1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Analog Devices AD7292 SPI ADC driver 4 * 5 * Copyright 2019 Analog Devices Inc. 6 */ 7 8 #include <linux/bitfield.h> 9 #include <linux/device.h> 10 #include <linux/module.h> 11 #include <linux/regulator/consumer.h> 12 #include <linux/spi/spi.h> 13 14 #include <linux/iio/iio.h> 15 16 #define ADI_VENDOR_ID 0x0018 17 18 /* AD7292 registers definition */ 19 #define AD7292_REG_VENDOR_ID 0x00 20 #define AD7292_REG_CONF_BANK 0x05 21 #define AD7292_REG_CONV_COMM 0x0E 22 #define AD7292_REG_ADC_CH(x) (0x10 + (x)) 23 24 /* AD7292 configuration bank subregisters definition */ 25 #define AD7292_BANK_REG_VIN_RNG0 0x10 26 #define AD7292_BANK_REG_VIN_RNG1 0x11 27 #define AD7292_BANK_REG_SAMP_MODE 0x12 28 29 #define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F)) 30 31 /* AD7292_REG_ADC_CONVERSION */ 32 #define AD7292_ADC_DATA_MASK GENMASK(15, 6) 33 #define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x) 34 35 /* AD7292_CHANNEL_SAMPLING_MODE */ 36 #define AD7292_CH_SAMP_MODE(reg, ch) (((reg) >> 8) & BIT(ch)) 37 38 /* AD7292_CHANNEL_VIN_RANGE */ 39 #define AD7292_CH_VIN_RANGE(reg, ch) ((reg) & BIT(ch)) 40 41 #define AD7292_VOLTAGE_CHAN(_chan) \ 42 { \ 43 .type = IIO_VOLTAGE, \ 44 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ 45 BIT(IIO_CHAN_INFO_SCALE), \ 46 .indexed = 1, \ 47 .channel = _chan, \ 48 } 49 50 static const struct iio_chan_spec ad7292_channels[] = { 51 AD7292_VOLTAGE_CHAN(0), 52 AD7292_VOLTAGE_CHAN(1), 53 AD7292_VOLTAGE_CHAN(2), 54 AD7292_VOLTAGE_CHAN(3), 55 AD7292_VOLTAGE_CHAN(4), 56 AD7292_VOLTAGE_CHAN(5), 57 AD7292_VOLTAGE_CHAN(6), 58 AD7292_VOLTAGE_CHAN(7) 59 }; 60 61 static const struct iio_chan_spec ad7292_channels_diff[] = { 62 { 63 .type = IIO_VOLTAGE, 64 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 65 .indexed = 1, 66 .differential = 1, 67 .channel = 0, 68 .channel2 = 1, 69 }, 70 AD7292_VOLTAGE_CHAN(2), 71 AD7292_VOLTAGE_CHAN(3), 72 AD7292_VOLTAGE_CHAN(4), 73 AD7292_VOLTAGE_CHAN(5), 74 AD7292_VOLTAGE_CHAN(6), 75 AD7292_VOLTAGE_CHAN(7) 76 }; 77 78 struct ad7292_state { 79 struct spi_device *spi; 80 struct regulator *reg; 81 unsigned short vref_mv; 82 83 __be16 d16 ____cacheline_aligned; 84 u8 d8[2]; 85 }; 86 87 static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr) 88 { 89 int ret; 90 91 st->d8[0] = AD7292_RD_FLAG_MSK(addr); 92 93 ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2); 94 if (ret < 0) 95 return ret; 96 97 return be16_to_cpu(st->d16); 98 } 99 100 static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr, 101 unsigned int sub_addr, unsigned int len) 102 { 103 unsigned int shift = 16 - (8 * len); 104 int ret; 105 106 st->d8[0] = AD7292_RD_FLAG_MSK(addr); 107 st->d8[1] = sub_addr; 108 109 ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len); 110 if (ret < 0) 111 return ret; 112 113 return (be16_to_cpu(st->d16) >> shift); 114 } 115 116 static int ad7292_single_conversion(struct ad7292_state *st, 117 unsigned int chan_addr) 118 { 119 int ret; 120 121 struct spi_transfer t[] = { 122 { 123 .tx_buf = &st->d8, 124 .len = 4, 125 .delay = { 126 .value = 6, 127 .unit = SPI_DELAY_UNIT_USECS 128 }, 129 }, { 130 .rx_buf = &st->d16, 131 .len = 2, 132 }, 133 }; 134 135 st->d8[0] = chan_addr; 136 st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM); 137 138 ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t)); 139 140 if (ret < 0) 141 return ret; 142 143 return be16_to_cpu(st->d16); 144 } 145 146 static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel) 147 { 148 int samp_mode, range0, range1, factor = 1; 149 150 /* 151 * Every AD7292 ADC channel may have its input range adjusted according 152 * to the settings at the ADC sampling mode and VIN range subregisters. 153 * For a given channel, the minimum input range is equal to Vref, and it 154 * may be increased by a multiplier factor of 2 or 4 according to the 155 * following rule: 156 * If channel is being sampled with respect to AGND: 157 * factor = 4 if VIN range0 and VIN range1 equal 0 158 * factor = 2 if only one of VIN ranges equal 1 159 * factor = 1 if both VIN range0 and VIN range1 equal 1 160 * If channel is being sampled with respect to AVDD: 161 * factor = 4 if VIN range0 and VIN range1 equal 0 162 * Behavior is undefined if any of VIN range doesn't equal 0 163 */ 164 165 samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK, 166 AD7292_BANK_REG_SAMP_MODE, 2); 167 168 if (samp_mode < 0) 169 return samp_mode; 170 171 range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK, 172 AD7292_BANK_REG_VIN_RNG0, 2); 173 174 if (range0 < 0) 175 return range0; 176 177 range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK, 178 AD7292_BANK_REG_VIN_RNG1, 2); 179 180 if (range1 < 0) 181 return range1; 182 183 if (AD7292_CH_SAMP_MODE(samp_mode, channel)) { 184 /* Sampling with respect to AGND */ 185 if (!AD7292_CH_VIN_RANGE(range0, channel)) 186 factor *= 2; 187 188 if (!AD7292_CH_VIN_RANGE(range1, channel)) 189 factor *= 2; 190 191 } else { 192 /* Sampling with respect to AVDD */ 193 if (AD7292_CH_VIN_RANGE(range0, channel) || 194 AD7292_CH_VIN_RANGE(range1, channel)) 195 return -EPERM; 196 197 factor = 4; 198 } 199 200 return factor; 201 } 202 203 static int ad7292_read_raw(struct iio_dev *indio_dev, 204 const struct iio_chan_spec *chan, 205 int *val, int *val2, long info) 206 { 207 struct ad7292_state *st = iio_priv(indio_dev); 208 unsigned int ch_addr; 209 int ret; 210 211 switch (info) { 212 case IIO_CHAN_INFO_RAW: 213 ch_addr = AD7292_REG_ADC_CH(chan->channel); 214 ret = ad7292_single_conversion(st, ch_addr); 215 if (ret < 0) 216 return ret; 217 218 *val = AD7292_ADC_DATA(ret); 219 220 return IIO_VAL_INT; 221 case IIO_CHAN_INFO_SCALE: 222 /* 223 * To convert a raw value to standard units, the IIO defines 224 * this formula: Scaled value = (raw + offset) * scale. 225 * For the scale to be a correct multiplier for (raw + offset), 226 * it must be calculated as the input range divided by the 227 * number of possible distinct input values. Given the ADC data 228 * is 10 bit long, it may assume 2^10 distinct values. 229 * Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2 230 * return type indicates to the IIO API to divide *val by 2 to 231 * the power of *val2 when returning from read_raw. 232 */ 233 234 ret = ad7292_vin_range_multiplier(st, chan->channel); 235 if (ret < 0) 236 return ret; 237 238 *val = st->vref_mv * ret; 239 *val2 = 10; 240 return IIO_VAL_FRACTIONAL_LOG2; 241 default: 242 break; 243 } 244 return -EINVAL; 245 } 246 247 static const struct iio_info ad7292_info = { 248 .read_raw = ad7292_read_raw, 249 }; 250 251 static void ad7292_regulator_disable(void *data) 252 { 253 struct ad7292_state *st = data; 254 255 regulator_disable(st->reg); 256 } 257 258 static int ad7292_probe(struct spi_device *spi) 259 { 260 struct ad7292_state *st; 261 struct iio_dev *indio_dev; 262 struct device_node *child; 263 bool diff_channels = false; 264 int ret; 265 266 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); 267 if (!indio_dev) 268 return -ENOMEM; 269 270 st = iio_priv(indio_dev); 271 st->spi = spi; 272 273 ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID); 274 if (ret != ADI_VENDOR_ID) { 275 dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret); 276 return -EINVAL; 277 } 278 279 st->reg = devm_regulator_get_optional(&spi->dev, "vref"); 280 if (!IS_ERR(st->reg)) { 281 ret = regulator_enable(st->reg); 282 if (ret) { 283 dev_err(&spi->dev, 284 "Failed to enable external vref supply\n"); 285 return ret; 286 } 287 288 ret = devm_add_action_or_reset(&spi->dev, 289 ad7292_regulator_disable, st); 290 if (ret) { 291 regulator_disable(st->reg); 292 return ret; 293 } 294 295 ret = regulator_get_voltage(st->reg); 296 if (ret < 0) 297 return ret; 298 299 st->vref_mv = ret / 1000; 300 } else { 301 /* Use the internal voltage reference. */ 302 st->vref_mv = 1250; 303 } 304 305 indio_dev->name = spi_get_device_id(spi)->name; 306 indio_dev->modes = INDIO_DIRECT_MODE; 307 indio_dev->info = &ad7292_info; 308 309 for_each_available_child_of_node(spi->dev.of_node, child) { 310 diff_channels = of_property_read_bool(child, "diff-channels"); 311 if (diff_channels) { 312 of_node_put(child); 313 break; 314 } 315 } 316 317 if (diff_channels) { 318 indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff); 319 indio_dev->channels = ad7292_channels_diff; 320 } else { 321 indio_dev->num_channels = ARRAY_SIZE(ad7292_channels); 322 indio_dev->channels = ad7292_channels; 323 } 324 325 return devm_iio_device_register(&spi->dev, indio_dev); 326 } 327 328 static const struct spi_device_id ad7292_id_table[] = { 329 { "ad7292", 0 }, 330 {} 331 }; 332 MODULE_DEVICE_TABLE(spi, ad7292_id_table); 333 334 static const struct of_device_id ad7292_of_match[] = { 335 { .compatible = "adi,ad7292" }, 336 { }, 337 }; 338 MODULE_DEVICE_TABLE(of, ad7292_of_match); 339 340 static struct spi_driver ad7292_driver = { 341 .driver = { 342 .name = "ad7292", 343 .of_match_table = ad7292_of_match, 344 }, 345 .probe = ad7292_probe, 346 .id_table = ad7292_id_table, 347 }; 348 module_spi_driver(ad7292_driver); 349 350 MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@gmail.com>"); 351 MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver"); 352 MODULE_LICENSE("GPL v2"); 353