From 6aa807d32170eb463ede46397cb43c1c4088cbe9 Mon Sep 17 00:00:00 2001
From: Rafaël Carré <rafael.carre@gmail.com>
Date: Thu, 4 Dec 2008 22:27:48 +0000
Subject: Sansa AMS: PCM driver (FS#9592)

Note that on low memory targets (Clip/m200v4 tested) you will encounter
random crashes. Applying FS#9332 seems to help a lot.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19342 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/arm/as3525/pcm-as3525.c | 102 ++++++++++++++++++++++++++++----
 1 file changed, 92 insertions(+), 10 deletions(-)

(limited to 'firmware/target/arm/as3525/pcm-as3525.c')

diff --git a/firmware/target/arm/as3525/pcm-as3525.c b/firmware/target/arm/as3525/pcm-as3525.c
index d91450c9cf..0386cc3336 100644
--- a/firmware/target/arm/as3525/pcm-as3525.c
+++ b/firmware/target/arm/as3525/pcm-as3525.c
@@ -21,58 +21,140 @@
 #include "system.h"
 #include "audio.h"
 #include "string.h"
-
-/* TODO */
-
+#include "as3525.h"
+#include "pl081.h"
+#include "dma-target.h"
+#include "clock-target.h"
+#include "panic.h"
+#include "as3514.h"
+#include "audiohw.h"
+
+#define MAX_TRANSFER (4*((1<<11)-1)) /* maximum data we can transfer via DMA
+                                      * i.e. 32 bits at once (size of I2SO_DATA)
+                                      * and the number of 32bits words has to
+                                      * fit in 11 bits of DMA register */
+
+static unsigned char *dma_start_addr;
+static size_t      dma_size;   /* in 4*32 bits */
+static void dma_callback(void);
+static int locked = 0;
+
+/* Mask the DMA interrupt */
 void pcm_play_lock(void)
 {
+    if(++locked == 1)
+        VIC_INT_EN_CLEAR |= INTERRUPT_DMAC;
 }
 
+/* Unmask the DMA interrupt if enabled */
 void pcm_play_unlock(void)
 {
+    if(--locked == 0)
+        VIC_INT_ENABLE |= INTERRUPT_DMAC;
 }
 
-void pcm_play_dma_start(const void *addr, size_t size)
+static void play_start_pcm(void)
 {
+    const unsigned char* addr = dma_start_addr;
+    size_t size = dma_size;
+    if(size > MAX_TRANSFER)
+        size = MAX_TRANSFER;
+
+    if((unsigned int)dma_start_addr & 3)
+        panicf("unaligned pointer!");
+
+    dma_size -= size;
+    dma_start_addr += size;
+
+    dma_enable_channel(1, (void*)addr, (void*)I2SOUT_DATA, DMA_PERI_I2SOUT,
+                DMAC_FLOWCTRL_DMAC_MEM_TO_PERI, true, false, size >> 2, DMA_S1,
+                dma_callback);
 }
 
-void pcm_play_dma_stop(void)
+static void dma_callback(void)
 {
+    if(!dma_size)
+    {
+        register pcm_more_callback_type get_more = pcm_callback_for_more;
+        if(get_more)
+            get_more(&dma_start_addr, &dma_size);
+    }
+
+    if(!dma_size)
+        pcm_play_dma_stop();
+    else
+        play_start_pcm();
 }
 
-void pcm_play_dma_pause(bool pause)
+void pcm_play_dma_start(const void *addr, size_t size)
 {
+    dma_size = size;
+    dma_start_addr = (unsigned char*)addr;
+
+    play_start_pcm();
 }
 
-unsigned long physical_address(void *p)
+void pcm_play_dma_stop(void)
+{
+    dma_disable_channel(1);
+    dma_size = 0;
+}
+
+void pcm_play_dma_pause(bool pause)
 {
-    return 0;
+    if(pause)
+        dma_disable_channel(1);
+    else
+        play_start_pcm();
 }
 
 void pcm_play_dma_init(void)
 {
+    CGU_PERI |= CGU_I2SOUT_APB_CLOCK_ENABLE;
+
+    /* enable I2SO_MCLK, clock source PLLA, minimal frequency */
+    CGU_AUDIO |= (1<<11) | (511<<2) | (1<<0);
+
+    I2SOUT_CONTROL |= (1<<6) ;  /* enable dma */
+    I2SOUT_CONTROL |= (1<<3) ;  /* stereo */
+    I2SOUT_CONTROL &= ~(1<<2);  /* 16 bit samples */
+
+    audiohw_preinit();
 }
 
 void pcm_postinit(void)
 {
+    audiohw_postinit();
+    pcm_apply_settings();
 }
 
 void pcm_set_frequency(unsigned int frequency)
 {
+    const int divider = (((AS3525_PLLA_FREQ/128) + (frequency/2)) / frequency) - 1;
+    if(divider < 0 || divider > 511)
+        panicf("unsupported frequency %d", frequency);
+
+    CGU_AUDIO &= ~(((511 ^ divider) << 2) /* I2SOUT */
+            /*| ((511 ^ divider) << 14) */ /* I2SIN */
+            );
+
+    pcm_curr_sampr = frequency;
 }
 
 void pcm_apply_settings(void)
 {
+    pcm_set_frequency(HW_SAMPR_DEFAULT);
 }
 
 size_t pcm_get_bytes_waiting(void)
 {
-    return 0;
+    return dma_size;
 }
 
 const void * pcm_play_dma_get_peak_buffer(int *count)
 {
-    return NULL;
+    *count = dma_size >> 2;
+    return (const void*)dma_start_addr;
 }
 
 
-- 
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