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SubjectRe: [RFC 4/4] input: misc: Add Gateworks System Controller support
Hi Tim,

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..."

> 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.

> +#define DEBUG

Please no.

> +
> +#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?

> + 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?

> + 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();

> + 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?

> +
> + 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().

> +
> + 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.

> +
> + 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

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