1 /* 2 * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver 3 * 4 * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com> 5 * 6 * This file is subject to the terms and conditions of version 2 of 7 * the GNU General Public License. See the file COPYING in the main 8 * directory of this archive for more details. 9 * 10 * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf 11 * 12 * SPI interface connections 13 * 14 * SPI MAXIM 15 * Master Direction MAX1117/8/9 16 * ------ --------- ----------- 17 * nCS --> CNVST 18 * SCK --> SCLK 19 * MISO <-- DOUT 20 * ------ --------- ----------- 21 */ 22 23 #include <linux/module.h> 24 #include <linux/spi/spi.h> 25 #include <linux/iio/iio.h> 26 #include <linux/iio/buffer.h> 27 #include <linux/iio/triggered_buffer.h> 28 #include <linux/iio/trigger_consumer.h> 29 #include <linux/regulator/consumer.h> 30 31 enum max1118_id { 32 max1117, 33 max1118, 34 max1119, 35 }; 36 37 struct max1118 { 38 struct spi_device *spi; 39 struct mutex lock; 40 struct regulator *reg; 41 42 u8 data ____cacheline_aligned; 43 }; 44 45 #define MAX1118_CHANNEL(ch) \ 46 { \ 47 .type = IIO_VOLTAGE, \ 48 .indexed = 1, \ 49 .channel = (ch), \ 50 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 51 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 52 .scan_index = ch, \ 53 .scan_type = { \ 54 .sign = 'u', \ 55 .realbits = 8, \ 56 .storagebits = 8, \ 57 }, \ 58 } 59 60 static const struct iio_chan_spec max1118_channels[] = { 61 MAX1118_CHANNEL(0), 62 MAX1118_CHANNEL(1), 63 IIO_CHAN_SOFT_TIMESTAMP(2), 64 }; 65 66 static int max1118_read(struct spi_device *spi, int channel) 67 { 68 struct iio_dev *indio_dev = spi_get_drvdata(spi); 69 struct max1118 *adc = iio_priv(indio_dev); 70 struct spi_transfer xfers[] = { 71 /* 72 * To select CH1 for conversion, CNVST pin must be brought high 73 * and low for a second time. 74 */ 75 { 76 .len = 0, 77 .delay_usecs = 1, /* > CNVST Low Time 100 ns */ 78 .cs_change = 1, 79 }, 80 /* 81 * The acquisition interval begins with the falling edge of 82 * CNVST. The total acquisition and conversion process takes 83 * <7.5us. 84 */ 85 { 86 .len = 0, 87 .delay_usecs = 8, 88 }, 89 { 90 .rx_buf = &adc->data, 91 .len = 1, 92 }, 93 }; 94 int ret; 95 96 if (channel == 0) 97 ret = spi_sync_transfer(spi, xfers + 1, 2); 98 else 99 ret = spi_sync_transfer(spi, xfers, 3); 100 101 if (ret) 102 return ret; 103 104 return adc->data; 105 } 106 107 static int max1118_get_vref_mV(struct spi_device *spi) 108 { 109 struct iio_dev *indio_dev = spi_get_drvdata(spi); 110 struct max1118 *adc = iio_priv(indio_dev); 111 const struct spi_device_id *id = spi_get_device_id(spi); 112 int vref_uV; 113 114 switch (id->driver_data) { 115 case max1117: 116 return 2048; 117 case max1119: 118 return 4096; 119 case max1118: 120 vref_uV = regulator_get_voltage(adc->reg); 121 if (vref_uV < 0) 122 return vref_uV; 123 return vref_uV / 1000; 124 } 125 126 return -ENODEV; 127 } 128 129 static int max1118_read_raw(struct iio_dev *indio_dev, 130 struct iio_chan_spec const *chan, 131 int *val, int *val2, long mask) 132 { 133 struct max1118 *adc = iio_priv(indio_dev); 134 135 switch (mask) { 136 case IIO_CHAN_INFO_RAW: 137 mutex_lock(&adc->lock); 138 *val = max1118_read(adc->spi, chan->channel); 139 mutex_unlock(&adc->lock); 140 if (*val < 0) 141 return *val; 142 143 return IIO_VAL_INT; 144 case IIO_CHAN_INFO_SCALE: 145 *val = max1118_get_vref_mV(adc->spi); 146 if (*val < 0) 147 return *val; 148 *val2 = 8; 149 150 return IIO_VAL_FRACTIONAL_LOG2; 151 } 152 153 return -EINVAL; 154 } 155 156 static const struct iio_info max1118_info = { 157 .read_raw = max1118_read_raw, 158 }; 159 160 static irqreturn_t max1118_trigger_handler(int irq, void *p) 161 { 162 struct iio_poll_func *pf = p; 163 struct iio_dev *indio_dev = pf->indio_dev; 164 struct max1118 *adc = iio_priv(indio_dev); 165 u8 data[16] = { }; /* 2x 8-bit ADC data + padding + 8 bytes timestamp */ 166 int scan_index; 167 int i = 0; 168 169 mutex_lock(&adc->lock); 170 171 for_each_set_bit(scan_index, indio_dev->active_scan_mask, 172 indio_dev->masklength) { 173 const struct iio_chan_spec *scan_chan = 174 &indio_dev->channels[scan_index]; 175 int ret = max1118_read(adc->spi, scan_chan->channel); 176 177 if (ret < 0) { 178 dev_warn(&adc->spi->dev, 179 "failed to get conversion data\n"); 180 goto out; 181 } 182 183 data[i] = ret; 184 i++; 185 } 186 iio_push_to_buffers_with_timestamp(indio_dev, data, 187 iio_get_time_ns(indio_dev)); 188 out: 189 mutex_unlock(&adc->lock); 190 191 iio_trigger_notify_done(indio_dev->trig); 192 193 return IRQ_HANDLED; 194 } 195 196 static int max1118_probe(struct spi_device *spi) 197 { 198 struct iio_dev *indio_dev; 199 struct max1118 *adc; 200 const struct spi_device_id *id = spi_get_device_id(spi); 201 int ret; 202 203 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); 204 if (!indio_dev) 205 return -ENOMEM; 206 207 adc = iio_priv(indio_dev); 208 adc->spi = spi; 209 mutex_init(&adc->lock); 210 211 if (id->driver_data == max1118) { 212 adc->reg = devm_regulator_get(&spi->dev, "vref"); 213 if (IS_ERR(adc->reg)) { 214 dev_err(&spi->dev, "failed to get vref regulator\n"); 215 return PTR_ERR(adc->reg); 216 } 217 ret = regulator_enable(adc->reg); 218 if (ret) 219 return ret; 220 } 221 222 spi_set_drvdata(spi, indio_dev); 223 224 indio_dev->name = spi_get_device_id(spi)->name; 225 indio_dev->dev.parent = &spi->dev; 226 indio_dev->info = &max1118_info; 227 indio_dev->modes = INDIO_DIRECT_MODE; 228 indio_dev->channels = max1118_channels; 229 indio_dev->num_channels = ARRAY_SIZE(max1118_channels); 230 231 /* 232 * To reinitiate a conversion on CH0, it is necessary to allow for a 233 * conversion to be complete and all of the data to be read out. Once 234 * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go 235 * into AutoShutdown mode until the next conversion is initiated. 236 */ 237 max1118_read(spi, 0); 238 239 ret = iio_triggered_buffer_setup(indio_dev, NULL, 240 max1118_trigger_handler, NULL); 241 if (ret) 242 goto err_reg_disable; 243 244 ret = iio_device_register(indio_dev); 245 if (ret) 246 goto err_buffer_cleanup; 247 248 return 0; 249 250 err_buffer_cleanup: 251 iio_triggered_buffer_cleanup(indio_dev); 252 err_reg_disable: 253 if (id->driver_data == max1118) 254 regulator_disable(adc->reg); 255 256 return ret; 257 } 258 259 static int max1118_remove(struct spi_device *spi) 260 { 261 struct iio_dev *indio_dev = spi_get_drvdata(spi); 262 struct max1118 *adc = iio_priv(indio_dev); 263 const struct spi_device_id *id = spi_get_device_id(spi); 264 265 iio_device_unregister(indio_dev); 266 iio_triggered_buffer_cleanup(indio_dev); 267 if (id->driver_data == max1118) 268 return regulator_disable(adc->reg); 269 270 return 0; 271 } 272 273 static const struct spi_device_id max1118_id[] = { 274 { "max1117", max1117 }, 275 { "max1118", max1118 }, 276 { "max1119", max1119 }, 277 {} 278 }; 279 MODULE_DEVICE_TABLE(spi, max1118_id); 280 281 #ifdef CONFIG_OF 282 283 static const struct of_device_id max1118_dt_ids[] = { 284 { .compatible = "maxim,max1117" }, 285 { .compatible = "maxim,max1118" }, 286 { .compatible = "maxim,max1119" }, 287 {}, 288 }; 289 MODULE_DEVICE_TABLE(of, max1118_dt_ids); 290 291 #endif 292 293 static struct spi_driver max1118_spi_driver = { 294 .driver = { 295 .name = "max1118", 296 .of_match_table = of_match_ptr(max1118_dt_ids), 297 }, 298 .probe = max1118_probe, 299 .remove = max1118_remove, 300 .id_table = max1118_id, 301 }; 302 module_spi_driver(max1118_spi_driver); 303 304 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>"); 305 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver"); 306 MODULE_LICENSE("GPL v2"); 307