = adc128_probe, 172 .remove = adc128_remove, 173 .id_table = adc128_id, 174 }; 175 module_spi_driver(adc128_driver); 176 177 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>"); 178 MODULE_DESCRIPTION("Texas Instruments ADC128S052"); 179 MODULE_LICENSE("GPL v2"); 180