[ALSA] Xilinx ML403 AC97 Controller Reference device driver

Add ALSA support for the opb_ac97_controller_ref_v1_00_a ip core found
in Xilinx' ML403 reference design.
Known issue: Currently this driver hits a WARN_ON_ONCE(1) statement in
kernel/irq/resend.c (line 70). According to Linus
(http://lkml.org/lkml/2007/8/5/5) this may be ignored, right? I haven't
had a look into this 'problem' yet.
Signed-off-by: Joachim Foerster <JOFT@gmx.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/drivers/Kconfig

@@ -120,4 +120,16 @@ config SND_PORTMAN2X4
 	  To compile this driver as a module, choose M here: the module
 	  will be called snd-portman2x4.
 
+config SND_ML403_AC97CR
+	tristate "Xilinx ML403 AC97 Controller Reference"
+	depends on SND && XILINX_VIRTEX
+	select SND_AC97_CODEC
+	help
+	  Say Y here to include support for the
+	  opb_ac97_controller_ref_v1_00_a ip core found in Xilinx' ML403
+	  reference design.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called snd-ml403_ac97cr.
+
 endmenu

sound/drivers/Makefile

@@ -9,6 +9,7 @@ snd-mts64-objs := mts64.o
 snd-portman2x4-objs := portman2x4.o
 snd-serial-u16550-objs := serial-u16550.o
 snd-virmidi-objs := virmidi.o
+snd-ml403-ac97cr-objs := ml403-ac97cr.o pcm-indirect2.o
 
 # Toplevel Module Dependency
 obj-$(CONFIG_SND_DUMMY) += snd-dummy.o
@@ -17,5 +18,6 @@ obj-$(CONFIG_SND_SERIAL_U16550) += snd-serial-u16550.o
 obj-$(CONFIG_SND_MTPAV) += snd-mtpav.o
 obj-$(CONFIG_SND_MTS64) += snd-mts64.o
 obj-$(CONFIG_SND_PORTMAN2X4) += snd-portman2x4.o
+obj-$(CONFIG_SND_ML403_AC97CR) += snd-ml403-ac97cr.o
 
 obj-$(CONFIG_SND) += opl3/ opl4/ mpu401/ vx/

sound/drivers/pcm-indirect2.h

+/*
+ * Helper functions for indirect PCM data transfer to a simple FIFO in
+ * hardware (small, no possibility to read "hardware io position",
+ * updating position done by interrupt, ...)
+ *
+ *  Copyright (c) by 2007  Joachim Foerster <JOFT@gmx.de>
+ *
+ *  Based on "pcm-indirect.h" (alsa-driver-1.0.13) by
+ *
+ *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
+ *                   Jaroslav Kysela <perex@suse.cz>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef __SOUND_PCM_INDIRECT2_H
+#define __SOUND_PCM_INDIRECT2_H
+
+/* struct snd_pcm_substream, struct snd_pcm_runtime, snd_pcm_uframes_t */
+#include <sound/pcm.h>
+
+/* Debug options for code which may be removed completely in a final version */
+#ifdef CONFIG_SND_DEBUG
+#define SND_PCM_INDIRECT2_STAT    /* turn on some "statistics" about the
+				   * process of copying bytes from the
+				   * intermediate buffer to the hardware
+				   * fifo and the other way round
+				   */
+#endif
+
+struct snd_pcm_indirect2 {
+	unsigned int hw_buffer_size;  /* Byte size of hardware buffer */
+	int hw_ready;		      /* playback: 1 = hw fifo has room left,
+				       * 0 = hw fifo is full
+				       */
+	unsigned int min_multiple;
+	int min_periods;	      /* counts number of min. periods until
+				       * min_multiple is reached
+				       */
+	int min_period_count;	      /* counts bytes to count number of
+				       * min. periods
+				       */
+
+	unsigned int sw_buffer_size;  /* Byte size of software buffer */
+
+	/* sw_data: position in intermediate buffer, where we will read (or
+	 *          write) from/to next time (to transfer data to/from HW)
+	 */
+	unsigned int sw_data;         /* Offset to next dst (or src) in sw
+				       * ring buffer
+				       */
+	/* easiest case (playback):
+	 * sw_data is nearly the same as ~ runtime->control->appl_ptr, with the
+	 * exception that sw_data is "behind" by the number if bytes ALSA wrote
+	 * to the intermediate buffer last time.
+	 * A call to ack() callback synchronizes both indirectly.
+	 */
+
+	/* We have no real sw_io pointer here. Usually sw_io is pointing to the
+	 * current playback/capture position _inside_ the hardware. Devices
+	 * with plain FIFOs often have no possibility to publish this position.
+	 * So we say: if sw_data is updated, that means bytes were copied to
+	 * the hardware, we increase sw_io by that amount, because there have
+	 * to be as much bytes which were played. So sw_io will stay behind
+	 * sw_data all the time and has to converge to sw_data at the end of
+	 * playback.
+	 */
+	unsigned int sw_io;           /* Current software pointer in bytes */
+
+	/* sw_ready: number of bytes ALSA copied to the intermediate buffer, so
+	 * it represents the number of bytes which wait for transfer to the HW
+	 */
+	int sw_ready;		  /* Bytes ready to be transferred to/from hw */
+
+	/* appl_ptr: last known position of ALSA (where ALSA is going to write
+	 * next time into the intermediate buffer
+	 */
+	snd_pcm_uframes_t appl_ptr;   /* Last seen appl_ptr */
+
+	unsigned int bytes2hw;
+	int check_alignment;
+
+#ifdef SND_PCM_INDIRECT2_STAT
+	unsigned int zeros2hw;
+	unsigned int mul_elapsed;
+	unsigned int mul_elapsed_real;
+	unsigned long firstbytetime;
+	unsigned long lastbytetime;
+	unsigned long firstzerotime;
+	unsigned int byte_sizes[64];
+	unsigned int zero_sizes[64];
+	unsigned int min_adds[8];
+	unsigned int mul_adds[8];
+	unsigned int zero_times[3750];	/* = 15s */
+	unsigned int zero_times_saved;
+	unsigned int zero_times_notsaved;
+	unsigned int irq_occured;
+	unsigned int pointer_calls;
+	unsigned int lastdifftime;
+#endif
+};
+
+typedef size_t (*snd_pcm_indirect2_copy_t) (struct snd_pcm_substream *substream,
+					   struct snd_pcm_indirect2 *rec,
+					   size_t bytes);
+typedef size_t (*snd_pcm_indirect2_zero_t) (struct snd_pcm_substream *substream,
+					   struct snd_pcm_indirect2 *rec);
+
+#ifdef SND_PCM_INDIRECT2_STAT
+void snd_pcm_indirect2_stat(struct snd_pcm_substream *substream,
+				   struct snd_pcm_indirect2 *rec);
+#endif
+
+snd_pcm_uframes_t
+snd_pcm_indirect2_pointer(struct snd_pcm_substream *substream,
+			  struct snd_pcm_indirect2 *rec);
+void
+snd_pcm_indirect2_playback_interrupt(struct snd_pcm_substream *substream,
+				     struct snd_pcm_indirect2 *rec,
+				     snd_pcm_indirect2_copy_t copy,
+				     snd_pcm_indirect2_zero_t zero);
+void
+snd_pcm_indirect2_capture_interrupt(struct snd_pcm_substream *substream,
+				    struct snd_pcm_indirect2 *rec,
+				    snd_pcm_indirect2_copy_t copy,
+				    snd_pcm_indirect2_zero_t null);
+
+#endif /* __SOUND_PCM_INDIRECT2_H */