Add AACI audio playback support to the ARM Versatile/PB platform

This driver emulates the ARM AACI interface (PL041) connected to a LM4549 codec.
It enables audio playback for the Versatile/PB platform.

Limitations:
- Supports only a playback on one channel (Versatile/Vexpress)
- Supports only one TX FIFO in compact-mode or non-compact mode.
- Supports playback of 12, 16, 18 and 20 bits samples.
- Record is not supported.
- The PL041 is hardwired to a LM4549 codec.

Versatile/PB test build:
linux-2.6.38.5
buildroot-2010.11
alsa-lib-1.0.22
alsa-utils-1.0.22
mpg123-0.66

Qemu host: Ubuntu 10.04 in Vmware/OS X

Playback tested successfully with speaker-test/aplay/mpg123.

Signed-off-by: Mathieu Sonet <contact@elasticsheep.com>
[Peter Maydell: fixed typo in code clearing SL1RXBUSY/SL2RXBUSY
 bits, as spotted by Andrzej Zaborowski]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andrzej Zaborowski <andrew.zaborowski@intel.com>

hw/lm4549.h

@@ -0,0 +1,43 @@
+/*
+ * LM4549 Audio Codec Interface
+ *
+ * Copyright (c) 2011
+ * Written by Mathieu Sonet - www.elasticsheep.com
+ *
+ * This code is licenced under the GPL.
+ *
+ * *****************************************************************
+ */
+
+#ifndef HW_LM4549_H
+#define HW_LM4549_H
+
+#include "audio/audio.h"
+
+typedef void (*lm4549_callback)(void *opaque);
+
+#define LM4549_BUFFER_SIZE (512 * 2) /* 512 16-bit stereo samples */
+
+
+typedef struct {
+    QEMUSoundCard card;
+    SWVoiceOut *voice;
+    uint32_t voice_is_active;
+
+    uint16_t regfile[128];
+    lm4549_callback data_req_cb;
+    void *opaque;
+
+    uint16_t buffer[LM4549_BUFFER_SIZE];
+    uint32_t buffer_level;
+} lm4549_state;
+
+extern const VMStateDescription vmstate_lm4549_state;
+
+
+void lm4549_init(lm4549_state *s, lm4549_callback data_req, void *opaque);
+uint32_t lm4549_read(lm4549_state *s, target_phys_addr_t offset);
+void lm4549_write(lm4549_state *s, target_phys_addr_t offset, uint32_t value);
+uint32_t lm4549_write_samples(lm4549_state *s, uint32_t left, uint32_t right);
+
+#endif /* #ifndef HW_LM4549_H */