1 files changed, 50 insertions, 0 deletions
diff --git a/include/linux/apple-gmux.h b/include/linux/apple-gmux.h
new file mode 100644
index 000000000000..b2d32e01dfe4
--- /dev/null
+++ b/include/linux/apple-gmux.h
@@ -0,0 +1,50 @@
+/*
+ * apple-gmux.h - microcontroller built into dual GPU MacBook Pro & Mac Pro
+ * Copyright (C) 2015 Lukas Wunner <lukas@wunner.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2) as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LINUX_APPLE_GMUX_H
+#define LINUX_APPLE_GMUX_H
+
+#include <linux/acpi.h>
+
+#define GMUX_ACPI_HID "APP000B"
+
+#if IS_ENABLED(CONFIG_APPLE_GMUX)
+
+/**
+ * apple_gmux_present() - detect if gmux is built into the machine
+ *
+ * Drivers may use this to activate quirks specific to dual GPU MacBook Pros
+ * and Mac Pros, e.g. for deferred probing, runtime pm and backlight.
+ *
+ * Return: %true if gmux is present and the kernel was configured
+ * with CONFIG_APPLE_GMUX, %false otherwise.
+ */
+static inline bool apple_gmux_present(void)
+{
+	return acpi_dev_present(GMUX_ACPI_HID);
+}
+
+#else  /* !CONFIG_APPLE_GMUX */
+
+static inline bool apple_gmux_present(void)
+{
+	return false;
+}
+
+#endif /* !CONFIG_APPLE_GMUX */
+
+#endif /* LINUX_APPLE_GMUX_H */