[2/2,v3] input: add SparkFun Qwiic Joystick driver

A simple analog joystick built on Low Power ATtiny85 Microcontroller.
Directional movements are measured with two 10 kΩ potentiometers
connected with a gimbal mechanism that separates the horizontal and
vertical movements. This joystick also has a select button that is actuated
when the joystick is pressed down.

Input events polled over the I2C bus.

Product page:
https://www.sparkfun.com/products/15168
Firmware and hardware sources:
https://github.com/sparkfun/Qwiic_Joystick

Tested on RPi4B and O4-iMX-NANO boards.

Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Device Tree mailing list <devicetree@vger.kernel.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Jeff LaBundy <jeff@labundy.com>
Cc: Jiri Kosina <jikos@jikos.cz>
Cc: Patchwork Bot <patchwork-bot@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Oleh Kravchenko <oleg@kaa.org.ua>
---

Changes for v3:
- update patch after code review.

Changes for v2:
- update code after code review

 drivers/input/joystick/Kconfig          |   9 ++
 drivers/input/joystick/Makefile         |   1 +
 drivers/input/joystick/qwiic-joystick.c | 147 ++++++++++++++++++++++++
 3 files changed, 157 insertions(+)
 create mode 100644 drivers/input/joystick/qwiic-joystick.c

Hi Oleh,

Great work; one last style-related comment but everything else looks
good to me.

On Fri, Jun 04, 2021 at 01:18:03AM +0300, Oleh Kravchenko wrote:
> A simple analog joystick built on Low Power ATtiny85 Microcontroller.
> Directional movements are measured with two 10 kΩ potentiometers
> connected with a gimbal mechanism that separates the horizontal and
> vertical movements. This joystick also has a select button that is actuated
> when the joystick is pressed down.
> 
> Input events polled over the I2C bus.
> 
> Product page:
> https://www.sparkfun.com/products/15168
> Firmware and hardware sources:
> https://github.com/sparkfun/Qwiic_Joystick
> 
> Tested on RPi4B and O4-iMX-NANO boards.
> 
> Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> Cc: Device Tree mailing list <devicetree@vger.kernel.org>
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: Jeff LaBundy <jeff@labundy.com>
> Cc: Jiri Kosina <jikos@jikos.cz>
> Cc: Patchwork Bot <patchwork-bot@kernel.org>
> Cc: Rob Herring <robh@kernel.org>
> Signed-off-by: Oleh Kravchenko <oleg@kaa.org.ua>
> ---
> 
> Changes for v3:
> - update patch after code review.
> 
> Changes for v2:
> - update code after code review
> 
>  drivers/input/joystick/Kconfig          |   9 ++
>  drivers/input/joystick/Makefile         |   1 +
>  drivers/input/joystick/qwiic-joystick.c | 147 ++++++++++++++++++++++++
>  3 files changed, 157 insertions(+)
>  create mode 100644 drivers/input/joystick/qwiic-joystick.c
> 
> diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
> index 5e38899058c1..7dfe8ea90923 100644
> --- a/drivers/input/joystick/Kconfig
> +++ b/drivers/input/joystick/Kconfig
> @@ -372,6 +372,15 @@ config JOYSTICK_PXRC
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called pxrc.
>  
> +config JOYSTICK_QWIIC
> +	tristate "SparkFun Qwiic Joystick"
> +	depends on I2C
> +	help
> +	  Say Y here if you want to use the SparkFun Qwiic Joystick.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called qwiic-joystick.
> +
>  config JOYSTICK_FSIA6B
>  	tristate "FlySky FS-iA6B RC Receiver"
>  	select SERIO
> diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
> index 31d720c9e493..5174b8aba2dd 100644
> --- a/drivers/input/joystick/Makefile
> +++ b/drivers/input/joystick/Makefile
> @@ -27,6 +27,7 @@ obj-$(CONFIG_JOYSTICK_MAPLE)		+= maplecontrol.o
>  obj-$(CONFIG_JOYSTICK_N64)		+= n64joy.o
>  obj-$(CONFIG_JOYSTICK_PSXPAD_SPI)	+= psxpad-spi.o
>  obj-$(CONFIG_JOYSTICK_PXRC)		+= pxrc.o
> +obj-$(CONFIG_JOYSTICK_QWIIC)		+= qwiic-joystick.o
>  obj-$(CONFIG_JOYSTICK_SIDEWINDER)	+= sidewinder.o
>  obj-$(CONFIG_JOYSTICK_SPACEBALL)	+= spaceball.o
>  obj-$(CONFIG_JOYSTICK_SPACEORB)		+= spaceorb.o
> diff --git a/drivers/input/joystick/qwiic-joystick.c b/drivers/input/joystick/qwiic-joystick.c
> new file mode 100644
> index 000000000000..d1748ca38de2
> --- /dev/null
> +++ b/drivers/input/joystick/qwiic-joystick.c
> @@ -0,0 +1,147 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Oleh Kravchenko <oleg@kaa.org.ua>
> + *
> + * SparkFun Qwiic Joystick
> + * Product page:https://www.sparkfun.com/products/15168
> + * Firmware and hardware sources:https://github.com/sparkfun/Qwiic_Joystick
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/bits.h>
> +#include <linux/i2c.h>
> +#include <linux/input.h>
> +#include <linux/module.h>

Nit: in general these should be alphabetized.

> +
> +#define DRV_NAME "qwiic-joystick"
> +
> +#define QWIIC_JSK_REG_VERS	1
> +#define QWIIC_JSK_REG_DATA	3
> +
> +#define QWIIC_JSK_MAX_AXIS	GENMASK(9, 0)
> +#define QWIIC_JSK_FUZZ		2
> +#define QWIIC_JSK_FLAT		2
> +#define QWIIC_JSK_POLL_INTERVAL	16
> +#define QWIIC_JSK_POLL_MIN	8
> +#define QWIIC_JSK_POLL_MAX	32
> +
> +struct qwiic_jsk {
> +	char phys[32];
> +	struct input_dev *dev;
> +	struct i2c_client *client;
> +};
> +
> +struct qwiic_ver {
> +	u8 major;
> +	u8 minor;
> +};
> +
> +struct qwiic_data {
> +	__be16 x;
> +	__be16 y;
> +	u8 thumb;
> +} __packed;
> +
> +static void qwiic_poll(struct input_dev *input)
> +{
> +	struct qwiic_jsk *priv;
> +	struct qwiic_data data;
> +	int err;
> +
> +	priv = input_get_drvdata(input);
> +
> +	err = i2c_smbus_read_i2c_block_data(priv->client, QWIIC_JSK_REG_DATA,
> +					    sizeof(data), (u8 *)&data);
> +	if (err != sizeof(data))
> +		return;
> +
> +	input_report_abs(input, ABS_X, be16_to_cpu(data.x) >> 6);
> +	input_report_abs(input, ABS_Y, be16_to_cpu(data.y) >> 6);
> +	input_report_key(input, BTN_THUMBL, !data.thumb);
> +	input_sync(input);
> +}
> +
> +static int qwiic_probe(struct i2c_client *client,
> +		       const struct i2c_device_id *id)
> +{
> +	struct qwiic_jsk *priv;
> +	struct qwiic_ver vers;
> +	int err;
> +
> +	err = i2c_smbus_read_i2c_block_data(client, QWIIC_JSK_REG_VERS,
> +					    sizeof(vers), (u8 *)&vers);
> +	if (err < 0)
> +		return err;
> +	if (err != sizeof(vers))
> +		return -EIO;
> +
> +	dev_dbg(&client->dev, "SparkFun Qwiic Joystick, FW: %u.%u\n",
> +		vers.major, vers.minor);
> +
> +	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->client = client;
> +	snprintf(priv->phys, sizeof(priv->phys),
> +		 "i2c/%s", dev_name(&client->dev));
> +	i2c_set_clientdata(client, priv);
> +
> +	priv->dev = devm_input_allocate_device(&client->dev);
> +	if (!priv->dev)
> +		return -ENOMEM;
> +
> +	priv->dev->id.bustype = BUS_I2C;
> +	priv->dev->name = "SparkFun Qwiic Joystick";
> +	priv->dev->phys = priv->phys;
> +	input_set_drvdata(priv->dev, priv);
> +
> +	input_set_abs_params(priv->dev, ABS_X, 0, QWIIC_JSK_MAX_AXIS,
> +			     QWIIC_JSK_FUZZ, QWIIC_JSK_FLAT);
> +	input_set_abs_params(priv->dev, ABS_Y, 0, QWIIC_JSK_MAX_AXIS,
> +			     QWIIC_JSK_FUZZ, QWIIC_JSK_FLAT);
> +	input_set_capability(priv->dev, EV_KEY, BTN_THUMBL);
> +
> +	err = input_setup_polling(priv->dev, qwiic_poll);
> +	if (err) {
> +		dev_err(&client->dev, "failed to set up polling: %d\n", err);
> +		return err;
> +	}
> +	input_set_poll_interval(priv->dev, QWIIC_JSK_POLL_INTERVAL);
> +	input_set_min_poll_interval(priv->dev, QWIIC_JSK_POLL_MIN);
> +	input_set_max_poll_interval(priv->dev, QWIIC_JSK_POLL_MAX);
> +
> +	err = input_register_device(priv->dev);
> +	if (err)
> +		dev_err(&client->dev, "failed to register joystick: %d\n", err);
> +
> +	return err;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id of_qwiic_match[] = {
> +	{ .compatible = "sparkfun,qwiic-joystick", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, of_qwiic_match);
> +#endif /* CONFIG_OF */
> +
> +static const struct i2c_device_id qwiic_id_table[] = {
> +	{ KBUILD_MODNAME, 0 },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(i2c, qwiic_id_table);
> +
> +static struct i2c_driver qwiic_driver = {
> +	.driver = {
> +		.name		= DRV_NAME,
> +		.of_match_table	= of_match_ptr(of_qwiic_match),
> +	},
> +	.id_table	= qwiic_id_table,
> +	.probe		= qwiic_probe,
> +};
> +module_i2c_driver(qwiic_driver);
> +
> +MODULE_AUTHOR("Oleh Kravchenko <oleg@kaa.org.ua>");
> +MODULE_DESCRIPTION("SparkFun Qwiic Joystick driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.26.3
> 

Other than that,

Reviewed-by: Jeff LaBundy <jeff@labundy.com>

Kind regards,
Jeff LaBundy