drivers/iio/adc/ti-tlc4541.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI tlc4541 ADC Driver
   4  *
   5  * Copyright (C) 2017 Phil Reid
   6  *
   7  * Datasheets can be found here:
   8  * http://www.ti.com/lit/gpn/tlc3541
   9  * http://www.ti.com/lit/gpn/tlc4541
  10  *
  11  * The tlc4541 requires 24 clock cycles to start a transfer.
  12  * Conversion then takes 2.94us to complete before data is ready
  13  * Data is returned MSB first.
  14  */
  15
  16 #include <linux/delay.h>
  17 #include <linux/device.h>
  18 #include <linux/err.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/sysfs.h>
  22 #include <linux/iio/buffer.h>
  23 #include <linux/iio/trigger_consumer.h>
  24 #include <linux/iio/triggered_buffer.h>
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/regulator/consumer.h>
  28 #include <linux/slab.h>
  29 #include <linux/spi/spi.h>
  30 #include <linux/sysfs.h>
  31
  32 struct tlc4541_state {
  33         struct spi_device               *spi;
  34         struct regulator                *reg;
  35         struct spi_transfer             scan_single_xfer[3];
  36         struct spi_message              scan_single_msg;
  37
  38         /*
  39          * DMA (thus cache coherency maintenance) requires the
  40          * transfer buffers to live in their own cache lines.
  41          * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
  42          * call iio_push_to_buffers_with_timestamp.
  43          */
  44         __be16                          rx_buf[8] ____cacheline_aligned;
  45 };
  46
  47 struct tlc4541_chip_info {
  48         const struct iio_chan_spec *channels;
  49         unsigned int num_channels;
  50 };
  51
  52 enum tlc4541_id {
  53         TLC3541,
  54         TLC4541,
  55 };
  56
  57 #define TLC4541_V_CHAN(bits, bitshift) {                              \
  58                 .type = IIO_VOLTAGE,                                  \
  59                 .info_mask_separate       = BIT(IIO_CHAN_INFO_RAW),   \
  60                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
  61                 .scan_type = {                                        \
  62                         .sign = 'u',                                  \
  63                         .realbits = (bits),                           \
  64                         .storagebits = 16,                            \
  65                         .shift = (bitshift),                          \
  66                         .endianness = IIO_BE,                         \
  67                 },                                                    \
  68         }
  69
  70 #define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
  71 const struct iio_chan_spec name ## _channels[] = { \
  72         TLC4541_V_CHAN(bits, bitshift), \
  73         IIO_CHAN_SOFT_TIMESTAMP(1), \
  74 }
  75
  76 static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
  77 static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
  78
  79 static const struct tlc4541_chip_info tlc4541_chip_info[] = {
  80         [TLC3541] = {
  81                 .channels = tlc3541_channels,
  82                 .num_channels = ARRAY_SIZE(tlc3541_channels),
  83         },
  84         [TLC4541] = {
  85                 .channels = tlc4541_channels,
  86                 .num_channels = ARRAY_SIZE(tlc4541_channels),
  87         },
  88 };
  89
  90 static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
  91 {
  92         struct iio_poll_func *pf = p;
  93         struct iio_dev *indio_dev = pf->indio_dev;
  94         struct tlc4541_state *st = iio_priv(indio_dev);
  95         int ret;
  96
  97         ret = spi_sync(st->spi, &st->scan_single_msg);
  98         if (ret < 0)
  99                 goto done;
 100
 101         iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 102                                            iio_get_time_ns(indio_dev));
 103
 104 done:
 105         iio_trigger_notify_done(indio_dev->trig);
 106         return IRQ_HANDLED;
 107 }
 108
 109 static int tlc4541_get_range(struct tlc4541_state *st)
 110 {
 111         int vref;
 112
 113         vref = regulator_get_voltage(st->reg);
 114         if (vref < 0)
 115                 return vref;
 116
 117         vref /= 1000;
 118
 119         return vref;
 120 }
 121
 122 static int tlc4541_read_raw(struct iio_dev *indio_dev,
 123                             struct iio_chan_spec const *chan,
 124                             int *val,
 125                             int *val2,
 126                             long m)
 127 {
 128         int ret = 0;
 129         struct tlc4541_state *st = iio_priv(indio_dev);
 130
 131         switch (m) {
 132         case IIO_CHAN_INFO_RAW:
 133                 ret = iio_device_claim_direct_mode(indio_dev);
 134                 if (ret)
 135                         return ret;
 136                 ret = spi_sync(st->spi, &st->scan_single_msg);
 137                 iio_device_release_direct_mode(indio_dev);
 138                 if (ret < 0)
 139                         return ret;
 140                 *val = be16_to_cpu(st->rx_buf[0]);
 141                 *val = *val >> chan->scan_type.shift;
 142                 *val &= GENMASK(chan->scan_type.realbits - 1, 0);
 143                 return IIO_VAL_INT;
 144         case IIO_CHAN_INFO_SCALE:
 145                 ret = tlc4541_get_range(st);
 146                 if (ret < 0)
 147                         return ret;
 148                 *val = ret;
 149                 *val2 = chan->scan_type.realbits;
 150                 return IIO_VAL_FRACTIONAL_LOG2;
 151         }
 152         return -EINVAL;
 153 }
 154
 155 static const struct iio_info tlc4541_info = {
 156         .read_raw = &tlc4541_read_raw,
 157 };
 158
 159 static int tlc4541_probe(struct spi_device *spi)
 160 {
 161         struct tlc4541_state *st;
 162         struct iio_dev *indio_dev;
 163         const struct tlc4541_chip_info *info;
 164         int ret;
 165         int8_t device_init = 0;
 166
 167         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 168         if (indio_dev == NULL)
 169                 return -ENOMEM;
 170
 171         st = iio_priv(indio_dev);
 172
 173         spi_set_drvdata(spi, indio_dev);
 174
 175         st->spi = spi;
 176
 177         info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
 178
 179         indio_dev->name = spi_get_device_id(spi)->name;
 180         indio_dev->dev.parent = &spi->dev;
 181         indio_dev->modes = INDIO_DIRECT_MODE;
 182         indio_dev->channels = info->channels;
 183         indio_dev->num_channels = info->num_channels;
 184         indio_dev->info = &tlc4541_info;
 185
 186         /* perform reset */
 187         spi_write(spi, &device_init, 1);
 188
 189         /* Setup default message */
 190         st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
 191         st->scan_single_xfer[0].len = 3;
 192         st->scan_single_xfer[1].delay.value = 3;
 193         st->scan_single_xfer[1].delay.unit = SPI_DELAY_UNIT_NSECS;
 194         st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 195         st->scan_single_xfer[2].len = 2;
 196
 197         spi_message_init_with_transfers(&st->scan_single_msg,
 198                                         st->scan_single_xfer, 3);
 199
 200         st->reg = devm_regulator_get(&spi->dev, "vref");
 201         if (IS_ERR(st->reg))
 202                 return PTR_ERR(st->reg);
 203
 204         ret = regulator_enable(st->reg);
 205         if (ret)
 206                 return ret;
 207
 208         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 209                         &tlc4541_trigger_handler, NULL);
 210         if (ret)
 211                 goto error_disable_reg;
 212
 213         ret = iio_device_register(indio_dev);
 214         if (ret)
 215                 goto error_cleanup_buffer;
 216
 217         return 0;
 218
 219 error_cleanup_buffer:
 220         iio_triggered_buffer_cleanup(indio_dev);
 221 error_disable_reg:
 222         regulator_disable(st->reg);
 223
 224         return ret;
 225 }
 226
 227 static int tlc4541_remove(struct spi_device *spi)
 228 {
 229         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 230         struct tlc4541_state *st = iio_priv(indio_dev);
 231
 232         iio_device_unregister(indio_dev);
 233         iio_triggered_buffer_cleanup(indio_dev);
 234         regulator_disable(st->reg);
 235
 236         return 0;
 237 }
 238
 239 #ifdef CONFIG_OF
 240 static const struct of_device_id tlc4541_dt_ids[] = {
 241         { .compatible = "ti,tlc3541", },
 242         { .compatible = "ti,tlc4541", },
 243         {}
 244 };
 245 MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
 246 #endif
 247
 248 static const struct spi_device_id tlc4541_id[] = {
 249         {"tlc3541", TLC3541},
 250         {"tlc4541", TLC4541},
 251         {}
 252 };
 253 MODULE_DEVICE_TABLE(spi, tlc4541_id);
 254
 255 static struct spi_driver tlc4541_driver = {
 256         .driver = {
 257                 .name   = "tlc4541",
 258                 .of_match_table = of_match_ptr(tlc4541_dt_ids),
 259         },
 260         .probe          = tlc4541_probe,
 261         .remove         = tlc4541_remove,
 262         .id_table       = tlc4541_id,
 263 };
 264 module_spi_driver(tlc4541_driver);
 265
 266 MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
 267 MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
 268 MODULE_LICENSE("GPL v2");