Date:   Wed, 7 Dec 2016 17:36:52 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Darren Hart <dvhart@...radead.org>,
        Bastien Nocera <hadess@...ess.net>,
        Stephen J <stephenjust@...il.com>, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH] platform: Introduce button support for the Surface 3

On Mon, Dec 05, 2016 at 04:10:33PM +0100, Benjamin Tissoires wrote:
> The Surface 3 is not following the ACPI spec for PNP0C40, but nearly.
> The device is connected to a I2C device that might have some magic
> but we don't know about.
> Just create the device after the enumeration and use the declared GPIOs
> to provide button support.
> 
> This driver is just an adaptation of drivers/input/misc/soc_button_array.c
> 
> The Surface Pro 3 is using an ACPI driver and matches against the bid
> of the device ("VGBI"). To prevent this incompatible driver to be used
> on the Surface Pro, we add a match on the Surface 3 bid "TEV2".
> 
> link: https://bugzilla.kernel.org/show_bug.cgi?id=102761
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> ---
> 
> Hi,
> 
> This driver is not in input/misc because I'd prefer keeping it closer
> to the surfacepro3_button, which is already in platform/x86.
> The Surface Pro 3 and non-Pro 3 both share the same PNPId for the button device
> with completely different way of handling those :/

Hmm, this is unfortunate that, while drivers look like twins, one is a
platform while another is i2c, but making this more generic is probably
not worth it.

Acked-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

if you need it.

> 
> Cheers,
> Benjamin
> 
> ---
>  drivers/platform/x86/Kconfig           |   6 +
>  drivers/platform/x86/Makefile          |   1 +
>  drivers/platform/x86/surface3_button.c | 250 +++++++++++++++++++++++++++++++++
>  3 files changed, 257 insertions(+)
>  create mode 100644 drivers/platform/x86/surface3_button.c
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 152aac6..7bf3924 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -1023,6 +1023,12 @@ config SURFACE_PRO3_BUTTON
>  	---help---
>  	  This driver handles the power/home/volume buttons on the Microsoft Surface Pro 3/4 tablet.
>  
> +config SURFACE_3_BUTTON
> +	tristate "Power/home/volume buttons driver for Microsoft Surface 3 tablet"
> +	depends on ACPI && KEYBOARD_GPIO
> +	---help---
> +	  This driver handles the power/home/volume buttons on the Microsoft Surface 3 tablet.
> +
>  config INTEL_PUNIT_IPC
>  	tristate "Intel P-Unit IPC Driver"
>  	---help---
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 38f5419..12c1482 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -67,6 +67,7 @@ obj-$(CONFIG_PVPANIC)           += pvpanic.o
>  obj-$(CONFIG_ALIENWARE_WMI)	+= alienware-wmi.o
>  obj-$(CONFIG_INTEL_PMC_IPC)	+= intel_pmc_ipc.o
>  obj-$(CONFIG_SURFACE_PRO3_BUTTON)	+= surfacepro3_button.o
> +obj-$(CONFIG_SURFACE_3_BUTTON)	+= surface3_button.o
>  obj-$(CONFIG_INTEL_PUNIT_IPC)  += intel_punit_ipc.o
>  obj-$(CONFIG_INTEL_TELEMETRY)	+= intel_telemetry_core.o \
>  				   intel_telemetry_pltdrv.o \
> diff --git a/drivers/platform/x86/surface3_button.c b/drivers/platform/x86/surface3_button.c
> new file mode 100644
> index 0000000..8bfd7f6
> --- /dev/null
> +++ b/drivers/platform/x86/surface3_button.c
> @@ -0,0 +1,250 @@
> +/*
> + * Supports for the button array on the Surface tablets.
> + *
> + * (C) Copyright 2016 Red Hat, Inc
> + *
> + * Based on soc_button_array.c:
> + *
> + * {C} Copyright 2014 Intel Corporation
> + *
> + * 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
> + * of the License.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/input.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/i2c.h>
> +#include <linux/slab.h>
> +#include <linux/acpi.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/gpio_keys.h>
> +#include <linux/gpio.h>
> +#include <linux/platform_device.h>
> +
> +
> +#define SURFACE_BUTTON_OBJ_NAME		"TEV2"
> +#define MAX_NBUTTONS			4
> +
> +/*
> + * Some of the buttons like volume up/down are auto repeat, while others
> + * are not. To support both, we register two platform devices, and put
> + * buttons into them based on whether the key should be auto repeat.
> + */
> +#define BUTTON_TYPES			2
> +
> +/*
> + * Power button, Home button, Volume buttons support is supposed to
> + * be covered by drivers/input/misc/soc_button_array.c, which is implemented
> + * according to "Windows ACPI Design Guide for SoC Platforms".
> + * However surface 3 seems not to obey the specs, instead it uses
> + * device TEV2(MSHW0028) for declaring the GPIOs. The gpios are also slightly
> + * different in which the Home button is active high.
> + * Compared to surfacepro3_button.c which also handles MSHW0028, the Surface 3
> + * is a reduce platform and thus uses GPIOs, not ACPI events.
> + * We choose an I2C driver here because we need to access the resources
> + * declared under the device node, while surfacepro3_button.c only needs
> + * the ACPI companion node.
> + */
> +static const struct acpi_device_id surface3_acpi_match[] = {
> +	{ "MSHW0028", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
> +
> +struct surface3_button_info {
> +	const char *name;
> +	int acpi_index;
> +	unsigned int event_type;
> +	unsigned int event_code;
> +	bool autorepeat;
> +	bool wakeup;
> +	bool active_low;
> +};
> +
> +struct surface3_button_data {
> +	struct platform_device *children[BUTTON_TYPES];
> +};
> +
> +/*
> + * Get the Nth GPIO number from the ACPI object.
> + */
> +static int surface3_button_lookup_gpio(struct device *dev, int acpi_index)
> +{
> +	struct gpio_desc *desc;
> +	int gpio;
> +
> +	desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
> +	if (IS_ERR(desc))
> +		return PTR_ERR(desc);
> +
> +	gpio = desc_to_gpio(desc);
> +
> +	gpiod_put(desc);
> +
> +	return gpio;
> +}
> +
> +static struct platform_device *
> +surface3_button_device_create(struct i2c_client *client,
> +			      const struct surface3_button_info *button_info,
> +			      bool autorepeat)
> +{
> +	const struct surface3_button_info *info;
> +	struct platform_device *pd;
> +	struct gpio_keys_button *gpio_keys;
> +	struct gpio_keys_platform_data *gpio_keys_pdata;
> +	int n_buttons = 0;
> +	int gpio;
> +	int error;
> +
> +	gpio_keys_pdata = devm_kzalloc(&client->dev,
> +				       sizeof(*gpio_keys_pdata) +
> +				       sizeof(*gpio_keys) * MAX_NBUTTONS,
> +				       GFP_KERNEL);
> +	if (!gpio_keys_pdata)
> +		return ERR_PTR(-ENOMEM);
> +
> +	gpio_keys = (void *)(gpio_keys_pdata + 1);
> +
> +	for (info = button_info; info->name; info++) {
> +		if (info->autorepeat != autorepeat)
> +			continue;
> +
> +		gpio = surface3_button_lookup_gpio(&client->dev,
> +						   info->acpi_index);
> +		if (!gpio_is_valid(gpio))
> +			continue;
> +
> +		gpio_keys[n_buttons].type = info->event_type;
> +		gpio_keys[n_buttons].code = info->event_code;
> +		gpio_keys[n_buttons].gpio = gpio;
> +		gpio_keys[n_buttons].active_low = info->active_low;
> +		gpio_keys[n_buttons].desc = info->name;
> +		gpio_keys[n_buttons].wakeup = info->wakeup;
> +		n_buttons++;
> +	}
> +
> +	if (n_buttons == 0) {
> +		error = -ENODEV;
> +		goto err_free_mem;
> +	}
> +
> +	gpio_keys_pdata->buttons = gpio_keys;
> +	gpio_keys_pdata->nbuttons = n_buttons;
> +	gpio_keys_pdata->rep = autorepeat;
> +
> +	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
> +	if (!pd) {
> +		error = -ENOMEM;
> +		goto err_free_mem;
> +	}
> +
> +	error = platform_device_add_data(pd, gpio_keys_pdata,
> +					 sizeof(*gpio_keys_pdata));
> +	if (error)
> +		goto err_free_pdev;
> +
> +	error = platform_device_add(pd);
> +	if (error)
> +		goto err_free_pdev;
> +
> +	return pd;
> +
> +err_free_pdev:
> +	platform_device_put(pd);
> +err_free_mem:
> +	devm_kfree(&client->dev, gpio_keys_pdata);
> +	return ERR_PTR(error);
> +}
> +
> +static int surface3_button_remove(struct i2c_client *client)
> +{
> +	struct surface3_button_data *priv = i2c_get_clientdata(client);
> +
> +	int i;
> +
> +	for (i = 0; i < BUTTON_TYPES; i++)
> +		if (priv->children[i])
> +			platform_device_unregister(priv->children[i]);
> +
> +	return 0;
> +}
> +
> +static struct surface3_button_info surface3_button_surface3[] = {
> +	{ "power", 0, EV_KEY, KEY_POWER, false, true, true },
> +	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
> +	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
> +	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
> +	{ }
> +};
> +
> +static int surface3_button_probe(struct i2c_client *client,
> +				 const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct surface3_button_data *priv;
> +	struct platform_device *pd;
> +	int i;
> +	int error;
> +
> +	if (strncmp(acpi_device_bid(ACPI_COMPANION(&client->dev)),
> +		    SURFACE_BUTTON_OBJ_NAME,
> +		    strlen(SURFACE_BUTTON_OBJ_NAME)))
> +		return -ENODEV;
> +
> +	if (gpiod_count(dev, KBUILD_MODNAME) <= 0) {
> +		dev_dbg(dev, "no GPIO attached, ignoring...\n");
> +		return -ENODEV;
> +	}
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, priv);
> +
> +	for (i = 0; i < BUTTON_TYPES; i++) {
> +		pd = surface3_button_device_create(client,
> +						   surface3_button_surface3,
> +						   i == 0);
> +		if (IS_ERR(pd)) {
> +			error = PTR_ERR(pd);
> +			if (error != -ENODEV) {
> +				surface3_button_remove(client);
> +				return error;
> +			}
> +			continue;
> +		}
> +
> +		priv->children[i] = pd;
> +	}
> +
> +	if (!priv->children[0] && !priv->children[1])
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id surface3_id[] = {
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, surface3_id);
> +
> +static struct i2c_driver surface3_driver = {
> +	.probe = surface3_button_probe,
> +	.remove = surface3_button_remove,
> +	.id_table = surface3_id,
> +	.driver = {
> +		.name = "surface3",
> +		.acpi_match_table = ACPI_PTR(surface3_acpi_match),
> +	},
> +};
> +module_i2c_driver(surface3_driver);
> +
> +MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@...il.com>");
> +MODULE_DESCRIPTION("surface3 button array driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.9.3
> 

-- 
Dmitry

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