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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 | /* * iio/adc/max11100.c * Maxim max11100 ADC Driver with IIO interface * * Copyright (C) 2016-17 Renesas Electronics Corporation * Copyright (C) 2016-17 Jacopo Mondi * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/delay.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/regulator/consumer.h> #include <linux/spi/spi.h> #include <linux/iio/iio.h> #include <linux/iio/driver.h> /* * LSB is the ADC single digital step * 1 LSB = (vref_mv / 2 ^ 16) * * LSB is used to calculate analog voltage value * from the number of ADC steps count * * Ain = (count * LSB) */ #define MAX11100_LSB_DIV (1 << 16) struct max11100_state { struct regulator *vref_reg; struct spi_device *spi; /* * DMA (thus cache coherency maintenance) requires the * transfer buffers to live in their own cache lines. */ u8 buffer[3] ____cacheline_aligned; }; static struct iio_chan_spec max11100_channels[] = { { /* [0] */ .type = IIO_VOLTAGE, .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), }, }; static int max11100_read_single(struct iio_dev *indio_dev, int *val) { int ret; struct max11100_state *state = iio_priv(indio_dev); ret = spi_read(state->spi, state->buffer, sizeof(state->buffer)); if (ret) { dev_err(&indio_dev->dev, "SPI transfer failed\n"); return ret; } /* the first 8 bits sent out from ADC must be 0s */ if (state->buffer[0]) { dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n"); return -EINVAL; } *val = (state->buffer[1] << 8) | state->buffer[2]; return 0; } static int max11100_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int *val, int *val2, long info) { int ret, vref_uv; struct max11100_state *state = iio_priv(indio_dev); switch (info) { case IIO_CHAN_INFO_RAW: ret = max11100_read_single(indio_dev, val); if (ret) return ret; return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: vref_uv = regulator_get_voltage(state->vref_reg); if (vref_uv < 0) /* dummy regulator "get_voltage" returns -EINVAL */ return -EINVAL; *val = vref_uv / 1000; *val2 = MAX11100_LSB_DIV; return IIO_VAL_FRACTIONAL; } return -EINVAL; } static const struct iio_info max11100_info = { .read_raw = max11100_read_raw, }; static int max11100_probe(struct spi_device *spi) { int ret; struct iio_dev *indio_dev; struct max11100_state *state; indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state)); if (!indio_dev) return -ENOMEM; spi_set_drvdata(spi, indio_dev); state = iio_priv(indio_dev); state->spi = spi; indio_dev->dev.parent = &spi->dev; indio_dev->dev.of_node = spi->dev.of_node; indio_dev->name = "max11100"; indio_dev->info = &max11100_info; indio_dev->modes = INDIO_DIRECT_MODE; indio_dev->channels = max11100_channels; indio_dev->num_channels = ARRAY_SIZE(max11100_channels); state->vref_reg = devm_regulator_get(&spi->dev, "vref"); if (IS_ERR(state->vref_reg)) return PTR_ERR(state->vref_reg); ret = regulator_enable(state->vref_reg); if (ret) return ret; ret = iio_device_register(indio_dev); if (ret) goto disable_regulator; return 0; disable_regulator: regulator_disable(state->vref_reg); return ret; } static int max11100_remove(struct spi_device *spi) { struct iio_dev *indio_dev = spi_get_drvdata(spi); struct max11100_state *state = iio_priv(indio_dev); iio_device_unregister(indio_dev); regulator_disable(state->vref_reg); return 0; } static const struct of_device_id max11100_ids[] = { {.compatible = "maxim,max11100"}, { }, }; MODULE_DEVICE_TABLE(of, max11100_ids); static struct spi_driver max11100_driver = { .driver = { .name = "max11100", .of_match_table = of_match_ptr(max11100_ids), }, .probe = max11100_probe, .remove = max11100_remove, }; module_spi_driver(max11100_driver); MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>"); MODULE_DESCRIPTION("Maxim max11100 ADC Driver"); MODULE_LICENSE("GPL v2"); |