[RFC v2 3/3] iio: chemical: add Atlas pH-SM sensor support

[Matt Ranostay <mranostay@gmail.com>]

Add support for the Atlas Scientific pH-SM chemical sensor that can
detect pH levels of solutions in the range of 0-14.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 .../bindings/iio/chemical/atlas,ph-sm.txt          |  22 ++
 drivers/iio/chemical/Kconfig                       |  13 +
 drivers/iio/chemical/Makefile                      |   1 +
 drivers/iio/chemical/atlas-ph-sensor.c             | 431 +++++++++++++++++++++
 4 files changed, 467 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/chemical/atlas,ph-sm.txt
 create mode 100644 drivers/iio/chemical/atlas-ph-sensor.c

diff --git a/Documentation/devicetree/bindings/iio/chemical/atlas,ph-sm.txt b/Documentation/devicetree/bindings/iio/chemical/atlas,ph-sm.txt
new file mode 100644
index 0000000..cffa190
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/chemical/atlas,ph-sm.txt
@@ -0,0 +1,22 @@
+* Atlas Scientific pH-SM OEM sensor
+
+http://www.atlas-scientific.com/_files/_datasheets/_oem/pH_oem_datasheet.pdf
+
+Required properties:
+
+  - compatible: must be "atlas,ph-sm"
+  - reg: the I2C address of the sensor
+  - interrupt-parent: should be the phandle for the interrupt controller
+  - interrupts: the sole interrupt generated by the device
+
+  Refer to interrupt-controller/interrupts.txt for generic interrupt client
+  node bindings.
+
+Example:
+
+atlas@65 {
+	compatible = "atlas,ph-sm";
+	reg = <0x65>;
+	interrupt-parent = <&gpio1>;
+	interrupts = <16 2>;
+};
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 3061b72..a358e4b 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -4,6 +4,19 @@
 
 menu "Chemical Sensors"
 
+config ATLAS_PH_SENSOR
+	tristate "Atlas Scientific OEM pH-SM sensor"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	 Say Y here to build I2C interface support for the Atlas
+	 Scientific OEM pH-SM sensor.
+
+	 To compile this driver as module, choose M here: the
+	 module will be called atlas-ph-sensor.
+
 config VZ89X
 	tristate "SGX Sensortech MiCS VZ89X VOC sensor"
 	depends on I2C
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index 7292f2d..e9eb852 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -3,4 +3,5 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_ATLAS_PH_SENSOR)	+= atlas-ph-sensor.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/atlas-ph-sensor.c b/drivers/iio/chemical/atlas-ph-sensor.c
new file mode 100644
index 0000000..63da26b
--- /dev/null
+++ b/drivers/iio/chemical/atlas-ph-sensor.c
@@ -0,0 +1,431 @@
+/*
+ * atlas-ph-sensor.c - Support for Atlas Scientific OEM pH-SM sensor
+ *
+ * Copyright (C) 2015 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/interrupt.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/err.h>
+#include <linux/irq.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/pm_runtime.h>
+
+#define ATLAS_REGMAP_NAME	"atlas_ph_regmap"
+#define ATLAS_DRV_NAME		"atlas_ph"
+
+#define ATLAS_REG_DEV_TYPE		0x00
+#define ATLAS_REG_DEV_VERSION		0x01
+
+#define ATLAS_REG_INT_CONTROL		0x04
+#define ATLAS_REG_INT_CONTROL_EN	BIT(2)
+
+#define ATLAS_REG_PWR_CONTROL		0x06
+
+#define ATLAS_REG_TEMP_DATA		0x0e
+#define ATLAS_REG_PH_DATA		0x16
+
+#define ATLAS_PH_INT_TIME_IN_US		450000
+
+struct atlas_data {
+	struct i2c_client *client;
+	struct iio_trigger *trig;
+	struct regmap *regmap;
+
+	__be32 buffer[4]; /* 32-bit pH data + 32-bit pad + 64-bit timestamp */
+};
+
+static bool atlas_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	if (reg == ATLAS_REG_INT_CONTROL)
+		return true;
+
+	return false;
+}
+
+static const struct regmap_config atlas_regmap_config = {
+	.name = ATLAS_REGMAP_NAME,
+
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.volatile_reg = atlas_is_volatile_reg,
+	.max_register = ATLAS_REG_PH_DATA + 4,
+	.cache_type = REGCACHE_FLAT,
+
+};
+
+static const struct iio_chan_spec atlas_channels[] = {
+	{
+		.type = IIO_PH,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 32,
+			.storagebits = 32,
+			.endianness = IIO_BE,
+		},
+	},
+	{
+		.type = IIO_TEMP,
+		.address = ATLAS_REG_TEMP_DATA,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.output = 1,
+		.scan_index = -1
+	},
+};
+
+static int atlas_set_powermode(struct atlas_data *data, int on)
+{
+	return regmap_write(data->regmap, ATLAS_REG_PWR_CONTROL, on);
+}
+
+static int atlas_set_interrupt(struct atlas_data *data, bool state)
+{
+	return regmap_update_bits(data->regmap, ATLAS_REG_INT_CONTROL,
+				  ATLAS_REG_INT_CONTROL_EN,
+				  state ? ATLAS_REG_INT_CONTROL_EN : 0);
+}
+
+static int atlas_buffer_postenable(struct iio_dev *indio_dev)
+{
+	struct atlas_data *data = iio_priv(indio_dev);
+
+	pm_runtime_get_sync(&data->client->dev);
+
+	return atlas_set_interrupt(data, true);
+}
+
+static int atlas_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct atlas_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = atlas_set_interrupt(data, false);
+	if (ret)
+		return ret;
+
+	pm_runtime_mark_last_busy(&data->client->dev);
+	return pm_runtime_put_autosuspend(&data->client->dev);
+}
+
+static const struct iio_trigger_ops atlas_interrupt_trigger_ops = {
+	.owner = THIS_MODULE,
+};
+
+static const struct iio_buffer_setup_ops atlas_buffer_setup_ops = {
+	.postenable = atlas_buffer_postenable,
+	.predisable = atlas_buffer_predisable,
+};
+
+static irqreturn_t atlas_trigger_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct atlas_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = i2c_smbus_read_i2c_block_data(data->client, ATLAS_REG_PH_DATA,
+				sizeof(data->buffer[0]), (u8 *) &data->buffer);
+
+	if (ret > 0)
+		iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+				iio_get_time_ns());
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t atlas_interrupt_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct atlas_data *data = iio_priv(indio_dev);
+
+	/* re-enable interrupt */
+	atlas_set_interrupt(data, true);
+
+	return IRQ_HANDLED;
+}
+
+static int atlas_read_ph_measurement(struct atlas_data *data, __be32 *val)
+{
+	struct device *dev = &data->client->dev;
+	int suspended = pm_runtime_suspended(dev);
+	int ret;
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret)
+		return ret;
+
+	if (suspended)
+		usleep_range(ATLAS_PH_INT_TIME_IN_US,
+			     ATLAS_PH_INT_TIME_IN_US + 100000);
+
+	ret = i2c_smbus_read_i2c_block_data(data->client, ATLAS_REG_PH_DATA,
+					    sizeof(*val), (u8 *) val);
+
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	return ret == sizeof(*val) ? 0 : -EINVAL;
+}
+
+static int atlas_read_raw(struct iio_dev *indio_dev,
+			  struct iio_chan_spec const *chan,
+			  int *val, int *val2, long mask)
+{
+	struct atlas_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		int ret;
+		__be32 reg;
+
+		mutex_lock(&indio_dev->mlock);
+
+		if (iio_buffer_enabled(indio_dev)) {
+			ret = -EBUSY;
+			goto error_busy;
+		}
+
+		switch (chan->type) {
+		case IIO_TEMP:
+			ret = regmap_bulk_read(data->regmap, chan->address,
+					      (u8 *) &reg, sizeof(reg));
+			break;
+		case IIO_PH:
+			ret = atlas_read_ph_measurement(data, &reg);
+			break;
+		default:
+			ret = -EINVAL;
+		}
+
+		if (!ret) {
+			*val = be32_to_cpu(reg);
+			ret = IIO_VAL_INT;
+		}
+error_busy:
+		mutex_unlock(&indio_dev->mlock);
+		return ret;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0; /* 0.001 */
+		*val2 = 1000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+
+	return -EINVAL;
+}
+
+static int atlas_write_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int val, int val2, long mask)
+{
+	struct atlas_data *data = iio_priv(indio_dev);
+	__be32 reg = cpu_to_be32(val);
+
+	if (val2 != 0)
+		return -EINVAL;
+
+	if (mask != IIO_CHAN_INFO_RAW || chan->type != IIO_TEMP)
+		return -EINVAL;
+
+	return regmap_bulk_write(data->regmap, chan->address, &reg, 4);
+}
+
+static const struct iio_info atlas_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = atlas_read_raw,
+	.write_raw = atlas_write_raw,
+};
+
+static int atlas_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct atlas_data *data;
+	struct iio_trigger *trig;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	indio_dev->info = &atlas_info;
+	indio_dev->name = ATLAS_DRV_NAME;
+	indio_dev->channels = atlas_channels;
+	indio_dev->modes = INDIO_BUFFER_SOFTWARE | INDIO_DIRECT_MODE;
+	indio_dev->setup_ops = &atlas_buffer_setup_ops;
+	indio_dev->dev.parent = &client->dev;
+
+	trig = devm_iio_trigger_alloc(&client->dev, "%s-dev%d",
+				      indio_dev->name, indio_dev->id);
+
+	if (!trig)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	data->trig = trig;
+	trig->dev.parent = indio_dev->dev.parent;
+	trig->ops = &atlas_interrupt_trigger_ops;
+	iio_trigger_set_drvdata(trig, indio_dev);
+
+	i2c_set_clientdata(client, indio_dev);
+
+	data->regmap = devm_regmap_init_i2c(client, &atlas_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "regmap initialization failed\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	ret = pm_runtime_set_active(&client->dev);
+	if (ret)
+		return ret;
+
+	if (client->irq <= 0) {
+		dev_err(&client->dev, "no valid irq defined\n");
+		return -EINVAL;
+	}
+
+	ret = iio_trigger_register(trig);
+	if (ret) {
+		dev_err(&client->dev, "failed to register trigger\n");
+		return ret;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+		&atlas_trigger_handler, NULL);
+
+	if (ret) {
+		dev_err(&client->dev, "cannot setup iio trigger\n");
+		goto unregister_trigger;
+	}
+
+	ret = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, atlas_interrupt_handler,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					"atlas_irq",
+					indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "request irq (%d) failed\n", client->irq);
+		goto unregister_buffer;
+	}
+
+	ret = atlas_set_powermode(data, 1);
+	if (ret) {
+		dev_err(&client->dev, "cannot power device on");
+		goto unregister_buffer;
+	}
+
+	pm_runtime_enable(&client->dev);
+	pm_runtime_set_autosuspend_delay(&client->dev, 2500);
+	pm_runtime_use_autosuspend(&client->dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "unable to register device\n");
+		goto unregister_buffer;
+	}
+
+	return 0;
+
+unregister_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+unregister_trigger:
+	iio_trigger_unregister(data->trig);
+
+	return ret;
+}
+
+static int atlas_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct atlas_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	iio_trigger_unregister(data->trig);
+
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+	pm_runtime_put_noidle(&client->dev);
+
+	return atlas_set_powermode(data, 0);
+}
+
+#ifdef CONFIG_PM
+static int atlas_runtime_suspend(struct device *dev)
+{
+	struct atlas_data *data =
+		     iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return atlas_set_powermode(data, 0);
+}
+
+static int atlas_runtime_resume(struct device *dev)
+{
+	struct atlas_data *data =
+		     iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return atlas_set_powermode(data, 1);
+}
+#endif
+
+static const struct dev_pm_ops atlas_pm_ops = {
+	SET_RUNTIME_PM_OPS(atlas_runtime_suspend,
+			   atlas_runtime_resume, NULL)
+};
+
+static const struct i2c_device_id atlas_id[] = {
+	{ "atlas-ph-sm", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, atlas_id);
+
+static const struct of_device_id atlas_dt_ids[] = {
+	{ .compatible = "atlas,ph-sm" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, atlas_dt_ids);
+
+static struct i2c_driver atlas_driver = {
+	.driver = {
+		.name	= ATLAS_DRV_NAME,
+		.of_match_table	= of_match_ptr(atlas_dt_ids),
+		.pm	= &atlas_pm_ops,
+	},
+	.probe		= atlas_probe,
+	.remove		= atlas_remove,
+	.id_table	= atlas_id,
+};
+module_i2c_driver(atlas_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("Atlas Scientific pH-SM sensor");
+MODULE_LICENSE("GPL");
-- 
1.9.1