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Message-ID: <9e55f768356892fcf10de3241419f97124efd4f7.camel@redhat.com>
Date: Tue, 08 Feb 2022 12:44:03 +0100
From: Nicolas Saenz Julienne <nsaenzju@...hat.com>
To: Charles Mirabile <cmirabil@...hat.com>,
linux-kernel@...r.kernel.org
Cc: Serge Schneider <serge@...pberrypi.org>,
Stefan Wahren <stefan.wahren@...e.com>,
Mattias Brugger <mbrugger@...e.com>,
linux-rpi-kernel@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, fedora-rpi@...glegroups.com,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
linux-input@...r.kernel.org, Mwesigwa Guma <mguma@...hat.com>,
Joel Savitz <jsavitz@...hat.com>
Subject: Re: [PATCH 2/6] drivers/input/joystick: sensehat: Raspberry Pi
Sense HAT joystick driver
On Wed, 2022-02-02 at 19:25 -0500, Charles Mirabile wrote:
> This patch adds the driver for the Sense HAT joystick. It outputs BTN_DPAD
> key events when moved in any of the four directions and the BTN_SELECT
> event when depressed.
>
> Co-developed-by: Mwesigwa Guma <mguma@...hat.com>
> Signed-off-by: Mwesigwa Guma <mguma@...hat.com>
> Co-developed-by: Joel Savitz <jsavitz@...hat.com>
> Signed-off-by: Joel Savitz <jsavitz@...hat.com>
> Signed-off-by: Charles Mirabile <cmirabil@...hat.com>
> ---
> drivers/input/joystick/Kconfig | 11 ++
> drivers/input/joystick/Makefile | 1 +
> drivers/input/joystick/sensehat-joystick.c | 128 +++++++++++++++++++++
> 3 files changed, 140 insertions(+)
> create mode 100644 drivers/input/joystick/sensehat-joystick.c
>
> diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
> index 3b23078bc7b5..505a032e2786 100644
> --- a/drivers/input/joystick/Kconfig
> +++ b/drivers/input/joystick/Kconfig
> @@ -399,4 +399,15 @@ config JOYSTICK_N64
> Say Y here if you want enable support for the four
> built-in controller ports on the Nintendo 64 console.
>
> +config JOYSTICK_SENSEHAT
> + tristate "Raspberry Pi Sense HAT joystick"
> + depends on INPUT && I2C
> + select MFD_SIMPLE_MFD_I2C
> + help
> + Say Y here if you want to enable the driver for the
> + the Raspberry Pi Sense HAT.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called sensehat_joystick.
> +
> endif
> diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
> index 5174b8aba2dd..39c8b5c6e5ae 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-$(CONFIG_JOYSTICK_SENSEHAT) += sensehat-joystick.o
> obj-$(CONFIG_JOYSTICK_SIDEWINDER) += sidewinder.o
> obj-$(CONFIG_JOYSTICK_SPACEBALL) += spaceball.o
> obj-$(CONFIG_JOYSTICK_SPACEORB) += spaceorb.o
> diff --git a/drivers/input/joystick/sensehat-joystick.c b/drivers/input/joystick/sensehat-joystick.c
> new file mode 100644
> index 000000000000..a688cc8fbde3
> --- /dev/null
> +++ b/drivers/input/joystick/sensehat-joystick.c
> @@ -0,0 +1,128 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Raspberry Pi Sense HAT joystick driver
> + * http://raspberrypi.org
> + *
> + * Copyright (C) 2015 Raspberry Pi
> + * Copyright (C) 2021 Charles Mirabile, Mwesigwa Guma, Joel Savitz
> + *
> + * Original Author: Serge Schneider
> + * Revised for upstream Linux by: Charles Mirabile, Mwesigwa Guma, Joel Savitz
> + */
> +
> +#include <linux/module.h>
> +#include <linux/input.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/of_irq.h>
> +#include <linux/property.h>
> +
> +struct sensehat_joystick {
> + struct platform_device *pdev;
> + struct input_dev *keys_dev;
> + unsigned long prev_states;
> + u32 joystick_register;
> +};
> +
> +static const unsigned int keymap[] = {
> + BTN_DPAD_DOWN, BTN_DPAD_RIGHT, BTN_DPAD_UP, BTN_SELECT, BTN_DPAD_LEFT,
> +};
> +
> +static irqreturn_t sensehat_joystick_report(int n, void *cookie)
> +{
> + int i, error, keys;
> + struct sensehat_joystick *sensehat_joystick = cookie;
> + struct regmap *regmap =
> + dev_get_regmap(sensehat_joystick->pdev->dev.parent, NULL);
I think it's better to get this during probe and save it in 'struct
sensehat_joystick'. You'll avoid having to search for it everytime.
> + unsigned long curr_states, changes;
> +
> + error = regmap_read(regmap, sensehat_joystick->joystick_register,
> + &keys);
> + if (error < 0) {
> + dev_err(&sensehat_joystick->pdev->dev,
> + "Failed to read joystick state: %d", error);
> + return IRQ_NONE;
> + }
> + curr_states = keys;
> + bitmap_xor(&changes, &curr_states, &sensehat_joystick->prev_states,
> + ARRAY_SIZE(keymap));
> +
> + for_each_set_bit(i, &changes, ARRAY_SIZE(keymap)) {
> + input_report_key(sensehat_joystick->keys_dev, keymap[i],
> + curr_states & BIT(i));
> + }
> +
> + input_sync(sensehat_joystick->keys_dev);
> + sensehat_joystick->prev_states = keys;
> + return IRQ_HANDLED;
> +}
> +
> +static int sensehat_joystick_probe(struct platform_device *pdev)
> +{
> + int error, i;
> + struct sensehat_joystick *sensehat_joystick = devm_kzalloc(
> + &pdev->dev, sizeof(*sensehat_joystick), GFP_KERNEL);
> +
> + sensehat_joystick->pdev = pdev;
> + sensehat_joystick->keys_dev = devm_input_allocate_device(&pdev->dev);
> + if (!sensehat_joystick->keys_dev) {
> + dev_err(&pdev->dev, "Could not allocate input device.\n");
> + return -ENOMEM;
> + }
> +
> + for (i = 0; i < ARRAY_SIZE(keymap); i++)
> + set_bit(keymap[i], sensehat_joystick->keys_dev->keybit);
> +
> + sensehat_joystick->keys_dev->name = "Raspberry Pi Sense HAT Joystick";
> + sensehat_joystick->keys_dev->phys = "sensehat-joystick/input0";
> + sensehat_joystick->keys_dev->id.bustype = BUS_I2C;
> + sensehat_joystick->keys_dev->evbit[0] =
> + BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
> +
> + error = input_register_device(sensehat_joystick->keys_dev);
> + if (error) {
> + dev_err(&pdev->dev, "Could not register input device.\n");
> + return error;
> + }
> +
> + error = device_property_read_u32(&pdev->dev, "reg",
> + &sensehat_joystick->joystick_register);
> + if (error) {
> + dev_err(&pdev->dev, "Could not read register property.\n");
> + return error;
> + }
I don't think you really need to pass this information through the devicetree.
It's just the address to a register, not a HW design detail (i.e. how the board
is layout). Using a define is good enough.
> +
> + error = devm_request_threaded_irq(&pdev->dev,
> + of_irq_get(pdev->dev.of_node, 0),
Use platform_get_irq() and remember the function may fail, both unrecoverable
errors and EPROBE_DEFER when the irqchip isn't ready yet.
> + NULL, sensehat_joystick_report,
> + IRQF_ONESHOT, "keys",
> + sensehat_joystick);
> +
> + if (error) {
> + dev_err(&pdev->dev, "IRQ request failed.\n");
> + return error;
> + }
nit: space here
> + return 0;
> +}
> +
> +static const struct of_device_id sensehat_joystick_device_id[] = {
> + { .compatible = "raspberrypi,sensehat-joystick" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, sensehat_joystick_device_id);
> +
> +static struct platform_driver sensehat_joystick_driver = {
> + .probe = sensehat_joystick_probe,
> + .driver = {
> + .name = "sensehat-joystick",
> + .of_match_table = sensehat_joystick_device_id,
> + },
> +};
> +
> +module_platform_driver(sensehat_joystick_driver);
> +
> +MODULE_DESCRIPTION("Raspberry Pi Sense HAT joystick driver");
> +MODULE_AUTHOR("Serge Schneider <serge@...pberrypi.org>");
> +MODULE_LICENSE("GPL");
--
Nicolás Sáenz
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