[RFC v3 0/3] iio: potentiostat: add LMP91000 support

[RFC v3 0/3] iio: potentiostat: add LMP91000 support

[Matt Ranostay]

Changes from v1:
 * Rename ti-adc1x1s.c driver to ti-adc161s626.c
 * Switch from iio_channel_read() to using the industrialio-buffer-cb
   interface
 * Process data in ADC trigger handler for buffer callbacks
  * Set the mux trigger to the ADC referenced by io-channels by default

Changes from v2:
 * Fix configuration index shifting values
 * Switch from wait_for_completion_interruptible to wait_for_completion_timeout

Matt Ranostay (3):
  iio: buffer-callback: allow getting underlying iio_dev
  iio: adc: ti-adc161s626: add support for TI 1-channel differential
    ADCs
  iio: potentiostat: add LMP91000 support

 .../devicetree/bindings/iio/adc/ti-adc161s626.txt  |  17 +
 .../bindings/iio/potentiostat/lmp91000.txt         |  30 ++
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/adc/Kconfig                            |  12 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/ti-adc161s626.c                    | 248 ++++++++++++++
 drivers/iio/buffer/industrialio-buffer-cb.c        |  24 +-
 drivers/iio/potentiostat/Kconfig                   |  22 ++
 drivers/iio/potentiostat/Makefile                  |   6 +
 drivers/iio/potentiostat/lmp91000.c                | 376 +++++++++++++++++++++
 include/linux/iio/consumer.h                       |  12 +
 12 files changed, 740 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-adc161s626.txt
 create mode 100644 Documentation/devicetree/bindings/iio/potentiostat/lmp91000.txt
 create mode 100644 drivers/iio/adc/ti-adc161s626.c
 create mode 100644 drivers/iio/potentiostat/Kconfig
 create mode 100644 drivers/iio/potentiostat/Makefile
 create mode 100644 drivers/iio/potentiostat/lmp91000.c

-- 
2.7.4

[RFC v3 1/3] iio: buffer-callback: allow getting underlying iio_dev

[Matt Ranostay]

Add iio_channel_cb_get_iio_dev function to allow getting the
underlying iio_dev. This is useful for setting the trigger of the
consumer ADC device.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 drivers/iio/buffer/industrialio-buffer-cb.c | 24 ++++++++++++++----------
 include/linux/iio/consumer.h                | 12 ++++++++++++
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/buffer/industrialio-buffer-cb.c b/drivers/iio/buffer/industrialio-buffer-cb.c
index 323079c3ccce..b8f550e47d3d 100644
--- a/drivers/iio/buffer/industrialio-buffer-cb.c
+++ b/drivers/iio/buffer/industrialio-buffer-cb.c
@@ -18,6 +18,7 @@ struct iio_cb_buffer {
 	int (*cb)(const void *data, void *private);
 	void *private;
 	struct iio_channel *channels;
+	struct iio_dev *indio_dev;
 };
 
 static struct iio_cb_buffer *buffer_to_cb_buffer(struct iio_buffer *buffer)
@@ -52,7 +53,6 @@ struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
 {
 	int ret;
 	struct iio_cb_buffer *cb_buff;
-	struct iio_dev *indio_dev;
 	struct iio_channel *chan;
 
 	cb_buff = kzalloc(sizeof(*cb_buff), GFP_KERNEL);
@@ -72,17 +72,17 @@ struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
 		goto error_free_cb_buff;
 	}
 
-	indio_dev = cb_buff->channels[0].indio_dev;
+	cb_buff->indio_dev = cb_buff->channels[0].indio_dev;
 	cb_buff->buffer.scan_mask
-		= kcalloc(BITS_TO_LONGS(indio_dev->masklength), sizeof(long),
-			  GFP_KERNEL);
+		= kcalloc(BITS_TO_LONGS(cb_buff->indio_dev->masklength),
+			  sizeof(long), GFP_KERNEL);
 	if (cb_buff->buffer.scan_mask == NULL) {
 		ret = -ENOMEM;
 		goto error_release_channels;
 	}
 	chan = &cb_buff->channels[0];
 	while (chan->indio_dev) {
-		if (chan->indio_dev != indio_dev) {
+		if (chan->indio_dev != cb_buff->indio_dev) {
 			ret = -EINVAL;
 			goto error_free_scan_mask;
 		}
@@ -105,17 +105,14 @@ EXPORT_SYMBOL_GPL(iio_channel_get_all_cb);
 
 int iio_channel_start_all_cb(struct iio_cb_buffer *cb_buff)
 {
-	return iio_update_buffers(cb_buff->channels[0].indio_dev,
-				  &cb_buff->buffer,
+	return iio_update_buffers(cb_buff->indio_dev, &cb_buff->buffer,
 				  NULL);
 }
 EXPORT_SYMBOL_GPL(iio_channel_start_all_cb);
 
 void iio_channel_stop_all_cb(struct iio_cb_buffer *cb_buff)
 {
-	iio_update_buffers(cb_buff->channels[0].indio_dev,
-			   NULL,
-			   &cb_buff->buffer);
+	iio_update_buffers(cb_buff->indio_dev, NULL, &cb_buff->buffer);
 }
 EXPORT_SYMBOL_GPL(iio_channel_stop_all_cb);
 
@@ -133,6 +130,13 @@ struct iio_channel
 }
 EXPORT_SYMBOL_GPL(iio_channel_cb_get_channels);
 
+struct iio_dev
+*iio_channel_cb_get_iio_dev(const struct iio_cb_buffer *cb_buffer)
+{
+	return cb_buffer->indio_dev;
+}
+EXPORT_SYMBOL_GPL(iio_channel_cb_get_iio_dev);
+
 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 MODULE_DESCRIPTION("Industrial I/O callback buffer");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 3d672f72e7ec..9edccfba1ffb 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -165,6 +165,18 @@ struct iio_channel
 *iio_channel_cb_get_channels(const struct iio_cb_buffer *cb_buffer);
 
 /**
+ * iio_channel_cb_get_iio_dev() - get access to the underlying device.
+ * @cb_buffer:		The callback buffer from whom we want the device
+ *			information.
+ *
+ * This function allows one to obtain information about the device.
+ * The primary aim is to allow drivers that are consuming a device to query
+ * things like current trigger.
+ */
+struct iio_dev
+*iio_channel_cb_get_iio_dev(const struct iio_cb_buffer *cb_buffer);
+
+/**
  * iio_read_channel_raw() - read from a given channel
  * @chan:		The channel being queried.
  * @val:		Value read back.
-- 
2.7.4

[RFC v3 2/3] iio: adc: ti-adc161s626: add support for TI 1-channel differential ADCs

[Matt Ranostay]

Add support for Texas Instruments ADC141S626, and ADC161S626 chips.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 .../devicetree/bindings/iio/adc/ti-adc161s626.txt  |  17 ++
 drivers/iio/adc/Kconfig                            |  12 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/ti-adc161s626.c                    | 248 +++++++++++++++++++++
 4 files changed, 278 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-adc161s626.txt
 create mode 100644 drivers/iio/adc/ti-adc161s626.c

diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc161s626.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc161s626.txt
new file mode 100644
index 000000000000..2bdad2d13d6f
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti-adc161s626.txt
@@ -0,0 +1,17 @@
+* Texas Instruments ADC141S626, and ADC161S626 chip
+
+Required properties:
+ - compatible: Should be "ti,adc141s626" or "ti,adc161s626"
+ - reg: spi chip select number for the device
+
+Recommended properties:
+ - spi-max-frequency: Definition as per
+		Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+adc@0 {
+	compatible = "ti,adc161s626";
+	reg = <0>;
+	spi-max-frequency = <4300000>;
+};
+
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 25378c5882e2..3d596a6b85d7 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -414,6 +414,18 @@ config TI_ADC128S052
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-adc128s052.
 
+config TI_ADC161S626
+	tristate "Texas Instruments ADC161S626 1-channel differential ADC"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  If you say yes here you get support for Texas Instruments ADC141S626,
+	  and ADC161S626 chips.
+
+	  This driver can also be build as a module. If so, the module will be
+	  called ti-adc161s626.
+
 config TI_ADS1015
 	tristate "Texas Instruments ADS1015 ADC"
 	depends on I2C && !SENSORS_ADS1015
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 38638d46f972..aabf6c4876d9 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
+obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
 obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
 obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
 obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
diff --git a/drivers/iio/adc/ti-adc161s626.c b/drivers/iio/adc/ti-adc161s626.c
new file mode 100644
index 000000000000..f94b69f9c288
--- /dev/null
+++ b/drivers/iio/adc/ti-adc161s626.c
@@ -0,0 +1,248 @@
+/*
+ * ti-adc161s626.c - Texas Instruments ADC161S626 1-channel differential ADC
+ *
+ * ADC Devices Supported:
+ *  adc141s626 - 14-bit ADC
+ *  adc161s626 - 16-bit ADC
+ *
+ * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/spi/spi.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define TI_ADC_DRV_NAME	"ti-adc161s626"
+
+enum {
+	TI_ADC141S626,
+	TI_ADC161S626,
+};
+
+static const struct iio_chan_spec ti_adc141s626_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 14,
+			.storagebits = 16,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct iio_chan_spec ti_adc161s626_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+struct ti_adc_data {
+	struct iio_dev *indio_dev;
+	struct spi_device *spi;
+	u8 read_size;
+	u8 shift;
+
+	u8 buffer[16] ____cacheline_aligned;
+};
+
+static int ti_adc_read_measurement(struct ti_adc_data *data,
+				   struct iio_chan_spec const *chan, int *val)
+{
+	int ret;
+
+	switch (data->read_size) {
+	case 2: {
+		__be16 buf;
+
+		ret = spi_read(data->spi, (void *) &buf, 2);
+		if (ret)
+			return ret;
+
+		*val = be16_to_cpu(buf);
+		break;
+	}
+	case 3: {
+		__be32 buf;
+
+		ret = spi_read(data->spi, (void *) &buf, 3);
+		if (ret)
+			return ret;
+
+		*val = be32_to_cpu(buf) >> 8;
+		break;
+	}
+	default:
+		return -EINVAL;
+	}
+
+	*val = sign_extend32(*val >> data->shift, chan->scan_type.realbits - 1);
+
+	return 0;
+}
+
+static irqreturn_t ti_adc_trigger_handler(int irq, void *private)
+{
+	struct iio_poll_func *pf = private;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct ti_adc_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = ti_adc_read_measurement(data, &indio_dev->channels[0],
+				     (int *) &data->buffer);
+	if (!ret)
+		iio_push_to_buffers_with_timestamp(indio_dev,
+					data->buffer,
+					iio_get_time_ns(indio_dev));
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int ti_adc_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct ti_adc_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = ti_adc_read_measurement(data, chan, val);
+	iio_device_release_direct_mode(indio_dev);
+
+	if (!ret)
+		return IIO_VAL_INT;
+
+	return 0;
+}
+
+static const struct iio_info ti_adc_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = ti_adc_read_raw,
+};
+
+static int ti_adc_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct ti_adc_data *data;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	indio_dev->info = &ti_adc_info;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->dev.of_node = spi->dev.of_node;
+	indio_dev->name = TI_ADC_DRV_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	spi_set_drvdata(spi, indio_dev);
+
+	data = iio_priv(indio_dev);
+	data->spi = spi;
+
+	switch (spi_get_device_id(spi)->driver_data) {
+	case TI_ADC141S626:
+		indio_dev->channels = ti_adc141s626_channels;
+		indio_dev->num_channels = ARRAY_SIZE(ti_adc141s626_channels);
+		data->shift = 0;
+		data->read_size = 2;
+		break;
+	case TI_ADC161S626:
+		indio_dev->channels = ti_adc161s626_channels;
+		indio_dev->num_channels = ARRAY_SIZE(ti_adc161s626_channels);
+		data->shift = 6;
+		data->read_size = 3;
+		break;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 ti_adc_trigger_handler, NULL);
+	if (ret)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto error_unreg_buffer;
+
+	return 0;
+
+error_unreg_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return ret;
+}
+
+static int ti_adc_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return 0;
+}
+
+static const struct of_device_id ti_adc_dt_ids[] = {
+	{ .compatible = "ti,adc141s626", },
+	{ .compatible = "ti,adc161s626", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ti_adc_dt_ids);
+
+static const struct spi_device_id ti_adc_id[] = {
+	{"adc141s626", TI_ADC141S626},
+	{"adc161s626", TI_ADC161S626},
+	{},
+};
+MODULE_DEVICE_TABLE(spi, ti_adc_id);
+
+static struct spi_driver ti_adc_driver = {
+	.driver = {
+		.name	= TI_ADC_DRV_NAME,
+		.of_match_table = of_match_ptr(ti_adc_dt_ids),
+	},
+	.probe		= ti_adc_probe,
+	.remove		= ti_adc_remove,
+	.id_table	= ti_adc_id,
+};
+module_spi_driver(ti_adc_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("Texas Instruments ADC1x1S 1-channel differential ADC");
+MODULE_LICENSE("GPL");
-- 
2.7.4

[RFC v3 3/3] iio: potentiostat: add LMP91000 support

[Matt Ranostay]

Add support for the LMP91000 potentiostat which is used for chemical
sensing applications.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 .../bindings/iio/potentiostat/lmp91000.txt         |  30 ++
 drivers/iio/Kconfig                                |   1 +
 drivers/iio/Makefile                               |   1 +
 drivers/iio/potentiostat/Kconfig                   |  22 ++
 drivers/iio/potentiostat/Makefile                  |   6 +
 drivers/iio/potentiostat/lmp91000.c                | 376 +++++++++++++++++++++
 6 files changed, 436 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/potentiostat/lmp91000.txt
 create mode 100644 drivers/iio/potentiostat/Kconfig
 create mode 100644 drivers/iio/potentiostat/Makefile
 create mode 100644 drivers/iio/potentiostat/lmp91000.c

diff --git a/Documentation/devicetree/bindings/iio/potentiostat/lmp91000.txt b/Documentation/devicetree/bindings/iio/potentiostat/lmp91000.txt
new file mode 100644
index 000000000000..b9b621e94cd7
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiostat/lmp91000.txt
@@ -0,0 +1,30 @@
+* Texas Instruments LMP91000 potentiostat
+
+http://www.ti.com/lit/ds/symlink/lmp91000.pdf
+
+Required properties:
+
+  - compatible: should be "ti,lmp91000"
+  - reg: the I2C address of the device
+  - io-channels: the phandle of the iio provider
+
+  - ti,external-tia-resistor: if the property ti,tia-gain-ohm is not defined this
+    needs to be set to signal that an external resistor value is being used.
+
+Optional properties:
+
+  - ti,tia-gain-ohm: ohm value of the internal resistor for the transimpedance
+    amplifier. Must be 2750, 3500, 7000, 14000, 35000, 120000, or 350000 ohms.
+
+  - ti,rload-ohm: ohm value of the internal resistor load applied to the gas
+    sensor. Must be 10, 33, 50, or 100 (default) ohms.
+
+Example:
+
+lmp91000@48 {
+	compatible = "ti,lmp91000";
+	reg = <0x48>;
+	ti,tia-gain-ohm = <7500>;
+	ti,rload = <100>;
+	io-channels = <&adc>;
+};
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 505e921f0b19..ad5bbaefc18e 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -79,6 +79,7 @@ if IIO_TRIGGER
    source "drivers/iio/trigger/Kconfig"
 endif #IIO_TRIGGER
 source "drivers/iio/potentiometer/Kconfig"
+source "drivers/iio/potentiostat/Kconfig"
 source "drivers/iio/pressure/Kconfig"
 source "drivers/iio/proximity/Kconfig"
 source "drivers/iio/temperature/Kconfig"
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 20f649073462..f7369b77ed94 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -28,6 +28,7 @@ obj-y += light/
 obj-y += magnetometer/
 obj-y += orientation/
 obj-y += potentiometer/
+obj-y += potentiostat/
 obj-y += pressure/
 obj-y += proximity/
 obj-y += temperature/
diff --git a/drivers/iio/potentiostat/Kconfig b/drivers/iio/potentiostat/Kconfig
new file mode 100644
index 000000000000..1e3baf2cc97d
--- /dev/null
+++ b/drivers/iio/potentiostat/Kconfig
@@ -0,0 +1,22 @@
+#
+# Potentiostat drivers
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Digital potentiostats"
+
+config LMP91000
+	tristate "Texas Instruments LMP91000 potentiostat driver"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_BUFFER_CB
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for the Texas Instruments
+	  LMP91000 digital potentiostat chip.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called lmp91000
+
+endmenu
diff --git a/drivers/iio/potentiostat/Makefile b/drivers/iio/potentiostat/Makefile
new file mode 100644
index 000000000000..64d315ef4449
--- /dev/null
+++ b/drivers/iio/potentiostat/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for industrial I/O potentiostat drivers
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_LMP91000) += lmp91000.o
diff --git a/drivers/iio/potentiostat/lmp91000.c b/drivers/iio/potentiostat/lmp91000.c
new file mode 100644
index 000000000000..33bcc11421d0
--- /dev/null
+++ b/drivers/iio/potentiostat/lmp91000.c
@@ -0,0 +1,376 @@
+/*
+ * lmp91000.c - Support for Texas Instruments digital potentiostats
+ *
+ * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * TODO: bias voltage + polarity control, and multiple chip support
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define LMP91000_REG_LOCK		0x01
+#define LMP91000_REG_TIACN		0x10
+#define LMP91000_REG_TIACN_GAIN_SHIFT	2
+
+#define LMP91000_REG_REFCN		0x11
+#define LMP91000_REG_REFCN_EXT_REF	0x20
+#define LMP91000_REG_REFCN_50_ZERO	0x80
+
+#define LMP91000_REG_MODECN		0x12
+#define LMP91000_REG_MODECN_3LEAD	0x03
+#define LMP91000_REG_MODECN_TEMP	0x07
+
+#define LMP91000_DRV_NAME	"lmp91000"
+
+static const int lmp91000_tia_gain[] = { 0, 2750, 3500, 7000, 14000, 35000,
+					 120000, 350000 };
+
+static const int lmp91000_rload[] = { 10, 33, 50, 100 };
+
+static const struct regmap_config lmp91000_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+struct lmp91000_data {
+	struct regmap *regmap;
+	struct device *dev;
+
+	struct iio_trigger *trig;
+	struct iio_cb_buffer *cb_buffer;
+
+	struct completion completion;
+	u8 chan_select;
+
+	u32 buffer[4]; /* 64-bit data + 64-bit timestamp */
+};
+
+static const struct iio_chan_spec lmp91000_channels[] = {
+	{ /* chemical channel mV */
+		.type = IIO_VOLTAGE,
+		.channel = 0,
+		.indexed = 1,
+		.address = LMP91000_REG_MODECN_3LEAD,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 32,
+			.storagebits = 32,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+	{ /* temperature channel mV */
+		.type = IIO_VOLTAGE,
+		.channel = 1,
+		.indexed = 1,
+		.address = LMP91000_REG_MODECN_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = -1,
+	},
+};
+
+static int lmp91000_read(struct lmp91000_data *data, int channel, int *val)
+{
+	int state, ret;
+
+	ret = regmap_read(data->regmap, LMP91000_REG_MODECN, &state);
+	if (ret)
+		return -EINVAL;
+
+	ret = regmap_write(data->regmap, LMP91000_REG_MODECN, channel);
+	if (ret)
+		return -EINVAL;
+
+	/* delay till first temperature reading is complete */
+	if ((state != channel) && (channel == LMP91000_REG_MODECN_TEMP))
+		usleep_range(3000, 4000);
+
+	data->chan_select = channel != LMP91000_REG_MODECN_3LEAD;
+
+	iio_trigger_poll_chained(data->trig);
+
+	ret = wait_for_completion_timeout(&data->completion, HZ);
+	reinit_completion(&data->completion);
+
+	if (!ret)
+		return -ETIMEDOUT;
+
+	*val = data->buffer[data->chan_select];
+
+	return 0;
+}
+
+static irqreturn_t lmp91000_buffer_handler(int irq, void *private)
+{
+	struct iio_poll_func *pf = private;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct lmp91000_data *data = iio_priv(indio_dev);
+	int ret, val;
+
+	memset(data->buffer, 0, sizeof(data->buffer));
+
+	ret = iio_channel_start_all_cb(data->cb_buffer);
+	if (ret)
+		goto error_out;
+
+	ret = lmp91000_read(data, LMP91000_REG_MODECN_3LEAD, &val);
+	iio_channel_stop_all_cb(data->cb_buffer);
+
+	if (!ret) {
+		data->buffer[0] = val;
+		iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+						   iio_get_time_ns(indio_dev));
+	}
+
+error_out:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int lmp91000_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct lmp91000_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (mask != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	ret = iio_channel_start_all_cb(data->cb_buffer);
+	if (ret)
+		return ret;
+
+	ret = lmp91000_read(data, chan->address, val);
+
+	iio_channel_stop_all_cb(data->cb_buffer);
+
+	if (!ret)
+		return IIO_VAL_INT;
+
+	return ret;
+}
+
+static const struct iio_info lmp91000_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = lmp91000_read_raw,
+};
+
+static int lmp91000_read_config(struct lmp91000_data *data)
+{
+	struct device *dev = data->dev;
+	struct device_node *np = dev->of_node;
+	unsigned int reg, val;
+	int i, ret;
+
+	ret = of_property_read_u32(np, "ti,tia-gain-ohm", &val);
+	if (ret) {
+		if (of_property_read_bool(np, "ti,external-tia-resistor"))
+			val = 0;
+		else {
+			dev_err(dev, "no ti,tia-gain-ohm defined");
+			return ret;
+		}
+	}
+
+	ret = -EINVAL;
+	for (i = 0; i < ARRAY_SIZE(lmp91000_tia_gain); i++) {
+		if (lmp91000_tia_gain[i] == val) {
+			reg = i << LMP91000_REG_TIACN_GAIN_SHIFT;
+			ret = 0;
+			break;
+		}
+	}
+
+	if (ret) {
+		dev_err(dev, "invalid ti,tia-gain-ohm %d\n", val);
+		return ret;
+	}
+
+	ret = of_property_read_u32(np, "ti,rload-ohm", &val);
+	if (ret) {
+		val = 100;
+		dev_info(dev, "no ti,rload-ohm defined, default to %d\n", val);
+	}
+
+	ret = -EINVAL;
+	for (i = 0; i < ARRAY_SIZE(lmp91000_rload); i++) {
+		if (lmp91000_rload[i] == val) {
+			reg |= i;
+			ret = 0;
+			break;
+		}
+	}
+
+	if (ret) {
+		dev_err(dev, "invalid ti,rload-ohm %d\n", val);
+		return ret;
+	}
+
+	regmap_write(data->regmap, LMP91000_REG_LOCK, 0);
+	regmap_write(data->regmap, LMP91000_REG_TIACN, reg);
+	regmap_write(data->regmap, LMP91000_REG_REFCN, LMP91000_REG_REFCN_EXT_REF
+					| LMP91000_REG_REFCN_50_ZERO);
+	regmap_write(data->regmap, LMP91000_REG_LOCK, 1);
+
+	return 0;
+}
+
+static int lmp91000_buffer_cb(const void *val, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct lmp91000_data *data = iio_priv(indio_dev);
+
+	data->buffer[data->chan_select] = *((int *)val);
+	complete_all(&data->completion);
+
+	return 0;
+}
+
+static const struct iio_trigger_ops lmp91000_trigger_ops = {
+	.owner = THIS_MODULE,
+};
+
+static int lmp91000_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct lmp91000_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	indio_dev->info = &lmp91000_info;
+	indio_dev->channels = lmp91000_channels;
+	indio_dev->num_channels = ARRAY_SIZE(lmp91000_channels);
+	indio_dev->name = LMP91000_DRV_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	i2c_set_clientdata(client, indio_dev);
+
+	data = iio_priv(indio_dev);
+	data->dev = dev;
+	data->regmap = devm_regmap_init_i2c(client, &lmp91000_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(dev, "regmap initialization failed.\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	data->trig = devm_iio_trigger_alloc(data->dev, "%s-mux%d",
+					    indio_dev->name, indio_dev->id);
+	if (!data->trig) {
+		dev_err(dev, "cannot allocate iio trigger.\n");
+		return -ENOMEM;
+	}
+
+	data->trig->ops = &lmp91000_trigger_ops;
+	data->trig->dev.parent = dev;
+	init_completion(&data->completion);
+
+	ret = iio_trigger_register(data->trig);
+	if (ret) {
+		dev_err(dev, "cannot register iio trigger.\n");
+		return ret;
+	}
+
+	ret = lmp91000_read_config(data);
+	if (ret)
+		return ret;
+
+	data->cb_buffer = iio_channel_get_all_cb(dev, &lmp91000_buffer_cb,
+						 indio_dev);
+	if (IS_ERR(data->cb_buffer)) {
+		if (PTR_ERR(data->cb_buffer) == -ENODEV)
+			return -EPROBE_DEFER;
+		return PTR_ERR(data->cb_buffer);
+	}
+	iio_channel_cb_get_iio_dev(data->cb_buffer)->trig =
+					iio_trigger_get(data->trig);
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 &lmp91000_buffer_handler, NULL);
+	if (ret)
+		goto error_unreg_cb_buffer;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto error_unreg_buffer;
+
+	return 0;
+
+error_unreg_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+	iio_trigger_unregister(data->trig);
+
+error_unreg_cb_buffer:
+	iio_channel_release_all_cb(data->cb_buffer);
+
+	return ret;
+}
+
+static int lmp91000_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct lmp91000_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	iio_channel_stop_all_cb(data->cb_buffer);
+	iio_channel_release_all_cb(data->cb_buffer);
+
+	iio_triggered_buffer_cleanup(indio_dev);
+	iio_trigger_unregister(data->trig);
+
+	return 0;
+}
+
+static const struct of_device_id lmp91000_of_match[] = {
+	{ .compatible = "ti,lmp91000", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, lmp91000_of_match);
+
+static const struct i2c_device_id lmp91000_id[] = {
+	{ "lmp91000", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, lmp91000_id);
+
+static struct i2c_driver lmp91000_driver = {
+	.driver = {
+		.name = LMP91000_DRV_NAME,
+		.of_match_table = of_match_ptr(lmp91000_of_match),
+	},
+	.probe = lmp91000_probe,
+	.remove = lmp91000_remove,
+	.id_table = lmp91000_id,
+};
+module_i2c_driver(lmp91000_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("LMP91000 digital potentiostat");
+MODULE_LICENSE("GPL");
-- 
2.7.4