Hi Anshul, On Fri, Oct 27, 2023 at 10:48:11AM +0530, Anshul Dalal wrote: > Adds a 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 > > Driver tested on RPi Zero 2W > > Reviewed-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> > Signed-off-by: Anshul Dalal <anshulusr@xxxxxxxxx> > --- > Changes for v6: > - Added TODO > - Removed `clang-format` directives > - Namespaced device buttons > - Removed `char physical_path[32]` field from `struct seesaw_gamepad` > - Added `packed` attribute to `struct seesaw_data` > - Moved from having booleans per button to single `u32 button_state` > - Added `seesaw_button_description` array to directly associate device > buttons with respective keycodes > - Added wrapper functions `seesaw_register_` around `i2c_master_` API > - Ratelimited input error reporting with `dev_err_ratelimited` > - Removed `of_device_id` > > Changes for v5: > - Added link to the datasheet > - Added debug log message when `seesaw_read_data` fails > > Changes for v4: > - Changed `1UL << BUTTON_` to BIT(BUTTON_) > - Removed `hardware_id` field from `struct seesaw_gamepad` > - Removed redundant checks for the number of bytes written and received by > `i2c_master_send` and `i2c_master_recv` > - Used `get_unaligned_be32` to instantiate `u32 result` from `read_buf` > - Changed `result & (1UL << BUTTON_)` to > `test_bit(BUTTON_, (long *)&result)` > - Changed `KBUILD_MODNAME` in id-tables to `SEESAW_DEVICE_NAME` > - Fixed formatting issues > - Changed button reporting: > Since the gamepad had the action buttons in a non-standard layout: > (X) > (Y) (A) > (B) > Therefore moved to using generic directional action button event codes > instead of BTN_[ABXY]. > > Changes for v3: > - no updates > > Changes for v2: > adafruit-seesaw.c: > - Renamed file from 'adafruit_seesaw.c' > - Changed device name from 'seesaw_gamepad' to 'seesaw-gamepad' > - Changed count parameter for receiving joystick x on line 118: > `2` to `sizeof(write_buf)` > - Fixed invalid buffer size on line 123 and 126: > `data->y` to `sizeof(data->y)` > - Added comment for the `mdelay(10)` on line 169 > - Changed inconsistent indentation on line 271 > Kconfig: > - Fixed indentation for the help text > - Updated module name > Makefile: > - Updated module object file name > MAINTAINERS: > - Updated file name for the driver and bindings > > MAINTAINERS | 7 + > drivers/input/joystick/Kconfig | 9 + > drivers/input/joystick/Makefile | 1 + > drivers/input/joystick/adafruit-seesaw.c | 310 +++++++++++++++++++++++ > 4 files changed, 327 insertions(+) > create mode 100644 drivers/input/joystick/adafruit-seesaw.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 4cc6bf79fdd8..0595c832c248 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-gamepad.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..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..1aa6fbe4fda4 > --- /dev/null > +++ b/drivers/input/joystick/adafruit-seesaw.c > @@ -0,0 +1,310 @@ > +// 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) > + * > + * 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 > + * > + * TODO: > + * - Add interrupt support > + */ > + > +#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> > + > +#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 SEESAW_BUTTON_A 5 > +#define SEESAW_BUTTON_B 1 > +#define SEESAW_BUTTON_X 6 > +#define SEESAW_BUTTON_Y 2 > +#define SEESAW_BUTTON_START 16 > +#define SEESAW_BUTTON_SELECT 0 > + > +#define SEESAW_ANALOG_X 14 > +#define SEESAW_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 > + > +u32 SEESAW_BUTTON_MASK = BIT(SEESAW_BUTTON_A) | BIT(SEESAW_BUTTON_B) | > + BIT(SEESAW_BUTTON_X) | BIT(SEESAW_BUTTON_Y) | > + BIT(SEESAW_BUTTON_START) | BIT(SEESAW_BUTTON_SELECT); > + > +struct seesaw_gamepad { > + struct input_dev *input_dev; > + struct i2c_client *i2c_client; > +}; > + > +struct seesaw_data { > + __be16 x; > + __be16 y; > + u32 button_state; > +} __packed; > + > +struct seesaw_button_description { > + unsigned int code; > + unsigned int bit; > +}; > + > +static const struct seesaw_button_description seesaw_buttons[] = { > + { > + .code = BTN_EAST, > + .bit = SEESAW_BUTTON_A, > + }, > + { > + .code = BTN_SOUTH, > + .bit = SEESAW_BUTTON_B, > + }, > + { > + .code = BTN_NORTH, > + .bit = SEESAW_BUTTON_X, > + }, > + { > + .code = BTN_WEST, > + .bit = SEESAW_BUTTON_Y, > + }, > + { > + .code = BTN_START, > + .bit = SEESAW_BUTTON_START, > + }, > + { > + .code = BTN_SELECT, > + .bit = SEESAW_BUTTON_SELECT, > + }, > +}; > + > +static int seesaw_register_read(struct i2c_client *client, u8 register_high, > + u8 register_low, char *buf, int count) I am curious why we have 2 u8s instead of u16 that we send as __be16? > +{ > + int ret; > + u8 register_buf[2] = { register_high, register_low }; > + > + ret = i2c_master_send(client, register_buf, sizeof(register_buf)); > + if (ret < 0) > + return ret; > + ret = i2c_master_recv(client, buf, count); I am curious can this be an i2c_transfer() with read/write messages instead (so 1 transaction)? > + if (ret < 0) > + return ret; > + > + return 0; > +} > + > +static int seesaw_register_write_u8(struct i2c_client *client, u8 register_high, > + u8 register_low, u8 value) > +{ > + int ret; > + u8 write_buf[3] = { register_high, register_low, value }; > + > + ret = i2c_master_send(client, write_buf, sizeof(write_buf)); > + if (ret < 0) > + return ret; > + > + return 0; > +} > + > +static int seesaw_register_write_u32(struct i2c_client *client, > + u8 register_high, u8 register_low, > + u32 value) > +{ > + int ret; > + u8 write_buf[6] = { register_high, register_low }; > + > + put_unaligned_be32(value, write_buf + 2); > + ret = i2c_master_send(client, write_buf, sizeof(write_buf)); > + if (ret < 0) > + return ret; > + > + return 0; > +} > + > +static int seesaw_read_data(struct i2c_client *client, struct seesaw_data *data) > +{ > + int ret; > + u8 read_buf[4]; Why is this u8 buffer and not __be32? > + > + ret = seesaw_register_read(client, SEESAW_GPIO_BASE, SEESAW_GPIO_BULK, > + read_buf, sizeof(read_buf)); > + if (ret) > + return ret; > + > + data->button_state = ~get_unaligned_be32(&read_buf); If you use __be32 you would not need to use get_unaligned_be32. > + > + ret = seesaw_register_read(client, SEESAW_ADC_BASE, > + SEESAW_ADC_OFFSET + SEESAW_ANALOG_X, > + (char *)&data->x, sizeof(data->x)); > + if (ret) > + return ret; > + /* > + * 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); > + > + ret = seesaw_register_read(client, SEESAW_ADC_BASE, > + SEESAW_ADC_OFFSET + SEESAW_ANALOG_Y, > + (char *)&data->y, sizeof(data->y)); > + if (ret) > + return ret; > + data->y = be16_to_cpu(data->y); This is endianness violation and sparse should have warned you about this. A variable can either carry BE data, LE data, or CPU-endianness data, but not both. I'd recommend combining seesaw_read_data() with seesaw_poll() into something like seesaw_report_events() and using temporaries for x and y and button data, and do not store them in the private structure at all. > + > + return 0; > +} > + > +static void seesaw_poll(struct input_dev *input) > +{ > + int err, i; > + struct seesaw_gamepad *private = input_get_drvdata(input); > + struct seesaw_data data; > + > + err = seesaw_read_data(private->i2c_client, &data); > + if (err != 0) { > + dev_err_ratelimited(&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); > + > + for (i = 0; i < ARRAY_SIZE(seesaw_buttons); i++) { > + input_report_key(input, seesaw_buttons[i].code, > + data.button_state & > + BIT(seesaw_buttons[i].bit)); > + } > + input_sync(input); > +} > + > +static int seesaw_probe(struct i2c_client *client) > +{ > + int err, i; > + u8 hardware_id; > + struct seesaw_gamepad *seesaw; > + > + err = seesaw_register_write_u8(client, SEESAW_STATUS_BASE, > + SEESAW_STATUS_SWRST, 0xFF); > + if (err) > + return err; > + > + /* Wait for the registers to reset before proceeding */ > + mdelay(10); Can this be usleep_range() instead? No need to block CPU. > + > + seesaw = devm_kzalloc(&client->dev, sizeof(*seesaw), GFP_KERNEL); > + if (!seesaw) > + return -ENOMEM; > + > + err = seesaw_register_read(client, SEESAW_STATUS_BASE, > + SEESAW_STATUS_HW_ID, &hardware_id, 1); sizeof(hardware_id) > + if (err) > + return err; > + > + dev_dbg(&client->dev, "Adafruit Seesaw Gamepad, Hardware ID: %02x\n", > + hardware_id); > + > + /* Set Pin Mode to input and enable pull-up resistors */ > + err = seesaw_register_write_u32(client, SEESAW_GPIO_BASE, > + SEESAW_GPIO_DIRCLR_BULK, > + SEESAW_BUTTON_MASK); > + if (err) > + return err; > + err = seesaw_register_write_u32(client, SEESAW_GPIO_BASE, > + SEESAW_GPIO_PULLENSET, > + SEESAW_BUTTON_MASK); > + if (err) > + return err; > + err = seesaw_register_write_u32(client, SEESAW_GPIO_BASE, > + SEESAW_GPIO_BULK_SET, > + SEESAW_BUTTON_MASK); > + if (err) > + return err; > + > + seesaw->i2c_client = client; > + i2c_set_clientdata(client, seesaw); > + > + seesaw->input_dev = devm_input_allocate_device(&client->dev); > + if (!seesaw->input_dev) > + return -ENOMEM; > + > + seesaw->input_dev->id.bustype = BUS_I2C; > + seesaw->input_dev->name = "Adafruit Seesaw Gamepad"; > + seesaw->input_dev->phys = "i2c/" SEESAW_DEVICE_NAME; > + input_set_drvdata(seesaw->input_dev, seesaw); > + input_set_abs_params(seesaw->input_dev, ABS_X, 0, > + SEESAW_JOYSTICK_MAX_AXIS, SEESAW_JOYSTICK_FUZZ, > + SEESAW_JOYSTICK_FLAT); > + input_set_abs_params(seesaw->input_dev, ABS_Y, 0, > + SEESAW_JOYSTICK_MAX_AXIS, SEESAW_JOYSTICK_FUZZ, > + SEESAW_JOYSTICK_FLAT); > + for (i = 0; i < ARRAY_SIZE(seesaw_buttons); i++) { > + input_set_capability(seesaw->input_dev, EV_KEY, > + seesaw_buttons[i].code); > + } > + > + err = input_setup_polling(seesaw->input_dev, seesaw_poll); > + if (err) { > + dev_err(&client->dev, "failed to set up polling: %d\n", err); > + return err; > + } > + > + input_set_poll_interval(seesaw->input_dev, > + SEESAW_GAMEPAD_POLL_INTERVAL); > + input_set_max_poll_interval(seesaw->input_dev, SEESAW_GAMEPAD_POLL_MAX); > + input_set_min_poll_interval(seesaw->input_dev, SEESAW_GAMEPAD_POLL_MIN); > + > + err = input_register_device(seesaw->input_dev); > + if (err) { > + dev_err(&client->dev, "failed to register joystick: %d\n", err); > + return err; > + } > + > + return 0; > +} > + > +static const struct i2c_device_id seesaw_id_table[] = { > + { SEESAW_DEVICE_NAME, 0 }, > + { /* Sentinel */ } > +}; > +MODULE_DEVICE_TABLE(i2c, seesaw_id_table); > + > +static struct i2c_driver seesaw_driver = { > + .driver = { > + .name = SEESAW_DEVICE_NAME, > + }, > + .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 > Thanks. -- Dmitry
