Index: rtems/c/src/lib/libbsp/lm32/shared/milkymist_ac97/ac97.c
===================================================================
--- rtems.orig/c/src/lib/libbsp/lm32/shared/milkymist_ac97/ac97.c	2012-03-20 17:11:20.087160002 +0800
+++ rtems/c/src/lib/libbsp/lm32/shared/milkymist_ac97/ac97.c	2012-03-20 17:12:23.731160001 +0800
@@ -372,6 +372,39 @@
   return sc;
 }
 
+static rtems_status_code ioctl_read_mic_boost(void *buf, unsigned int chan)
+{
+  unsigned int *val = (unsigned int *)buf;
+  int codec;
+
+  codec = read_cr(chan);
+  if (codec < 0)
+    return RTEMS_UNSATISFIED;
+
+  *val = (codec & (1 << 6)) >> 6;
+  return RTEMS_SUCCESSFUL;
+}
+
+static rtems_status_code ioctl_write_mic_boost(void *buf, unsigned int chan)
+{
+  unsigned int *val = (unsigned int *)buf;
+  int codec;
+
+  codec = read_cr(chan);
+  if (codec < 0)
+    return RTEMS_UNSATISFIED;
+
+  if (*val)
+    codec |= (1 << 6);
+  else
+    codec &= ~(1 << 6);
+
+  if (!write_cr(chan, codec))
+    return RTEMS_UNSATISFIED;
+
+  return RTEMS_SUCCESSFUL;
+}
+
 rtems_device_driver ac97_control(
   rtems_device_major_number major,
   rtems_device_minor_number minor,
@@ -419,6 +452,16 @@
         if(sc == RTEMS_SUCCESSFUL)
           args->ioctl_return = 0;
         return sc;
+      case SOUND_MIXER_READ(SOUND_MIXER_MIC_BOOST):
+	sc = ioctl_read_mic_boost(args->buffer, 0x0e);
+        if(sc == RTEMS_SUCCESSFUL)
+          args->ioctl_return = 0;
+        return sc;
+      case SOUND_MIXER_WRITE(SOUND_MIXER_MIC_BOOST):
+	sc = ioctl_write_mic_boost(args->buffer, 0x0e);
+        if(sc == RTEMS_SUCCESSFUL)
+          args->ioctl_return = 0;
+        return sc;
       default:
         return RTEMS_UNSATISFIED;
     }
Index: rtems/c/src/lib/libbsp/lm32/shared/milkymist_ac97/milkymist_ac97.h
===================================================================
--- rtems.orig/c/src/lib/libbsp/lm32/shared/milkymist_ac97/milkymist_ac97.h	2012-03-20 17:11:23.791160002 +0800
+++ rtems/c/src/lib/libbsp/lm32/shared/milkymist_ac97/milkymist_ac97.h	2012-03-20 17:12:23.731160001 +0800
@@ -21,6 +21,7 @@
 /* Ioctls. 0x41 is 'A' */
 #define SOUND_MIXER_MIC             0x0
 #define SOUND_MIXER_LINE            0x1
+#define SOUND_MIXER_MIC_BOOST       0x2
 #define SOUND_MIXER_READ(x)         (0x4100+x)
 #define SOUND_MIXER_WRITE(x)        (0x4110+x)