[v5,2/2] input: joystick: driver for Adafruit Seesaw Gamepad

diff --git a/MAINTAINERS b/MAINTAINERS
index 6c4cce45a09d..a314f9b48e21 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-gamepad.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..df9cd1830b29 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..9976f596a920 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..2a1eae8d2861
--- /dev/null
+++ b/drivers/input/joystick/adafruit-seesaw.c
@@ -0,0 +1,273 @@ 
+// 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)
+ *
+ * Datasheet: https://cdn-learn.adafruit.com/downloads/pdf/gamepad-qt.pdf
+ * Product page: https://www.adafruit.com/product/5743
+ * Firmware and hardware sources: https://github.com/adafruit/Adafruit_Seesaw
+ */
+
+#include <asm-generic/unaligned.h>
+#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 = BIT(BUTTON_A) | BIT(BUTTON_B) | BIT(BUTTON_X) |
+		  BIT(BUTTON_Y) | BIT(BUTTON_START) | BIT(BUTTON_SELECT);
+
+struct seesaw_gamepad {
+	char physical_path[32];
+	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;
+	err = i2c_master_recv(client, read_buf, sizeof(read_buf));
+	if (err < 0)
+		return err;
+
+	u32 result = get_unaligned_be32(&read_buf);
+
+	data->button_a = !test_bit(BUTTON_A, (long *)&result);
+	data->button_b = !test_bit(BUTTON_B, (long *)&result);
+	data->button_x = !test_bit(BUTTON_X, (long *)&result);
+	data->button_y = !test_bit(BUTTON_Y, (long *)&result);
+	data->button_start = !test_bit(BUTTON_START, (long *)&result);
+	data->button_select = !test_bit(BUTTON_SELECT, (long *)&result);
+
+	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;
+	err = i2c_master_recv(client, (char *)&data->x, sizeof(data->x));
+	if (err < 0)
+		return err;
+	/*
+	 * 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, sizeof(write_buf));
+	if (err < 0)
+		return err;
+	err = i2c_master_recv(client, (char *)&data->y, sizeof(data->y));
+	if (err < 0)
+		return err;
+	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) {
+		dev_dbg(&input->dev, "failed to read joystick state: %d\n",
+			err);
+		return;
+	}
+
+	input_report_abs(input, ABS_X, data.x);
+	input_report_abs(input, ABS_Y, data.y);
+	input_report_key(input, BTN_EAST, data.button_a);
+	input_report_key(input, BTN_SOUTH, data.button_b);
+	input_report_key(input, BTN_NORTH, data.button_x);
+	input_report_key(input, BTN_WEST, 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;
+
+	/* Wait for the registers to reset before proceeding */
+	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;
+
+	unsigned char hardware_id;
+
+	err = i2c_master_recv(client, &hardware_id, 1);
+	if (err < 0)
+		return err;
+
+	dev_dbg(&client->dev, "Adafruit Seesaw Gamepad, Hardware ID: %02x\n",
+		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_EAST);
+	input_set_capability(private->input_dev, EV_KEY, BTN_SOUTH);
+	input_set_capability(private->input_dev, EV_KEY, BTN_NORTH);
+	input_set_capability(private->input_dev, EV_KEY, BTN_WEST);
+	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));
+	if (err < 0)
+		return err;
+	pin_mode[1] = SEESAW_GPIO_PULLENSET;
+	err = i2c_master_send(client, pin_mode, sizeof(pin_mode));
+	if (err < 0)
+		return err;
+	pin_mode[1] = SEESAW_GPIO_BULK_SET;
+	err = i2c_master_send(client, pin_mode, sizeof(pin_mode));
+	if (err < 0)
+		return err;
+
+	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 */
+
+/* clang-format off */
+static const struct i2c_device_id seesaw_id_table[] = {
+	{ SEESAW_DEVICE_NAME, 0 },
+	{ /* Sentinel */ }
+};
+/* clang-format on */
+
+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");