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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver4 *5 * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com>6 *7 * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf8 *9 * SPI interface connections10 *11 * SPI MAXIM12 * Master Direction MAX1117/8/913 * ------ --------- -----------14 * nCS --> CNVST15 * SCK --> SCLK16 * MISO <-- DOUT17 * ------ --------- -----------18 */19 20#include <linux/module.h>21#include <linux/mod_devicetable.h>22#include <linux/spi/spi.h>23#include <linux/iio/iio.h>24#include <linux/iio/buffer.h>25#include <linux/iio/triggered_buffer.h>26#include <linux/iio/trigger_consumer.h>27#include <linux/regulator/consumer.h>28 29enum max1118_id {30 max1117,31 max1118,32 max1119,33};34 35struct max1118 {36 struct spi_device *spi;37 struct mutex lock;38 struct regulator *reg;39 /* Ensure natural alignment of buffer elements */40 struct {41 u8 channels[2];42 s64 ts __aligned(8);43 } scan;44 45 u8 data __aligned(IIO_DMA_MINALIGN);46};47 48#define MAX1118_CHANNEL(ch) \49 { \50 .type = IIO_VOLTAGE, \51 .indexed = 1, \52 .channel = (ch), \53 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \54 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \55 .scan_index = ch, \56 .scan_type = { \57 .sign = 'u', \58 .realbits = 8, \59 .storagebits = 8, \60 }, \61 }62 63static const struct iio_chan_spec max1118_channels[] = {64 MAX1118_CHANNEL(0),65 MAX1118_CHANNEL(1),66 IIO_CHAN_SOFT_TIMESTAMP(2),67};68 69static int max1118_read(struct iio_dev *indio_dev, int channel)70{71 struct max1118 *adc = iio_priv(indio_dev);72 struct spi_transfer xfers[] = {73 /*74 * To select CH1 for conversion, CNVST pin must be brought high75 * and low for a second time.76 */77 {78 .len = 0,79 .delay = { /* > CNVST Low Time 100 ns */80 .value = 1,81 .unit = SPI_DELAY_UNIT_USECS82 },83 .cs_change = 1,84 },85 /*86 * The acquisition interval begins with the falling edge of87 * CNVST. The total acquisition and conversion process takes88 * <7.5us.89 */90 {91 .len = 0,92 .delay = {93 .value = 8,94 .unit = SPI_DELAY_UNIT_USECS95 },96 },97 {98 .rx_buf = &adc->data,99 .len = 1,100 },101 };102 int ret;103 104 if (channel == 0)105 ret = spi_sync_transfer(adc->spi, xfers + 1, 2);106 else107 ret = spi_sync_transfer(adc->spi, xfers, 3);108 109 if (ret)110 return ret;111 112 return adc->data;113}114 115static int max1118_get_vref_mV(struct iio_dev *indio_dev)116{117 struct max1118 *adc = iio_priv(indio_dev);118 const struct spi_device_id *id = spi_get_device_id(adc->spi);119 int vref_uV;120 121 switch (id->driver_data) {122 case max1117:123 return 2048;124 case max1119:125 return 4096;126 case max1118:127 vref_uV = regulator_get_voltage(adc->reg);128 if (vref_uV < 0)129 return vref_uV;130 return vref_uV / 1000;131 }132 133 return -ENODEV;134}135 136static int max1118_read_raw(struct iio_dev *indio_dev,137 struct iio_chan_spec const *chan,138 int *val, int *val2, long mask)139{140 struct max1118 *adc = iio_priv(indio_dev);141 142 switch (mask) {143 case IIO_CHAN_INFO_RAW:144 mutex_lock(&adc->lock);145 *val = max1118_read(indio_dev, chan->channel);146 mutex_unlock(&adc->lock);147 if (*val < 0)148 return *val;149 150 return IIO_VAL_INT;151 case IIO_CHAN_INFO_SCALE:152 *val = max1118_get_vref_mV(indio_dev);153 if (*val < 0)154 return *val;155 *val2 = 8;156 157 return IIO_VAL_FRACTIONAL_LOG2;158 }159 160 return -EINVAL;161}162 163static const struct iio_info max1118_info = {164 .read_raw = max1118_read_raw,165};166 167static irqreturn_t max1118_trigger_handler(int irq, void *p)168{169 struct iio_poll_func *pf = p;170 struct iio_dev *indio_dev = pf->indio_dev;171 struct max1118 *adc = iio_priv(indio_dev);172 int scan_index;173 int i = 0;174 175 mutex_lock(&adc->lock);176 177 iio_for_each_active_channel(indio_dev, scan_index) {178 const struct iio_chan_spec *scan_chan =179 &indio_dev->channels[scan_index];180 int ret = max1118_read(indio_dev, scan_chan->channel);181 182 if (ret < 0) {183 dev_warn(&adc->spi->dev,184 "failed to get conversion data\n");185 goto out;186 }187 188 adc->scan.channels[i] = ret;189 i++;190 }191 iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,192 iio_get_time_ns(indio_dev));193out:194 mutex_unlock(&adc->lock);195 196 iio_trigger_notify_done(indio_dev->trig);197 198 return IRQ_HANDLED;199}200 201static void max1118_reg_disable(void *reg)202{203 regulator_disable(reg);204}205 206static int max1118_probe(struct spi_device *spi)207{208 struct iio_dev *indio_dev;209 struct max1118 *adc;210 const struct spi_device_id *id = spi_get_device_id(spi);211 int ret;212 213 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));214 if (!indio_dev)215 return -ENOMEM;216 217 adc = iio_priv(indio_dev);218 adc->spi = spi;219 mutex_init(&adc->lock);220 221 if (id->driver_data == max1118) {222 adc->reg = devm_regulator_get(&spi->dev, "vref");223 if (IS_ERR(adc->reg))224 return dev_err_probe(&spi->dev, PTR_ERR(adc->reg),225 "failed to get vref regulator\n");226 ret = regulator_enable(adc->reg);227 if (ret)228 return ret;229 230 ret = devm_add_action_or_reset(&spi->dev, max1118_reg_disable,231 adc->reg);232 if (ret)233 return ret;234 235 }236 237 indio_dev->name = spi_get_device_id(spi)->name;238 indio_dev->info = &max1118_info;239 indio_dev->modes = INDIO_DIRECT_MODE;240 indio_dev->channels = max1118_channels;241 indio_dev->num_channels = ARRAY_SIZE(max1118_channels);242 243 /*244 * To reinitiate a conversion on CH0, it is necessary to allow for a245 * conversion to be complete and all of the data to be read out. Once246 * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go247 * into AutoShutdown mode until the next conversion is initiated.248 */249 max1118_read(indio_dev, 0);250 251 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,252 max1118_trigger_handler, NULL);253 if (ret)254 return ret;255 256 return devm_iio_device_register(&spi->dev, indio_dev);257}258 259static const struct spi_device_id max1118_id[] = {260 { "max1117", max1117 },261 { "max1118", max1118 },262 { "max1119", max1119 },263 { }264};265MODULE_DEVICE_TABLE(spi, max1118_id);266 267static const struct of_device_id max1118_dt_ids[] = {268 { .compatible = "maxim,max1117" },269 { .compatible = "maxim,max1118" },270 { .compatible = "maxim,max1119" },271 { }272};273MODULE_DEVICE_TABLE(of, max1118_dt_ids);274 275static struct spi_driver max1118_spi_driver = {276 .driver = {277 .name = "max1118",278 .of_match_table = max1118_dt_ids,279 },280 .probe = max1118_probe,281 .id_table = max1118_id,282};283module_spi_driver(max1118_spi_driver);284 285MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");286MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");287MODULE_LICENSE("GPL v2");288