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Diffstat (limited to '')
| -rw-r--r-- | drivers/iio/adc/max1118.c | 310 |
1 files changed, 310 insertions, 0 deletions
diff --git a/drivers/iio/adc/max1118.c b/drivers/iio/adc/max1118.c new file mode 100644 index 000000000..b372b226a --- /dev/null +++ b/drivers/iio/adc/max1118.c @@ -0,0 +1,310 @@ +/* + * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver + * + * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com> + * + * This file is subject to the terms and conditions of version 2 of + * the GNU General Public License. See the file COPYING in the main + * directory of this archive for more details. + * + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf + * + * SPI interface connections + * + * SPI MAXIM + * Master Direction MAX1117/8/9 + * ------ --------- ----------- + * nCS --> CNVST + * SCK --> SCLK + * MISO <-- DOUT + * ------ --------- ----------- + */ + +#include <linux/module.h> +#include <linux/spi/spi.h> +#include <linux/iio/iio.h> +#include <linux/iio/buffer.h> +#include <linux/iio/triggered_buffer.h> +#include <linux/iio/trigger_consumer.h> +#include <linux/regulator/consumer.h> + +enum max1118_id { + max1117, + max1118, + max1119, +}; + +struct max1118 { + struct spi_device *spi; + struct mutex lock; + struct regulator *reg; + /* Ensure natural alignment of buffer elements */ + struct { + u8 channels[2]; + s64 ts __aligned(8); + } scan; + + u8 data ____cacheline_aligned; +}; + +#define MAX1118_CHANNEL(ch) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (ch), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + .scan_index = ch, \ + .scan_type = { \ + .sign = 'u', \ + .realbits = 8, \ + .storagebits = 8, \ + }, \ + } + +static const struct iio_chan_spec max1118_channels[] = { + MAX1118_CHANNEL(0), + MAX1118_CHANNEL(1), + IIO_CHAN_SOFT_TIMESTAMP(2), +}; + +static int max1118_read(struct spi_device *spi, int channel) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct max1118 *adc = iio_priv(indio_dev); + struct spi_transfer xfers[] = { + /* + * To select CH1 for conversion, CNVST pin must be brought high + * and low for a second time. + */ + { + .len = 0, + .delay_usecs = 1, /* > CNVST Low Time 100 ns */ + .cs_change = 1, + }, + /* + * The acquisition interval begins with the falling edge of + * CNVST. The total acquisition and conversion process takes + * <7.5us. + */ + { + .len = 0, + .delay_usecs = 8, + }, + { + .rx_buf = &adc->data, + .len = 1, + }, + }; + int ret; + + if (channel == 0) + ret = spi_sync_transfer(spi, xfers + 1, 2); + else + ret = spi_sync_transfer(spi, xfers, 3); + + if (ret) + return ret; + + return adc->data; +} + +static int max1118_get_vref_mV(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct max1118 *adc = iio_priv(indio_dev); + const struct spi_device_id *id = spi_get_device_id(spi); + int vref_uV; + + switch (id->driver_data) { + case max1117: + return 2048; + case max1119: + return 4096; + case max1118: + vref_uV = regulator_get_voltage(adc->reg); + if (vref_uV < 0) + return vref_uV; + return vref_uV / 1000; + } + + return -ENODEV; +} + +static int max1118_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct max1118 *adc = iio_priv(indio_dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&adc->lock); + *val = max1118_read(adc->spi, chan->channel); + mutex_unlock(&adc->lock); + if (*val < 0) + return *val; + + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + *val = max1118_get_vref_mV(adc->spi); + if (*val < 0) + return *val; + *val2 = 8; + + return IIO_VAL_FRACTIONAL_LOG2; + } + + return -EINVAL; +} + +static const struct iio_info max1118_info = { + .read_raw = max1118_read_raw, +}; + +static irqreturn_t max1118_trigger_handler(int irq, void *p) +{ + struct iio_poll_func *pf = p; + struct iio_dev *indio_dev = pf->indio_dev; + struct max1118 *adc = iio_priv(indio_dev); + int scan_index; + int i = 0; + + mutex_lock(&adc->lock); + + for_each_set_bit(scan_index, indio_dev->active_scan_mask, + indio_dev->masklength) { + const struct iio_chan_spec *scan_chan = + &indio_dev->channels[scan_index]; + int ret = max1118_read(adc->spi, scan_chan->channel); + + if (ret < 0) { + dev_warn(&adc->spi->dev, + "failed to get conversion data\n"); + goto out; + } + + adc->scan.channels[i] = ret; + i++; + } + iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan, + iio_get_time_ns(indio_dev)); +out: + mutex_unlock(&adc->lock); + + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +static int max1118_probe(struct spi_device *spi) +{ + struct iio_dev *indio_dev; + struct max1118 *adc; + const struct spi_device_id *id = spi_get_device_id(spi); + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->spi = spi; + mutex_init(&adc->lock); + + if (id->driver_data == max1118) { + adc->reg = devm_regulator_get(&spi->dev, "vref"); + if (IS_ERR(adc->reg)) { + dev_err(&spi->dev, "failed to get vref regulator\n"); + return PTR_ERR(adc->reg); + } + ret = regulator_enable(adc->reg); + if (ret) + return ret; + } + + spi_set_drvdata(spi, indio_dev); + + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->info = &max1118_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = max1118_channels; + indio_dev->num_channels = ARRAY_SIZE(max1118_channels); + + /* + * To reinitiate a conversion on CH0, it is necessary to allow for a + * conversion to be complete and all of the data to be read out. Once + * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go + * into AutoShutdown mode until the next conversion is initiated. + */ + max1118_read(spi, 0); + + ret = iio_triggered_buffer_setup(indio_dev, NULL, + max1118_trigger_handler, NULL); + if (ret) + goto err_reg_disable; + + ret = iio_device_register(indio_dev); + if (ret) + goto err_buffer_cleanup; + + return 0; + +err_buffer_cleanup: + iio_triggered_buffer_cleanup(indio_dev); +err_reg_disable: + if (id->driver_data == max1118) + regulator_disable(adc->reg); + + return ret; +} + +static int max1118_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct max1118 *adc = iio_priv(indio_dev); + const struct spi_device_id *id = spi_get_device_id(spi); + + iio_device_unregister(indio_dev); + iio_triggered_buffer_cleanup(indio_dev); + if (id->driver_data == max1118) + return regulator_disable(adc->reg); + + return 0; +} + +static const struct spi_device_id max1118_id[] = { + { "max1117", max1117 }, + { "max1118", max1118 }, + { "max1119", max1119 }, + {} +}; +MODULE_DEVICE_TABLE(spi, max1118_id); + +#ifdef CONFIG_OF + +static const struct of_device_id max1118_dt_ids[] = { + { .compatible = "maxim,max1117" }, + { .compatible = "maxim,max1118" }, + { .compatible = "maxim,max1119" }, + {}, +}; +MODULE_DEVICE_TABLE(of, max1118_dt_ids); + +#endif + +static struct spi_driver max1118_spi_driver = { + .driver = { + .name = "max1118", + .of_match_table = of_match_ptr(max1118_dt_ids), + }, + .probe = max1118_probe, + .remove = max1118_remove, + .id_table = max1118_id, +}; +module_spi_driver(max1118_spi_driver); + +MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>"); +MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver"); +MODULE_LICENSE("GPL v2"); |