linux/drivers/iio/adc/ti-tlc4541.c
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   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 * https://www.ti.com/lit/gpn/tlc3541
   9 * https://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/mod_devicetable.h>
  28#include <linux/regulator/consumer.h>
  29#include <linux/slab.h>
  30#include <linux/spi/spi.h>
  31#include <linux/sysfs.h>
  32
  33struct tlc4541_state {
  34        struct spi_device               *spi;
  35        struct regulator                *reg;
  36        struct spi_transfer             scan_single_xfer[3];
  37        struct spi_message              scan_single_msg;
  38
  39        /*
  40         * DMA (thus cache coherency maintenance) requires the
  41         * transfer buffers to live in their own cache lines.
  42         * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
  43         * call iio_push_to_buffers_with_timestamp.
  44         */
  45        __be16                          rx_buf[8] ____cacheline_aligned;
  46};
  47
  48struct tlc4541_chip_info {
  49        const struct iio_chan_spec *channels;
  50        unsigned int num_channels;
  51};
  52
  53enum tlc4541_id {
  54        TLC3541,
  55        TLC4541,
  56};
  57
  58#define TLC4541_V_CHAN(bits, bitshift) {                              \
  59                .type = IIO_VOLTAGE,                                  \
  60                .info_mask_separate       = BIT(IIO_CHAN_INFO_RAW),   \
  61                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
  62                .scan_type = {                                        \
  63                        .sign = 'u',                                  \
  64                        .realbits = (bits),                           \
  65                        .storagebits = 16,                            \
  66                        .shift = (bitshift),                          \
  67                        .endianness = IIO_BE,                         \
  68                },                                                    \
  69        }
  70
  71#define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
  72const struct iio_chan_spec name ## _channels[] = { \
  73        TLC4541_V_CHAN(bits, bitshift), \
  74        IIO_CHAN_SOFT_TIMESTAMP(1), \
  75}
  76
  77static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
  78static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
  79
  80static const struct tlc4541_chip_info tlc4541_chip_info[] = {
  81        [TLC3541] = {
  82                .channels = tlc3541_channels,
  83                .num_channels = ARRAY_SIZE(tlc3541_channels),
  84        },
  85        [TLC4541] = {
  86                .channels = tlc4541_channels,
  87                .num_channels = ARRAY_SIZE(tlc4541_channels),
  88        },
  89};
  90
  91static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
  92{
  93        struct iio_poll_func *pf = p;
  94        struct iio_dev *indio_dev = pf->indio_dev;
  95        struct tlc4541_state *st = iio_priv(indio_dev);
  96        int ret;
  97
  98        ret = spi_sync(st->spi, &st->scan_single_msg);
  99        if (ret < 0)
 100                goto done;
 101
 102        iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
 103                                           iio_get_time_ns(indio_dev));
 104
 105done:
 106        iio_trigger_notify_done(indio_dev->trig);
 107        return IRQ_HANDLED;
 108}
 109
 110static int tlc4541_get_range(struct tlc4541_state *st)
 111{
 112        int vref;
 113
 114        vref = regulator_get_voltage(st->reg);
 115        if (vref < 0)
 116                return vref;
 117
 118        vref /= 1000;
 119
 120        return vref;
 121}
 122
 123static int tlc4541_read_raw(struct iio_dev *indio_dev,
 124                            struct iio_chan_spec const *chan,
 125                            int *val,
 126                            int *val2,
 127                            long m)
 128{
 129        int ret = 0;
 130        struct tlc4541_state *st = iio_priv(indio_dev);
 131
 132        switch (m) {
 133        case IIO_CHAN_INFO_RAW:
 134                ret = iio_device_claim_direct_mode(indio_dev);
 135                if (ret)
 136                        return ret;
 137                ret = spi_sync(st->spi, &st->scan_single_msg);
 138                iio_device_release_direct_mode(indio_dev);
 139                if (ret < 0)
 140                        return ret;
 141                *val = be16_to_cpu(st->rx_buf[0]);
 142                *val = *val >> chan->scan_type.shift;
 143                *val &= GENMASK(chan->scan_type.realbits - 1, 0);
 144                return IIO_VAL_INT;
 145        case IIO_CHAN_INFO_SCALE:
 146                ret = tlc4541_get_range(st);
 147                if (ret < 0)
 148                        return ret;
 149                *val = ret;
 150                *val2 = chan->scan_type.realbits;
 151                return IIO_VAL_FRACTIONAL_LOG2;
 152        }
 153        return -EINVAL;
 154}
 155
 156static const struct iio_info tlc4541_info = {
 157        .read_raw = &tlc4541_read_raw,
 158};
 159
 160static int tlc4541_probe(struct spi_device *spi)
 161{
 162        struct tlc4541_state *st;
 163        struct iio_dev *indio_dev;
 164        const struct tlc4541_chip_info *info;
 165        int ret;
 166        int8_t device_init = 0;
 167
 168        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 169        if (indio_dev == NULL)
 170                return -ENOMEM;
 171
 172        st = iio_priv(indio_dev);
 173
 174        spi_set_drvdata(spi, indio_dev);
 175
 176        st->spi = spi;
 177
 178        info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
 179
 180        indio_dev->name = spi_get_device_id(spi)->name;
 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
 219error_cleanup_buffer:
 220        iio_triggered_buffer_cleanup(indio_dev);
 221error_disable_reg:
 222        regulator_disable(st->reg);
 223
 224        return ret;
 225}
 226
 227static void 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
 237static const struct of_device_id tlc4541_dt_ids[] = {
 238        { .compatible = "ti,tlc3541", },
 239        { .compatible = "ti,tlc4541", },
 240        {}
 241};
 242MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
 243
 244static const struct spi_device_id tlc4541_id[] = {
 245        {"tlc3541", TLC3541},
 246        {"tlc4541", TLC4541},
 247        {}
 248};
 249MODULE_DEVICE_TABLE(spi, tlc4541_id);
 250
 251static struct spi_driver tlc4541_driver = {
 252        .driver = {
 253                .name   = "tlc4541",
 254                .of_match_table = tlc4541_dt_ids,
 255        },
 256        .probe          = tlc4541_probe,
 257        .remove         = tlc4541_remove,
 258        .id_table       = tlc4541_id,
 259};
 260module_spi_driver(tlc4541_driver);
 261
 262MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
 263MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
 264MODULE_LICENSE("GPL v2");
 265