[PATCH v2 2/2] iio: proximity: add support for PulsedLight LIDAR

[Matt Ranostay <mranostay@gmail.com>]

Add support for the PulsedLight LIDAR rangefinder sensor which allows
high speed (over 300Hz) distance measurements using Barker Coding within
40 meter range.

Support only tested on the "blue label" rev 2, but may work using low
sample frequencies on the original version.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 drivers/iio/proximity/Kconfig  |  12 ++
 drivers/iio/proximity/Makefile |   1 +
 drivers/iio/proximity/lidar.c  | 284 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 297 insertions(+)
 create mode 100644 drivers/iio/proximity/lidar.c

diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
index 41a8d8f..e64fc5b 100644
--- a/drivers/iio/proximity/Kconfig
+++ b/drivers/iio/proximity/Kconfig
@@ -20,6 +20,18 @@ endmenu
 
 menu "Proximity sensors"
 
+config LIDAR
+	tristate "PulsedLight LIDAR sensor"
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	depends on I2C
+	help
+	  Say Y to build a driver for PulsedLight LIDAR range finding
+	  sensor.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called lidar.
+
 config SX9500
 	tristate "SX9500 Semtech proximity sensor"
 	select IIO_BUFFER
diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile
index 9818dc5..36a95f3 100644
--- a/drivers/iio/proximity/Makefile
+++ b/drivers/iio/proximity/Makefile
@@ -4,4 +4,5 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AS3935)		+= as3935.o
+obj-$(CONFIG_LIDAR)		+= lidar.o
 obj-$(CONFIG_SX9500)		+= sx9500.o
diff --git a/drivers/iio/proximity/lidar.c b/drivers/iio/proximity/lidar.c
new file mode 100644
index 0000000..e7c2df4
--- /dev/null
+++ b/drivers/iio/proximity/lidar.c
@@ -0,0 +1,284 @@
+/*
+ * lidar.c - Support for PulsedLight LIDAR range finding 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.
+ *
+ * TODO: runtime pm, interrupt mode, and signal strength reporting
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
+#define LIDAR_REG_CONTROL		0x00
+#define LIDAR_REG_CONTROL_ACQUIRE	BIT(2)
+
+#define LIDAR_REG_STATUS		0x01
+#define LIDAR_REG_STATUS_INVALID	BIT(3)
+#define LIDAR_REG_STATUS_READY		BIT(0)
+
+#define LIDAR_REG_DATA_HBYTE	0x0f
+#define LIDAR_REG_DATA_LBYTE	0x10
+
+#define LIDAR_DRV_NAME "lidar"
+
+struct lidar_data {
+	struct mutex lock;
+	struct iio_dev *indio_dev;
+	struct i2c_client *client;
+
+	/* 2 byte distance + 8 byte timestamp */
+	u16 buffer[5] ____cacheline_aligned;
+};
+
+static const struct iio_chan_spec lidar_channels[] = {
+	{
+		.type = IIO_DISTANCE,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static int lidar_read_byte(struct lidar_data *data, int reg)
+{
+	struct i2c_client *client = data->client;
+	int ret;
+
+	ret = i2c_smbus_write_byte(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot write addr value");
+		return ret;
+	}
+
+	ret = i2c_smbus_read_byte(client);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot read data value");
+		return ret;
+	}
+
+	return ret;
+}
+
+static inline int lidar_write_control(struct lidar_data *data, int val)
+{
+	return i2c_smbus_write_byte_data(data->client, LIDAR_REG_CONTROL, val);
+}
+
+static int lidar_read_measurement(struct lidar_data *data, u16 *reg)
+{
+	int ret;
+	int val;
+
+	ret = lidar_read_byte(data, LIDAR_REG_DATA_HBYTE);
+	if (ret < 0)
+		return ret;
+	val = ret << 8;
+
+	ret = lidar_read_byte(data, LIDAR_REG_DATA_LBYTE);
+	if (ret < 0)
+		return ret;
+
+	val |= ret;
+	*reg = val;
+
+	return 0;
+}
+
+static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
+{
+	struct i2c_client *client = data->client;
+	int tries = 10;
+	int ret;
+
+	/* start sample */
+	ret = lidar_write_control(data, LIDAR_REG_CONTROL_ACQUIRE);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot send start measurement command");
+		return ret;
+	}
+
+	while (tries--) {
+		usleep_range(1000, 2000);
+
+		ret = lidar_read_byte(data, LIDAR_REG_STATUS);
+		if (ret < 0)
+			break;
+
+		/* return 0 since laser is likely pointed out of range */
+		if (ret & LIDAR_REG_STATUS_INVALID) {
+			*reg = 0;
+			ret = 0;
+			break;
+		}
+
+		/* sample ready to read */
+		if (!(ret & LIDAR_REG_STATUS_READY)) {
+			ret = lidar_read_measurement(data, reg);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static int lidar_read_raw(struct iio_dev *indio_dev,
+			  struct iio_chan_spec const *chan,
+			  int *val, int *val2, long mask)
+{
+	struct lidar_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&data->lock);
+
+	if (iio_buffer_enabled(indio_dev) && mask == IIO_CHAN_INFO_RAW) {
+		ret = -EBUSY;
+		goto error_busy;
+	}
+
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		u16 reg;
+
+		ret = lidar_get_measurement(data, &reg);
+		if (!ret) {
+			*val = reg;
+			ret = IIO_VAL_INT;
+		}
+		break;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = 10000;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	}
+
+error_busy:
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static irqreturn_t lidar_trigger_handler(int irq, void *private)
+{
+	struct iio_poll_func *pf = private;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct lidar_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = lidar_get_measurement(data, &data->buffer[0]);
+	if (!ret) {
+		iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+						   iio_get_time_ns());
+	} else {
+		dev_err(&data->client->dev, "cannot read LIDAR measurement");
+	}
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_info lidar_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = lidar_read_raw,
+};
+
+static int lidar_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct lidar_data *data;
+	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 = &lidar_info;
+	indio_dev->name = LIDAR_DRV_NAME;
+	indio_dev->channels = lidar_channels;
+	indio_dev->num_channels = ARRAY_SIZE(lidar_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+
+	data->client = client;
+	data->indio_dev = indio_dev;
+	mutex_init(&data->lock);
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 lidar_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 lidar_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id lidar_id[] = {
+	{"lidar", 0},
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, lidar_id);
+
+static struct i2c_driver lidar_driver = {
+	.driver = {
+		.name	= LIDAR_DRV_NAME,
+	},
+	.probe		= lidar_probe,
+	.remove		= lidar_remove,
+	.id_table	= lidar_id,
+};
+module_i2c_driver(lidar_driver);
+
+MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
+MODULE_DESCRIPTION("PulsedLight LIDAR sensor");
+MODULE_LICENSE("GPL");
-- 
1.9.1