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@xxxxxxxxx>
---
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@xxxxxxxxx>
+L: linux-input@xxxxxxxxxxxxxxx
+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@xxxxxxxxxx>
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@xxxxxxxxx>
+ *
+ * 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@xxxxxxxxx>");
+MODULE_DESCRIPTION("Adafruit Mini I2C Gamepad driver");
+MODULE_LICENSE("GPL");
--
2.42.0
