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Date: Fri, 20 May 2016 09:34:04 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Vignesh R <vigneshr@...com>
Cc: Rob Herring <robh+dt@...nel.org>, Tony Lindgren <tony@...mide.com>,
Jonathan Corbet <corbet@....net>,
Johan Hovold <johan@...nel.org>,
Sylvain Rochet <sylvain.rochet@...secur.com>,
Masanari Iida <standby24x7@...il.com>,
Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
S Twiss <stwiss.opensource@...semi.com>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Moritz Fischer <moritz.fischer@...us.com>,
Arnd Bergmann <arnd@...db.de>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Timo Teras <timo.teras@....fi>,
Guido Martinez <guido@...guardiasur.com.ar>,
Clifton Barnes <clifton.a.barnes@...il.com>,
Uwe Kleine-Konig <u.kleine-koenig@...gutronix.de>,
linux-input@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 1/2] Input: rotary-encoder- Add support for absolute
encoder
On Thu, May 19, 2016 at 02:34:00PM +0530, Vignesh R wrote:
> There are rotary-encoders where GPIO lines reflect the actual position
> of the rotary encoder dial. For example, if dial points to 9, then four
> GPIO lines connected to the rotary encoder will read HLLH(1001b = 9).
> Add support for such rotary-encoder.
> The driver relies on rotary-encoder,absolute-encoder DT property to
> detect such encoders.
> Since, GPIO IRQs are not necessary to work with
> such encoders, optional polling mode support is added using
> input_poll_dev skeleton. This is can be used by enabling
> CONFIG_INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT.
Does this really belong to a rotary encoder and not a new driver that
simply translates gpio-encoded value into ABS* event?
>
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
> .../devicetree/bindings/input/rotary-encoder.txt | 4 +
> Documentation/input/rotary-encoder.txt | 9 ++
> drivers/input/misc/Kconfig | 11 ++
> drivers/input/misc/rotary_encoder.c | 165 ++++++++++++++++-----
> 4 files changed, 155 insertions(+), 34 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/input/rotary-encoder.txt b/Documentation/devicetree/bindings/input/rotary-encoder.txt
> index 6c9f0c8a846c..9c928dbd1500 100644
> --- a/Documentation/devicetree/bindings/input/rotary-encoder.txt
> +++ b/Documentation/devicetree/bindings/input/rotary-encoder.txt
> @@ -12,6 +12,10 @@ Optional properties:
> - rotary-encoder,relative-axis: register a relative axis rather than an
> absolute one. Relative axis will only generate +1/-1 events on the input
> device, hence no steps need to be passed.
> +- rotary-encoder,absolute-encoder: support encoders where GPIO lines
> + reflect the actual position of the rotary encoder dial. For example,
> + if dial points to 9, then four GPIO lines read HLLH(1001b = 9).
> + In this case, rotary-encoder,steps-per-period needed not be defined.
> - rotary-encoder,rollover: Automatic rollove when the rotary value becomes
> greater than the specified steps or smaller than 0. For absolute axis only.
> - rotary-encoder,steps-per-period: Number of steps (stable states) per period.
> diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt
> index 46a74f0c551a..dc76092f5618 100644
> --- a/Documentation/input/rotary-encoder.txt
> +++ b/Documentation/input/rotary-encoder.txt
> @@ -36,6 +36,15 @@ The phase diagram of these two outputs look like this:
> |<>|
> one step (quarter-period mode)
>
> +
> +In some encoders, the value pointed by rotary encoders switch is directly
> +reflected by status of the GPIOs connecting rotary encoder to CPU. For
> +example, if rotary encoder dial points to 9, then the four GPIOs
> +conncting rotary encoder will read HLLH(1001b = 9). Such encoders are
> +supported by defining devictree binding "rotary-encoder,absolute-encoder".
> +These encoders are also supported without need for event(IRQ) generation
> +using Input subsytem's polling mode support.
> +
> For more information, please see
> https://en.wikipedia.org/wiki/Rotary_encoder
>
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 1f2337abcf2f..81805f9a534c 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -566,6 +566,17 @@ config INPUT_GPIO_ROTARY_ENCODER
> To compile this driver as a module, choose M here: the
> module will be called rotary_encoder.
>
> +config INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT
> + bool "Polling mode support for rotary encoder"
> + depends on INPUT_GPIO_ROTARY_ENCODER
> + select INPUT_POLLDEV
> + help
> + Say Y here to enable polling mode support for rotary encoders
> + connected to GPIO lines that do have interrupt capability and
> + report rotary encoder position as absolute value over GPIO
> + lines. Check file: Documentation/input/rotary-encoder.txt for
> + more information.
> +
> config INPUT_RB532_BUTTON
> tristate "Mikrotik Routerboard 532 button interface"
> depends on MIKROTIK_RB532
> diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
> index c7fc8d4fb080..8f60289fb6cd 100644
> --- a/drivers/input/misc/rotary_encoder.c
> +++ b/drivers/input/misc/rotary_encoder.c
> @@ -25,24 +25,29 @@
> #include <linux/of.h>
> #include <linux/pm.h>
> #include <linux/property.h>
> +#include <linux/input-polldev.h>
>
> #define DRV_NAME "rotary-encoder"
>
> struct rotary_encoder {
> struct input_dev *input;
> -
> +#ifdef CONFIG_INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT
> + struct input_polled_dev *poll_dev;
> +#endif
> struct mutex access_mutex;
>
> u32 steps;
> u32 axis;
> bool relative_axis;
> bool rollover;
> + bool absolute_encoder;
>
> unsigned int pos;
>
> struct gpio_descs *gpios;
> + struct device *dev;
>
> - unsigned int *irq;
> + int *irq;
>
> bool armed;
> signed char dir; /* 1 - clockwise, -1 - CCW */
> @@ -67,6 +72,21 @@ static unsigned int rotary_encoder_get_state(struct rotary_encoder *encoder)
> return ret & 3;
> }
>
> +static unsigned int rotary_encoder_get_gpios_state(struct rotary_encoder
> + *encoder)
> +{
> + int i;
> + unsigned int ret = 0;
> +
> + for (i = 0; i < encoder->gpios->ndescs; ++i) {
> + int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
> +
> + ret = ret << 1 | val;
> + }
> +
> + return ret;
> +}
> +
> static void rotary_encoder_report_event(struct rotary_encoder *encoder)
> {
> if (encoder->relative_axis) {
> @@ -178,6 +198,72 @@ out:
> return IRQ_HANDLED;
> }
>
> +static void rotary_encoder_setup_input_params(struct rotary_encoder *encoder)
> +{
> + struct input_dev *input = encoder->input;
> + struct platform_device *pdev = to_platform_device(encoder->dev);
> +
> + input->name = pdev->name;
> + input->id.bustype = BUS_HOST;
> + input->dev.parent = encoder->dev;
> +
> + if (encoder->relative_axis)
> + input_set_capability(input, EV_REL, encoder->axis);
> + else
> + input_set_abs_params(input,
> + encoder->axis, 0, encoder->steps, 0, 1);
> +}
> +
> +static irqreturn_t rotary_absolute_encoder_irq(int irq, void *dev_id)
> +{
> + struct rotary_encoder *encoder = dev_id;
> + unsigned int state;
> +
> + mutex_lock(&encoder->access_mutex);
> +
> + state = rotary_encoder_get_gpios_state(encoder);
> + if (state != encoder->last_stable) {
> + input_report_abs(encoder->input, encoder->axis, state);
> + input_sync(encoder->input);
> + encoder->last_stable = state;
> + }
> +
> + mutex_lock(&encoder->access_mutex);
> +
> + return IRQ_HANDLED;
> +}
> +
> +#ifdef CONFIG_INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT
> +static void rotary_encoder_poll_gpios(struct input_polled_dev *poll_dev)
> +{
> + struct rotary_encoder *encoder = poll_dev->private;
> + unsigned int state = rotary_encoder_get_gpios_state(encoder);
> +
> + if (state != encoder->last_stable) {
> + input_report_abs(encoder->input, encoder->axis, state);
> + input_sync(encoder->input);
> + encoder->last_stable = state;
> + }
> +}
> +
> +static int rotary_encoder_register_poll_device(struct rotary_encoder
> + *encoder)
> +{
> + struct input_polled_dev *poll_dev =
> + devm_input_allocate_polled_device(encoder->dev);
> +
> + if (!poll_dev)
> + return -ENOMEM;
> + poll_dev->private = encoder;
> + poll_dev->poll = rotary_encoder_poll_gpios;
> + encoder->input = poll_dev->input;
> + rotary_encoder_setup_input_params(encoder);
> + encoder->poll_dev = poll_dev;
> +
> + return input_register_polled_device(poll_dev);
> +}
> +#endif
> +
> static int rotary_encoder_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -227,38 +313,32 @@ static int rotary_encoder_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> - input = devm_input_allocate_device(dev);
> - if (!input)
> - return -ENOMEM;
> -
> - encoder->input = input;
> -
> - input->name = pdev->name;
> - input->id.bustype = BUS_HOST;
> - input->dev.parent = dev;
> -
> - if (encoder->relative_axis)
> - input_set_capability(input, EV_REL, encoder->axis);
> - else
> - input_set_abs_params(input,
> - encoder->axis, 0, encoder->steps, 0, 1);
> -
> - switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
> - case 4:
> - handler = &rotary_encoder_quarter_period_irq;
> - encoder->last_stable = rotary_encoder_get_state(encoder);
> - break;
> - case 2:
> - handler = &rotary_encoder_half_period_irq;
> - encoder->last_stable = rotary_encoder_get_state(encoder);
> - break;
> - case 1:
> - handler = &rotary_encoder_irq;
> - break;
> - default:
> - dev_err(dev, "'%d' is not a valid steps-per-period value\n",
> - steps_per_period);
> - return -EINVAL;
> + encoder->dev = dev;
> + encoder->absolute_encoder =
> + device_property_read_bool(dev,
> + "rotary-encoder,absolute-encoder");
> + if (encoder->absolute_encoder) {
> + handler = rotary_absolute_encoder_irq;
> + } else {
> + switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
> + case 4:
> + handler = &rotary_encoder_quarter_period_irq;
> + encoder->last_stable =
> + rotary_encoder_get_state(encoder);
> + break;
> + case 2:
> + handler = &rotary_encoder_half_period_irq;
> + encoder->last_stable =
> + rotary_encoder_get_state(encoder);
> + break;
> + case 1:
> + handler = &rotary_encoder_irq;
> + break;
> + default:
> + dev_err(dev, "'%d' is not a valid steps-per-period value\n",
> + steps_per_period);
> + return -EINVAL;
> + }
> }
>
> encoder->irq =
> @@ -271,6 +351,18 @@ static int rotary_encoder_probe(struct platform_device *pdev)
> for (i = 0; i < encoder->gpios->ndescs; ++i) {
> encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
>
> +#ifdef CONFIG_INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT
> + if (encoder->irq[i] < 0 && encoder->absolute_encoder) {
> + dev_info(dev, "Using poll mode\n");
> + err = rotary_encoder_register_poll_device(encoder);
> + if (err) {
> + dev_err(dev, "failed to register poll dev\n");
> + return err;
> + }
> + platform_set_drvdata(pdev, encoder);
> + return 0;
> + }
> +#endif
> err = devm_request_threaded_irq(dev, encoder->irq[i],
> NULL, handler,
> IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
> @@ -283,6 +375,11 @@ static int rotary_encoder_probe(struct platform_device *pdev)
> }
> }
>
> + input = devm_input_allocate_device(dev);
> + if (!input)
> + return -ENOMEM;
> + encoder->input = input;
> + rotary_encoder_setup_input_params(encoder);
> err = input_register_device(input);
> if (err) {
> dev_err(dev, "failed to register input device\n");
> --
> 2.8.2
>
--
Dmitry
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