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From:   Tim Harvey <tharvey@gateworks.com>
Date:   Wed, 28 Feb 2018 11:44:12 -0800
Message-ID: <CAJ+vNU04YO5KOgMcqvxaZDwgRBJrxhOAe0jXVCYv_9k6-2XpAQ@mail.gmail.com>
Subject: Re: [RFC 4/4] input: misc: Add Gateworks System Controller support
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     Lee Jones <lee.jones@linaro.org>, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Mark Brown <broonie@kernel.org>, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-hwmon@vger.kernel.org, linux-input@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org
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On Tue, Feb 27, 2018 at 8:54 PM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> Hi Tim,

Hi Dmitry - thanks for the review!

>
> On Tue, Feb 27, 2018 at 05:21:14PM -0800, Tim Harvey wrote:
>> Add support for dispatching Linux Input events for the various interrupts
>> the Gateworks System Controller provides.
>>
>> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
>> ---
>>  drivers/input/misc/Kconfig     |   6 ++
>>  drivers/input/misc/Makefile    |   1 +
>>  drivers/input/misc/gsc-input.c | 196 +++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 203 insertions(+)
>>  create mode 100644 drivers/input/misc/gsc-input.c
>>
>> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
>> index 9f082a3..3d18a0e 100644
>> --- a/drivers/input/misc/Kconfig
>> +++ b/drivers/input/misc/Kconfig
>> @@ -117,6 +117,12 @@ 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
>> +       Say Y here if you want Gateworks System Controller input support.
>> +
>
> "To compile this driver as a module..."
>

ok

>>  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..7cf217c
>> --- /dev/null
>> +++ b/drivers/input/misc/gsc-input.c
>> @@ -0,0 +1,196 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2018 Gateworks Corporation
>> + */
>
> Let's keep the same // comment block fir the copyright notice as well.
> An one-line describing what this driver is would be appreciated too.

ok - will have this in v2:

// SPDX-License-Identifier: GPL-2.0
//
// Copyright (C) 2018 Gateworks Corporation
//
// This driver dispatches Linux input events for GSC interrupt events
//


>
>> +#define DEBUG
>
> Please no.
>

oops, did not mean to submit that

>> +
>> +#include <linux/input.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +
>> +#include <linux/mfd/gsc.h>
>> +
>> +struct gsc_irq {
>> +     unsigned int irq;
>> +     const char *name;
>> +     unsigned int virq;
>> +};
>> +
>> +static struct gsc_irq gsc_irqs[] = {
>> +     { GSC_IRQ_PB,           "button" },
>> +     { GSC_IRQ_KEY_ERASED,   "key-erased" },
>> +     { GSC_IRQ_EEPROM_WP,    "eeprom-wp" },
>> +     { GSC_IRQ_TAMPER,       "tamper" },
>> +     { GSC_IRQ_SWITCH_HOLD,  "button-held" },
>> +};
>> +
>> +struct gsc_input_info {
>> +     struct device *dev;
>> +     struct gsc_dev *gsc;
>> +     struct input_dev *input;
>> +
>> +     int irq;
>> +     struct work_struct irq_work;
>> +     struct mutex mutex;
>> +};
>> +
>> +static void gsc_input_irq_work(struct work_struct *work)
>> +{
>> +     struct gsc_input_info *info = container_of(work, struct gsc_input_info,
>> +                                                irq_work);
>> +     struct gsc_dev *gsc = info->gsc;
>> +     int i, ret = 0;
>> +     int key, sts;
>> +     struct gsc_irq *gsc_irq = NULL;
>> +
>> +     dev_dbg(gsc->dev, "%s irq%d\n", __func__, info->irq);
>> +     mutex_lock(&info->mutex);
>> +
>> +     for (i = 0; i < ARRAY_SIZE(gsc_irqs);i++)
>> +             if (info->irq == gsc_irqs[i].virq)
>> +                     gsc_irq = &gsc_irqs[i];
>> +     if (!gsc_irq) {
>> +             dev_err(info->dev, "interrupt: irq%d occurred\n", info->irq);
>> +             mutex_unlock(&info->mutex);
>> +             return;
>> +     }
>> +
>> +     ret = regmap_read(info->gsc->regmap, GSC_IRQ_STATUS, &sts);
>
> Why is this needed? To clear irq? What happens if several events happen
> at the same time? Do we lose one of them?

it was for original debugging and not needed - will remove

>
>> +     if (ret) {
>> +             dev_err(info->dev, "failed to read status register\n");
>> +             mutex_unlock(&info->mutex);
>> +             return;
>> +     }
>> +
>> +     key = -1;
>> +     switch (gsc_irq->virq) {
>> +     case GSC_IRQ_PB:
>> +             key = BTN_0;
>> +             break;
>> +     case GSC_IRQ_KEY_ERASED:
>> +             key = BTN_1;
>> +             break;
>> +     case GSC_IRQ_EEPROM_WP:
>> +             key = BTN_2;
>> +             break;
>> +     case GSC_IRQ_GPIO:
>> +             key = BTN_3;
>> +             break;
>> +     case GSC_IRQ_TAMPER:
>> +             key = BTN_4;
>> +             break;
>> +     case GSC_IRQ_SWITCH_HOLD:
>> +             key = BTN_5;
>
> Could we provide the mapping in DTS instead of hard-coding them?

Yes, that makes sense. I'll propose something like the following in v2:

gsc_input {
   compatible = "gw,gsc-input";

   button {
      label = "user pushbutton";
      linux,code = <256>;
      interrupts = <0>
   };

   key-erased {
      label = "key erased";
      linux,code = <257>;
      interrupts = <1>
   };

   ...
};


>
>> +             break;
>> +     }
>> +
>> +     if (key != -1) {
>> +             dev_dbg(&info->input->dev, "bit%d: key=0x%03x %s\n",
>> +                     gsc_irq->virq, key, gsc_irq->name);
>> +             input_report_key(info->input, key, 1);
>
>                 input_sync();

right - thanks!

>
>> +             input_report_key(info->input, key, 0);
>> +             input_sync(info->input);
>> +     }
>> +
>> +     mutex_unlock(&info->mutex);
>> +}
>> +
>> +static irqreturn_t gsc_input_irq(int irq, void *data)
>> +{
>> +     struct gsc_input_info *info = data;
>> +
>> +     dev_dbg(info->gsc->dev, "%s irq%d\n", __func__, irq);
>> +     info->irq = irq;
>> +     schedule_work(&info->irq_work);
>
> Why not use threaded interrupt?

I am using request_threaded_irq with thread_fn with thread_fn (vs handler).

Do you mean why use a work procedure? I guess I don't need that and
can call input_report_key directly from the irq.

>
>> +
>> +     return IRQ_HANDLED;
>> +}
>> +
>> +static int gsc_input_probe(struct platform_device *pdev)
>> +{
>> +     struct gsc_dev *gsc = dev_get_drvdata(pdev->dev.parent);
>> +     struct gsc_input_info *info;
>> +     struct input_dev *input;
>> +     int ret, i;
>> +
>> +     dev_dbg(&pdev->dev, "%s\n", __func__);
>> +     info = devm_kzalloc(&pdev->dev, sizeof(struct gsc_input_info),
>> +                         GFP_KERNEL);
>> +     if (!info)
>> +             return -ENOMEM;
>> +     info->dev = &pdev->dev;
>> +     info->gsc = gsc;
>> +
>> +     /* Register input device */
>> +     input = devm_input_allocate_device(&pdev->dev);
>> +     if (!input) {
>> +             dev_err(&pdev->dev, "Can't allocate input device\n");
>> +             return -ENOMEM;
>> +     }
>> +     info->input = input;
>> +
>> +     input->name = KBUILD_MODNAME;
>> +     input->dev.parent = &pdev->dev;
>
> Not needed - it is set by devm_input_allocate_device().

ok

>
>> +
>> +     input_set_capability(input, EV_KEY, BTN_0); /* button */
>> +     input_set_capability(input, EV_KEY, BTN_1); /* key erased */
>> +     input_set_capability(input, EV_KEY, BTN_2); /* ee wp */
>> +     input_set_capability(input, EV_KEY, BTN_3); /* gpio */
>> +     input_set_capability(input, EV_KEY, BTN_4); /* tamper */
>> +     input_set_capability(input, EV_KEY, BTN_5); /* button held */
>> +
>> +     ret = input_register_device(input);
>> +     if (ret < 0) {
>> +             dev_err(&pdev->dev, "Can't register input device: %d\n", ret);
>> +             return ret;
>> +     }
>> +
>> +     platform_set_drvdata(pdev, gsc);
>> +     mutex_init(&info->mutex);
>> +     INIT_WORK(&info->irq_work, gsc_input_irq_work);
>> +
>> +     /* Support irq domain */
>> +     for (i = 0; i < ARRAY_SIZE(gsc_irqs); i++) {
>> +             struct gsc_irq *gsc_irq = &gsc_irqs[i];
>> +             int virq;
>> +
>> +             virq = regmap_irq_get_virq(gsc->irq_chip_data, gsc_irq->irq);
>> +             if (virq <= 0)
>> +                     return -EINVAL;
>> +             gsc_irq->virq = virq;
>
> I'd say mapping should be done by MFD piece. You can add interrupts as
> resources and fetch them here.

can you point me to an example dts/driver?

Tim

>
>> +
>> +             ret = devm_request_threaded_irq(&pdev->dev, virq, NULL,
>> +                                             gsc_input_irq, 0,
>> +                                             gsc_irq->name, info);
>> +             if (ret) {
>> +                     dev_err(&pdev->dev,
>> +                             "failed: irq request (IRQ: %d, error: %d\n)",
>> +                             gsc_irq->irq, ret);
>> +                     return ret;
>> +             }
>> +     }
>> +
>> +     return 0;
>> +}
>> +
>> +static const struct of_device_id gsc_input_dt_ids[] = {
>> +     { .compatible = "gw,gsc-input", },
>> +     {}
>> +};
>> +
>> +static struct platform_driver gsc_input_driver = {
>> +     .driver = {
>> +             .name = KBUILD_MODNAME,
>> +             .of_match_table = gsc_input_dt_ids,
>> +     },
>> +     .probe = gsc_input_probe,
>> +};
>> +
>> +module_platform_driver(gsc_input_driver);
>> +
>> +MODULE_AUTHOR("Tim Harvey <tharvey@gateworks.com>");
>> +MODULE_DESCRIPTION("GSC input driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 2.7.4
>>
>
> Thanks.
>
> --
> Dmitry