Merge tag 'asoc-v4.2-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-linus

ASoC: Updates for v4.3

Not many updates to the core here, but an awful lot of driver updates
this time round:

 - Factoring out of AC'97 reset code into the core
 - New drivers for Cirrus CS4349, GTM601, InvenSense ICS43432, Realtek
   RT298 and ST STI controllers.
 - Machine drivers for Rockchip systems with MAX98090 and RT5645 and
   RT5650.
 - Initial driver support for Intel Skylake devices.
 - A large number of cleanups for Lars-Peter Clausen and Axel Lin.

sound/ac97_bus.c

@@ -17,6 +17,68 @@
 #include <linux/string.h>
 #include <sound/ac97_codec.h>
 
+/*
+ * snd_ac97_check_id() - Reads and checks the vendor ID of the device
+ * @ac97: The AC97 device to check
+ * @id: The ID to compare to
+ * @id_mask: Mask that is applied to the device ID before comparing to @id
+ *
+ * If @id is 0 this function returns true if the read device vendor ID is
+ * a valid ID. If @id is non 0 this functions returns true if @id
+ * matches the read vendor ID. Otherwise the function returns false.
+ */
+static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id,
+	unsigned int id_mask)
+{
+	ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16;
+	ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2);
+
+	if (ac97->id == 0x0 || ac97->id == 0xffffffff)
+		return false;
+
+	if (id != 0 && id != (ac97->id & id_mask))
+		return false;
+
+	return true;
+}
+
+/**
+ * snd_ac97_reset() - Reset AC'97 device
+ * @ac97: The AC'97 device to reset
+ * @try_warm: Try a warm reset first
+ * @id: Expected device vendor ID
+ * @id_mask: Mask that is applied to the device ID before comparing to @id
+ *
+ * This function resets the AC'97 device. If @try_warm is true the function
+ * first performs a warm reset. If the warm reset is successful the function
+ * returns 1. Otherwise or if @try_warm is false the function issues cold reset
+ * followed by a warm reset. If this is successful the function returns 0,
+ * otherwise a negative error code. If @id is 0 any valid device ID will be
+ * accepted, otherwise only the ID that matches @id and @id_mask is accepted.
+ */
+int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id,
+	unsigned int id_mask)
+{
+	struct snd_ac97_bus_ops *ops = ac97->bus->ops;
+
+	if (try_warm && ops->warm_reset) {
+		ops->warm_reset(ac97);
+		if (snd_ac97_check_id(ac97, id, id_mask))
+			return 1;
+	}
+
+	if (ops->reset)
+		ops->reset(ac97);
+	if (ops->warm_reset)
+		ops->warm_reset(ac97);
+
+	if (snd_ac97_check_id(ac97, id, id_mask))
+		return 0;
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(snd_ac97_reset);
+
 /*
  * Let drivers decide whether they want to support given codec from their
  * probe method. Drivers have direct access to the struct snd_ac97