ALSA: ac97: Add helper function to reset the AC97 device

[sfrench/cifs-2.6.git] / sound / ac97_bus.c

diff --git a/sound/ac97_bus.c b/sound/ac97_bus.c
index 2b50cbe6aca90089a12cd9b8f774ec59690bbdf4..55791a0b3943c81f5dc5c65133bcc5a8d0d07827 100644 (file)
--- a/sound/ac97_bus.c
+++ b/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