platform/x86: intel-hid: Add support for SW_TABLET_MODE

Some convertible use the intel-hid ACPI interface to report SW_TABLET_MODE,
implement this with DMI based allow-list to be sure to activate support
only on models that effectively have it.

Signed-off-by: Elia Devito <eliadevito@gmail.com>
Link: https://lore.kernel.org/r/20201204160121.36703-1-elia@xvalue.it
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/drivers/platform/x86/intel-hid.c b/drivers/platform/x86/intel-hid.c
index 9a52e56..c69c2cc 100644 (file)
--- a/drivers/platform/x86/intel-hid.c
+++ b/drivers/platform/x86/intel-hid.c
@@ -15,6 +15,9 @@
 #include <linux/platform_device.h>
 #include <linux/suspend.h>
 
+/* When NOT in tablet mode, VGBS returns with the flag 0x40 */
+#define TABLET_MODE_FLAG BIT(6)
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Alex Hung");
 
@@ -89,9 +92,26 @@ static const struct dmi_system_id button_array_table[] = {
        { }
 };
 
+/*
+ * Some convertible use the intel-hid ACPI interface to report SW_TABLET_MODE,
+ * these need to be compared via a DMI based authorization list because some
+ * models have unreliable VGBS return which could cause incorrect
+ * SW_TABLET_MODE report.
+ */
+static const struct dmi_system_id dmi_vgbs_allow_list[] = {
+       {
+               .matches = {
+                       DMI_MATCH(DMI_SYS_VENDOR, "HP"),
+                       DMI_MATCH(DMI_PRODUCT_NAME, "HP Spectre x360 Convertible 15-df0xxx"),
+               },
+       },
+       { }
+};
+
 struct intel_hid_priv {
        struct input_dev *input_dev;
        struct input_dev *array;
+       struct input_dev *switches;
        bool wakeup_mode;
 };
 
@@ -359,6 +379,57 @@ static int intel_button_array_input_setup(struct platform_device *device)
        return input_register_device(priv->array);
 }
 
+static int intel_hid_switches_setup(struct platform_device *device)
+{
+       struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
+
+       /* Setup input device for switches */
+       priv->switches = devm_input_allocate_device(&device->dev);
+       if (!priv->switches)
+               return -ENOMEM;
+
+       __set_bit(EV_SW, priv->switches->evbit);
+       __set_bit(SW_TABLET_MODE, priv->switches->swbit);
+
+       priv->switches->name = "Intel HID switches";
+       priv->switches->id.bustype = BUS_HOST;
+       return input_register_device(priv->switches);
+}
+
+static void report_tablet_mode_state(struct platform_device *device)
+{
+       struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
+       acpi_handle handle = ACPI_HANDLE(&device->dev);
+       unsigned long long vgbs;
+       int m;
+
+       if (!intel_hid_evaluate_method(handle, INTEL_HID_DSM_VGBS_FN, &vgbs))
+               return;
+
+       m = !(vgbs & TABLET_MODE_FLAG);
+       input_report_switch(priv->switches, SW_TABLET_MODE, m);
+       input_sync(priv->switches);
+}
+
+static bool report_tablet_mode_event(struct input_dev *input_dev, u32 event)
+{
+       if (!input_dev)
+               return false;
+
+       switch (event) {
+       case 0xcc:
+               input_report_switch(input_dev, SW_TABLET_MODE, 1);
+               input_sync(input_dev);
+               return true;
+       case 0xcd:
+               input_report_switch(input_dev, SW_TABLET_MODE, 0);
+               input_sync(input_dev);
+               return true;
+       default:
+               return false;
+       }
+}
+
 static void notify_handler(acpi_handle handle, u32 event, void *context)
 {
        struct platform_device *device = context;
@@ -375,6 +446,13 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
                if (event == 0xce)
                        goto wakeup;
 
+               /*
+                * Switch events will wake the device and report the new switch
+                * position to the input subsystem.
+                */
+               if (priv->switches && (event == 0xcc || event == 0xcd))
+                       goto wakeup;
+
                /* Wake up on 5-button array events only. */
                if (event == 0xc0 || !priv->array)
                        return;
@@ -386,6 +464,10 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
 
 wakeup:
                pm_wakeup_hard_event(&device->dev);
+
+               if (report_tablet_mode_event(priv->switches, event))
+                       return;
+
                return;
        }
 
@@ -410,6 +492,9 @@ wakeup:
                }
        }
 
+       if (report_tablet_mode_event(priv->switches, event))
+               return;
+
        /* 0xC0 is for HID events, other values are for 5 button array */
        if (event != 0xc0) {
                if (!priv->array ||
@@ -497,6 +582,16 @@ static int intel_hid_probe(struct platform_device *device)
                        pr_err("Failed to setup Intel 5 button array hotkeys\n");
        }
 
+       /* Setup switches for devices that we know VGBS return correctly */
+       if (dmi_check_system(dmi_vgbs_allow_list)) {
+               dev_info(&device->dev, "platform supports switches\n");
+               err = intel_hid_switches_setup(device);
+               if (err)
+                       pr_err("Failed to setup Intel HID switches\n");
+               else
+                       report_tablet_mode_state(device);
+       }
+
        status = acpi_install_notify_handler(handle,
                                             ACPI_DEVICE_NOTIFY,
                                             notify_handler,