drivers/iio/adc/ti-lmp92064.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Texas Instruments LMP92064 SPI ADC driver
   4  *
   5  * Copyright (c) 2022 Leonard Göhrs <kernel@pengutronix.de>, Pengutronix
   6  *
   7  * Based on linux/drivers/iio/adc/ti-tsc2046.c
   8  * Copyright (c) 2021 Oleksij Rempel <kernel@pengutronix.de>, Pengutronix
   9  */
  10
  11 #include <linux/delay.h>
  12 #include <linux/gpio/consumer.h>
  13 #include <linux/module.h>
  14 #include <linux/regmap.h>
  15 #include <linux/regulator/consumer.h>
  16 #include <linux/spi/spi.h>
  17
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/buffer.h>
  20 #include <linux/iio/driver.h>
  21 #include <linux/iio/triggered_buffer.h>
  22 #include <linux/iio/trigger_consumer.h>
  23
  24 #define TI_LMP92064_REG_CONFIG_A 0x0000
  25 #define TI_LMP92064_REG_CONFIG_B 0x0001
  26 #define TI_LMP92064_REG_CHIP_REV 0x0006
  27
  28 #define TI_LMP92064_REG_MFR_ID1 0x000C
  29 #define TI_LMP92064_REG_MFR_ID2 0x000D
  30
  31 #define TI_LMP92064_REG_REG_UPDATE 0x000F
  32 #define TI_LMP92064_REG_CONFIG_REG 0x0100
  33 #define TI_LMP92064_REG_STATUS 0x0103
  34
  35 #define TI_LMP92064_REG_DATA_VOUT_LSB 0x0200
  36 #define TI_LMP92064_REG_DATA_VOUT_MSB 0x0201
  37 #define TI_LMP92064_REG_DATA_COUT_LSB 0x0202
  38 #define TI_LMP92064_REG_DATA_COUT_MSB 0x0203
  39
  40 #define TI_LMP92064_VAL_CONFIG_A 0x99
  41 #define TI_LMP92064_VAL_CONFIG_B 0x00
  42 #define TI_LMP92064_VAL_STATUS_OK 0x01
  43
  44 /*
  45  * Channel number definitions for the two channels of the device
  46  * - IN Current (INC)
  47  * - IN Voltage (INV)
  48  */
  49 #define TI_LMP92064_CHAN_INC 0
  50 #define TI_LMP92064_CHAN_INV 1
  51
  52 static const struct regmap_range lmp92064_readable_reg_ranges[] = {
  53         regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CHIP_REV),
  54         regmap_reg_range(TI_LMP92064_REG_MFR_ID1, TI_LMP92064_REG_MFR_ID2),
  55         regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
  56         regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
  57         regmap_reg_range(TI_LMP92064_REG_STATUS, TI_LMP92064_REG_STATUS),
  58         regmap_reg_range(TI_LMP92064_REG_DATA_VOUT_LSB, TI_LMP92064_REG_DATA_COUT_MSB),
  59 };
  60
  61 static const struct regmap_access_table lmp92064_readable_regs = {
  62         .yes_ranges = lmp92064_readable_reg_ranges,
  63         .n_yes_ranges = ARRAY_SIZE(lmp92064_readable_reg_ranges),
  64 };
  65
  66 static const struct regmap_range lmp92064_writable_reg_ranges[] = {
  67         regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CONFIG_B),
  68         regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
  69         regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
  70 };
  71
  72 static const struct regmap_access_table lmp92064_writable_regs = {
  73         .yes_ranges = lmp92064_writable_reg_ranges,
  74         .n_yes_ranges = ARRAY_SIZE(lmp92064_writable_reg_ranges),
  75 };
  76
  77 static const struct regmap_config lmp92064_spi_regmap_config = {
  78         .reg_bits = 16,
  79         .val_bits = 8,
  80         .max_register = TI_LMP92064_REG_DATA_COUT_MSB,
  81         .rd_table = &lmp92064_readable_regs,
  82         .wr_table = &lmp92064_writable_regs,
  83 };
  84
  85 struct lmp92064_adc_priv {
  86         int shunt_resistor_uohm;
  87         struct spi_device *spi;
  88         struct regmap *regmap;
  89 };
  90
  91 static const struct iio_chan_spec lmp92064_adc_channels[] = {
  92         {
  93                 .type = IIO_CURRENT,
  94                 .address = TI_LMP92064_CHAN_INC,
  95                 .info_mask_separate =
  96                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
  97                 .scan_index = TI_LMP92064_CHAN_INC,
  98                 .scan_type = {
  99                         .sign = 'u',
 100                         .realbits = 12,
 101                         .storagebits = 16,
 102                 },
 103                 .datasheet_name = "INC",
 104         },
 105         {
 106                 .type = IIO_VOLTAGE,
 107                 .address = TI_LMP92064_CHAN_INV,
 108                 .info_mask_separate =
 109                         BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
 110                 .scan_index = TI_LMP92064_CHAN_INV,
 111                 .scan_type = {
 112                         .sign = 'u',
 113                         .realbits = 12,
 114                         .storagebits = 16,
 115                 },
 116                 .datasheet_name = "INV",
 117         },
 118         IIO_CHAN_SOFT_TIMESTAMP(2),
 119 };
 120
 121 static const unsigned long lmp92064_scan_masks[] = {
 122         BIT(TI_LMP92064_CHAN_INC) | BIT(TI_LMP92064_CHAN_INV),
 123         0
 124 };
 125
 126 static int lmp92064_read_meas(struct lmp92064_adc_priv *priv, u16 *res)
 127 {
 128         __be16 raw[2];
 129         int ret;
 130
 131         /*
 132          * The ADC only latches in new samples if all DATA registers are read
 133          * in descending sequential order.
 134          * The ADC auto-decrements the register index with each clocked byte.
 135          * Read both channels in single SPI transfer by selecting the highest
 136          * register using the command below and clocking out all four data
 137          * bytes.
 138          */
 139
 140         ret = regmap_bulk_read(priv->regmap, TI_LMP92064_REG_DATA_COUT_MSB,
 141                          &raw, sizeof(raw));
 142
 143         if (ret) {
 144                 dev_err(&priv->spi->dev, "regmap_bulk_read failed: %pe\n",
 145                         ERR_PTR(ret));
 146                 return ret;
 147         }
 148
 149         res[0] = be16_to_cpu(raw[0]);
 150         res[1] = be16_to_cpu(raw[1]);
 151
 152         return 0;
 153 }
 154
 155 static int lmp92064_read_raw(struct iio_dev *indio_dev,
 156                              struct iio_chan_spec const *chan, int *val,
 157                              int *val2, long mask)
 158 {
 159         struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
 160         u16 raw[2];
 161         int ret;
 162
 163         switch (mask) {
 164         case IIO_CHAN_INFO_RAW:
 165                 ret = lmp92064_read_meas(priv, raw);
 166                 if (ret < 0)
 167                         return ret;
 168
 169                 *val = (chan->address == TI_LMP92064_CHAN_INC) ? raw[0] : raw[1];
 170
 171                 return IIO_VAL_INT;
 172         case IIO_CHAN_INFO_SCALE:
 173                 if (chan->address == TI_LMP92064_CHAN_INC) {
 174                         /*
 175                          * processed (mA) = raw * current_lsb (mA)
 176                          * current_lsb (mA) = shunt_voltage_lsb (nV) / shunt_resistor (uOhm)
 177                          * shunt_voltage_lsb (nV) = 81920000 / 4096 = 20000
 178                          */
 179                         *val = 20000;
 180                         *val2 = priv->shunt_resistor_uohm;
 181                 } else {
 182                         /*
 183                          * processed (mV) = raw * voltage_lsb (mV)
 184                          * voltage_lsb (mV) = 2048 / 4096
 185                          */
 186                         *val = 2048;
 187                         *val2 = 4096;
 188                 }
 189                 return IIO_VAL_FRACTIONAL;
 190         default:
 191                 return -EINVAL;
 192         }
 193 }
 194
 195 static irqreturn_t lmp92064_trigger_handler(int irq, void *p)
 196 {
 197         struct iio_poll_func *pf = p;
 198         struct iio_dev *indio_dev = pf->indio_dev;
 199         struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
 200         struct {
 201                 u16 values[2];
 202                 int64_t timestamp __aligned(8);
 203         } data;
 204         int ret;
 205
 206         memset(&data, 0, sizeof(data));
 207
 208         ret = lmp92064_read_meas(priv, data.values);
 209         if (ret)
 210                 goto err;
 211
 212         iio_push_to_buffers_with_timestamp(indio_dev, &data,
 213                                            iio_get_time_ns(indio_dev));
 214
 215 err:
 216         iio_trigger_notify_done(indio_dev->trig);
 217
 218         return IRQ_HANDLED;
 219 }
 220
 221 static int lmp92064_reset(struct lmp92064_adc_priv *priv,
 222                           struct gpio_desc *gpio_reset)
 223 {
 224         unsigned int status;
 225         int ret, i;
 226
 227         if (gpio_reset) {
 228                 /*
 229                  * Perform a hard reset if gpio_reset is available.
 230                  * The datasheet specifies a very low 3.5ns reset pulse duration and does not
 231                  * specify how long to wait after a reset to access the device.
 232                  * Use more conservative pulse lengths to allow analog RC filtering of the
 233                  * reset line at the board level (as recommended in the datasheet).
 234                  */
 235                 gpiod_set_value_cansleep(gpio_reset, 1);
 236                 usleep_range(1, 10);
 237                 gpiod_set_value_cansleep(gpio_reset, 0);
 238                 usleep_range(500, 750);
 239         } else {
 240                 /*
 241                  * Perform a soft-reset if not.
 242                  * Also write default values to the config registers that are not
 243                  * affected by soft reset.
 244                  */
 245                 ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_A,
 246                                    TI_LMP92064_VAL_CONFIG_A);
 247                 if (ret < 0)
 248                         return ret;
 249
 250                 ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_B,
 251                                    TI_LMP92064_VAL_CONFIG_B);
 252                 if (ret < 0)
 253                         return ret;
 254         }
 255
 256         /*
 257          * Wait for the device to signal readiness to prevent reading bogus data
 258          * and make sure device is actually connected.
 259          * The datasheet does not specify how long this takes but usually it is
 260          * not more than 3-4 iterations of this loop.
 261          */
 262         for (i = 0; i < 10; i++) {
 263                 ret = regmap_read(priv->regmap, TI_LMP92064_REG_STATUS, &status);
 264                 if (ret < 0)
 265                         return ret;
 266
 267                 if (status == TI_LMP92064_VAL_STATUS_OK)
 268                         return 0;
 269
 270                 usleep_range(1000, 2000);
 271         }
 272
 273         /*
 274          * No (correct) response received.
 275          * Device is mostly likely not connected to the bus.
 276          */
 277         return -ENXIO;
 278 }
 279
 280 static const struct iio_info lmp92064_adc_info = {
 281         .read_raw = lmp92064_read_raw,
 282 };
 283
 284 static int lmp92064_adc_probe(struct spi_device *spi)
 285 {
 286         struct device *dev = &spi->dev;
 287         struct lmp92064_adc_priv *priv;
 288         struct gpio_desc *gpio_reset;
 289         struct iio_dev *indio_dev;
 290         u32 shunt_resistor_uohm;
 291         struct regmap *regmap;
 292         int ret;
 293
 294         ret = spi_setup(spi);
 295         if (ret < 0)
 296                 return dev_err_probe(dev, ret, "Error in SPI setup\n");
 297
 298         regmap = devm_regmap_init_spi(spi, &lmp92064_spi_regmap_config);
 299         if (IS_ERR(regmap))
 300                 return dev_err_probe(dev, PTR_ERR(regmap),
 301                                      "Failed to set up SPI regmap\n");
 302
 303         indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
 304         if (!indio_dev)
 305                 return -ENOMEM;
 306
 307         priv = iio_priv(indio_dev);
 308
 309         priv->spi = spi;
 310         priv->regmap = regmap;
 311
 312         ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms",
 313                                        &shunt_resistor_uohm);
 314         if (ret < 0)
 315                 return dev_err_probe(dev, ret,
 316                                      "Failed to get shunt-resistor value\n");
 317
 318         /*
 319          * The shunt resistance is passed to userspace as the denominator of an iio
 320          * fraction. Make sure it is in range for that.
 321          */
 322         if (shunt_resistor_uohm == 0 || shunt_resistor_uohm > INT_MAX) {
 323                 dev_err(dev, "Shunt resistance is out of range\n");
 324                 return -EINVAL;
 325         }
 326
 327         priv->shunt_resistor_uohm = shunt_resistor_uohm;
 328
 329         ret = devm_regulator_get_enable(dev, "vdd");
 330         if (ret)
 331                 return ret;
 332
 333         ret = devm_regulator_get_enable(dev, "vdig");
 334         if (ret)
 335                 return ret;
 336
 337         gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
 338         if (IS_ERR(gpio_reset))
 339                 return dev_err_probe(dev, PTR_ERR(gpio_reset),
 340                                      "Failed to get GPIO reset pin\n");
 341
 342         ret = lmp92064_reset(priv, gpio_reset);
 343         if (ret < 0)
 344                 return dev_err_probe(dev, ret, "Failed to reset device\n");
 345
 346         indio_dev->name = "lmp92064";
 347         indio_dev->modes = INDIO_DIRECT_MODE;
 348         indio_dev->channels = lmp92064_adc_channels;
 349         indio_dev->num_channels = ARRAY_SIZE(lmp92064_adc_channels);
 350         indio_dev->info = &lmp92064_adc_info;
 351         indio_dev->available_scan_masks = lmp92064_scan_masks;
 352
 353         ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
 354                                               lmp92064_trigger_handler, NULL);
 355         if (ret)
 356                 return dev_err_probe(dev, ret, "Failed to setup buffered read\n");
 357
 358         return devm_iio_device_register(dev, indio_dev);
 359 }
 360
 361 static const struct spi_device_id lmp92064_id_table[] = {
 362         { "lmp92064" },
 363         { }
 364 };
 365 MODULE_DEVICE_TABLE(spi, lmp92064_id_table);
 366
 367 static const struct of_device_id lmp92064_of_table[] = {
 368         { .compatible = "ti,lmp92064" },
 369         {}
 370 };
 371 MODULE_DEVICE_TABLE(of, lmp92064_of_table);
 372
 373 static struct spi_driver lmp92064_adc_driver = {
 374         .driver = {
 375                 .name = "lmp92064",
 376                 .of_match_table = lmp92064_of_table,
 377         },
 378         .probe = lmp92064_adc_probe,
 379         .id_table = lmp92064_id_table,
 380 };
 381 module_spi_driver(lmp92064_adc_driver);
 382
 383 MODULE_AUTHOR("Leonard Göhrs <kernel@pengutronix.de>");
 384 MODULE_DESCRIPTION("TI LMP92064 ADC");
 385 MODULE_LICENSE("GPL");