Re: [PATCH 2/2] input: add Adafruit Seesaw Gamepad driver

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 07/10/2023 16:40, Anshul Dalal wrote:
> A simple driver for a mini gamepad that communicates over i2c, the gamepad
> has bidirectional thumb stick input and six buttons.
> 
> The gamepad chip utilizes the open framework from Adafruit called 'Seesaw'
> to transmit the ADC data for the joystick and digital pin state for the
> buttons. I have only implemented the functionality required to receive the
> thumb stick and button state.
> 
> Steps in reading the gamepad state over i2c:
>   1. Reset the registers
>   2. Set the pin mode of the pins specified by the `BUTTON_MASK` to input
>       `BUTTON_MASK`: A bit-map for the six digital pins internally
>        connected to the joystick buttons.
>   3. Enable internal pullup resistors for the `BUTTON_MASK`
>   4. Bulk set the pin state HIGH for `BUTTON_MASK`
>   5. Poll the device for button and joystick state done by:
>       `seesaw_read_data(struct i2c_client *client, struct seesaw_data *data)`
> 
> Product page:
>   https://www.adafruit.com/product/5743
> Arduino driver:
>   https://github.com/adafruit/Adafruit_Seesaw
> 
> Tested on RPi Zero 2W
> 
> Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
> ---
>  MAINTAINERS                              |   7 +
>  drivers/input/joystick/Kconfig           |   9 +
>  drivers/input/joystick/Makefile          |   1 +
>  drivers/input/joystick/adafruit_seesaw.c | 275 +++++++++++++++++++++++
>  4 files changed, 292 insertions(+)
>  create mode 100644 drivers/input/joystick/adafruit_seesaw.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 81d5fc0bba68..cd4f9deb77e2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -441,6 +441,13 @@ W:	http://wiki.analog.com/AD7879
>  W:	https://ez.analog.com/linux-software-drivers
>  F:	drivers/input/touchscreen/ad7879.c
>  
> +ADAFRUIT MINI I2C GAMEPAD
> +M:	Anshul Dalal <anshulusr@gmail.com>
> +L:	linux-input@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/input/adafruit_seesaw.yaml
> +F:	drivers/input/joystick/adafruit_seesaw.c
> +
>  ADDRESS SPACE LAYOUT RANDOMIZATION (ASLR)
>  M:	Jiri Kosina <jikos@kernel.org>
>  S:	Maintained
> diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
> index ac6925ce8366..b8337edc6e22 100644
> --- a/drivers/input/joystick/Kconfig
> +++ b/drivers/input/joystick/Kconfig
> @@ -412,4 +412,13 @@ config JOYSTICK_SENSEHAT
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called sensehat_joystick.
>  
> +config JOYSTICK_SEESAW
> +	tristate "Adafruit Mini I2C Gamepad with Seesaw"
> +	depends on I2C
> +	help
> +		Say Y here if you want to use the Adafruit Mini I2C Gamepad.

This does not look like correct indentation. Just look at other code and
do not do it differently.

> +
> +		To compile this driver as a module, choose M here: the module will be
> +		called adafruit_seesaw.
> +
>  endif

...

> +
> +static int seesaw_probe(struct i2c_client *client)
> +{
> +	int err;
> +	struct seesaw_gamepad *private;
> +	unsigned char register_reset[] = { SEESAW_STATUS_BASE,
> +					   SEESAW_STATUS_SWRST, 0xFF };
> +	unsigned char get_hw_id[] = { SEESAW_STATUS_BASE, SEESAW_STATUS_HW_ID };
> +
> +	err = i2c_master_send(client, register_reset, sizeof(register_reset));
> +	if (err < 0)
> +		return err;
> +	if (err != sizeof(register_reset))
> +		return -EIO;
> +	mdelay(10);

Why 10? This should be explained somehow in the code.


> +
> +	private = devm_kzalloc(&client->dev, sizeof(*private), GFP_KERNEL);
> +	if (!private)
> +		return -ENOMEM;
> +
> +	err = i2c_master_send(client, get_hw_id, sizeof(get_hw_id));
> +	if (err < 0)
> +		return err;
> +	if (err != sizeof(get_hw_id))
> +		return -EIO;
> +	err = i2c_master_recv(client, &private->hardware_id, 1);
> +	if (err < 0)
> +		return err;
> +	if (err != 1)
> +		return -EIO;
> +
> +	dev_dbg(&client->dev, "Adafruit Seesaw Gamepad, Hardware ID: %02x\n",
> +		private->hardware_id);
> +
> +	private->i2c_client = client;
> +	scnprintf(private->physical_path, sizeof(private->physical_path),
> +		  "i2c/%s", dev_name(&client->dev));
> +	i2c_set_clientdata(client, private);
> +
> +	private->input_dev = devm_input_allocate_device(&client->dev);
> +	if (!private->input_dev)
> +		return -ENOMEM;
> +
> +	private->input_dev->id.bustype = BUS_I2C;
> +	private->input_dev->name = "Adafruit Seesaw Gamepad";
> +	private->input_dev->phys = private->physical_path;
> +	input_set_drvdata(private->input_dev, private);
> +	input_set_abs_params(private->input_dev, ABS_X, 0,
> +			     SEESAW_JOYSTICK_MAX_AXIS, SEESAW_JOYSTICK_FUZZ,
> +			     SEESAW_JOYSTICK_FLAT);
> +	input_set_abs_params(private->input_dev, ABS_Y, 0,
> +			     SEESAW_JOYSTICK_MAX_AXIS, SEESAW_JOYSTICK_FUZZ,
> +			     SEESAW_JOYSTICK_FLAT);
> +	input_set_capability(private->input_dev, EV_KEY, BTN_A);
> +	input_set_capability(private->input_dev, EV_KEY, BTN_B);
> +	input_set_capability(private->input_dev, EV_KEY, BTN_X);
> +	input_set_capability(private->input_dev, EV_KEY, BTN_Y);
> +	input_set_capability(private->input_dev, EV_KEY, BTN_START);
> +	input_set_capability(private->input_dev, EV_KEY, BTN_SELECT);
> +
> +	err = input_setup_polling(private->input_dev, seesaw_poll);
> +	if (err) {
> +		dev_err(&client->dev, "failed to set up polling: %d\n", err);
> +		return err;
> +	}
> +
> +	input_set_poll_interval(private->input_dev,
> +				SEESAW_GAMEPAD_POLL_INTERVAL);
> +	input_set_max_poll_interval(private->input_dev,
> +				    SEESAW_GAMEPAD_POLL_MAX);
> +	input_set_min_poll_interval(private->input_dev,
> +				    SEESAW_GAMEPAD_POLL_MIN);
> +
> +	err = input_register_device(private->input_dev);
> +	if (err) {
> +		dev_err(&client->dev, "failed to register joystick: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Set Pin Mode to input and enable pull-up resistors */
> +	unsigned char pin_mode[] = { SEESAW_GPIO_BASE,	SEESAW_GPIO_DIRCLR_BULK,
> +				     BUTTON_MASK >> 24, BUTTON_MASK >> 16,
> +				     BUTTON_MASK >> 8,	BUTTON_MASK };
> +	err = i2c_master_send(client, pin_mode, sizeof(pin_mode));
> +	pin_mode[1] = SEESAW_GPIO_PULLENSET;
> +	err |= i2c_master_send(client, pin_mode, sizeof(pin_mode));
> +	pin_mode[1] = SEESAW_GPIO_BULK_SET;
> +	err |= i2c_master_send(client, pin_mode, sizeof(pin_mode));
> +	if (err < 0)
> +		return err;
> +	if (err != sizeof(pin_mode))
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id of_seesaw_match[] = {
> +	{
> +		.compatible = "adafruit,seesaw_gamepad",
> +	},
> +	{ /* Sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, of_seesaw_match);
> +#endif /* CONFIG_OF */
> +
> +static const struct i2c_device_id seesaw_id_table[] = { { KBUILD_MODNAME, 0 },
> +							{ /* Sentinel */ } };

Please format it just like all other drivers have it.

> +MODULE_DEVICE_TABLE(i2c, seesaw_id_table);
> +
> +static struct i2c_driver seesaw_driver = {
> +	.driver = {
> +		.name = SEESAW_DEVICE_NAME,
> +		.of_match_table = of_match_ptr(of_seesaw_match),
> +	},
> +	.id_table = seesaw_id_table,
> +	.probe		= seesaw_probe,

Some mixed indentation before =.

> +};
> +module_i2c_driver(seesaw_driver);
> +
> +MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
> +MODULE_DESCRIPTION("Adafruit Mini I2C Gamepad driver");
> +MODULE_LICENSE("GPL");

Best regards,
Krzysztof