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Unverified Commit b418f741 authored by Gwendal Grignou's avatar Gwendal Grignou Committed by Benson Leung
Browse files

platform: chrome: Add Tablet Switch ACPI driver 



Add a kernel driver for GOOG0006, an ACPI driver reporting an event when
the tablet switch status changes.

On an ACPI based convertible chromebook check evtest display tablet mode
switch changes:
Available devices:
..
/dev/input/event3:      Tablet Mode Switch
..
Testing ... (interrupt to exit)
Event: time 1484879712.604360, type 5 (EV_SW), code 1 (SW_TABLET_MODE),
value 1
Event: time 1484879712.604360, -------------- SYN_REPORT ------------
Event: time 1484879715.132228, type 5 (EV_SW), code 1 (SW_TABLET_MODE),
value 0
Event: time 1484879715.132228, -------------- SYN_REPORT ------------
...
Check state is updated at resume time when different from suspend time.

Signed-off-by: default avatarGwendal Grignou <gwendal@chromium.org>
Signed-off-by: default avatarBenson Leung <bleung@chromium.org>
parent b410b122

drivers/platform/chrome/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -38,6 +38,16 @@ config CHROMEOS_PSTORE 
	  If you have a supported Chromebook, choose Y or M here.

	  The module will be called chromeos_pstore.



config CHROMEOS_TBMC

	tristate "ChromeOS Tablet Switch Controller"

	depends on ACPI

	help

	  This option adds a driver for the tablet switch on

	  select Chrome OS systems.



	  To compile this driver as a module, choose M here: the

	  module will be called chromeos_tbmc.



config CROS_EC_CTL

        tristate

drivers/platform/chrome/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 


obj-$(CONFIG_CHROMEOS_LAPTOP)		+= chromeos_laptop.o

obj-$(CONFIG_CHROMEOS_PSTORE)		+= chromeos_pstore.o

obj-$(CONFIG_CHROMEOS_TBMC)		+= chromeos_tbmc.o

cros_ec_ctl-objs			:= cros_ec_sysfs.o cros_ec_lightbar.o \

					   cros_ec_vbc.o cros_ec_debugfs.o

obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o

drivers/platform/chrome/chromeos_tbmc.c

0 → 100644
+128 −0
Original line number Diff line number Diff line 
/*

 * chromeos_tbmc - Driver to detect Tablet Mode for ChromeOS convertible.

 *

 * Copyright 2017 Google, Inc

 *

 * This software is licensed under the terms of the GNU General Public

 * License version 2, as published by the Free Software Foundation, and

 * may be copied, distributed, and modified under those terms.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * On Chromebook using ACPI, this device listens for notification

 * from GOOG0006 and issue method TBMC to retrieve the status.

 *

 * GOOG0006 issues the notification when it receives EC_HOST_EVENT_MODE_CHANGE

 * from the EC.

 * Method TBMC reads EC_ACPI_MEM_DEVICE_ORIENTATION byte from the shared

 * memory region.

 */



#include <linux/acpi.h>

#include <linux/input.h>

#include <linux/io.h>

#include <linux/module.h>

#include <linux/printk.h>



#define DRV_NAME "chromeos_tbmc"

#define ACPI_DRV_NAME "GOOG0006"



static int chromeos_tbmc_query_switch(struct acpi_device *adev,

				     struct input_dev *idev)

{

	unsigned long long state;

	acpi_status status;



	status = acpi_evaluate_integer(adev->handle, "TBMC", NULL, &state);

	if (ACPI_FAILURE(status))

		return -ENODEV;



	/* input layer checks if event is redundant */

	input_report_switch(idev, SW_TABLET_MODE, state);

	input_sync(idev);



	return 0;

}



static __maybe_unused int chromeos_tbmc_resume(struct device *dev)

{

	struct acpi_device *adev = to_acpi_device(dev);



	return chromeos_tbmc_query_switch(adev, adev->driver_data);

}



static void chromeos_tbmc_notify(struct acpi_device *adev, u32 event)

{

	switch (event) {

	case 0x80:

		chromeos_tbmc_query_switch(adev, adev->driver_data);

		break;

	default:

		dev_err(&adev->dev, "Unexpected event: 0x%08X\n", event);

	}

}



static int chromeos_tbmc_open(struct input_dev *idev)

{

	struct acpi_device *adev = input_get_drvdata(idev);



	return chromeos_tbmc_query_switch(adev, idev);

}



static int chromeos_tbmc_add(struct acpi_device *adev)

{

	struct input_dev *idev;

	struct device *dev = &adev->dev;

	int ret;



	idev = devm_input_allocate_device(dev);

	if (!idev)

		return -ENOMEM;



	idev->name = "Tablet Mode Switch";

	idev->phys = acpi_device_hid(adev);



	idev->id.bustype = BUS_HOST;

	idev->id.version = 1;

	idev->id.product = 0;

	idev->open = chromeos_tbmc_open;



	input_set_drvdata(idev, adev);

	adev->driver_data = idev;



	input_set_capability(idev, EV_SW, SW_TABLET_MODE);

	ret = input_register_device(idev);

	if (ret) {

		dev_err(dev, "cannot register input device\n");

		return ret;

	}

	return 0;

}



static const struct acpi_device_id chromeos_tbmc_acpi_device_ids[] = {

	{ ACPI_DRV_NAME, 0 },

	{ }

};

MODULE_DEVICE_TABLE(acpi, chromeos_tbmc_acpi_device_ids);



static const SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,

		chromeos_tbmc_resume);



static struct acpi_driver chromeos_tbmc_driver = {

	.name = DRV_NAME,

	.class = DRV_NAME,

	.ids = chromeos_tbmc_acpi_device_ids,

	.ops = {

		.add = chromeos_tbmc_add,

		.notify = chromeos_tbmc_notify,

	},

	.drv.pm = &chromeos_tbmc_pm_ops,

};



module_acpi_driver(chromeos_tbmc_driver);



MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");