--- /dev/null
+/*
+ * 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;
+
+ 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,
+ .driver_module = THIS_MODULE,
+};
+
+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);
+ u8 data[16] = { }; /* 2x 8-bit ADC data + padding + 8 bytes timestamp */
+ 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;
+ }
+
+ data[i] = ret;
+ i++;
+ }
+ iio_push_to_buffers_with_timestamp(indio_dev, data,
+ 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");
projects / karo-tx-linux.git / commitdiff