linux-kernel - Re: [PATCH v2 4/4] input: misc: Add Gateworks System Controller support

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Date:   Sat, 10 Mar 2018 10:45:02 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Tim Harvey <tharvey@...eworks.com>
Cc:     Lee Jones <lee.jones@...aro.org>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-hwmon@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH v2 4/4] input: misc: Add Gateworks System Controller
 support

On Mon, Mar 05, 2018 at 02:02:41PM -0800, Tim Harvey wrote:
> Add support for dispatching Linux Input events for the various interrupts
> the Gateworks System Controller provides.
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Signed-off-by: Tim Harvey <tharvey@...eworks.com>
> ---
> v2:
> - reword Kconfig
> - revise license comment block
> - remove unnecessary read of status register
> - remove unnecessary setting of input->dev.parent
> - use dt bindings for irq to keycode mapping
> - add support for platform-data
> - remove work-queue
> 
>  drivers/input/misc/Kconfig              |   9 ++
>  drivers/input/misc/Makefile             |   1 +
>  drivers/input/misc/gsc-input.c          | 180 ++++++++++++++++++++++++++++++++
>  include/linux/platform_data/gsc_input.h |  30 ++++++
>  4 files changed, 220 insertions(+)
>  create mode 100644 drivers/input/misc/gsc-input.c
>  create mode 100644 include/linux/platform_data/gsc_input.h
> 
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 9f082a3..e05f4fe 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -117,6 +117,15 @@ config INPUT_E3X0_BUTTON
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called e3x0_button.
>  
> +config INPUT_GSC
> +	tristate "Gateworks System Controller input support"
> +	depends on MFD_GSC
> +	help
> +	  Support GSC events as Linux input events.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called gsc_input.
> +
>  config INPUT_PCSPKR
>  	tristate "PC Speaker support"
>  	depends on PCSPKR_PLATFORM
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index 4b6118d..969debe 100644
> --- a/drivers/input/misc/Makefile
> +++ b/drivers/input/misc/Makefile
> @@ -38,6 +38,7 @@ obj-$(CONFIG_INPUT_GP2A)		+= gp2ap002a00f.o
>  obj-$(CONFIG_INPUT_GPIO_BEEPER)		+= gpio-beeper.o
>  obj-$(CONFIG_INPUT_GPIO_TILT_POLLED)	+= gpio_tilt_polled.o
>  obj-$(CONFIG_INPUT_GPIO_DECODER)	+= gpio_decoder.o
> +obj-$(CONFIG_INPUT_GSC)			+= gsc-input.o
>  obj-$(CONFIG_INPUT_HISI_POWERKEY)	+= hisi_powerkey.o
>  obj-$(CONFIG_HP_SDC_RTC)		+= hp_sdc_rtc.o
>  obj-$(CONFIG_INPUT_IMS_PCU)		+= ims-pcu.o
> diff --git a/drivers/input/misc/gsc-input.c b/drivers/input/misc/gsc-input.c
> new file mode 100644
> index 0000000..27b5e93
> --- /dev/null
> +++ b/drivers/input/misc/gsc-input.c
> @@ -0,0 +1,180 @@
> +/* SPDX-License-Identifier: GPL-2.0
> + *
> + * Copyright (C) 2018 Gateworks Corporation
> + *
> + * This driver dispatches Linux input events for GSC interrupt events
> + */
> +#include <linux/input.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/mfd/gsc.h>
> +#include <linux/platform_data/gsc_input.h>
> +
> +struct gsc_input_button_priv {
> +	struct input_dev *input;
> +	const struct gsc_input_button *button;
> +};
> +
> +struct gsc_input_data {
> +	struct gsc_dev *gsc;
> +	struct gsc_input_platform_data *pdata;
> +	struct input_dev *input;
> +	struct gsc_input_button_priv *buttons;
> +	int nbuttons;
> +	unsigned int irqs[];
> +#if 0
> +	int irq;
> +	struct work_struct irq_work;
> +	struct mutex mutex;
> +#endif
> +};
> +
> +static irqreturn_t gsc_input_irq(int irq, void *data)
> +{
> +	const struct gsc_input_button_priv *button_priv = data;
> +	struct input_dev *input = button_priv->input;
> +
> +	dev_dbg(&input->dev, "irq%d code=%d\n", irq, button_priv->button->code);
> +	input_report_key(input, button_priv->button->code, 1);
> +	input_sync(input);
> +	input_report_key(input, button_priv->button->code, 0);
> +	input_sync(input);
> +
> +	return IRQ_HANDLED;

Hmm, so in the end this is just a bunch of buttons connected to
interrupt lines. We already have a driver for that, called gpio-keys. It
can work in pure interrupt mode (i.e. do not need real GPIO pin, just
interrupt, and it will generate key down and up events when interrupt
arrives, with possible delay for the up event).

Thanks.

-- 
Dmitry