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Subject[PATCH] platform: chrome: Add Tablet Switch ACPI driver
Date
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@chromium.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.

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,
+ },
+};
+
+module_acpi_driver(chromeos_tbmc_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ChromeOS ACPI tablet switch driver");
--
2.11.0.483.g087da7b7c-goog
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