iio/adc/ti-adc108s102.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * TI ADC108S102 SPI ADC driver
0004  *
0005  * Copyright (c) 2013-2015 Intel Corporation.
0006  * Copyright (c) 2017 Siemens AG
0007  *
0008  * This IIO device driver is designed to work with the following
0009  * analog to digital converters from Texas Instruments:
0010  *  ADC108S102
0011  *  ADC128S102
0012  * The communication with ADC chip is via the SPI bus (mode 3).
0013  */
0014
0015 #include <linux/acpi.h>
0016 #include <linux/iio/iio.h>
0017 #include <linux/iio/buffer.h>
0018 #include <linux/iio/types.h>
0019 #include <linux/iio/triggered_buffer.h>
0020 #include <linux/iio/trigger_consumer.h>
0021 #include <linux/interrupt.h>
0022 #include <linux/module.h>
0023 #include <linux/mod_devicetable.h>
0024 #include <linux/property.h>
0025 #include <linux/regulator/consumer.h>
0026 #include <linux/spi/spi.h>
0027
0028 /*
0029  * In case of ACPI, we use the hard-wired 5000 mV of the Galileo and IOT2000
0030  * boards as default for the reference pin VA. Device tree users encode that
0031  * via the vref-supply regulator.
0032  */
0033 #define ADC108S102_VA_MV_ACPI_DEFAULT   5000
0034
0035 /*
0036  * Defining the ADC resolution being 12 bits, we can use the same driver for
0037  * both ADC108S102 (10 bits resolution) and ADC128S102 (12 bits resolution)
0038  * chips. The ADC108S102 effectively returns a 12-bit result with the 2
0039  * least-significant bits unset.
0040  */
0041 #define ADC108S102_BITS     12
0042 #define ADC108S102_MAX_CHANNELS 8
0043
0044 /*
0045  * 16-bit SPI command format:
0046  *   [15:14] Ignored
0047  *   [13:11] 3-bit channel address
0048  *   [10:0]  Ignored
0049  */
0050 #define ADC108S102_CMD(ch)      ((u16)(ch) << 11)
0051
0052 /*
0053  * 16-bit SPI response format:
0054  *   [15:12] Zeros
0055  *   [11:0]  12-bit ADC sample (for ADC108S102, [1:0] will always be 0).
0056  */
0057 #define ADC108S102_RES_DATA(res)    ((u16)res & GENMASK(11, 0))
0058
0059 struct adc108s102_state {
0060     struct spi_device       *spi;
0061     struct regulator        *reg;
0062     u32             va_millivolt;
0063     /* SPI transfer used by triggered buffer handler*/
0064     struct spi_transfer     ring_xfer;
0065     /* SPI transfer used by direct scan */
0066     struct spi_transfer     scan_single_xfer;
0067     /* SPI message used by ring_xfer SPI transfer */
0068     struct spi_message      ring_msg;
0069     /* SPI message used by scan_single_xfer SPI transfer */
0070     struct spi_message      scan_single_msg;
0071
0072     /*
0073      * SPI message buffers:
0074      *  tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX|
0075      *  rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt|
0076      *
0077      *  tx_buf: 8 channel read commands, plus 1 dummy command
0078      *  rx_buf: 1 dummy response, 8 channel responses
0079      */
0080     __be16              rx_buf[9] __aligned(IIO_DMA_MINALIGN);
0081     __be16              tx_buf[9] __aligned(IIO_DMA_MINALIGN);
0082 };
0083
0084 #define ADC108S102_V_CHAN(index)                    \
0085     {                               \
0086         .type = IIO_VOLTAGE,                    \
0087         .indexed = 1,                       \
0088         .channel = index,                   \
0089         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |      \
0090             BIT(IIO_CHAN_INFO_SCALE),           \
0091         .address = index,                   \
0092         .scan_index = index,                    \
0093         .scan_type = {                      \
0094             .sign = 'u',                    \
0095             .realbits = ADC108S102_BITS,            \
0096             .storagebits = 16,              \
0097             .endianness = IIO_BE,               \
0098         },                          \
0099     }
0100
0101 static const struct iio_chan_spec adc108s102_channels[] = {
0102     ADC108S102_V_CHAN(0),
0103     ADC108S102_V_CHAN(1),
0104     ADC108S102_V_CHAN(2),
0105     ADC108S102_V_CHAN(3),
0106     ADC108S102_V_CHAN(4),
0107     ADC108S102_V_CHAN(5),
0108     ADC108S102_V_CHAN(6),
0109     ADC108S102_V_CHAN(7),
0110     IIO_CHAN_SOFT_TIMESTAMP(8),
0111 };
0112
0113 static int adc108s102_update_scan_mode(struct iio_dev *indio_dev,
0114         unsigned long const *active_scan_mask)
0115 {
0116     struct adc108s102_state *st = iio_priv(indio_dev);
0117     unsigned int bit, cmds;
0118
0119     /*
0120      * Fill in the first x shorts of tx_buf with the number of channels
0121      * enabled for sampling by the triggered buffer.
0122      */
0123     cmds = 0;
0124     for_each_set_bit(bit, active_scan_mask, ADC108S102_MAX_CHANNELS)
0125         st->tx_buf[cmds++] = cpu_to_be16(ADC108S102_CMD(bit));
0126
0127     /* One dummy command added, to clock in the last response */
0128     st->tx_buf[cmds++] = 0x00;
0129
0130     /* build SPI ring message */
0131     st->ring_xfer.tx_buf = &st->tx_buf[0];
0132     st->ring_xfer.rx_buf = &st->rx_buf[0];
0133     st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]);
0134
0135     spi_message_init_with_transfers(&st->ring_msg, &st->ring_xfer, 1);
0136
0137     return 0;
0138 }
0139
0140 static irqreturn_t adc108s102_trigger_handler(int irq, void *p)
0141 {
0142     struct iio_poll_func *pf = p;
0143     struct iio_dev *indio_dev = pf->indio_dev;
0144     struct adc108s102_state *st = iio_priv(indio_dev);
0145     int ret;
0146
0147     ret = spi_sync(st->spi, &st->ring_msg);
0148     if (ret < 0)
0149         goto out_notify;
0150
0151     /* Skip the dummy response in the first slot */
0152     iio_push_to_buffers_with_ts_unaligned(indio_dev,
0153                           &st->rx_buf[1],
0154                           st->ring_xfer.len - sizeof(st->rx_buf[1]),
0155                           iio_get_time_ns(indio_dev));
0156
0157 out_notify:
0158     iio_trigger_notify_done(indio_dev->trig);
0159
0160     return IRQ_HANDLED;
0161 }
0162
0163 static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch)
0164 {
0165     int ret;
0166
0167     st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch));
0168     ret = spi_sync(st->spi, &st->scan_single_msg);
0169     if (ret)
0170         return ret;
0171
0172     /* Skip the dummy response in the first slot */
0173     return be16_to_cpu(st->rx_buf[1]);
0174 }
0175
0176 static int adc108s102_read_raw(struct iio_dev *indio_dev,
0177                    struct iio_chan_spec const *chan,
0178                    int *val, int *val2, long m)
0179 {
0180     struct adc108s102_state *st = iio_priv(indio_dev);
0181     int ret;
0182
0183     switch (m) {
0184     case IIO_CHAN_INFO_RAW:
0185         ret = iio_device_claim_direct_mode(indio_dev);
0186         if (ret)
0187             return ret;
0188
0189         ret = adc108s102_scan_direct(st, chan->address);
0190
0191         iio_device_release_direct_mode(indio_dev);
0192
0193         if (ret < 0)
0194             return ret;
0195
0196         *val = ADC108S102_RES_DATA(ret);
0197
0198         return IIO_VAL_INT;
0199     case IIO_CHAN_INFO_SCALE:
0200         if (chan->type != IIO_VOLTAGE)
0201             break;
0202
0203         *val = st->va_millivolt;
0204         *val2 = chan->scan_type.realbits;
0205
0206         return IIO_VAL_FRACTIONAL_LOG2;
0207     default:
0208         break;
0209     }
0210
0211     return -EINVAL;
0212 }
0213
0214 static const struct iio_info adc108s102_info = {
0215     .read_raw       = &adc108s102_read_raw,
0216     .update_scan_mode   = &adc108s102_update_scan_mode,
0217 };
0218
0219 static void adc108s102_reg_disable(void *reg)
0220 {
0221     regulator_disable(reg);
0222 }
0223
0224 static int adc108s102_probe(struct spi_device *spi)
0225 {
0226     struct adc108s102_state *st;
0227     struct iio_dev *indio_dev;
0228     int ret;
0229
0230     indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
0231     if (!indio_dev)
0232         return -ENOMEM;
0233
0234     st = iio_priv(indio_dev);
0235
0236     if (ACPI_COMPANION(&spi->dev)) {
0237         st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT;
0238     } else {
0239         st->reg = devm_regulator_get(&spi->dev, "vref");
0240         if (IS_ERR(st->reg))
0241             return PTR_ERR(st->reg);
0242
0243         ret = regulator_enable(st->reg);
0244         if (ret < 0) {
0245             dev_err(&spi->dev, "Cannot enable vref regulator\n");
0246             return ret;
0247         }
0248         ret = devm_add_action_or_reset(&spi->dev, adc108s102_reg_disable,
0249                            st->reg);
0250         if (ret)
0251             return ret;
0252
0253         ret = regulator_get_voltage(st->reg);
0254         if (ret < 0) {
0255             dev_err(&spi->dev, "vref get voltage failed\n");
0256             return ret;
0257         }
0258
0259         st->va_millivolt = ret / 1000;
0260     }
0261
0262     st->spi = spi;
0263
0264     indio_dev->name = spi->modalias;
0265     indio_dev->modes = INDIO_DIRECT_MODE;
0266     indio_dev->channels = adc108s102_channels;
0267     indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels);
0268     indio_dev->info = &adc108s102_info;
0269
0270     /* Setup default message */
0271     st->scan_single_xfer.tx_buf = st->tx_buf;
0272     st->scan_single_xfer.rx_buf = st->rx_buf;
0273     st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]);
0274
0275     spi_message_init_with_transfers(&st->scan_single_msg,
0276                     &st->scan_single_xfer, 1);
0277
0278     ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL,
0279                           &adc108s102_trigger_handler,
0280                           NULL);
0281     if (ret)
0282         return ret;
0283
0284     ret = devm_iio_device_register(&spi->dev, indio_dev);
0285     if (ret)
0286         dev_err(&spi->dev, "Failed to register IIO device\n");
0287     return ret;
0288 }
0289
0290 static const struct of_device_id adc108s102_of_match[] = {
0291     { .compatible = "ti,adc108s102" },
0292     { }
0293 };
0294 MODULE_DEVICE_TABLE(of, adc108s102_of_match);
0295
0296 #ifdef CONFIG_ACPI
0297 static const struct acpi_device_id adc108s102_acpi_ids[] = {
0298     { "INT3495", 0 },
0299     { }
0300 };
0301 MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids);
0302 #endif
0303
0304 static const struct spi_device_id adc108s102_id[] = {
0305     { "adc108s102", 0 },
0306     { }
0307 };
0308 MODULE_DEVICE_TABLE(spi, adc108s102_id);
0309
0310 static struct spi_driver adc108s102_driver = {
0311     .driver = {
0312         .name   = "adc108s102",
0313         .of_match_table = adc108s102_of_match,
0314         .acpi_match_table = ACPI_PTR(adc108s102_acpi_ids),
0315     },
0316     .probe      = adc108s102_probe,
0317     .id_table   = adc108s102_id,
0318 };
0319 module_spi_driver(adc108s102_driver);
0320
0321 MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>");
0322 MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver");
0323 MODULE_LICENSE("GPL v2");