[PATCH 1/2] dt-bindings: Add bindings for Adafruit Seesaw Gamepad

[PATCH 1/2] dt-bindings: Add bindings for Adafruit Seesaw Gamepad

[Anshul Dalal]

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>
---
 .../bindings/input/adafruit_seesaw.yaml       | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/adafruit_seesaw.yaml

diff --git a/Documentation/devicetree/bindings/input/adafruit_seesaw.yaml b/Documentation/devicetree/bindings/input/adafruit_seesaw.yaml
new file mode 100644
index 000000000000..1d00d9da637a
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/adafruit_seesaw.yaml
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/input/adafruit_seesaw.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Adafruit Mini I2C Gamepad with seesaw
+
+maintainers:
+  - Anshul Dalal <anshulusr@gmail.com>
+
+description: |
+  Bindings for Adafruit Mini I2C Gamepad
+
+    +-----------------------------+
+    |   ___                       |
+    |  /   \               (X)    |
+    | |  S  |  __   __  (Y)   (A) |
+    |  \___/  |ST| |SE|    (B)    |
+    |                             |
+    +-----------------------------+
+
+  S -> 10-bit percision bidirectional analog joystick
+  ST -> Start
+  SE -> Select
+  X, A, B, Y -> Digital action buttons
+
+  Product page: https://www.adafruit.com/product/5743
+  Arduino Driver: https://github.com/adafruit/Adafruit_Seesaw
+
+properties:
+  compatible:
+    const: adafruit,seesaw_gamepad
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    seesaw_gamepad@50 {
+        compatible = "adafruit,seesaw_gamepad";
+        reg = <0x50>;
+    };
-- 
2.42.0

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

[Anshul Dalal]

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.
+
+		To compile this driver as a module, choose M here: the module will be
+		called adafruit_seesaw.
+
 endif
diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
index 3937535f0098..fdc653209542 100644
--- a/drivers/input/joystick/Makefile
+++ b/drivers/input/joystick/Makefile
@@ -28,6 +28,7 @@ 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-$(CONFIG_JOYSTICK_SEESAW)		+= adafruit_seesaw.o
 obj-$(CONFIG_JOYSTICK_SENSEHAT)	+= sensehat-joystick.o
 obj-$(CONFIG_JOYSTICK_SIDEWINDER)	+= sidewinder.o
 obj-$(CONFIG_JOYSTICK_SPACEBALL)	+= spaceball.o
diff --git a/drivers/input/joystick/adafruit_seesaw.c b/drivers/input/joystick/adafruit_seesaw.c
new file mode 100644
index 000000000000..a04df0469595
--- /dev/null
+++ b/drivers/input/joystick/adafruit_seesaw.c
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
+ *
+ * Driver for Adafruit Mini I2C Gamepad
+ *
+ * Based on the work of:
+ *	Oleh Kravchenko (Sparkfun Qwiic Joystick driver)
+ *
+ * Product page: https://www.adafruit.com/product/5743
+ * Firmware and hardware sources: https://github.com/adafruit/Adafruit_Seesaw
+ */
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+/* clang-format off */
+#define SEESAW_DEVICE_NAME	"seesaw_gamepad"
+
+#define SEESAW_STATUS_BASE	0
+#define SEESAW_GPIO_BASE	1
+#define SEESAW_ADC_BASE		9
+
+#define SEESAW_GPIO_DIRCLR_BULK	3
+#define SEESAW_GPIO_BULK	4
+#define SEESAW_GPIO_BULK_SET	5
+#define SEESAW_GPIO_PULLENSET	11
+
+#define SEESAW_STATUS_HW_ID	1
+#define SEESAW_STATUS_SWRST	127
+
+#define SEESAW_ADC_OFFSET	7
+
+#define BUTTON_A	5
+#define BUTTON_B	1
+#define BUTTON_X	6
+#define BUTTON_Y	2
+#define BUTTON_START	16
+#define BUTTON_SELECT	0
+
+#define ANALOG_X	14
+#define ANALOG_Y	15
+
+#define SEESAW_JOYSTICK_MAX_AXIS	1023
+#define SEESAW_JOYSTICK_FUZZ		2
+#define SEESAW_JOYSTICK_FLAT		4
+
+#define SEESAW_GAMEPAD_POLL_INTERVAL	16
+#define SEESAW_GAMEPAD_POLL_MIN		8
+#define SEESAW_GAMEPAD_POLL_MAX		32
+/* clang-format on */
+
+u32 BUTTON_MASK = (1UL << BUTTON_A) | (1UL << BUTTON_B) | (1UL << BUTTON_X) |
+		  (1UL << BUTTON_Y) | (1UL << BUTTON_START) |
+		  (1UL << BUTTON_SELECT);
+
+struct seesaw_gamepad {
+	char physical_path[32];
+	unsigned char hardware_id;
+	struct input_dev *input_dev;
+	struct i2c_client *i2c_client;
+};
+
+struct seesaw_data {
+	__be16 x;
+	__be16 y;
+	u8 button_a, button_b, button_x, button_y, button_start, button_select;
+};
+
+static int seesaw_read_data(struct i2c_client *client, struct seesaw_data *data)
+{
+	int err;
+	unsigned char write_buf[2] = { SEESAW_GPIO_BASE, SEESAW_GPIO_BULK };
+	unsigned char read_buf[4];
+
+	err = i2c_master_send(client, write_buf, sizeof(write_buf));
+	if (err < 0)
+		return err;
+	if (err != sizeof(write_buf))
+		return -EIO;
+	err = i2c_master_recv(client, read_buf, sizeof(read_buf));
+	if (err < 0)
+		return err;
+	if (err != sizeof(read_buf))
+		return -EIO;
+	u32 result = ((u32)read_buf[0] << 24) | ((u32)read_buf[1] << 16) |
+		     ((u32)read_buf[2] << 8) | (u32)read_buf[3];
+	data->button_a = !(result & (1UL << BUTTON_A));
+	data->button_b = !(result & (1UL << BUTTON_B));
+	data->button_x = !(result & (1UL << BUTTON_X));
+	data->button_y = !(result & (1UL << BUTTON_Y));
+	data->button_start = !(result & (1UL << BUTTON_START));
+	data->button_select = !(result & (1UL << BUTTON_SELECT));
+
+	write_buf[0] = SEESAW_ADC_BASE;
+	write_buf[1] = SEESAW_ADC_OFFSET + ANALOG_X;
+	err = i2c_master_send(client, write_buf, sizeof(write_buf));
+	if (err < 0)
+		return err;
+	if (err != sizeof(write_buf))
+		return -EIO;
+	err = i2c_master_recv(client, (char *)&data->x, sizeof(data->x));
+	if (err < 0)
+		return err;
+	if (err != sizeof(data->x))
+		return -EIO;
+	/*
+	 * ADC reads left as max and right as 0, must be reversed since kernel
+	 * expects reports in opposite order.
+	 */
+	data->x = SEESAW_JOYSTICK_MAX_AXIS - be16_to_cpu(data->x);
+
+	write_buf[1] = SEESAW_ADC_OFFSET + ANALOG_Y;
+	err = i2c_master_send(client, write_buf, 2);
+	if (err < 0)
+		return err;
+	if (err != sizeof(write_buf))
+		return -EIO;
+	err = i2c_master_recv(client, (char *)&data->y, data->y);
+	if (err < 0)
+		return err;
+	if (err != data->y)
+		return -EIO;
+	data->y = be16_to_cpu(data->y);
+
+	return 0;
+}
+
+static void seesaw_poll(struct input_dev *input)
+{
+	struct seesaw_gamepad *private = input_get_drvdata(input);
+	struct seesaw_data data;
+	int err;
+
+	err = seesaw_read_data(private->i2c_client, &data);
+	if (err != 0)
+		return;
+
+	input_report_abs(input, ABS_X, data.x);
+	input_report_abs(input, ABS_Y, data.y);
+	input_report_key(input, BTN_A, data.button_a);
+	input_report_key(input, BTN_B, data.button_b);
+	input_report_key(input, BTN_X, data.button_x);
+	input_report_key(input, BTN_Y, data.button_y);
+	input_report_key(input, BTN_START, data.button_start);
+	input_report_key(input, BTN_SELECT, data.button_select);
+	input_sync(input);
+}
+
+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);
+
+	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 */ } };
+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,
+};
+module_i2c_driver(seesaw_driver);
+
+MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
+MODULE_DESCRIPTION("Adafruit Mini I2C Gamepad driver");
+MODULE_LICENSE("GPL");
-- 
2.42.0

Re: [PATCH 1/2] dt-bindings: Add bindings for Adafruit Seesaw Gamepad

[Krzysztof Kozlowski]

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.

Thank you for your patch. There is something to discuss/improve.

Please use subject prefixes matching the subsystem. You can get them for
example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory
your patch is touching.

> 
> 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)`


This describes driver, not bindings or hardware Please instead describe
hardware.

> 
> Product page:
>   https://www.adafruit.com/product/5743
> Arduino driver:
>   https://github.com/adafruit/Adafruit_Seesaw
> 
> Tested on RPi Zero 2W

How can you test bindings on RPi Zero 2W? Somehow I don't believe you,
see below.

> 
> Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
> ---
>  .../bindings/input/adafruit_seesaw.yaml       | 45 +++++++++++++++++++
>  1 file changed, 45 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/adafruit_seesaw.yaml
> 
> diff --git a/Documentation/devicetree/bindings/input/adafruit_seesaw.yaml b/Documentation/devicetree/bindings/input/adafruit_seesaw.yaml
> new file mode 100644
> index 000000000000..1d00d9da637a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/adafruit_seesaw.yaml

Use compatible syntax, so vendor-prefix,device-name.yaml

> @@ -0,0 +1,45 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/input/adafruit_seesaw.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"

Drop quotes.

It does not look like you tested the bindings, at least after quick
look. Please run `make dt_binding_check` (see
Documentation/devicetree/bindings/writing-schema.rst for instructions).
Maybe you need to update your dtschema and yamllint.

> +
> +title: Adafruit Mini I2C Gamepad with seesaw
> +
> +maintainers:
> +  - Anshul Dalal <anshulusr@gmail.com>
> +
> +description: |
> +  Bindings for Adafruit Mini I2C Gamepad

Drop "Bindings for"

> +
> +    +-----------------------------+
> +    |   ___                       |
> +    |  /   \               (X)    |
> +    | |  S  |  __   __  (Y)   (A) |
> +    |  \___/  |ST| |SE|    (B)    |
> +    |                             |
> +    +-----------------------------+
> +
> +  S -> 10-bit percision bidirectional analog joystick
> +  ST -> Start
> +  SE -> Select
> +  X, A, B, Y -> Digital action buttons
> +
> +  Product page: https://www.adafruit.com/product/5743
> +  Arduino Driver: https://github.com/adafruit/Adafruit_Seesaw
> +
> +properties:
> +  compatible:
> +    const: adafruit,seesaw_gamepad
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    seesaw_gamepad@50 {

No underscores, generic node names.

Node names should be generic. See also an explanation and list of
examples (not exhaustive) in DT specification:
https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation


> +        compatible = "adafruit,seesaw_gamepad";
> +        reg = <0x50>;

Second hint that you did not test it...

> +    };

Best regards,
Krzysztof

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

[Krzysztof Kozlowski]

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

Re: [PATCH 1/2] dt-bindings: Add bindings for Adafruit Seesaw Gamepad

[Rob Herring]

On Sat, 07 Oct 2023 20:10:49 +0530, 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>
> ---
>  .../bindings/input/adafruit_seesaw.yaml       | 45 +++++++++++++++++++
>  1 file changed, 45 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/input/adafruit_seesaw.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/input/adafruit_seesaw.yaml:4:6: [error] string value is redundantly quoted with any quotes (quoted-strings)
./Documentation/devicetree/bindings/input/adafruit_seesaw.yaml:5:10: [error] string value is redundantly quoted with any quotes (quoted-strings)

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/input/adafruit_seesaw.example.dts:20.13-26: Warning (reg_format): /example-0/seesaw_gamepad@50:reg: property has invalid length (4 bytes) (#address-cells == 1, #size-cells == 1)
Documentation/devicetree/bindings/input/adafruit_seesaw.example.dtb: Warning (pci_device_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/input/adafruit_seesaw.example.dtb: Warning (pci_device_bus_num): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/input/adafruit_seesaw.example.dtb: Warning (simple_bus_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/input/adafruit_seesaw.example.dtb: Warning (i2c_bus_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/input/adafruit_seesaw.example.dtb: Warning (spi_bus_reg): Failed prerequisite 'reg_format'
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/input/adafruit_seesaw.example.dtb: seesaw_gamepad@50: 'reg' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/input/adafruit_seesaw.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20231007144052.1535417-1-anshulusr@gmail.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

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

[Anshul Dalal]

Hello Krzysztof,
Thank you very much for the review, I am planning to address the changes
in my next patch series though I had a question.

On 10/7/23 20:26, Krzysztof Kozlowski wrote:
> On 07/10/2023 16:40, Anshul Dalal wrote:
>> +
>> +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.

The reason for the delay is to ensure the register reset process is
finished before going further. The reference Arduino driver from the
manufacturer also had a delay for the same amount though my hardware
unit worked fine till 5ms delay. Is there some kernel abstraction I
could use to indicate a short delay or will the previous explanation in
a comment above the line do?

Best wishes,
Anshul

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

[Krzysztof Kozlowski]

On 07/10/2023 18:13, Anshul Dalal wrote:
>>> +	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.
> 
> The reason for the delay is to ensure the register reset process is
> finished before going further. The reference Arduino driver from the
> manufacturer also had a delay for the same amount though my hardware
> unit worked fine till 5ms delay. Is there some kernel abstraction I
> could use to indicate a short delay or will the previous explanation in
> a comment above the line do?
> 

Just explain it briefly as a comment.

Best regards,
Krzysztof