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Diffstat (limited to 'drivers/iio/adc/max1241.c')
-rw-r--r--drivers/iio/adc/max1241.c223
1 files changed, 223 insertions, 0 deletions
diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c
new file mode 100644
index 000000000..a815ad1f6
--- /dev/null
+++ b/drivers/iio/adc/max1241.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MAX1241 low-power, 12-bit serial ADC
+ *
+ * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define MAX1241_VAL_MASK GENMASK(11, 0)
+#define MAX1241_SHUTDOWN_DELAY_USEC 4
+
+enum max1241_id {
+ max1241,
+};
+
+struct max1241 {
+ struct spi_device *spi;
+ struct mutex lock;
+ struct regulator *vdd;
+ struct regulator *vref;
+ struct gpio_desc *shutdown;
+
+ __be16 data __aligned(IIO_DMA_MINALIGN);
+};
+
+static const struct iio_chan_spec max1241_channels[] = {
+ {
+ .type = IIO_VOLTAGE,
+ .indexed = 1,
+ .channel = 0,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE),
+ },
+};
+
+static int max1241_read(struct max1241 *adc)
+{
+ struct spi_transfer xfers[] = {
+ /*
+ * Begin conversion by bringing /CS low for at least
+ * tconv us.
+ */
+ {
+ .len = 0,
+ .delay.value = 8,
+ .delay.unit = SPI_DELAY_UNIT_USECS,
+ },
+ /*
+ * Then read two bytes of data in our RX buffer.
+ */
+ {
+ .rx_buf = &adc->data,
+ .len = 2,
+ },
+ };
+
+ return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));
+}
+
+static int max1241_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ int ret, vref_uV;
+ struct max1241 *adc = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ mutex_lock(&adc->lock);
+
+ if (adc->shutdown) {
+ gpiod_set_value(adc->shutdown, 0);
+ udelay(MAX1241_SHUTDOWN_DELAY_USEC);
+ ret = max1241_read(adc);
+ gpiod_set_value(adc->shutdown, 1);
+ } else
+ ret = max1241_read(adc);
+
+ if (ret) {
+ mutex_unlock(&adc->lock);
+ return ret;
+ }
+
+ *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;
+
+ mutex_unlock(&adc->lock);
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ vref_uV = regulator_get_voltage(adc->vref);
+
+ if (vref_uV < 0)
+ return vref_uV;
+
+ *val = vref_uV / 1000;
+ *val2 = 12;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info max1241_info = {
+ .read_raw = max1241_read_raw,
+};
+
+static void max1241_disable_vdd_action(void *data)
+{
+ struct max1241 *adc = data;
+ struct device *dev = &adc->spi->dev;
+ int err;
+
+ err = regulator_disable(adc->vdd);
+ if (err)
+ dev_err(dev, "could not disable vdd regulator.\n");
+}
+
+static void max1241_disable_vref_action(void *data)
+{
+ struct max1241 *adc = data;
+ struct device *dev = &adc->spi->dev;
+ int err;
+
+ err = regulator_disable(adc->vref);
+ if (err)
+ dev_err(dev, "could not disable vref regulator.\n");
+}
+
+static int max1241_probe(struct spi_device *spi)
+{
+ struct device *dev = &spi->dev;
+ struct iio_dev *indio_dev;
+ struct max1241 *adc;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ adc = iio_priv(indio_dev);
+ adc->spi = spi;
+ mutex_init(&adc->lock);
+
+ adc->vdd = devm_regulator_get(dev, "vdd");
+ if (IS_ERR(adc->vdd))
+ return dev_err_probe(dev, PTR_ERR(adc->vdd),
+ "failed to get vdd regulator\n");
+
+ ret = regulator_enable(adc->vdd);
+ if (ret)
+ return ret;
+
+ ret = devm_add_action_or_reset(dev, max1241_disable_vdd_action, adc);
+ if (ret) {
+ dev_err(dev, "could not set up vdd regulator cleanup action\n");
+ return ret;
+ }
+
+ adc->vref = devm_regulator_get(dev, "vref");
+ if (IS_ERR(adc->vref))
+ return dev_err_probe(dev, PTR_ERR(adc->vref),
+ "failed to get vref regulator\n");
+
+ ret = regulator_enable(adc->vref);
+ if (ret)
+ return ret;
+
+ ret = devm_add_action_or_reset(dev, max1241_disable_vref_action, adc);
+ if (ret) {
+ dev_err(dev, "could not set up vref regulator cleanup action\n");
+ return ret;
+ }
+
+ adc->shutdown = devm_gpiod_get_optional(dev, "shutdown",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(adc->shutdown))
+ return dev_err_probe(dev, PTR_ERR(adc->shutdown),
+ "cannot get shutdown gpio\n");
+
+ if (adc->shutdown)
+ dev_dbg(dev, "shutdown pin passed, low-power mode enabled");
+ else
+ dev_dbg(dev, "no shutdown pin passed, low-power mode disabled");
+
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->info = &max1241_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = max1241_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max1241_channels);
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct spi_device_id max1241_id[] = {
+ { "max1241", max1241 },
+ {}
+};
+
+static const struct of_device_id max1241_dt_ids[] = {
+ { .compatible = "maxim,max1241" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, max1241_dt_ids);
+
+static struct spi_driver max1241_spi_driver = {
+ .driver = {
+ .name = "max1241",
+ .of_match_table = max1241_dt_ids,
+ },
+ .probe = max1241_probe,
+ .id_table = max1241_id,
+};
+module_spi_driver(max1241_spi_driver);
+
+MODULE_AUTHOR("Alexandru Lazar <alazar@startmail.com>");
+MODULE_DESCRIPTION("MAX1241 ADC driver");
+MODULE_LICENSE("GPL v2");