1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * IIO driver for Texas Instruments ADS7924 ADC, 12-bit, 4-Channels, I2C 4 * 5 * Author: Hugo Villeneuve <hvilleneuve@dimonoff.com> 6 * Copyright 2022 DimOnOff 7 * 8 * based on iio/adc/ti-ads1015.c 9 * Copyright (c) 2016, Intel Corporation. 10 * 11 * Datasheet: https://www.ti.com/lit/gpn/ads7924 12 */ 13 14 #include <linux/bitfield.h> 15 #include <linux/delay.h> 16 #include <linux/gpio/consumer.h> 17 #include <linux/init.h> 18 #include <linux/irq.h> 19 #include <linux/i2c.h> 20 #include <linux/module.h> 21 #include <linux/mutex.h> 22 #include <linux/regmap.h> 23 #include <linux/regulator/consumer.h> 24 25 #include <linux/iio/iio.h> 26 #include <linux/iio/types.h> 27 28 #define ADS7924_CHANNELS 4 29 #define ADS7924_BITS 12 30 #define ADS7924_DATA_SHIFT 4 31 32 /* Registers. */ 33 #define ADS7924_MODECNTRL_REG 0x00 34 #define ADS7924_INTCNTRL_REG 0x01 35 #define ADS7924_DATA0_U_REG 0x02 36 #define ADS7924_DATA0_L_REG 0x03 37 #define ADS7924_DATA1_U_REG 0x04 38 #define ADS7924_DATA1_L_REG 0x05 39 #define ADS7924_DATA2_U_REG 0x06 40 #define ADS7924_DATA2_L_REG 0x07 41 #define ADS7924_DATA3_U_REG 0x08 42 #define ADS7924_DATA3_L_REG 0x09 43 #define ADS7924_ULR0_REG 0x0A 44 #define ADS7924_LLR0_REG 0x0B 45 #define ADS7924_ULR1_REG 0x0C 46 #define ADS7924_LLR1_REG 0x0D 47 #define ADS7924_ULR2_REG 0x0E 48 #define ADS7924_LLR2_REG 0x0F 49 #define ADS7924_ULR3_REG 0x10 50 #define ADS7924_LLR3_REG 0x11 51 #define ADS7924_INTCONFIG_REG 0x12 52 #define ADS7924_SLPCONFIG_REG 0x13 53 #define ADS7924_ACQCONFIG_REG 0x14 54 #define ADS7924_PWRCONFIG_REG 0x15 55 #define ADS7924_RESET_REG 0x16 56 57 /* 58 * Register address INC bit: when set to '1', the register address is 59 * automatically incremented after every register read which allows convenient 60 * reading of multiple registers. Set INC to '0' when reading a single register. 61 */ 62 #define ADS7924_AUTO_INCREMENT_BIT BIT(7) 63 64 #define ADS7924_MODECNTRL_MODE_MASK GENMASK(7, 2) 65 66 #define ADS7924_MODECNTRL_SEL_MASK GENMASK(1, 0) 67 68 #define ADS7924_CFG_INTPOL_BIT 1 69 #define ADS7924_CFG_INTTRIG_BIT 0 70 71 #define ADS7924_CFG_INTPOL_MASK BIT(ADS7924_CFG_INTPOL_BIT) 72 #define ADS7924_CFG_INTTRIG_MASK BIT(ADS7924_CFG_INTTRIG_BIT) 73 74 /* Interrupt pin polarity */ 75 #define ADS7924_CFG_INTPOL_LOW 0 76 #define ADS7924_CFG_INTPOL_HIGH 1 77 78 /* Interrupt pin signaling */ 79 #define ADS7924_CFG_INTTRIG_LEVEL 0 80 #define ADS7924_CFG_INTTRIG_EDGE 1 81 82 /* Mode control values */ 83 #define ADS7924_MODECNTRL_IDLE 0x00 84 #define ADS7924_MODECNTRL_AWAKE 0x20 85 #define ADS7924_MODECNTRL_MANUAL_SINGLE 0x30 86 #define ADS7924_MODECNTRL_MANUAL_SCAN 0x32 87 #define ADS7924_MODECNTRL_AUTO_SINGLE 0x31 88 #define ADS7924_MODECNTRL_AUTO_SCAN 0x33 89 #define ADS7924_MODECNTRL_AUTO_SINGLE_SLEEP 0x39 90 #define ADS7924_MODECNTRL_AUTO_SCAN_SLEEP 0x3B 91 #define ADS7924_MODECNTRL_AUTO_BURST_SLEEP 0x3F 92 93 #define ADS7924_ACQTIME_MASK GENMASK(4, 0) 94 95 #define ADS7924_PWRUPTIME_MASK GENMASK(4, 0) 96 97 /* 98 * The power-up time is allowed to elapse whenever the device has been shutdown 99 * in idle mode. Power-up time can allow external circuits, such as an 100 * operational amplifier, between the MUXOUT and ADCIN pins to turn on. 101 * The nominal time programmed by the PUTIME[4:0] register bits is given by: 102 * t PU = PWRUPTIME[4:0] × 2 μs 103 * If a power-up time is not required, set the bits to '0' to effectively bypass. 104 */ 105 #define ADS7924_PWRUPTIME_US 0 /* Bypass (0us). */ 106 107 /* 108 * Acquisition Time according to ACQTIME[4:0] register bits. 109 * The Acquisition Time is given by: 110 * t ACQ = (ACQTIME[4:0] × 2 μs) + 6 μs 111 * Using default value of 0 for ACQTIME[4:0] results in a minimum acquisition 112 * time of 6us. 113 */ 114 #define ADS7924_ACQTIME_US 6 115 116 /* The conversion time is always 4μs and cannot be programmed by the user. */ 117 #define ADS7924_CONVTIME_US 4 118 119 #define ADS7924_TOTAL_CONVTIME_US (ADS7924_PWRUPTIME_US + ADS7924_ACQTIME_US + \ 120 ADS7924_CONVTIME_US) 121 122 #define ADS7924_V_CHAN(_chan, _addr) { \ 123 .type = IIO_VOLTAGE, \ 124 .indexed = 1, \ 125 .channel = _chan, \ 126 .address = _addr, \ 127 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 128 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 129 .datasheet_name = "AIN"#_chan, \ 130 } 131 132 struct ads7924_data { 133 struct device *dev; 134 struct regmap *regmap; 135 struct regulator *vref_reg; 136 137 /* GPIO descriptor for device hard-reset pin. */ 138 struct gpio_desc *reset_gpio; 139 140 /* 141 * Protects ADC ops, e.g: concurrent sysfs/buffered 142 * data reads, configuration updates 143 */ 144 struct mutex lock; 145 146 /* 147 * Set to true when the ADC is switched to the continuous-conversion 148 * mode and exits from a power-down state. This flag is used to avoid 149 * getting the stale result from the conversion register. 150 */ 151 bool conv_invalid; 152 }; 153 154 static bool ads7924_is_writeable_reg(struct device *dev, unsigned int reg) 155 { 156 switch (reg) { 157 case ADS7924_MODECNTRL_REG: 158 case ADS7924_INTCNTRL_REG: 159 case ADS7924_ULR0_REG: 160 case ADS7924_LLR0_REG: 161 case ADS7924_ULR1_REG: 162 case ADS7924_LLR1_REG: 163 case ADS7924_ULR2_REG: 164 case ADS7924_LLR2_REG: 165 case ADS7924_ULR3_REG: 166 case ADS7924_LLR3_REG: 167 case ADS7924_INTCONFIG_REG: 168 case ADS7924_SLPCONFIG_REG: 169 case ADS7924_ACQCONFIG_REG: 170 case ADS7924_PWRCONFIG_REG: 171 case ADS7924_RESET_REG: 172 return true; 173 default: 174 return false; 175 } 176 } 177 178 static const struct regmap_config ads7924_regmap_config = { 179 .reg_bits = 8, 180 .val_bits = 8, 181 .max_register = ADS7924_RESET_REG, 182 .writeable_reg = ads7924_is_writeable_reg, 183 }; 184 185 static const struct iio_chan_spec ads7924_channels[] = { 186 ADS7924_V_CHAN(0, ADS7924_DATA0_U_REG), 187 ADS7924_V_CHAN(1, ADS7924_DATA1_U_REG), 188 ADS7924_V_CHAN(2, ADS7924_DATA2_U_REG), 189 ADS7924_V_CHAN(3, ADS7924_DATA3_U_REG), 190 }; 191 192 static int ads7924_get_adc_result(struct ads7924_data *data, 193 struct iio_chan_spec const *chan, int *val) 194 { 195 int ret; 196 __be16 be_val; 197 198 if (chan->channel < 0 || chan->channel >= ADS7924_CHANNELS) 199 return -EINVAL; 200 201 if (data->conv_invalid) { 202 int conv_time; 203 204 conv_time = ADS7924_TOTAL_CONVTIME_US; 205 /* Allow 10% for internal clock inaccuracy. */ 206 conv_time += conv_time / 10; 207 usleep_range(conv_time, conv_time + 1); 208 data->conv_invalid = false; 209 } 210 211 ret = regmap_raw_read(data->regmap, ADS7924_AUTO_INCREMENT_BIT | 212 chan->address, &be_val, sizeof(be_val)); 213 if (ret) 214 return ret; 215 216 *val = be16_to_cpu(be_val) >> ADS7924_DATA_SHIFT; 217 218 return 0; 219 } 220 221 static int ads7924_read_raw(struct iio_dev *indio_dev, 222 struct iio_chan_spec const *chan, int *val, 223 int *val2, long mask) 224 { 225 int ret, vref_uv; 226 struct ads7924_data *data = iio_priv(indio_dev); 227 228 switch (mask) { 229 case IIO_CHAN_INFO_RAW: 230 mutex_lock(&data->lock); 231 ret = ads7924_get_adc_result(data, chan, val); 232 mutex_unlock(&data->lock); 233 if (ret < 0) 234 return ret; 235 236 return IIO_VAL_INT; 237 case IIO_CHAN_INFO_SCALE: 238 vref_uv = regulator_get_voltage(data->vref_reg); 239 if (vref_uv < 0) 240 return vref_uv; 241 242 *val = vref_uv / 1000; /* Convert reg voltage to mV */ 243 *val2 = ADS7924_BITS; 244 return IIO_VAL_FRACTIONAL_LOG2; 245 default: 246 return -EINVAL; 247 } 248 } 249 250 static const struct iio_info ads7924_info = { 251 .read_raw = ads7924_read_raw, 252 }; 253 254 static int ads7924_get_channels_config(struct device *dev) 255 { 256 struct fwnode_handle *node; 257 int num_channels = 0; 258 259 device_for_each_child_node(dev, node) { 260 u32 pval; 261 unsigned int channel; 262 263 if (fwnode_property_read_u32(node, "reg", &pval)) { 264 dev_err(dev, "invalid reg on %pfw\n", node); 265 continue; 266 } 267 268 channel = pval; 269 if (channel >= ADS7924_CHANNELS) { 270 dev_err(dev, "invalid channel index %d on %pfw\n", 271 channel, node); 272 continue; 273 } 274 275 num_channels++; 276 } 277 278 if (!num_channels) 279 return -EINVAL; 280 281 return 0; 282 } 283 284 static int ads7924_set_conv_mode(struct ads7924_data *data, int mode) 285 { 286 int ret; 287 unsigned int mode_field; 288 struct device *dev = data->dev; 289 290 /* 291 * When switching between modes, be sure to first select the Awake mode 292 * and then switch to the desired mode. This procedure ensures the 293 * internal control logic is properly synchronized. 294 */ 295 if (mode != ADS7924_MODECNTRL_IDLE) { 296 mode_field = FIELD_PREP(ADS7924_MODECNTRL_MODE_MASK, 297 ADS7924_MODECNTRL_AWAKE); 298 299 ret = regmap_update_bits(data->regmap, ADS7924_MODECNTRL_REG, 300 ADS7924_MODECNTRL_MODE_MASK, 301 mode_field); 302 if (ret) { 303 dev_err(dev, "failed to set awake mode (%pe)\n", 304 ERR_PTR(ret)); 305 return ret; 306 } 307 } 308 309 mode_field = FIELD_PREP(ADS7924_MODECNTRL_MODE_MASK, mode); 310 311 ret = regmap_update_bits(data->regmap, ADS7924_MODECNTRL_REG, 312 ADS7924_MODECNTRL_MODE_MASK, mode_field); 313 if (ret) 314 dev_err(dev, "failed to set mode %d (%pe)\n", mode, 315 ERR_PTR(ret)); 316 317 return ret; 318 } 319 320 static int ads7924_reset(struct iio_dev *indio_dev) 321 { 322 struct ads7924_data *data = iio_priv(indio_dev); 323 324 if (data->reset_gpio) { 325 gpiod_set_value(data->reset_gpio, 1); /* Assert. */ 326 /* Educated guess: assert time not specified in datasheet... */ 327 mdelay(100); 328 gpiod_set_value(data->reset_gpio, 0); /* Deassert. */ 329 return 0; 330 } 331 332 /* 333 * A write of 10101010 to this register will generate a 334 * software reset of the ADS7924. 335 */ 336 return regmap_write(data->regmap, ADS7924_RESET_REG, 0b10101010); 337 }; 338 339 static void ads7924_reg_disable(void *data) 340 { 341 regulator_disable(data); 342 } 343 344 static void ads7924_set_idle_mode(void *data) 345 { 346 ads7924_set_conv_mode(data, ADS7924_MODECNTRL_IDLE); 347 } 348 349 static int ads7924_probe(struct i2c_client *client) 350 { 351 struct iio_dev *indio_dev; 352 struct ads7924_data *data; 353 struct device *dev = &client->dev; 354 int ret; 355 356 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 357 if (!indio_dev) 358 return -ENOMEM; 359 360 data = iio_priv(indio_dev); 361 362 data->dev = dev; 363 364 /* Initialize the reset GPIO as output with an initial value of 0. */ 365 data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW); 366 if (IS_ERR(data->reset_gpio)) 367 return dev_err_probe(dev, PTR_ERR(data->reset_gpio), 368 "failed to get request reset GPIO\n"); 369 370 mutex_init(&data->lock); 371 372 indio_dev->name = "ads7924"; 373 indio_dev->modes = INDIO_DIRECT_MODE; 374 375 indio_dev->channels = ads7924_channels; 376 indio_dev->num_channels = ARRAY_SIZE(ads7924_channels); 377 indio_dev->info = &ads7924_info; 378 379 ret = ads7924_get_channels_config(dev); 380 if (ret < 0) 381 return dev_err_probe(dev, ret, 382 "failed to get channels configuration\n"); 383 384 data->regmap = devm_regmap_init_i2c(client, &ads7924_regmap_config); 385 if (IS_ERR(data->regmap)) 386 return dev_err_probe(dev, PTR_ERR(data->regmap), 387 "failed to init regmap\n"); 388 389 data->vref_reg = devm_regulator_get(dev, "vref"); 390 if (IS_ERR(data->vref_reg)) 391 return dev_err_probe(dev, PTR_ERR(data->vref_reg), 392 "failed to get vref regulator\n"); 393 394 ret = regulator_enable(data->vref_reg); 395 if (ret) 396 return dev_err_probe(dev, ret, 397 "failed to enable regulator\n"); 398 399 ret = devm_add_action_or_reset(dev, ads7924_reg_disable, data->vref_reg); 400 if (ret) 401 return ret; 402 403 ret = ads7924_reset(indio_dev); 404 if (ret < 0) 405 return dev_err_probe(dev, ret, 406 "failed to reset device\n"); 407 408 ret = ads7924_set_conv_mode(data, ADS7924_MODECNTRL_AUTO_SCAN); 409 if (ret) 410 return dev_err_probe(dev, ret, 411 "failed to set conversion mode\n"); 412 413 ret = devm_add_action_or_reset(dev, ads7924_set_idle_mode, data); 414 if (ret) 415 return ret; 416 417 /* Use minimum signal acquire time. */ 418 ret = regmap_update_bits(data->regmap, ADS7924_ACQCONFIG_REG, 419 ADS7924_ACQTIME_MASK, 420 FIELD_PREP(ADS7924_ACQTIME_MASK, 0)); 421 if (ret < 0) 422 return dev_err_probe(dev, ret, 423 "failed to configure signal acquire time\n"); 424 425 /* Disable power-up time. */ 426 ret = regmap_update_bits(data->regmap, ADS7924_PWRCONFIG_REG, 427 ADS7924_PWRUPTIME_MASK, 428 FIELD_PREP(ADS7924_PWRUPTIME_MASK, 0)); 429 if (ret < 0) 430 return dev_err_probe(dev, ret, 431 "failed to configure power-up time\n"); 432 433 data->conv_invalid = true; 434 435 ret = devm_iio_device_register(dev, indio_dev); 436 if (ret < 0) 437 return dev_err_probe(dev, ret, 438 "failed to register IIO device\n"); 439 440 return 0; 441 } 442 443 static const struct i2c_device_id ads7924_id[] = { 444 { "ads7924" }, 445 { } 446 }; 447 MODULE_DEVICE_TABLE(i2c, ads7924_id); 448 449 static const struct of_device_id ads7924_of_match[] = { 450 { .compatible = "ti,ads7924", }, 451 { } 452 }; 453 MODULE_DEVICE_TABLE(of, ads7924_of_match); 454 455 static struct i2c_driver ads7924_driver = { 456 .driver = { 457 .name = "ads7924", 458 .of_match_table = ads7924_of_match, 459 }, 460 .probe = ads7924_probe, 461 .id_table = ads7924_id, 462 }; 463 464 module_i2c_driver(ads7924_driver); 465 466 MODULE_AUTHOR("Hugo Villeneuve <hvilleneuve@dimonoff.com>"); 467 MODULE_DESCRIPTION("Texas Instruments ADS7924 ADC I2C driver"); 468 MODULE_LICENSE("GPL"); 469