From: Jacopo Mondi <jacopo@xxxxxxxxxx>
Add IIO driver for Maxim MAX11100 single-channel ADC.
Add DT bindings documentation.
Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
Tested-by: Marek Vasut <marek.vasut@xxxxxxxxx>
---
Sending v3 incorporating last comments from review and from testing.
One final thing I would like to be clarified is about the measure unit
returned by read_raw().
Currently (value_raw * value_scale) return the ADC input value in mV.
While testing the patch I've been questioned if that should not actually
be in uV. This is easily achievable making _scale return a value in uV.
I have found no mention of this in the ABI documentation as it speaks of
generic voltage.
Can we have a final word on this?
Thanks Marek for having tested this.
v1 -> v2:
- incorporated pmeerw's review comments
- retrieve vref from dts and use that to convert read_raw result
to mV
- add device tree bindings documentation
v2 -> v3:
- add _SCALE bit of read_raw function and change _RAW bit accordingly
- call regulator_get_voltage when accessing the _SCALE part of read_raw
and not during probe
- add back remove function as regulator has to be disabled when detaching
the module. Do not use devm_ version of iio_register/unregister functions
anymore but do unregister in the remove.
- remove mutex as access to SPI bus is protected by SPI core. Thanks marex
---
.../devicetree/bindings/iio/adc/max11100.txt | 17 ++
drivers/iio/adc/Kconfig | 9 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/max11100.c | 187 +++++++++++++++++++++
4 files changed, 214 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/adc/max11100.txt
create mode 100644 drivers/iio/adc/max11100.c
diff --git a/Documentation/devicetree/bindings/iio/adc/max11100.txt b/Documentation/devicetree/bindings/iio/adc/max11100.txt
new file mode 100644
index 0000000..6877c11
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/max11100.txt
@@ -0,0 +1,17 @@
+* Maxim max11100 Analog to Digital Converter (ADC)
+
+Required properties:
+ - compatible: Should be "maxim,max11100"
+ - vref-supply: phandle to the regulator that provides reference voltage
+
+Optional properties:
+ - spi-max-frequency: SPI maximum frequency
+
+Example:
+
+adc0: max11100@0 {
+ compatible = "maxim,max11100";
+ vref-supply = <&adc0_vref>;
+ spi-max-frequency = <240000>;
+};
+
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 38bc319..c32bc7a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -307,6 +307,15 @@ config MAX1027
To compile this driver as a module, choose M here: the module will be
called max1027.
+config MAX11100
+ tristate "Maxim max11100 ADC driver"
+ depends on SPI_MASTER
+ help
+ Say yes here to build support for Maxim max11100 SPI ADC
+
+ To compile this driver as a module, choose M here: the module will be
+ called max11100.
+
config MAX1363
tristate "Maxim max1363 ADC driver"
depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d36c4be..5684369 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
obj-$(CONFIG_LTC2485) += ltc2485.o
obj-$(CONFIG_MAX1027) += max1027.o
+obj-$(CONFIG_MAX11100) += max11100.o
obj-$(CONFIG_MAX1363) += max1363.o
obj-$(CONFIG_MCP320X) += mcp320x.o
obj-$(CONFIG_MCP3422) += mcp3422.o
diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c
new file mode 100644
index 0000000..78e2a45
--- /dev/null
+++ b/drivers/iio/adc/max11100.c
@@ -0,0 +1,187 @@
+/*
+ * iio/adc/max11100.c
+ * Maxim max11100 ADC Driver with IIO interface
+ *
+ * Copyright (C) 2016 Renesas Electronics Corporation
+ * Copyright (C) 2016 Jacopo Mondi
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/driver.h>
+
+/*
+ * LSB is the ADC single digital step
+ * 1 LSB = (vref_mv / 2 ^ 16)
+ *
+ * LSB is used to calculate analog voltage value
+ * from the number of ADC steps count
+ *
+ * Ain = (count * LSB)
+ */
+#define MAX11100_LSB_DIV (1 << 16)
+
+struct max11100_state {
+ const struct max11100_chip_desc *desc;
+ struct regulator *vref_reg;
+ struct spi_device *spi;
+};
+
+static struct iio_chan_spec max11100_channels[] = {
+ { /* [0] */
+ .type = IIO_VOLTAGE,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE),
+ },
+};
+
+static struct max11100_chip_desc {
+ unsigned int num_chan;
+ const struct iio_chan_spec *channels;
+} max11100_desc = {
+ .num_chan = ARRAY_SIZE(max11100_channels),
+ .channels = max11100_channels,
+};
+
+static int max11100_read_single(struct iio_dev *indio_dev, int *val)
+{
+ int ret;
+ struct max11100_state *state = iio_priv(indio_dev);
+ uint8_t buffer[3];
+
+ ret = spi_read(state->spi, buffer, sizeof(buffer));
+ if (ret) {
+ dev_err(&indio_dev->dev, "SPI transfer failed\n");
+ return ret;
+ }
+
+ /* the first 8 bits sent out from ADC must be 0s */
+ if (buffer[0]) {
+ dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
+ return -EINVAL;
+ }
+
+ *val = (buffer[1] << 8) | buffer[2];
+
+ return 0;
+}
+
+static int max11100_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long info)
+{
+ int ret, vref_uv;
+ struct max11100_state *state = iio_priv(indio_dev);
+
+ switch (info) {
+ case IIO_CHAN_INFO_RAW:
+ ret = max11100_read_single(indio_dev, val);
+ if (ret)
+ return ret;
+
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ vref_uv = regulator_get_voltage(state->vref_reg);
+ if (vref_uv < 0)
+ /* dummy regulator "get_voltage" returns -EINVAL */
+ return -EINVAL;
+
+ *val = vref_uv / 1000;
+ *val2 = MAX11100_LSB_DIV;
+ return IIO_VAL_FRACTIONAL;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info max11100_info = {
+ .driver_module = THIS_MODULE,
+ .read_raw = max11100_read_raw,
+};
+
+static int max11100_probe(struct spi_device *spi)
+{
+ int ret;
+ struct iio_dev *indio_dev;
+ struct max11100_state *state;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ spi_set_drvdata(spi, indio_dev);
+
+ state = iio_priv(indio_dev);
+ state->spi = spi;
+ state->desc = &max11100_desc;
+
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->dev.of_node = spi->dev.of_node;
+ indio_dev->info = &max11100_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = state->desc->channels;
+ indio_dev->num_channels = state->desc->num_chan;
+
+ state->vref_reg = devm_regulator_get(&spi->dev, "vref");
+ if (IS_ERR(state->vref_reg))
+ return PTR_ERR(state->vref_reg);
+
+ ret = regulator_enable(state->vref_reg);
+ if (ret)
+ return ret;
+
+ ret = iio_device_register(indio_dev);
+ if (ret)
+ goto disable_regulator;
+
+ return 0;
+
+disable_regulator:
+ regulator_disable(state->vref_reg);
+
+ return ret;
+}
+
+static int max11100_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct max11100_state *state = iio_priv(indio_dev);
+
+ regulator_disable(state->vref_reg);
+
+ iio_device_unregister(indio_dev);
+
+ return 0;
+}
+
+static const struct of_device_id max11100_ids[] = {
+ {.compatible = "maxim,max11100"},
+ { },
+};
+MODULE_DEVICE_TABLE(of, max11100_ids);
+
+static struct spi_driver max11100_driver = {
+ .driver = {
+ .name = "max11100",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(max11100_ids),
+ },
+ .probe = max11100_probe,
+ .remove = max11100_remove,
+};
+
+module_spi_driver(max11100_driver);
+
+MODULE_AUTHOR("Jacopo Mondi <jacopo@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
+MODULE_LICENSE("GPL v2");
--
2.7.4
