1 files changed, 119 insertions, 0 deletions
diff --git a/drivers/platform/chrome/chromeos_tbmc.c b/drivers/platform/chrome/chromeos_tbmc.c
new file mode 100644
index 000000000..1e81f8144
--- /dev/null
+++ b/drivers/platform/chrome/chromeos_tbmc.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+// Driver to detect Tablet Mode for ChromeOS convertible.
+//
+// Copyright (C) 2017 Google, Inc.
+// Author: Gwendal Grignou <gwendal@chromium.org>
+//
+// 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");