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

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On 1 August 2015 09:39:11 BST, Vladimir Barinov <vladimir.barinov@xxxxxxxxxxxxxxxxxx> wrote:
>Hi Matt,
>
>Find minor comments.
>
>On 01.08.2015 06:58, Matt Ranostay wrote:
>> 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
>polling
>> at low sample frequencies on the original version.
>>
>> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
>> ---
>>   drivers/iio/proximity/Kconfig  |  13 ++
>>   drivers/iio/proximity/Makefile |   1 +
>>   drivers/iio/proximity/lidar.c  | 309
>+++++++++++++++++++++++++++++++++++++++++
>Add ABI documentation 
>Documentation/ABI/testing/sysfs-bus-iio-proximity-lidar
Why?  Reading on phone so may have missed something but all ABI is standard.
Covered by top level docs.

>>   3 files changed, 323 insertions(+)
>>   create mode 100644 drivers/iio/proximity/lidar.c
>>
>> diff --git a/drivers/iio/proximity/Kconfig
>b/drivers/iio/proximity/Kconfig
>> index 41a8d8f..8111e11 100644
>> --- a/drivers/iio/proximity/Kconfig
>> +++ b/drivers/iio/proximity/Kconfig
>> @@ -20,6 +20,19 @@ endmenu
>>   
>>   menu "Proximity sensors"
>>   
>> +config LIDAR
>> +	tristate "PulsedLight LIDAR sensor"
>> +	select IIO_BUFFER
>> +	select IIO_TRIGGERED_BUFFER
>> +	select REGMAP_I2C
>You did not use REGMAP in your driver.
>Probably it would be better to use this API in your driver since the 
>chip seems fully SMBUS compatible.
Unless there is a significant gain don't bother. Now if the device also has an spi bus
or the driver does extensive caching it would be worthwhile.

>> +	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..e56df58
>> --- /dev/null
>> +++ b/drivers/iio/proximity/lidar.c
>> @@ -0,0 +1,309 @@
>> +/*
>> + * lidar.c - Support for PulsedLight LIDAR range finding sensor
>> + *
>> + * Copyright (C) 2015 Matt Ranostay <mranostay@xxxxxxxxx>
>> + *
>> + * 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/module.h>
>> +#include <linux/init.h>
>> +#include <linux/delay.h>
>> +#include <linux/mutex.h>
>> +#include <linux/err.h>
>> +#include <linux/i2c.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +#include <linux/iio/trigger.h>
>> +#include <linux/iio/trigger_consumer.h>
>> +#include <linux/iio/buffer.h>
>> +#include <linux/iio/triggered_buffer.h>
>put it in alphabetic order
>> +
>> +#define LIDAR_REG_CONTROL	0x00
>> +#define LIDAR_REG_CONTROL_ACQUIRE	BIT(2)
>tab aligned
>> +
>> +#define LIDAR_REG_STATUS	0x01
>> +#define LIDAR_REG_STATUS_RDY	BIT(0)
>> +
>> +#define LIDAR_REG_DATA_HBYTE	0x0f
>> +#define LIDAR_REG_DATA_LBYTE	0x10
>> +#define LIDAR_REG_DATA_MAX	0xffff
>> +
>> +#define LIDAR_DRV_NAME	"lidar"
>> +
>> +struct lidar_data {
>> +	struct mutex lock;
>> +	struct iio_dev *indio_dev;
>> +	struct i2c_client *client;
>> +
>> +	/* config */
>> +	int calib_bias;
>> +
>> +	u16 buffer[5]; /* 2 byte distance + 8 byte timestamp */
>> +};
>> +
>> +static const struct iio_chan_spec lidar_channels[] = {
>> +	{
>> +		.type = IIO_DISTANCE,
>> +		.info_mask_separate =
>> +			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_CALIBBIAS),
>> +		.scan_index = 0,
>> +		.scan_type = {
>> +			.sign = 'u',
>> +			.realbits = 16,
>> +			.storagebits = 16,
>> +		},
>> +	},
>> +	IIO_CHAN_SOFT_TIMESTAMP(1),
>> +};
>> +
>> +static inline 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;
>> +
>> +	/* correct any possible overflow or underflow */
>> +	val += data->calib_bias / 10000;
>> +	if (val < 0)
>> +		val = 0;
>> +
>> +	if (val > LIDAR_REG_DATA_MAX)
>> +		val = LIDAR_REG_DATA_MAX;
>> +
>> +	*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;
>> +
>> +		/* sample ready to read */
>> +		if (!(ret & LIDAR_REG_STATUS_RDY)) {
>> +			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;
>> +
>> +	if (iio_buffer_enabled(indio_dev) && mask == IIO_CHAN_INFO_RAW)
>> +		return -EBUSY;
>> +
>> +	mutex_lock(&data->lock);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW: {
>> +		u16 reg;
>> +
>> +		ret = lidar_get_measurement(data, &reg);
>> +		if (!ret) {
>> +			*val = reg / 100;
>> +			*val2 = (reg % 100) * 10000;
>> +			ret = IIO_VAL_INT_PLUS_MICRO;
>> +		}
>> +		break;
>> +	}
>> +	case IIO_CHAN_INFO_CALIBBIAS:
>> +		*val = 0;
>> +		*val2 = data->calib_bias;
>> +		ret = IIO_VAL_INT_PLUS_MICRO;
>> +		break;
>> +	}
>> +
>> +	mutex_unlock(&data->lock);
>> +
>> +	return ret;
>> +}
>> +
>> +static int lidar_write_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);
>> +
>> +	if (mask == IIO_CHAN_INFO_CALIBBIAS) {
>> +		if (val != 0)
>> +			return -EINVAL;
>> +
>> +		/* cm increments only */
>> +		if (val2 % 10000)
>> +			return -EINVAL;
>> +
>> +		mutex_lock(&data->lock);
>> +		data->calib_bias = val2;
>> +		mutex_unlock(&data->lock);
>> +		return 0;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +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 struct iio_info lidar_info = {
>> +	.driver_module = THIS_MODULE,
>> +	.read_raw = lidar_read_raw,
>> +	.write_raw = lidar_write_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,
>> +		.owner	= THIS_MODULE,
>the .owner field is not needed since it is overridden in
>i2c_register_driver
>> +	},
>> +	.probe		= lidar_probe,
>> +	.remove		= lidar_remove,
>> +	.id_table	= lidar_id,
>> +};
>> +module_i2c_driver(lidar_driver);
>> +
>> +MODULE_AUTHOR("Matt Ranostay <mranostay@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("PulsedLight LIDAR sensor");
>> +MODULE_LICENSE("GPL");
>
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