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Date:   Sat, 22 Sep 2018 15:46:58 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Song Qiang <songqiang1304521@gmail.com>
Cc:     knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net,
        robh+dt@kernel.org, mark.rutland@arm.com,
        andriy.shevchenko@linux.intel.com, matt.ranostay@konsulko.com,
        tglx@linutronix.de, ak@it-klinger.de, linux-iio@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v6 1/2] iio: proximity: Add driver support for ST's
 VL53L0X ToF ranging sensor.
Message-ID: <20180922154658.752f2fbf@archlinux>
In-Reply-To: <20180918082422.13050-1-songqiang1304521@gmail.com>
References: <20180918082422.13050-1-songqiang1304521@gmail.com>
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On Tue, 18 Sep 2018 16:24:21 +0800
Song Qiang <songqiang1304521@gmail.com> wrote:

> This driver was originally written by ST in 2016 as a misc input device
> driver, and hasn't been maintained for a long time. I grabbed some code
> from it's API and reformed it into an iio proximity device driver.
> This version of driver uses i2c bus to talk to the sensor and
> polling for measuring completes, so no irq line is needed.
> It can be tested with reading from
> /sys/bus/iio/devices/iio:deviceX/in_distance_input
> 
> Signed-off-by: Song Qiang <songqiang1304521@gmail.com>
There are a few bits and bobs in here, but as they are all minor and
one at least was me giving you wrong advise, I've fixed it up.

Please check I haven't made a mess of it! 

Applied with changes to the togreg branch of iio.git and pushed out
as testing (where it should be visible now) for the autobuilders to
play with it.

Thanks,

Jonathan
> ---
> Changes in v6:
> 	- Remove '.' in mail address. Google doesn't care, these two
> 	  email address is the same when I log in.
> 	- Clean register table.
> 	- Put some seperated statements into one line.
> 	- Change channel type to *_PROCESSED.
> 	- Remove some unneccessary dev_err.
> 	- changes iio device name to vl53l0x.
> 
> Changes in v5:
> 	- Correct some spell problems.
> 	- Change tries-- to --tries to fix the count error.
> 	- Add MODULE_DEVICE_TABLE().
> 	- Add some comments.
> 
> Changes in v4:
> 	- Add datasheet link, default i2c address and TODO list.
> 	- Make capitalization of defines consistent.
> 	- Replace i2c_transfer() with i2c_smbus_read_i2c_block_data().
> 	- Remove IIO_CHAN_SOFT_TIMESTAMP() since no buffer/trigger
> 	  support.
> 	- Add information to MAINTAINERS.
> 
> Changes in v3:
> 	- Recover ST's copyright.
> 	- Clean up indio_dev member in vl53l0x_data struct since it's
> 	  useless now.
> 	- Replace __le16_to_cpu() with le16_to_cpu().
> 	- Remove the iio_device_{claim|release}_direct_mode() since it's
> 	  only needed when we use buffered mode.
> 	- Clean up some coding style problems.
> 
> Changes in v2:
> 	- Clean up the register table.
> 	- Sort header files declarations.
> 	- Replace some bit definations with GENMASK() and BIT().
> 	- Clean up some code and comments that's useless for now.
> 	- Change the order of some the definations of some variables to reversed
> 	  xmas tree order.
> 	- Using do...while() rather while and check.
> 	- Replace pr_err() with dev_err().
> 	- Remove device id declaration since we recommend to use DT.
> 	- Remove .owner = THIS_MODULE.
> 	- Replace probe() with probe_new() hook.
> 	- Remove IIO_BUFFER and IIO_TRIGGERED_BUFFER dependences.
> 	- Change the driver module name to vl53l0x-i2c.
> 	- Align all the parameters if they are in the same function with open
> 	  parentheses.
> 	- Replace iio_device_register() with devm_iio_device_register
> 	  for better resource management.
> 	- Remove the vl53l0x_remove() since it's not needed.
> 	- Remove dev_set_drvdata() since it's already setted above.
> 
>  .../bindings/iio/proximity/vl53l0x.txt        |  12 ++
>  MAINTAINERS                                   |   7 +
>  drivers/iio/proximity/Kconfig                 |  11 ++
>  drivers/iio/proximity/Makefile                |   2 +
>  drivers/iio/proximity/vl53l0x-i2c.c           | 157 ++++++++++++++++++
>  5 files changed, 189 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
>  create mode 100644 drivers/iio/proximity/vl53l0x-i2c.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt b/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> new file mode 100644
> index 000000000000..ab9a9539fec4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> @@ -0,0 +1,12 @@
> +ST VL53L0X ToF ranging sensor
> +
> +Required properties:
> +	- compatible: must be "st,vl53l0x-i2c"
> +	- reg: i2c address where to find the device
> +
> +Example:
> +
> +vl53l0x@29 {
> +	compatible = "st,vl53l0x-i2c";
> +	reg = <0x29>;
> +};
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 967ce8cdd1cc..349e2bc97cec 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13510,6 +13510,13 @@ L:	linux-i2c@vger.kernel.org
>  S:	Maintained
>  F:	drivers/i2c/busses/i2c-stm32*
>  
> +ST VL53L0X ToF RANGER(I2C) IIO DRIVER
> +M:	Song Qiang <songqiang1304521@gmail.com>
> +L:	linux-iio@vger.kernel.org
> +S:	Maintained
> +F:	drivers/iio/proximity/vl53l0x-i2c.c
> +F:	Documentation/devicetree/bindings/iio/proximity/vl53l0x.txt
> +
>  STABLE BRANCH
>  M:	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>  L:	stable@vger.kernel.org
> diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
> index f726f9427602..5f421cbd37f3 100644
> --- a/drivers/iio/proximity/Kconfig
> +++ b/drivers/iio/proximity/Kconfig
> @@ -79,4 +79,15 @@ config SRF08
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called srf08.
>  
> +config VL53L0X_I2C
> +	tristate "STMicroelectronics VL53L0X ToF ranger sensor (I2C)"
> +	depends on I2C
> +	help
> +	  Say Y here to build a driver for STMicroelectronics VL53L0X
> +	  ToF ranger sensors with i2c interface.
> +	  This driver can be used to measure the distance of objects.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called vl53l0x-i2c.
> +
>  endmenu
> diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile
> index 4f4ed45e87ef..dedfb5bf3475 100644
> --- a/drivers/iio/proximity/Makefile
> +++ b/drivers/iio/proximity/Makefile
> @@ -10,3 +10,5 @@ obj-$(CONFIG_RFD77402)		+= rfd77402.o
>  obj-$(CONFIG_SRF04)		+= srf04.o
>  obj-$(CONFIG_SRF08)		+= srf08.o
>  obj-$(CONFIG_SX9500)		+= sx9500.o
> +obj-$(CONFIG_VL53L0X_I2C)	+= vl53l0x-i2c.o
> +
> diff --git a/drivers/iio/proximity/vl53l0x-i2c.c b/drivers/iio/proximity/vl53l0x-i2c.c
> new file mode 100644
> index 000000000000..1aad45df8d95
> --- /dev/null
> +++ b/drivers/iio/proximity/vl53l0x-i2c.c
> @@ -0,0 +1,157 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Support for ST VL53L0X FlightSense ToF Ranging Sensor on a i2c bus.
> + *
> + * Copyright (C) 2016 STMicroelectronics Imaging Division.
> + * Copyright (C) 2018 Song Qiang <songqiang1304521@gmail.com>
> + *
> + * Datasheet available at
> + * <https://www.st.com/resource/en/datasheet/vl53l0x.pdf>
> + *
> + * Default 7-bit i2c slave address 0x29.
> + *
> + * TODO: FIFO buffer, continuous mode, interrupts, range selection,
> + * sensor ID check.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/delay.h>
> +
> +#include <linux/iio/iio.h>
> +
> +#define VL_REG_SYSRANGE_START				0x00
> +
> +#define VL_REG_SYSRANGE_MODE_MASK			GENMASK(3, 0)
> +#define VL_REG_SYSRANGE_MODE_SINGLESHOT			0x00
> +#define VL_REG_SYSRANGE_MODE_START_STOP			BIT(0)
> +#define VL_REG_SYSRANGE_MODE_BACKTOBACK			BIT(1)
> +#define VL_REG_SYSRANGE_MODE_TIMED			BIT(2)
> +#define VL_REG_SYSRANGE_MODE_HISTOGRAM			BIT(3)
> +
> +#define VL_REG_RESULT_INT_STATUS			0x13
> +#define VL_REG_RESULT_RANGE_STATUS			0x14
> +#define VL_REG_RESULT_RANGE_STATUS_COMPLETE		BIT(0)
> +
> +struct vl53l0x_data {
> +	struct i2c_client *client;
> +};
> +
> +static int vl53l0x_read_proximity(struct vl53l0x_data *data,
> +				  const struct iio_chan_spec *chan,
> +				  int *val)
> +{
> +	struct i2c_client *client = data->client;
> +	u16 tries = 20;
> +	u8 buffer[12];
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, VL_REG_SYSRANGE_START, 1);
> +	if (ret < 0)
> +		return ret;
> +
> +	do {
> +		ret = i2c_smbus_read_byte_data(client,
> +			VL_REG_RESULT_RANGE_STATUS);
> +		if (ret < 0)
> +			return ret;
> +
> +		if (ret & VL_REG_RESULT_RANGE_STATUS_COMPLETE)
> +			break;
> +
> +		usleep_range(1000, 5000);
> +	} while (--tries);
> +	if (!tries)
> +		return -ETIMEDOUT;
> +
> +	ret = i2c_smbus_read_i2c_block_data(client, VL_REG_RESULT_RANGE_STATUS,
> +		12, buffer);

Please align with the opening brackets.

> +	if (ret < 0)
> +		return ret;
> +	else if (ret != 12)
> +		return -EREMOTEIO;
> +
> +	/* Values should be between 30~1200 in millimeters. */
> +	*val = le16_to_cpu((buffer[10] << 8) + buffer[11]);

This is wrong.  You are effectively the ordering twice...

Ah. Sorry. I failed to check this last time.   The units of
in_distance_processed are m, not mm.  So this will need
to be _RAW and have a scale of 0.0001.

See Documentation/ABI/testing/sysfs-bus-iio

> +
> +	return 0;
> +}
> +
> +static const struct iio_chan_spec vl53l0x_channels[] = {
> +	{
> +		.type = IIO_DISTANCE,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	},
> +};
> +
> +static int vl53l0x_read_raw(struct iio_dev *indio_dev,
> +			    const struct iio_chan_spec *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct vl53l0x_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	if (chan->type != IIO_DISTANCE)
> +		return -EINVAL;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		ret = vl53l0x_read_proximity(data, chan, val);
> +		if (ret < 0)
> +			return ret;
> +
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info vl53l0x_info = {
> +	.read_raw = vl53l0x_read_raw,
> +};
> +
> +static int vl53l0x_probe(struct i2c_client *client)
> +{
> +	struct vl53l0x_data *data;
> +	struct iio_dev *indio_dev;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	data->client = client;
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	if (!i2c_check_functionality(client->adapter,
> +		I2C_FUNC_SMBUS_READ_I2C_BLOCK | I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EOPNOTSUPP;
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->name = "vl53l0x";
> +	indio_dev->info = &vl53l0x_info;
> +	indio_dev->channels = vl53l0x_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(vl53l0x_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +static const struct of_device_id st_vl53l0x_dt_match[] = {
> +	{ .compatible = "st,vl53l0x-i2c", },

Ah, this suffers from the same thing that was picked up in a driver
you sent later in the week.  No need to have -i2c in the compatible
as this is clear from the bus type.

(I might just fix this up).

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, st_vl53l0x_dt_match);
> +
> +static struct i2c_driver vl53l0x_driver = {
> +	.driver = {
> +		.name = "vl53l0x-i2c",
> +		.of_match_table = st_vl53l0x_dt_match,
> +	},
> +	.probe_new = vl53l0x_probe,
> +};
> +module_i2c_driver(vl53l0x_driver);
> +
> +MODULE_AUTHOR("Song Qiang <songqiang1304521@gmail.com>");
> +MODULE_DESCRIPTION("ST vl53l0x ToF ranging sensor driver");
> +MODULE_LICENSE("GPL v2");