Re: [PATCHv2] iio: adc: Add Maxim MAX11100 driver

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Hi Jonathan,

On 30/12/2016 17:08, Jonathan Cameron wrote:
On 13/12/16 12:37, Jacopo Mondi wrote:
Add IIO driver for Maxim MAX11100 single-channel ADC.
Add DT bindings documentation.

Signed-off-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
A quick process related thing.  Please don't post a new
version of a driver as a reply to an old version. It very rapidly
leads to deep and difficult to follow threads.

Much easier to just start a new thread.


Noted!
Thanks for suggestion ;)
   j


---

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

---
 .../devicetree/bindings/iio/adc/max11100.txt       |  17 +++
 drivers/iio/adc/Kconfig                            |   9 ++
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/max11100.c                         | 166 +++++++++++++++++++++
 4 files changed, 193 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 99c0514..a909484 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -285,6 +285,15 @@ 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
+	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 7a40c04..1463044 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -29,6 +29,7 @@ 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..f372ad8
--- /dev/null
+++ b/drivers/iio/adc/max11100.c
@@ -0,0 +1,166 @@
+/*
+ * 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 / 2 ^ 16)
+ * AIN = (DIN * LSB)
+ */
+#define MAX11100_LSB_DIV		(1 << 16)
+#define MAX11100_LSB(vref) 		(vref / MAX11100_LSB_DIV)
+
+struct max11100_state {
+	const struct max11100_chip_desc *desc;
+	struct spi_device *spi;
+	int vref_uv;
+	struct mutex lock;
+};
+
+static struct iio_chan_spec max11100_channels[] = {
+	{ /* [0] */
+		.type = IIO_VOLTAGE,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 24,
+			.shift = 8,
+			.repeat = 1,
+			.endianness = IIO_BE,
+		},
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	},
+};
+
+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_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	int ret;
+	struct max11100_state *state = iio_priv(indio_dev);
+	uint8_t buffer[3];
+
+	mutex_lock(&state->lock);
+
+	ret = spi_read(state->spi, buffer, sizeof(buffer));
+	if (ret) {
+		mutex_unlock(&state->lock);
+		dev_err(&indio_dev->dev, "SPI transfer failed\n");
+		return ret;
+	}
+	mutex_unlock(&state->lock);
+
+	/* 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 = be16_to_cpu(*(uint16_t *)&buffer[1]);
+	*val = *val * MAX11100_LSB(state->vref_uv) / 1000;
+
+	return IIO_VAL_INT;
+}
+
+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 regulator *vref_reg;
+	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;
+
+	mutex_init(&state->lock);
+
+	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;
+
+	vref_reg = devm_regulator_get(&spi->dev, "vref");
+	if (IS_ERR(vref_reg))
+		return PTR_ERR(vref_reg);
+
+	ret = regulator_enable(vref_reg);
+	if (ret)
+		return ret;
+
+	state->vref_uv = regulator_get_voltage(vref_reg);
+	if (state->vref_uv < 0) {
+		/* dummy regulator "get_voltage" returns -EINVAL as well */
+		ret = -EINVAL;
+		goto disable_regulator;
+	}
+
+	ret = devm_iio_device_register(&spi->dev, indio_dev);
+	if (ret)
+		goto disable_regulator;
+
+	return 0;
+
+disable_regulator:
+	regulator_disable(vref_reg);
+	return ret;
+}
+
+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,
+};
+
+module_spi_driver(max11100_driver);
+
+MODULE_AUTHOR("Jacopo Mondi <jacopo@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
+MODULE_LICENSE("GPL v2");



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