Hi Oleh, Neat little device; some comments below. On Mon, May 31, 2021 at 04:32:43PM +0300, Oleh Kravchenko wrote: > A simple analog joystick built on Low Power ATtiny85 Microcontroller. > Directional movements are measured with two 10 kΩ potentiometers > connected with a gimbal mechanism that separates the horizontal and > vertical movements. This joystick also has a select button that is actuated > when the joystick is pressed down. > > Input events polled over the I2C bus. > > Product page: > https://www.sparkfun.com/products/15168 > Firmware and hardware sources: > https://github.com/sparkfun/Qwiic_Joystick > > Tested on RPi4B and O4-iMX-NANO boards. > > Cc: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> > Cc: Device Tree mailing list <devicetree@xxxxxxxxxxxxxxx> > Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> > Cc: Jiri Kosina <jikos@xxxxxxxx> > Cc: Patchwork Bot <patchwork-bot@xxxxxxxxxx> > Signed-off-by: Oleh Kravchenko <oleg@xxxxxxxxxx> > --- Please use a version number (e.g. v2, v3) and add a change log under the '---' when sending new versions. > .../bindings/input/qwiic-joystick.yaml | 31 ++++ > .../devicetree/bindings/vendor-prefixes.yaml | 2 + > drivers/input/joystick/Kconfig | 9 + > drivers/input/joystick/Makefile | 1 + > drivers/input/joystick/qwiic-joystick.c | 169 ++++++++++++++++++ > 5 files changed, 212 insertions(+) > create mode 100644 Documentation/devicetree/bindings/input/qwiic-joystick.yaml > create mode 100644 drivers/input/joystick/qwiic-joystick.c Bindings must be a separate patch with Rob Herring (see MAINTAINERS) on the To: list. > > diff --git a/Documentation/devicetree/bindings/input/qwiic-joystick.yaml b/Documentation/devicetree/bindings/input/qwiic-joystick.yaml > new file mode 100644 > index 000000000000..51cadeb350f2 > --- /dev/null > +++ b/Documentation/devicetree/bindings/input/qwiic-joystick.yaml > @@ -0,0 +1,31 @@ > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > +# Copyright 2021 Oleh Kravchenko > +%YAML 1.2 > +--- > +$id: "http://devicetree.org/schemas/input/qwiic-joystick.yaml#"; > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"; > + > +title: SparkFun Qwiic Joystick > + > +maintainers: > + - Oleh Kravchenko <oleg@xxxxxxxxxx> > + > +description: | > + Bindings for SparkFun Qwiic Joystick (COM-15168). > + https://www.sparkfun.com/products/15168 > + > +properties: > + compatible: > + const: sparkfun,qwiic-joystick > + > +required: > + - compatible 'reg' is required as well. > + > +additionalProperties: false > + > +examples: > + - | > + qwiic@20 { > + compatible = "sparkfun,qwiic-joystick"; > + reg = <0x20>; > + }; > diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml > index 944b02bb96d7..a5631e68f5d1 100644 > --- a/Documentation/devicetree/bindings/vendor-prefixes.yaml > +++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml > @@ -1060,6 +1060,8 @@ patternProperties: > description: Sony Corporation > "^spansion,.*": > description: Spansion Inc. > + "^sparkfun,.*": > + description: SparkFun Electronics > "^sprd,.*": > description: Spreadtrum Communications Inc. > "^sst,.*": > diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig > index 5e38899058c1..7dfe8ea90923 100644 > --- a/drivers/input/joystick/Kconfig > +++ b/drivers/input/joystick/Kconfig > @@ -372,6 +372,15 @@ config JOYSTICK_PXRC > To compile this driver as a module, choose M here: the > module will be called pxrc. > > +config JOYSTICK_QWIIC > + tristate "SparkFun Qwiic Joystick" > + depends on I2C > + help > + Say Y here if you want to use the SparkFun Qwiic Joystick. > + > + To compile this driver as a module, choose M here: the > + module will be called qwiic-joystick. > + > config JOYSTICK_FSIA6B > tristate "FlySky FS-iA6B RC Receiver" > select SERIO > diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile > index 31d720c9e493..5174b8aba2dd 100644 > --- a/drivers/input/joystick/Makefile > +++ b/drivers/input/joystick/Makefile > @@ -27,6 +27,7 @@ obj-$(CONFIG_JOYSTICK_MAPLE) += maplecontrol.o > obj-$(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_SIDEWINDER) += sidewinder.o > obj-$(CONFIG_JOYSTICK_SPACEBALL) += spaceball.o > obj-$(CONFIG_JOYSTICK_SPACEORB) += spaceorb.o > diff --git a/drivers/input/joystick/qwiic-joystick.c b/drivers/input/joystick/qwiic-joystick.c > new file mode 100644 > index 000000000000..9b7ab0dd1218 > --- /dev/null > +++ b/drivers/input/joystick/qwiic-joystick.c > @@ -0,0 +1,169 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (C) 2021 Oleh Kravchenko <oleg@xxxxxxxxxx> > + > +/* > + * SparkFun Qwiic Joystick > + * Product page:https://www.sparkfun.com/products/15168 > + * Firmware and hardware sources:https://github.com/sparkfun/Qwiic_Joystick > + */ Nit: typically the copyright information goes in the multi-line introductory comments; there is no need for a newline after the SPDX identifier either. > + > +#include <linux/bits.h> > +#include <linux/i2c.h> > +#include <linux/input.h> > +#include <linux/module.h> > + > +#define QWIIC_JSK_REG_VERS 0 > +#define QWIIC_JSK_REG_DATA 3 > + > +#define QWIIC_JSK_MAX_AXIS GENMASK(10, 0) > +#define QWIIC_JSK_FUZZ 2 > +#define QWIIC_JSK_FLAT 2 > + > +struct qwiic_jsk { > + char phys[32]; > + struct input_dev *dev; > + struct i2c_client *i2c; > +}; > + > +struct qwiic_ver { > + u8 addr; > + u8 major; > + u8 minor; > +} __packed; > + > +struct qwiic_data { > + u8 hx; > + u8 lx; > + u8 hy; > + u8 ly; > + u8 thumb; > +} __packed; Let's use __be16 for 16-bit big-endian horizontal and vertical position. > + > +static void qwiic_poll(struct input_dev *input) > +{ > + struct qwiic_jsk *priv; > + struct qwiic_data data; > + int ret; > + int x, y, btn; No need to align these declarations. > + > + priv = input_get_drvdata(input); > + > + ret = i2c_smbus_read_i2c_block_data(priv->i2c, QWIIC_JSK_REG_DATA, > + sizeof(data), (u8 *)&data); > + if (ret == sizeof(data)) { This is personal preference, but returning early on error avoids having to indent the rest of the function. > + x = (data.hx << 8 | data.lx) >> 6; > + y = (data.hy << 8 | data.ly) >> 6; With hx/lx and hy/ly defined using __be16, you can use be16_to_cpu() to resolve the 16-bit value. A comment to explain the 6-bit shift from the documentation would be useful too. > + btn = !!!data.thumb; I don't think the triple-not is necessary as input_report_key() already squashes non-zero values to 1 with '!!'. If register 0x07's polarity is inverted, just pass !data.thumb to input_report_key(). > + > + input_report_abs(input, ABS_X, x); > + input_report_abs(input, ABS_Y, y); > + input_report_key(input, BTN_THUMBL, btn); > + > + input_sync(input); > + } > +} > + > +static int qwiic_probe(struct i2c_client *i2c, const struct i2c_device_id *id) It's much more common (and easier to read) if the i2c_client struct is passed as *client. > +{ > + struct qwiic_jsk *priv; > + struct qwiic_ver vers; > + int ret; No need to align these declarations. > + > + ret = i2c_smbus_read_i2c_block_data(i2c, QWIIC_JSK_REG_VERS, > + sizeof(vers), (u8 *)&vers); > + if (ret != sizeof(vers)) { > + ret = -EIO; > + goto err; > + } If i2c_smbus_read_i2c_block_data() returned a negative value, the original return value should be preserved. Only return -EIO if 0 <= ret < sizeof(). You can also simply return directly; there is nothing to be undone at this stage. > + > + if (i2c->addr != vers.addr) { > + dev_err(&i2c->dev, "address doesn't match!\n"); > + ret = -ENODEV; > + goto err; > + } This error should be impossible. If the address in dts does not match what the hardware is expecting, i2c_smbus_read_i2c_block_data() would have been NAK'd in the first place. > + > + dev_info(&i2c->dev, "SparkFun Qwiic Joystick, FW: %d.%d\n", > + vers.major, vers.minor); This should be dev_dbg() at most. > + > + priv = devm_kzalloc(&i2c->dev, sizeof(*priv), GFP_KERNEL); > + if (!priv) { > + ret = -ENOMEM; > + goto err; > + } Just return -ENOMEM here. > + > + priv->i2c = i2c; > + snprintf(priv->phys, sizeof(priv->phys), "i2c/%s", dev_name(&i2c->dev)); > + i2c_set_clientdata(i2c, priv); > + > + priv->dev = devm_input_allocate_device(&i2c->dev); > + if (!priv->dev) { > + dev_err(&i2c->dev, "failed to allocate input device\n"); No need for a print here. > + ret = -ENOMEM; > + goto err; Just return -ENOMEM here. > + } > + > + priv->dev->dev.parent = &i2c->dev; This is not necessary; devm_input_allocate_device() takes care of it. > + priv->dev->id.bustype = BUS_I2C; > + priv->dev->name = "SparkFun Qwiic Joystick"; > + priv->dev->phys = priv->phys; > + input_set_drvdata(priv->dev, priv); > + > + input_set_abs_params(priv->dev, ABS_X, 0, QWIIC_JSK_MAX_AXIS, > + QWIIC_JSK_FUZZ, QWIIC_JSK_FLAT); > + input_set_abs_params(priv->dev, ABS_Y, 0, QWIIC_JSK_MAX_AXIS, > + QWIIC_JSK_FUZZ, QWIIC_JSK_FLAT); > + input_set_capability(priv->dev, EV_KEY, BTN_THUMBL); > + > + ret = input_setup_polling(priv->dev, qwiic_poll); > + if (ret) { > + dev_err(&i2c->dev, "failed to set up polling: %d\n", ret); > + goto err; > + } Again, you can just return 'ret' here. > + input_set_poll_interval(priv->dev, 16); > + input_set_min_poll_interval(priv->dev, 8); > + input_set_max_poll_interval(priv->dev, 32); Is there any reason not to #define these intervals? > + > + ret = input_register_device(priv->dev); > + if (ret) > + dev_err(&i2c->dev, "failed to register joystick: %d\n", ret); > + > +err: This goto label is unnecessary. > + return ret; > +} > + > +static int qwiic_remove(struct i2c_client *i2c) > +{ > + struct qwiic_jsk *priv; > + > + priv = i2c_get_clientdata(i2c); > + input_unregister_device(priv->dev); > + > + return 0; > +} Because the input device was created with devm_input_allocate_device(), input_register_device() is managed as well. Therefore you can drop the remove callback altogether. > + > +static const struct of_device_id of_qwiic_match[] = { > + { .compatible = "sparkfun,qwiic-joystick", }, > + {}, Nit: { } > +}; > +MODULE_DEVICE_TABLE(of, of_qwiic_match); > + > +static const struct i2c_device_id qwiic_id_table[] = { > + { KBUILD_MODNAME, 0 }, > + {}, And here (see other drivers). > +}; > +MODULE_DEVICE_TABLE(i2c, qwiic_id_table); > + > +static struct i2c_driver qwiic_driver = { > + .driver = { > + .name = KBUILD_MODNAME, > + .of_match_table = of_match_ptr(of_qwiic_match), > + }, > + .id_table = qwiic_id_table, > + .probe = qwiic_probe, > + .remove = qwiic_remove, > +}; > +module_i2c_driver(qwiic_driver); No need for alignment here either. > + > +MODULE_AUTHOR("Oleh Kravchenko <oleg@xxxxxxxxxx>"); > +MODULE_DESCRIPTION("SparkFun Qwiic Joystick driver"); > +MODULE_LICENSE("GPL v2"); > -- > 2.26.3 > Kind regards, Jeff LaBundy
