Re: [PATCH v2 2/2] platform/x86: Add driver for Yoga Tablet Mode switch

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Am 23.03.23 um 03:52 schrieb Andrew Kallmeyer:

From: Gergo Koteles <soyer@xxxxxx>

This WMI driver for the tablet mode control switch for Lenovo Yoga
notebooks was originally written by Gergo Koteles. The mode is mapped to
a SW_TABLET_MODE switch capable input device.

Andrew followed the suggestions that were posted in reply to Gergo's RFC
patch, and on the v1 version of this patch to follow-up and get it
merged.

Changes from Gergo's RFC:

  - Refactored obtaining a reference to the EC ACPI device needed for the
    quirk implementation as suggested by Hans de Goede
  - Applied small fixes and switched to devm_input_allocate_device() and
    removing input_unregister_device() as suggested by Barnabás Pőcze.
  - Merged the lenovo_ymc_trigger_ec function with the
    ideapad_trigger_ymc_next_read function since it was no longer
    external.
  - Added the word "Tablet" to the driver description to hopefully make
    it more clear.
  - Fixed the LENOVO_YMC_QUERY_METHOD ID and the name string for the EC
    APCI device trigged for the quirk
  - Triggered the input event on probe so that the initial tablet mode
    state when the driver is loaded is reported to userspace as suggested
    by Armin Wolf.

We have tested this on the Yoga 7 14AIL7 for the non-quirk path and on
the Yoga 7 14ARB7 which has the firmware bug that requires triggering
the embedded controller to send the mode change events. This workaround
is also used by the Windows drivers.

According to reports at https://github.com/lukas-w/yoga-usage-mode,
which uses the same WMI devices, the following models should also work:
Yoga C940, Ideapad flex 14API, Yoga 9 14IAP7, Yoga 7 14ARB7, etc.

Signed-off-by: Gergo Koteles <soyer@xxxxxx>
Co-developed-by: Andrew Kallmeyer <kallmeyeras@xxxxxxxxx>
Signed-off-by: Andrew Kallmeyer <kallmeyeras@xxxxxxxxx>
Link: https://lore.kernel.org/r/20221004214332.35934-1-soyer@xxxxxx/
Link: https://lore.kernel.org/platform-driver-x86/20230310041726.217447-1-kallmeyeras@xxxxxxxxx/
---
  drivers/platform/x86/Kconfig          |  10 ++
  drivers/platform/x86/Makefile         |   1 +
  drivers/platform/x86/ideapad-laptop.h |   1 +
  drivers/platform/x86/lenovo-ymc.c     | 187 ++++++++++++++++++++++++++
  4 files changed, 199 insertions(+)
  create mode 100644 drivers/platform/x86/lenovo-ymc.c

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 5692385e2..858be0c65 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -470,6 +470,16 @@ config IDEAPAD_LAPTOP
  	  This is a driver for Lenovo IdeaPad netbooks contains drivers for
  	  rfkill switch, hotkey, fan control and backlight control.

+config LENOVO_YMC
+	tristate "Lenovo Yoga Tablet Mode Control"
+	depends on ACPI_WMI
+	depends on INPUT
+	depends on IDEAPAD_LAPTOP
+	select INPUT_SPARSEKMAP
+	help
+	  This driver maps the Tablet Mode Control switch to SW_TABLET_MODE input
+	  events for Lenovo Yoga notebooks.
+
  config SENSORS_HDAPS
  	tristate "Thinkpad Hard Drive Active Protection System (hdaps)"
  	depends on INPUT
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 1d3d1b025..10054cdea 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -63,6 +63,7 @@ obj-$(CONFIG_UV_SYSFS)       += uv_sysfs.o
  # IBM Thinkpad and Lenovo
  obj-$(CONFIG_IBM_RTL)		+= ibm_rtl.o
  obj-$(CONFIG_IDEAPAD_LAPTOP)	+= ideapad-laptop.o
+obj-$(CONFIG_LENOVO_YMC)	+= lenovo-ymc.o
  obj-$(CONFIG_SENSORS_HDAPS)	+= hdaps.o
  obj-$(CONFIG_THINKPAD_ACPI)	+= thinkpad_acpi.o
  obj-$(CONFIG_THINKPAD_LMI)	+= think-lmi.o
diff --git a/drivers/platform/x86/ideapad-laptop.h b/drivers/platform/x86/ideapad-laptop.h
index 7dd8ce027..2564cb1cd 100644
--- a/drivers/platform/x86/ideapad-laptop.h
+++ b/drivers/platform/x86/ideapad-laptop.h
@@ -35,6 +35,7 @@ enum {
  	VPCCMD_W_FAN,
  	VPCCMD_R_RF,
  	VPCCMD_W_RF,
+	VPCCMD_W_YMC = 0x2A,
  	VPCCMD_R_FAN = 0x2B,
  	VPCCMD_R_SPECIAL_BUTTONS = 0x31,
  	VPCCMD_W_BL_POWER = 0x33,
diff --git a/drivers/platform/x86/lenovo-ymc.c b/drivers/platform/x86/lenovo-ymc.c
new file mode 100644
index 000000000..c64f7ec85
--- /dev/null
+++ b/drivers/platform/x86/lenovo-ymc.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * lenovo-ymc.c - Lenovo Yoga Mode Control driver
+ *
+ * Copyright © 2022 Gergo Koteles <soyer@xxxxxx>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/dmi.h>
+#include <linux/input.h>
+#include <linux/input/sparse-keymap.h>
+#include <linux/wmi.h>
+#include "ideapad-laptop.h"
+
+#define LENOVO_YMC_EVENT_GUID	"06129D99-6083-4164-81AD-F092F9D773A6"
+#define LENOVO_YMC_QUERY_GUID	"09B0EE6E-C3FD-4243-8DA1-7911FF80BB8C"
+
+#define LENOVO_YMC_QUERY_INSTANCE 0
+#define LENOVO_YMC_QUERY_METHOD 0x01
+
+static bool ec_trigger __read_mostly;
+module_param(ec_trigger, bool, 0644);
+MODULE_PARM_DESC(ec_trigger, "Enable EC triggering to emit YMC events");

Hi,

is it really necessary to allow userspace to read/write ec_trigger? The ACPI device
used for triggering the EC is only initialized during probing, so changing the value
of ec_trigger will make no difference in such cases.

Maybe you could change module_param(ec_trigger, bool, 0644) to module_param(ec_trigger, bool, 0)?

Armin Wolf

+
+static const struct dmi_system_id ec_trigger_quirk_dmi_table[] = {
+	{
+		// Lenovo Yoga 7 14ARB7
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "82QF"),
+		},
+	},
+	{ },
+};
+
+struct lenovo_ymc_private {
+	struct input_dev *input_dev;
+	struct acpi_device *ec_acpi_dev;
+};
+
+static void lenovo_ymc_trigger_ec(struct wmi_device *wdev, struct lenovo_ymc_private *priv)
+{
+	int err;
+
+	if (!ec_trigger || !priv || !priv->ec_acpi_dev)
+		return;
+	err = write_ec_cmd(priv->ec_acpi_dev->handle, VPCCMD_W_YMC, 1);
+	if (err)
+		dev_warn(&wdev->dev, "Could not write YMC: %d\n", err);
+}
+
+static const struct key_entry lenovo_ymc_keymap[] = {
+	// Laptop
+	{ KE_SW, 0x01, { .sw = { SW_TABLET_MODE, 0 } } },
+	// Tablet
+	{ KE_SW, 0x02, { .sw = { SW_TABLET_MODE, 1 } } },
+	// Drawing Board
+	{ KE_SW, 0x03, { .sw = { SW_TABLET_MODE, 1 } } },
+	// Tent
+	{ KE_SW, 0x04, { .sw = { SW_TABLET_MODE, 1 } } },
+	{ KE_END },
+};
+
+static void lenovo_ymc_notify(struct wmi_device *wdev, union acpi_object *data)
+{
+	struct lenovo_ymc_private *priv = dev_get_drvdata(&wdev->dev);
+
+	u32 input_val = 0;
+	struct acpi_buffer input = {sizeof(input_val), &input_val};
+	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+	acpi_status status;
+	union acpi_object *obj;
+	int code;
+
+	status = wmi_evaluate_method(LENOVO_YMC_QUERY_GUID,
+				LENOVO_YMC_QUERY_INSTANCE,
+				LENOVO_YMC_QUERY_METHOD,
+				&input, &output);
+
+	if (ACPI_FAILURE(status)) {
+		dev_warn(&wdev->dev,
+			"Failed to evaluate query method: %s\n",
+			acpi_format_exception(status));
+		return;
+	}
+
+	obj = output.pointer;
+
+	if (obj->type != ACPI_TYPE_INTEGER) {
+		dev_warn(&wdev->dev,
+			"WMI event data is not an integer\n");
+		goto free_obj;
+	}
+	code = obj->integer.value;
+
+	if (!sparse_keymap_report_event(priv->input_dev, code, 1, true))
+		dev_warn(&wdev->dev, "Unknown key %d pressed\n", code);
+
+free_obj:
+	kfree(obj);
+	lenovo_ymc_trigger_ec(wdev, priv);
+}
+
+static void lenovo_ymc_remove(struct wmi_device *wdev)
+{
+	struct lenovo_ymc_private *priv = dev_get_drvdata(&wdev->dev);
+	acpi_dev_put(priv->ec_acpi_dev);
+}
+
+static int lenovo_ymc_probe(struct wmi_device *wdev, const void *ctx)
+{
+	struct input_dev *input_dev;
+	struct lenovo_ymc_private *priv;
+	int err;
+
+	ec_trigger |= dmi_check_system(ec_trigger_quirk_dmi_table);
+
+	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	if (ec_trigger) {
+		pr_debug("Lenovo YMC enable EC triggering.\n");
+		priv->ec_acpi_dev = acpi_dev_get_first_match_dev("VPC2004", NULL, -1);
+		if (!priv->ec_acpi_dev) {
+			dev_err(&wdev->dev, "Could not find EC ACPI device.\n");
+			return -ENODEV;
+		}
+	}
+
+	input_dev = devm_input_allocate_device(&wdev->dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	input_dev->name = "Lenovo Yoga Tablet Mode Control switch";
+	input_dev->phys = LENOVO_YMC_EVENT_GUID "/input0";
+	input_dev->id.bustype = BUS_HOST;
+	input_dev->dev.parent = &wdev->dev;
+
+	input_set_capability(input_dev, EV_SW, SW_TABLET_MODE);
+
+	err = sparse_keymap_setup(input_dev, lenovo_ymc_keymap, NULL);
+	if (err) {
+		dev_err(&wdev->dev,
+			"Could not set up input device keymap: %d\n", err);
+		return err;
+	}
+
+	err = input_register_device(input_dev);
+	if (err) {
+		dev_err(&wdev->dev,
+			"Could not register input device: %d\n", err);
+		return err;
+	}
+
+	priv->input_dev = input_dev;
+	dev_set_drvdata(&wdev->dev, priv);
+
+	// Report the state for the first time on probe
+	lenovo_ymc_trigger_ec(wdev, priv);
+	lenovo_ymc_notify(wdev, NULL);
+	return 0;
+}
+
+static const struct wmi_device_id lenovo_ymc_wmi_id_table[] = {
+	{ .guid_string = LENOVO_YMC_EVENT_GUID },
+	{ }
+};
+MODULE_DEVICE_TABLE(wmi, lenovo_ymc_wmi_id_table);
+
+static struct wmi_driver lenovo_ymc_driver = {
+	.driver = {
+		.name = "lenovo-ymc",
+	},
+	.id_table = lenovo_ymc_wmi_id_table,
+	.probe = lenovo_ymc_probe,
+	.notify = lenovo_ymc_notify,
+	.remove = lenovo_ymc_remove,
+};
+
+module_wmi_driver(lenovo_ymc_driver);
+
+MODULE_AUTHOR("Gergo Koteles <soyer@xxxxxx>");
+MODULE_DESCRIPTION("Lenovo Yoga Mode Control driver");
+MODULE_LICENSE("GPL");




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