e200v1/c200v1: Implement limited samplerate switching. Rates 24kHz and below are being a bear as far as minor crackling at higher amplitude-- leave them out for the time being since no solution is currently evident. 48, 44, 32 (rec rates 24, 22, 16) seem perfectly fine. I'm betting c200 is ok to include because it uses the same setup as e200.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27139 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 89 insertions, 0 deletions

diff --git a/firmware/target/arm/i2s-pp.c b/firmware/target/arm/i2s-pp.c
index c9d66d53ae..83f39515c4 100644
--- a/firmware/target/arm/i2s-pp.c
+++ b/firmware/target/arm/i2s-pp.c
@@ -28,6 +28,10 @@
 #include "system.h"
 #include "cpu.h"
 #include "i2s.h"
+#if defined (SANSA_E200) || defined (SANSA_C200)
+#include "audiohw.h"
+#include "pcm_sampr.h"
+#endif
 
 #if CONFIG_CPU == PP5002
 void i2s_reset(void)
@@ -70,6 +74,8 @@ void i2s_reset(void)
     IISCLK = (IISCLK & ~0x1ff) | 31;
     IISDIV = (IISDIV & ~0xc0000000) | (2 << 30);
     IISDIV = (IISDIV & ~0x3f) | 16;
+#elif defined (SANSA_E200) || defined (SANSA_C200)
+    audiohw_set_sampr_dividers(HW_FREQ_DEFAULT);
 #else
     IISCLK = (IISCLK & ~0x1ff) | 33;
     IISDIV = 7;
diff --git a/firmware/target/arm/sandisk/audio-c200_e200.c b/firmware/target/arm/sandisk/audio-c200_e200.c
index 1d78e71541..0037bac58b 100644
--- a/firmware/target/arm/sandisk/audio-c200_e200.c
+++ b/firmware/target/arm/sandisk/audio-c200_e200.c
@@ -22,6 +22,7 @@
 #include "cpu.h"
 #include "audio.h"
 #include "sound.h"
+#include "general.h"
 
 int audio_channels = 2;
 int audio_output_source = AUDIO_SRC_PLAYBACK;
@@ -92,3 +93,85 @@ void audio_input_mux(int source, unsigned flags)
 
     last_source = source;
 } /* audio_input_mux */
+
+
+void audiohw_set_sampr_dividers(int fsel)
+{
+    /* Seems to predivide 24MHz by 2 for a source clock of 12MHz. Maybe
+     * there's a way to set that? */
+    static const struct
+    {
+        unsigned char iisclk;
+        unsigned char iisdiv;
+    } regvals[HW_NUM_FREQ] =
+    {
+        /* 8kHz - 24kHz work well but there seems to be a minor crackling
+         * issue for playback at times and all possibilities were checked
+         * for the divisors without any positive change.
+         * 32kHz - 48kHz seem fine all around. */
+#if 0
+        [HW_FREQ_8] =       /* CLK / 1500 (8000Hz) */
+        {
+            .iisclk = 24,
+            .iisdiv = 59,
+        },
+        [HW_FREQ_11] =      /* CLK / 1088 (~11029.41Hz) */
+        {
+            .iisclk = 33,
+            .iisdiv = 31,
+        },
+        [HW_FREQ_12] =      /* CLK / 1000 (120000Hz) */
+        {
+            .iisclk = 49,
+            .iisdiv = 19,
+        },
+        [HW_FREQ_16] =      /* CLK / 750 (16000Hz) */
+        {
+            .iisclk = 24,
+            .iisdiv = 29,
+        },
+        [HW_FREQ_22] =      /* CLK / 544 (~22058.82Hz)  */
+        {
+            .iisclk = 33,
+            .iisdiv = 15,
+        },
+        [HW_FREQ_24] =      /* CLK / 500 (24000Hz) */
+        {
+            .iisclk = 49,
+            .iisdiv = 9,
+        },
+#endif
+        [HW_FREQ_32] =      /* CLK / 375 (32000Hz) */
+        {
+            .iisclk = 24,
+            .iisdiv = 14,
+        },
+        [HW_FREQ_44] =      /* CLK / 272 (~44117.68Hz) */
+        {
+            .iisclk = 33,
+            .iisdiv = 7,
+        },
+        [HW_FREQ_48] =      /* CLK / 250 (48000Hz) */
+        {
+            .iisclk = 49,
+            .iisdiv = 4,
+        },
+        /* going a bit higher would be nice to get 64kHz play, 32kHz rec, but a
+         * close enough division isn't obtainable unless CLK can be changed */
+    };
+
+    IISCLK = (IISCLK & ~0x17ff) | regvals[fsel].iisclk;
+    IISDIV = (IISDIV & ~0xc000003f) | regvals[fsel].iisdiv;
+}
+
+unsigned int pcm_sampr_type_rec_to_play(unsigned int samplerate)
+{
+    /* Check if the samplerate is in the list of recordable rates.
+     * Fail to default if not */
+    int index = round_value_to_list32(samplerate, rec_freq_sampr,
+                                      REC_NUM_FREQ, false);
+    if (samplerate != rec_freq_sampr[index])
+        return HW_SAMPR_DEFAULT;
+
+    return samplerate * 2; /* Recording rates are 1/2 the codec clock */
+}