[PATCH] iio: adc: add max1117/max1118/max1119 ADC driver

[Akinobu Mita <akinobu.mita-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

This adds max1117/max1118/max1119 8-bit, dual-channel ADC driver.

Signed-off-by: Akinobu Mita <akinobu.mita-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Hartmut Knaack <knaack.h-Mmb7MZpHnFY@public.gmane.org>
Cc: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
Cc: Peter Meerwald-Stadler <pmeerw-jW+XmwGofnusTnJN9+BGXg@public.gmane.org>
Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>
---
 .../devicetree/bindings/iio/adc/max1118.txt        |  21 ++
 drivers/iio/adc/Kconfig                            |  12 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/max1118.c                          | 310 +++++++++++++++++++++
 4 files changed, 344 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/max1118.txt
 create mode 100644 drivers/iio/adc/max1118.c

diff --git a/Documentation/devicetree/bindings/iio/adc/max1118.txt b/Documentation/devicetree/bindings/iio/adc/max1118.txt
new file mode 100644
index 0000000..cf33d0b
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/max1118.txt
@@ -0,0 +1,21 @@
+* MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs
+
+Required properties:
+ - compatible: Should be one of
+	* "maxim,max1117"
+	* "maxim,max1118"
+	* "maxim,max1119"
+ - reg: spi chip select number for the device
+ - (max1118 only) vref-supply: The regulator supply for ADC reference voltage
+
+Recommended properties:
+ - spi-max-frequency: Definition as per
+		Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+adc@0 {
+	compatible = "maxim,max1118";
+	reg = <0>;
+	vref-supply = <&vdd_supply>;
+	spi-max-frequency = <1000000>;
+};
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index dedae7a..66262d1 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -335,6 +335,18 @@ config MAX11100
 	  To compile this driver as a module, choose M here: the module will be
 	  called max11100.
 
+config MAX1118
+	tristate "Maxim max1117/max1118/max1119 ADCs driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Maxim max1117/max1118/max1119
+	  8-bit, dual-channel ADCs.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called max1118.
+
 config MAX1363
 	tristate "Maxim max1363 ADC driver"
 	depends on I2C
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d001262..5ef3470 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
 obj-$(CONFIG_LTC2485) += ltc2485.o
 obj-$(CONFIG_MAX1027) += max1027.o
 obj-$(CONFIG_MAX11100) += max11100.o
+obj-$(CONFIG_MAX1118) += max1118.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
diff --git a/drivers/iio/adc/max1118.c b/drivers/iio/adc/max1118.c
new file mode 100644
index 0000000..f2597b7
--- /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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * 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:
+		if (IS_ERR_OR_NULL(adc->reg))
+			return -EINVAL;
+
+		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 int max1118_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct max1118 *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	if (!IS_ERR_OR_NULL(adc->reg))
+		return regulator_disable(adc->reg);
+
+	return 0;
+}
+
+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);
+
+	adc->reg = devm_regulator_get(&spi->dev, "vref");
+	if (PTR_ERR(adc->reg) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	if (IS_ERR_OR_NULL(adc->reg) && id->driver_data == max1118) {
+		dev_warn(&spi->dev, "max1118 requires vref-supply\n");
+	} else {
+		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 (!IS_ERR_OR_NULL(adc->reg))
+		regulator_disable(adc->reg);
+
+	return ret;
+}
+
+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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
+MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4