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Message-ID: <20170128003007.GA4191@google.com>
Date: Fri, 27 Jan 2017 16:30:08 -0800
From: Benson Leung <bleung@...gle.com>
To: Gwendal Grignou <gwendal@...omium.org>
Cc: bleung@...omium.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform: chrome: Add Tablet Switch ACPI driver
Hi Gwendal,
Thanks for sending this!
On Mon, Jan 23, 2017 at 03:39:55PM -0800, Gwendal Grignou wrote:
> 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 ------------
> ...
>
> Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
> ---
> drivers/platform/chrome/Kconfig | 46 ++++++++-----
> drivers/platform/chrome/Makefile | 1 +
> drivers/platform/chrome/chromeos_tbmc.c | 117 ++++++++++++++++++++++++++++++++
> 3 files changed, 146 insertions(+), 18 deletions(-)
> create mode 100644 drivers/platform/chrome/chromeos_tbmc.c
>
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index 76bdae1a93bb..51f8d7df4ad4 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -38,31 +38,41 @@ 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_CHARDEV
> - tristate "Chrome OS Embedded Controller userspace device interface"
> - depends on MFD_CROS_EC
> - ---help---
> - This driver adds support to talk with the ChromeOS EC from userspace.
> + tristate "Chrome OS Embedded Controller userspace device interface"
> + depends on MFD_CROS_EC
> + ---help---
> + This driver adds support to talk with the ChromeOS EC from userspace.
>
> - If you have a supported Chromebook, choose Y or M here.
> - The module will be called cros_ec_dev.
> + If you have a supported Chromebook, choose Y or M here.
> + The module will be called cros_ec_dev.
>
> config CROS_EC_LPC
> - tristate "ChromeOS Embedded Controller (LPC)"
> - depends on MFD_CROS_EC && (X86 || COMPILE_TEST)
> - help
> - If you say Y here, you get support for talking to the ChromeOS EC
> - over an LPC bus. This uses a simple byte-level protocol with a
> - checksum. This is used for userspace access only. The kernel
> - typically has its own communication methods.
> + tristate "ChromeOS Embedded Controller (LPC)"
> + depends on MFD_CROS_EC && (X86 || COMPILE_TEST)
> + help
> + If you say Y here, you get support for talking to the ChromeOS EC
> + over an LPC bus. This uses a simple byte-level protocol with a
> + checksum. This is used for userspace access only. The kernel
> + typically has its own communication methods.
>
> - To compile this driver as a module, choose M here: the
> - module will be called cros_ec_lpc.
> + To compile this driver as a module, choose M here: the
> + module will be called cros_ec_lpc.
>
> config CROS_EC_PROTO
> - bool
> - help
> - ChromeOS EC communication protocol helpers.
> + bool
> + help
> + ChromeOS EC communication protocol helpers.
>
Let's leave the cleanup of the Kconfig (for whitespace) for another patch.
Just add the CHROMEOS_TBMC.
> config CROS_KBD_LED_BACKLIGHT
> tristate "Backlight LED support for Chrome OS keyboards"
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index 4f3462783a3c..b61a0166c0ce 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -1,6 +1,7 @@
>
> obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
> obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
> +obj-$(CONFIG_CHROMEOS_TBMC) += chromeos_tbmc.o
> cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o \
> cros_ec_lightbar.o cros_ec_vbc.o
> obj-$(CONFIG_CROS_EC_CHARDEV) += cros_ec_devs.o
> diff --git a/drivers/platform/chrome/chromeos_tbmc.c b/drivers/platform/chrome/chromeos_tbmc.c
> new file mode 100644
> index 000000000000..c159eb38d79b
> --- /dev/null
> +++ b/drivers/platform/chrome/chromeos_tbmc.c
> @@ -0,0 +1,117 @@
> +/*
> + * 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 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 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,
> + },
> +};
I talked to you about this offline, but can you check if you do or do not
need special resume handling of this switch? I suspect there's a
decent chance the notify might not result in an event if the tablet
mode changed during the time the Chromebook is sleeping.
Thanks!
Benson
--
Benson Leung
Senior Software Engineer
Chrome OS Kernel
Google Inc.
bleung@...gle.com
Chromium OS Project
bleung@...omium.org
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