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Message-ID: <YbPgCdkVpEJw5XQM@google.com>
Date: Fri, 10 Dec 2021 15:17:29 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Charles Mirabile <cmirabil@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
Serge Schneider <serge@...pberrypi.org>,
Stefan Wahren <stefan.wahren@...e.com>,
Nicolas Saenz Julienne <nsaenzju@...hat.com>,
Mattias Brugger <mbrugger@...e.com>,
linux-rpi-kernel@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, fedora-rpi@...glegroups.com,
Mwesigwa Guma <mguma@...hat.com>,
Joel Savitz <jsavitz@...hat.com>
Subject: Re: [PATCH V5 2/6] drivers/input/joystick: sensehat: Raspberry Pi
Sense HAT joystick driver
Hi Charles,
On Fri, Dec 10, 2021 at 05:10:29PM -0500, Charles Mirabile wrote:
> This patch implements support for the joystick.
> It supports left/right/up/down/enter and is
> attached via i2c and a gpio pin for irq.
This is not really a joystick, at least not in current incarnation, but
rather a set of keys. I'd also question whether the selected set is
right for the application, I'd look into BTN_DPAD_* maybe?
Or, if you want it to be a joystick, map ABS_X/ABS_Y.
>
> Signed-off-by: Charles Mirabile <cmirabil@...hat.com>
> 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>
> ---
> drivers/input/joystick/Kconfig | 8 ++
> drivers/input/joystick/Makefile | 1 +
> drivers/input/joystick/sensehat-joystick.c | 119 +++++++++++++++++++++
> 3 files changed, 128 insertions(+)
> create mode 100644 drivers/input/joystick/sensehat-joystick.c
>
> diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
> index 3b23078bc7b5..d5c5ffe13903 100644
> --- a/drivers/input/joystick/Kconfig
> +++ b/drivers/input/joystick/Kconfig
> @@ -399,4 +399,12 @@ 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 GPIOLIB && INPUT && I2C
I do not see I2C accessed directly in this driver, nor GPIO interface.
You also do not need to depend on INPUT explicitly here.
> + select MFD_SENSEHAT_CORE
> +
> + help
> + This is the joystick driver for the Raspberry Pi Sense HAT
> +
> 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..1f6bb09b4d1f
> --- /dev/null
> +++ b/drivers/input/joystick/sensehat-joystick.c
> @@ -0,0 +1,119 @@
> +// 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>
Don't think you need this.
> +#include <linux/interrupt.h>
> +#include <linux/gpio/consumer.h>
Not needed.
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/sensehat.h>
> +
> +#define SENSEHAT_KEYS 0xF2
> +
> +static int sensehat_get_joystick_state(struct sensehat *sensehat);
> +
> +static unsigned char keymap[] = {
> + KEY_DOWN, KEY_RIGHT, KEY_UP, KEY_ENTER, KEY_LEFT,
> +};
Because you allowing manipulating keymap from userspace you need to make
a copy of it when setting up input device so that changes do would not
persist across bind/unbind.
This array needs to be marked const.
> +
> +static irqreturn_t sensehat_joystick_report(int n, void *cookie)
> +{
> + int i;
> + static s32 prev_keys;
> + struct sensehat *sensehat = cookie;
> + struct sensehat_joystick *sensehat_joystick = &sensehat->joystick;
> + s32 keys = sensehat_get_joystick_state(sensehat);
> + s32 changes = keys ^ prev_keys;
> +
> + prev_keys = keys;
> + for (i = 0; i < ARRAY_SIZE(keymap); ++i) {
> + if (changes & (1 << i)) {
> + input_report_key(sensehat_joystick->keys_dev, keymap[i],
> + keys & (1 << i));
> + }
> + }
If you go with keys/buttons approach, then use
bitmap_xor()/for_each_set_bit() - see
drivers/input/keyboard/cypress-sf.c::cypress_sf_irq_handler() for
example of use.
> + input_sync(sensehat_joystick->keys_dev);
> + return IRQ_HANDLED;
> +}
> +
> +static int sensehat_joystick_probe(struct platform_device *pdev)
> +{
> + int ret;
Please call it "error";
> + int i;
> + struct sensehat *sensehat = dev_get_drvdata(&pdev->dev);
> + struct sensehat_joystick *sensehat_joystick = &sensehat->joystick;
This structure (struct sensehat_joystick) should probably be private to
this driver.
> +
> + 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 = "rpi-sense-joy/input0";
> + sensehat_joystick->keys_dev->id.bustype = BUS_I2C;
> + sensehat_joystick->keys_dev->evbit[0] =
> + BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
> + sensehat_joystick->keys_dev->keycode = keymap;
> + sensehat_joystick->keys_dev->keycodesize = sizeof(unsigned char);
> + sensehat_joystick->keys_dev->keycodemax = ARRAY_SIZE(keymap);
> +
> + ret = input_register_device(sensehat_joystick->keys_dev);
> + if (ret) {
> + dev_err(&pdev->dev, "Could not register input device.\n");
> + return ret;
> + }
> +
> + ret = devm_request_threaded_irq(&pdev->dev, sensehat->i2c_client->irq,
> + NULL, sensehat_joystick_report,
> + IRQF_TRIGGER_RISING | IRQF_ONESHOT,
Do not specify trigger type, whoever set up client's interrupt should
have set up appropriate trigger.
> + "keys", sensehat);
> +
> + if (ret) {
> + dev_err(&pdev->dev, "IRQ request failed.\n");
> + return ret;
> + }
> + return 0;
> +}
> +
> +int sensehat_get_joystick_state(struct sensehat *sensehat)
> +{
> + unsigned int reg;
> + int ret = regmap_read(sensehat->regmap, SENSEHAT_KEYS, ®);
> +
> + return ret < 0 ? ret : reg;
I do not see the point in having this wrapper.
> +}
> +
> +static struct platform_device_id sensehat_joystick_device_id[] = {
> + { .name = "sensehat-joystick" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(platform, sensehat_joystick_device_id);
> +
> +static struct platform_driver sensehat_joystick_driver = {
> + .probe = sensehat_joystick_probe,
> + .driver = {
> + .name = "sensehat-joystick",
> + },
> +};
> +
> +module_platform_driver(sensehat_joystick_driver);
> +
> +MODULE_DESCRIPTION("Raspberry Pi Sense HAT joystick driver");
> +MODULE_AUTHOR("Serge Schneider <serge@...pberrypi.org>");
> +MODULE_LICENSE("GPL");
> --
> 2.31.1
>
Thanks.
--
Dmitry
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