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Message-ID: <a41d31b7-9d7a-0d94-a045-1e2285064040@ti.com>
Date: Mon, 29 Aug 2016 09:50:28 +0530
From: Vignesh R <vigneshr@...com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
CC: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Tony Lindgren <tony@...mide.com>,
Russell King <linux@...linux.org.uk>,
Arnd Bergmann <arnd@...db.de>,
Daniel Hung-yu Wu <hywu@...gle.com>,
Grant Grundler <grundler@...omium.org>,
S Twiss <stwiss.opensource@...semi.com>,
Moritz Fischer <moritz.fischer@...us.com>,
Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>,
John Stultz <john.stultz@...aro.org>,
"Davis, Andrew" <afd@...com>,
"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 1/2] input: misc: Add generic input driver to read
encoded GPIO lines
On Thursday 25 August 2016 10:26 PM, Dmitry Torokhov wrote:
> On Wed, Aug 24, 2016 at 01:28:58PM +0530, Vignesh R wrote:
>> Add a driver to read group of GPIO lines and provide its status as a
>> numerical value as input event to the system. This will help in
>> interfacing devices, that can be connected over GPIOs, that provide
>> input to the system by driving GPIO lines connected to them like a
>> rotary dial or a switch.
>>
>> For example, a rotary switch can be connected to four GPIO lines. The
>> status of the GPIO lines reflect the actual position of the rotary
>> switch dial. For example, if dial points to 9, then the four GPIO lines
>> connected to the switch will read HLLH(0b'1001 = 9). This value
>> can be reported as an ABS_* event to the input subsystem.
>>
>> Signed-off-by: Vignesh R <vigneshr@...com>
>> Acked-by: Rob Herring <robh@...nel.org>
>> ---
>>
>> v3: Fix comments by Andrew and Dmitry
>> Link to v2: https://lkml.org/lkml/2016/8/23/79
>>
>> .../devicetree/bindings/input/gpio-decoder.txt | 23 ++++
>> drivers/input/misc/Kconfig | 12 ++
>> drivers/input/misc/Makefile | 1 +
>> drivers/input/misc/gpio_decoder.c | 134 +++++++++++++++++++++
>> 4 files changed, 170 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/input/gpio-decoder.txt
>> create mode 100644 drivers/input/misc/gpio_decoder.c
>>
>> diff --git a/Documentation/devicetree/bindings/input/gpio-decoder.txt b/Documentation/devicetree/bindings/input/gpio-decoder.txt
>> new file mode 100644
>> index 000000000000..14a77fb96cf0
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/input/gpio-decoder.txt
>> @@ -0,0 +1,23 @@
>> +* GPIO Decoder DT bindings
>> +
>> +Required Properties:
>> +- compatible: should be "gpio-decoder"
>> +- gpios: a spec of gpios (at least two) to be decoded to a number with
>> + first entry representing the MSB.
>> +
>> +Optional Properties:
>> +- decoder-max-value: Maximum possible value that can be reported by
>> + the gpios.
>> +- linux,axis: the input subsystem axis to map to (ABS_X/ABS_Y).
>> + Defaults to 0 (ABS_X).
>> +
>> +Example:
>> + gpio-decoder0 {
>> + compatible = "gpio-decoder";
>> + gpios = <&pca9536 3 GPIO_ACTIVE_HIGH>,
>> + <&pca9536 2 GPIO_ACTIVE_HIGH>,
>> + <&pca9536 1 GPIO_ACTIVE_HIGH>,
>> + <&pca9536 0 GPIO_ACTIVE_HIGH>;
>> + linux,axis = <0>; /* ABS_X */
>> + decoder-max-value = <9>;
>> + };
>> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
>> index efb0ca871327..7cdb89397d18 100644
>> --- a/drivers/input/misc/Kconfig
>> +++ b/drivers/input/misc/Kconfig
>> @@ -292,6 +292,18 @@ config INPUT_GPIO_TILT_POLLED
>> To compile this driver as a module, choose M here: the
>> module will be called gpio_tilt_polled.
>>
>> +config INPUT_GPIO_DECODER
>> + tristate "Polled GPIO Decoder Input driver"
>> + depends on GPIOLIB || COMPILE_TEST
>> + select INPUT_POLLDEV
>> + help
>> + Say Y here if you want driver to read status of multiple GPIO
>> + lines and report the encoded value as an absolute integer to
>> + input subsystem.
>> +
>> + To compile this driver as a module, choose M here: the module
>> + will be called gpio_decoder.
>> +
>> config INPUT_IXP4XX_BEEPER
>> tristate "IXP4XX Beeper support"
>> depends on ARCH_IXP4XX
>> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
>> index 6a1e5e20fc1c..0b6d025f0487 100644
>> --- a/drivers/input/misc/Makefile
>> +++ b/drivers/input/misc/Makefile
>> @@ -35,6 +35,7 @@ obj-$(CONFIG_INPUT_DRV2667_HAPTICS) += drv2667.o
>> obj-$(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_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/gpio_decoder.c b/drivers/input/misc/gpio_decoder.c
>> new file mode 100644
>> index 000000000000..1c2191d4b143
>> --- /dev/null
>> +++ b/drivers/input/misc/gpio_decoder.c
>> @@ -0,0 +1,134 @@
>> +/*
>> + * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License as
>> + * published by the Free Software Foundation version 2.
>> + *
>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> + * kind, whether express or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * A generic driver to read multiple gpio lines and translate the
>> + * encoded numeric value into an input event.
>> + */
>> +
>> +#include <linux/device.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/input.h>
>> +#include <linux/input-polldev.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +
>> +struct gpio_decoder {
>> + struct input_polled_dev *poll_dev;
>> + struct gpio_descs *input_gpios;
>> + struct device *dev;
>> + u32 axis;
>> + u32 last_stable;
>> +};
>> +
>> +static unsigned int gpio_decoder_get_gpios_state(struct gpio_decoder
>> + *decoder)
>> +{
>> + struct gpio_descs *gpios = decoder->input_gpios;
>> + unsigned int ret = 0;
>> + int i, val;
>> +
>> + for (i = 0; i < gpios->ndescs; i++) {
>> + val = gpiod_get_value_cansleep(gpios->desc[i]);
>> + if (val >= 0) {
>> + ret = (ret << 1) | !!val;
>> + } else {
>> + dev_err(decoder->dev, "Error reading gpio\n");
>> + break;
>
> I think if we fail reading any one of gpio lines we should skip
> reporting the event.
>
Ok.
>> + }
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static void gpio_decoder_poll_gpios(struct input_polled_dev *poll_dev)
>> +{
>> + struct gpio_decoder *decoder = poll_dev->private;
>> + unsigned int state = gpio_decoder_get_gpios_state(decoder);
>> +
>> + if (state != decoder->last_stable) {
>> + input_report_abs(poll_dev->input, decoder->axis, state);
>> + input_sync(poll_dev->input);
>> + decoder->last_stable = state;
>> + }
>> +}
>> +
>> +static int gpio_decoder_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct gpio_decoder *decoder;
>> + struct input_polled_dev *poll_dev;
>> + u32 max;
>> + int err;
>> +
>> + decoder = devm_kzalloc(dev, sizeof(struct gpio_decoder), GFP_KERNEL);
>> + if (!decoder)
>> + return -ENOMEM;
>> +
>> + device_property_read_u32(dev, "linux,axis", &decoder->axis);
>> + decoder->input_gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
>> + if (IS_ERR(decoder->input_gpios)) {
>> + dev_err(dev, "unable to acquire input gpios\n");
>> + return PTR_ERR(decoder->input_gpios);
>> + }
>> + if (decoder->input_gpios->ndescs < 2) {
>> + dev_err(dev, "not enough gpios found\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (device_property_read_u32(dev, "decoder-max-value", &max))
>> + max = BIT(decoder->input_gpios->ndescs);
>
> Shouldn't this be
>
> max = (1U << decoder->input_gpios->ndescs) - 1;
>
> ?
Oops, you are right.
>
>> +
>> + decoder->dev = dev;
>> + poll_dev = devm_input_allocate_polled_device(decoder->dev);
>> + if (!poll_dev)
>> + return -ENOMEM;
>> +
>> + poll_dev->private = decoder;
>> + poll_dev->poll = gpio_decoder_poll_gpios;
>> + decoder->poll_dev = poll_dev;
>> +
>> + poll_dev->input->name = pdev->name;
>> + poll_dev->input->id.bustype = BUS_HOST;
>> + input_set_abs_params(poll_dev->input, decoder->axis, 0, max, 0, 1);
>
> Why do you need flat == 1? Do you actually use joydev for this device?
>
Sorry, I overlooked flat param when I copied this line from
rotary-encoder.c.
>> +
>> + err = input_register_polled_device(poll_dev);
>> + if (err) {
>> + dev_err(dev, "failed to register polled device\n");
>> + return err;
>> + }
>> + platform_set_drvdata(pdev, decoder);
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id gpio_decoder_of_match[] = {
>> + { .compatible = "gpio-decoder", },
>> + { },
>> +};
>> +MODULE_DEVICE_TABLE(of, gpio_decoder_of_match);
>> +#endif
>> +
>> +static struct platform_driver gpio_decoder_driver = {
>> + .probe = gpio_decoder_probe,
>> + .driver = {
>> + .name = "gpio-decoder",
>> + .of_match_table = of_match_ptr(gpio_decoder_of_match),
>> + }
>> +};
>> +module_platform_driver(gpio_decoder_driver);
>> +
>> +MODULE_DESCRIPTION("GPIO decoder input driver");
>> +MODULE_AUTHOR("Vignesh R <vigneshr@...com>");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 2.9.2
>>
>
> No need to resubmit, I can adjust on my side.
Thanks a lot!
--
Regards
Vignesh
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