vga_switcheroo: Add a helper function to get the client state

Add vga_switcheroo_get_client_state() to get the current state of the
client.  This is necessary to determine the proper initial state of
audio clients in HD-audio driver.
Acked-by: NDave Airlie <airlied@redhat.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

drivers/gpu/vga/vga_switcheroo.c

@@ -190,6 +190,19 @@ find_active_client(struct list_head *head)
 	return NULL;
 }
 
+int vga_switcheroo_get_client_state(struct pci_dev *pdev)
+{
+	struct vga_switcheroo_client *client;
+
+	client = find_client_from_pci(&vgasr_priv.clients, pdev);
+	if (!client)
+		return VGA_SWITCHEROO_NOT_FOUND;
+	if (!vgasr_priv.active)
+		return VGA_SWITCHEROO_INIT;
+	return client->pwr_state;
+}
+EXPORT_SYMBOL(vga_switcheroo_get_client_state);
+
 void vga_switcheroo_unregister_client(struct pci_dev *pdev)
 {
 	struct vga_switcheroo_client *client;

include/linux/vga_switcheroo.h

@@ -12,6 +12,9 @@
 enum vga_switcheroo_state {
 	VGA_SWITCHEROO_OFF,
 	VGA_SWITCHEROO_ON,
+	/* below are referred only from vga_switcheroo_get_client_state() */
+	VGA_SWITCHEROO_INIT,
+	VGA_SWITCHEROO_NOT_FOUND,
 };
 
 enum vga_switcheroo_client_id {
@@ -50,6 +53,8 @@ void vga_switcheroo_unregister_handler(void);
 
 int vga_switcheroo_process_delayed_switch(void);
 
+int vga_switcheroo_get_client_state(struct pci_dev *dev);
+
 #else
 
 static inline void vga_switcheroo_unregister_client(struct pci_dev *dev) {}
@@ -62,5 +67,7 @@ static inline int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
 	int id, bool active) { return 0; }
 static inline void vga_switcheroo_unregister_handler(void) {}
 static inline int vga_switcheroo_process_delayed_switch(void) { return 0; }
+static inline int vga_switcheroo_get_client_state(struct pci_dev *dev) { return VGA_SWITCHEROO_CLIENT_ON; }
+
 
 #endif