diff options
Diffstat (limited to 'drivers/iio/adc/ti-adc108s102.c')
| -rw-r--r-- | drivers/iio/adc/ti-adc108s102.c | 347 |
1 files changed, 347 insertions, 0 deletions
diff --git a/drivers/iio/adc/ti-adc108s102.c b/drivers/iio/adc/ti-adc108s102.c new file mode 100644 index 000000000..841203eda --- /dev/null +++ b/drivers/iio/adc/ti-adc108s102.c @@ -0,0 +1,347 @@ +/* + * TI ADC108S102 SPI ADC driver + * + * Copyright (c) 2013-2015 Intel Corporation. + * Copyright (c) 2017 Siemens AG + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * This IIO device driver is designed to work with the following + * analog to digital converters from Texas Instruments: + * ADC108S102 + * ADC128S102 + * The communication with ADC chip is via the SPI bus (mode 3). + */ + +#include <linux/acpi.h> +#include <linux/iio/iio.h> +#include <linux/iio/buffer.h> +#include <linux/iio/types.h> +#include <linux/iio/triggered_buffer.h> +#include <linux/iio/trigger_consumer.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/property.h> +#include <linux/regulator/consumer.h> +#include <linux/spi/spi.h> + +/* + * In case of ACPI, we use the hard-wired 5000 mV of the Galileo and IOT2000 + * boards as default for the reference pin VA. Device tree users encode that + * via the vref-supply regulator. + */ +#define ADC108S102_VA_MV_ACPI_DEFAULT 5000 + +/* + * Defining the ADC resolution being 12 bits, we can use the same driver for + * both ADC108S102 (10 bits resolution) and ADC128S102 (12 bits resolution) + * chips. The ADC108S102 effectively returns a 12-bit result with the 2 + * least-significant bits unset. + */ +#define ADC108S102_BITS 12 +#define ADC108S102_MAX_CHANNELS 8 + +/* + * 16-bit SPI command format: + * [15:14] Ignored + * [13:11] 3-bit channel address + * [10:0] Ignored + */ +#define ADC108S102_CMD(ch) ((u16)(ch) << 11) + +/* + * 16-bit SPI response format: + * [15:12] Zeros + * [11:0] 12-bit ADC sample (for ADC108S102, [1:0] will always be 0). + */ +#define ADC108S102_RES_DATA(res) ((u16)res & GENMASK(11, 0)) + +struct adc108s102_state { + struct spi_device *spi; + struct regulator *reg; + u32 va_millivolt; + /* SPI transfer used by triggered buffer handler*/ + struct spi_transfer ring_xfer; + /* SPI transfer used by direct scan */ + struct spi_transfer scan_single_xfer; + /* SPI message used by ring_xfer SPI transfer */ + struct spi_message ring_msg; + /* SPI message used by scan_single_xfer SPI transfer */ + struct spi_message scan_single_msg; + + /* + * SPI message buffers: + * tx_buf: |C0|C1|C2|C3|C4|C5|C6|C7|XX| + * rx_buf: |XX|R0|R1|R2|R3|R4|R5|R6|R7|tt|tt|tt|tt| + * + * tx_buf: 8 channel read commands, plus 1 dummy command + * rx_buf: 1 dummy response, 8 channel responses, plus 64-bit timestamp + */ + __be16 rx_buf[13] ____cacheline_aligned; + __be16 tx_buf[9] ____cacheline_aligned; +}; + +#define ADC108S102_V_CHAN(index) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = index, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ + BIT(IIO_CHAN_INFO_SCALE), \ + .address = index, \ + .scan_index = index, \ + .scan_type = { \ + .sign = 'u', \ + .realbits = ADC108S102_BITS, \ + .storagebits = 16, \ + .endianness = IIO_BE, \ + }, \ + } + +static const struct iio_chan_spec adc108s102_channels[] = { + ADC108S102_V_CHAN(0), + ADC108S102_V_CHAN(1), + ADC108S102_V_CHAN(2), + ADC108S102_V_CHAN(3), + ADC108S102_V_CHAN(4), + ADC108S102_V_CHAN(5), + ADC108S102_V_CHAN(6), + ADC108S102_V_CHAN(7), + IIO_CHAN_SOFT_TIMESTAMP(8), +}; + +static int adc108s102_update_scan_mode(struct iio_dev *indio_dev, + unsigned long const *active_scan_mask) +{ + struct adc108s102_state *st = iio_priv(indio_dev); + unsigned int bit, cmds; + + /* + * Fill in the first x shorts of tx_buf with the number of channels + * enabled for sampling by the triggered buffer. + */ + cmds = 0; + for_each_set_bit(bit, active_scan_mask, ADC108S102_MAX_CHANNELS) + st->tx_buf[cmds++] = cpu_to_be16(ADC108S102_CMD(bit)); + + /* One dummy command added, to clock in the last response */ + st->tx_buf[cmds++] = 0x00; + + /* build SPI ring message */ + st->ring_xfer.tx_buf = &st->tx_buf[0]; + st->ring_xfer.rx_buf = &st->rx_buf[0]; + st->ring_xfer.len = cmds * sizeof(st->tx_buf[0]); + + spi_message_init_with_transfers(&st->ring_msg, &st->ring_xfer, 1); + + return 0; +} + +static irqreturn_t adc108s102_trigger_handler(int irq, void *p) +{ + struct iio_poll_func *pf = p; + struct iio_dev *indio_dev = pf->indio_dev; + struct adc108s102_state *st = iio_priv(indio_dev); + int ret; + + ret = spi_sync(st->spi, &st->ring_msg); + if (ret < 0) + goto out_notify; + + /* Skip the dummy response in the first slot */ + iio_push_to_buffers_with_timestamp(indio_dev, + (u8 *)&st->rx_buf[1], + iio_get_time_ns(indio_dev)); + +out_notify: + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +static int adc108s102_scan_direct(struct adc108s102_state *st, unsigned int ch) +{ + int ret; + + st->tx_buf[0] = cpu_to_be16(ADC108S102_CMD(ch)); + ret = spi_sync(st->spi, &st->scan_single_msg); + if (ret) + return ret; + + /* Skip the dummy response in the first slot */ + return be16_to_cpu(st->rx_buf[1]); +} + +static int adc108s102_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long m) +{ + struct adc108s102_state *st = iio_priv(indio_dev); + int ret; + + switch (m) { + case IIO_CHAN_INFO_RAW: + ret = iio_device_claim_direct_mode(indio_dev); + if (ret) + return ret; + + ret = adc108s102_scan_direct(st, chan->address); + + iio_device_release_direct_mode(indio_dev); + + if (ret < 0) + return ret; + + *val = ADC108S102_RES_DATA(ret); + + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + if (chan->type != IIO_VOLTAGE) + break; + + *val = st->va_millivolt; + *val2 = chan->scan_type.realbits; + + return IIO_VAL_FRACTIONAL_LOG2; + default: + break; + } + + return -EINVAL; +} + +static const struct iio_info adc108s102_info = { + .read_raw = &adc108s102_read_raw, + .update_scan_mode = &adc108s102_update_scan_mode, +}; + +static int adc108s102_probe(struct spi_device *spi) +{ + struct adc108s102_state *st; + struct iio_dev *indio_dev; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); + if (!indio_dev) + return -ENOMEM; + + st = iio_priv(indio_dev); + + if (ACPI_COMPANION(&spi->dev)) { + st->va_millivolt = ADC108S102_VA_MV_ACPI_DEFAULT; + } else { + st->reg = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(st->reg)) + return PTR_ERR(st->reg); + + ret = regulator_enable(st->reg); + if (ret < 0) { + dev_err(&spi->dev, "Cannot enable vref regulator\n"); + return ret; + } + + ret = regulator_get_voltage(st->reg); + if (ret < 0) { + dev_err(&spi->dev, "vref get voltage failed\n"); + return ret; + } + + st->va_millivolt = ret / 1000; + } + + spi_set_drvdata(spi, indio_dev); + st->spi = spi; + + indio_dev->name = spi->modalias; + indio_dev->dev.parent = &spi->dev; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = adc108s102_channels; + indio_dev->num_channels = ARRAY_SIZE(adc108s102_channels); + indio_dev->info = &adc108s102_info; + + /* Setup default message */ + st->scan_single_xfer.tx_buf = st->tx_buf; + st->scan_single_xfer.rx_buf = st->rx_buf; + st->scan_single_xfer.len = 2 * sizeof(st->tx_buf[0]); + + spi_message_init_with_transfers(&st->scan_single_msg, + &st->scan_single_xfer, 1); + + ret = iio_triggered_buffer_setup(indio_dev, NULL, + &adc108s102_trigger_handler, NULL); + if (ret) + goto error_disable_reg; + + ret = iio_device_register(indio_dev); + if (ret) { + dev_err(&spi->dev, "Failed to register IIO device\n"); + goto error_cleanup_triggered_buffer; + } + return 0; + +error_cleanup_triggered_buffer: + iio_triggered_buffer_cleanup(indio_dev); + +error_disable_reg: + regulator_disable(st->reg); + + return ret; +} + +static int adc108s102_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct adc108s102_state *st = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + iio_triggered_buffer_cleanup(indio_dev); + + regulator_disable(st->reg); + + return 0; +} + +#ifdef CONFIG_OF +static const struct of_device_id adc108s102_of_match[] = { + { .compatible = "ti,adc108s102" }, + { } +}; +MODULE_DEVICE_TABLE(of, adc108s102_of_match); +#endif + +#ifdef CONFIG_ACPI +static const struct acpi_device_id adc108s102_acpi_ids[] = { + { "INT3495", 0 }, + { } +}; +MODULE_DEVICE_TABLE(acpi, adc108s102_acpi_ids); +#endif + +static const struct spi_device_id adc108s102_id[] = { + { "adc108s102", 0 }, + { } +}; +MODULE_DEVICE_TABLE(spi, adc108s102_id); + +static struct spi_driver adc108s102_driver = { + .driver = { + .name = "adc108s102", + .of_match_table = of_match_ptr(adc108s102_of_match), + .acpi_match_table = ACPI_PTR(adc108s102_acpi_ids), + }, + .probe = adc108s102_probe, + .remove = adc108s102_remove, + .id_table = adc108s102_id, +}; +module_spi_driver(adc108s102_driver); + +MODULE_AUTHOR("Bogdan Pricop <bogdan.pricop@emutex.com>"); +MODULE_DESCRIPTION("Texas Instruments ADC108S102 and ADC128S102 driver"); +MODULE_LICENSE("GPL v2"); |