iPod Classic: capture support for CS42L55 codec

There are a couple of power saving options that can be selected using
defines, they configure the CODEC in a different way than OF does:

 MONO_MIC: jack microphone is connected to left channel, disabling
 right channel saves ~1 mW, there is no reason to not to do it.

 BYPASS_PGA: this option only applies to the line-in, OF does not
 bypass the PGA and configures it to 0 dB gain. At the beginning,
 this patch was written based on CODEC datasheet, bypassing PGA
 because it saves power and incrementes dinamic range ~1dB, i have
 used this setup for a while without problems. Finally this option
 was disabled at the last minute, i decided to do it after reviewing
 the OF and realizing that CS42L55 datasheet recommends to bypass the
 PGA only if the HW includes a couple of capacitors (see Typical
 Connection Diagram, Note 4), at this moment i don't know if Classic
 includes these capacitors (probably not). Anyway, i am not able to
 tell the difference listening to voice recodings.

TODO:
- Use variable PGA gain for jack microphone (it is fixed to +12 dB.
  as OF does).
- I am not a fan of having lots of unused #define options, these could
  be useful for a generic driver but actually this driver is Classic
  oriented, i am not sure if it could be considered disirable to
  eliminate them in the final version.

Change-Id: I3dadf2341f44d5e13f3847e6c9de4a76cd6f0918

firmware/drivers/audio/cs42l55.c

@@ -32,6 +32,7 @@
 #include "cs42l55.h"
 
 static int bass, treble;
+static int active_dsp_modules;  /* powered DSP modules mask */
 
 /* convert tenth of dB volume (-600..120) to volume register value */
 static int vol_tenthdb2hw(int db)
@@ -66,6 +67,7 @@ void audiohw_preinit(void)
 
     bass = 0;
     treble = 0;
+    active_dsp_modules = 0;
 
     /* Ask Cirrus or maybe Apple what the hell this means */
     cscodec_write(HIDDENCTL, HIDDENCTL_UNLOCK);
@@ -143,24 +145,40 @@ void audiohw_enable_lineout(bool enable)
                         PWRCTL2_PDN_LINA_ALWAYS | PWRCTL2_PDN_LINB_ALWAYS);
 }
 
-static void handle_dsp_power(void)
+static void handle_dsp_power(int dsp_module, bool onoff)
+{
+    if (onoff)
+    {
+        if (!active_dsp_modules)
+            cscodec_setbits(PLAYCTL, PLAYCTL_PDN_DSP, 0);
+        active_dsp_modules |= dsp_module;
+    }
+    else
+    {
+        active_dsp_modules &= ~dsp_module;
+        if (!active_dsp_modules)
+            cscodec_setbits(PLAYCTL, 0, PLAYCTL_PDN_DSP);
+    }
+}
+
+static void handle_tone_onoff(void)
 {
     if (bass || treble)
     {
-        cscodec_setbits(PLAYCTL, PLAYCTL_PDN_DSP, 0);
+        handle_dsp_power(DSP_MODULE_TONE, 1);
         cscodec_setbits(BTCTL, 0, BTCTL_TCEN);
     }
     else
     {
         cscodec_setbits(BTCTL, BTCTL_TCEN, 0);
-        cscodec_setbits(PLAYCTL, 0, PLAYCTL_PDN_DSP);
+        handle_dsp_power(DSP_MODULE_TONE, 0);
     }
 }
 
 void audiohw_set_bass(int value)
 {
     bass = value;
-    handle_dsp_power();
+    handle_tone_onoff();
     if (value >= -105 && value <= 120)
         cscodec_setbits(TONECTL, TONECTL_BASS_MASK,
                         (8 - value / 15) << TONECTL_BASS_SHIFT);
@@ -169,7 +187,7 @@ void audiohw_set_bass(int value)
 void audiohw_set_treble(int value)
 {
     treble = value;
-    handle_dsp_power();
+    handle_tone_onoff();
     if (value >= -105 && value <= 120)
         cscodec_setbits(TONECTL, TONECTL_TREB_MASK,
                         (8 - value / 15) << TONECTL_TREB_SHIFT);
@@ -225,5 +243,110 @@ void audiohw_set_frequency(int fsel)
 }
 
 #ifdef HAVE_RECORDING
-//TODO: Implement
+/* Saves power for targets supporting only mono microphone. */
+#define MONO_MIC
+
+/* Classic OF does not bypass PGA when line-in is selected. It can be
+ * bypassed for power saving instead of using it at fixed 0 dB gain.
+ * See CS42L55 DS, Figure 1 (Typical Connection Diagram), Note 4.
+ */
+/*#define BYPASS_PGA*/
+
+void audiohw_enable_recording(bool source_mic)
+{
+    /* mute ADCs */
+    cscodec_write(ADCCTL, ADCCTL_ADCAMUTE | ADCCTL_ADCBMUTE);
+
+    /* from cs42l55 DS:
+     *  PWRCTL1[3]: ADC charge pump, for optimal ADC performance
+     *  and power consumption, set to ‘1’b when VA > 2.1 V and
+     *  set to ‘0’b when VA < 2.1 V.
+     */
+    if (source_mic)
+    {
+        #ifdef MONO_MIC
+        /* power-up CODEC, ADCA and ADC pump */
+        cscodec_write(PWRCTL1, PWRCTL1_PDN_ADCB);
+        #else
+        /* power-up CODEC, ADCA, ADCB and ADC pump */
+        cscodec_write(PWRCTL1, 0);
+        #endif
+
+        #ifdef BYPASS_PGA
+        /* select PGA as input */
+        cscodec_setbits(ALHMUX, ALHMUX_ADCAMUX_MASK | ALHMUX_ADCBMUX_MASK,
+                            ALHMUX_ADCAMUX_PGAA | ALHMUX_ADCBMUX_PGAB);
+        #endif
+
+        /* configure PGA: select AIN2 and set gain */
+        cscodec_write(PGAACTL, PGAACTL_MUX_AIN2A |
+                            ((PGA_GAIN_DB << 1) & PGAACTL_VOLUME_MASK));
+        #ifndef MONO_MIC
+        cscodec_write(PGABCTL, PGABCTL_MUX_AIN2B |
+                            ((PGA_GAIN_DB << 1) & PGABCTL_VOLUME_MASK));
+        #endif
+    }
+    else /* line-in */
+    {
+        /* power-up CODEC, ADCA, ADCB and ADC pump */
+        cscodec_write(PWRCTL1, 0);
+
+        #ifdef BYPASS_PGA
+        /* selects AIN1 as input (PGA is bypassed) */
+        cscodec_setbits(ALHMUX, ALHMUX_ADCAMUX_MASK | ALHMUX_ADCBMUX_MASK,
+                            ALHMUX_ADCAMUX_AIN1A | ALHMUX_ADCBMUX_AIN1B);
+        #else
+        /* configure PGA: select AIN1 and set gain to 0dB */
+        cscodec_write(PGAACTL, PGAACTL_MUX_AIN1A);
+        cscodec_write(PGABCTL, PGABCTL_MUX_AIN1B);
+        #endif
+    }
+
+    cscodec_write(ADCCTL, 0);   /* unmute ADCs */
+}
+
+void audiohw_disable_recording(void)
+{
+    /* reset used registers to default values */
+    cscodec_write(PGAACTL, 0);
+    cscodec_write(PGABCTL, 0);
+#ifdef BYPASS_PGA
+    cscodec_setbits(ALHMUX, ALHMUX_ADCAMUX_MASK | ALHMUX_ADCBMUX_MASK,
+                        ALHMUX_ADCAMUX_PGAA | ALHMUX_ADCBMUX_PGAB);
+#endif
+    /* power-down ADC section */
+    cscodec_write(PWRCTL1, PWRCTL1_PDN_CHRG |
+                        PWRCTL1_PDN_ADCA | PWRCTL1_PDN_ADCB);
+}
+
+void audiohw_set_recvol(int left, int right, int type)
+{
+#ifndef MONO_MIC
+    (void) type;
+#else
+    if (type == AUDIO_GAIN_LINEIN)
+#endif
+    cscodec_write(ADCBATT, right);
+    cscodec_write(ADCAATT, left);
+}
+
+void audiohw_set_monitor(bool enable)
+{
+    if (enable)
+    {
+        /* enable DSP power if it is actually disabled */
+        handle_dsp_power(DSP_MODULE_MONITOR, 1);
+        /* unmute ADC mixer */
+        cscodec_write(AMIXACTL, 0);
+        cscodec_write(AMIXBCTL, 0);
+    }
+    else
+    {
+        /* mute ADC mixer */
+        cscodec_write(AMIXACTL, AMIXACTL_AMIXAMUTE);
+        cscodec_write(AMIXBCTL, AMIXBCTL_AMIXBMUTE);
+        /* disable DSP power if it is not being used by other modules */
+        handle_dsp_power(DSP_MODULE_MONITOR, 0);
+    }
+}
 #endif /* HAVE_RECORDING */

firmware/export/cs42l55.h

@@ -23,13 +23,24 @@
 #define __CS42L55_H__
 
 #define AUDIOHW_CAPS (BASS_CAP | TREBLE_CAP | BASS_CUTOFF_CAP | \
-                      TREBLE_CUTOFF_CAP | PRESCALER_CAP | LINEOUT_CAP)
+                      TREBLE_CUTOFF_CAP | PRESCALER_CAP | LINEOUT_CAP | \
+                      LIN_GAIN_CAP | MIC_GAIN_CAP)
 
 AUDIOHW_SETTING(VOLUME,       "dB", 0,  1, -60,  12, -25)
 AUDIOHW_SETTING(BASS,         "dB", 1, 15,-105, 120,   0)
 AUDIOHW_SETTING(TREBLE,       "dB", 1, 15,-105, 120,   0)
 AUDIOHW_SETTING(BASS_CUTOFF,    "", 0,  1,   1,   4,   2)
 AUDIOHW_SETTING(TREBLE_CUTOFF,  "", 0,  1,   1,   4,   1)
+#ifdef HAVE_RECORDING
+#define PGA_GAIN_DB     12  /* PGA fixed gain, range: -6 to +12 dB */
+AUDIOHW_SETTING(LEFT_GAIN,    "dB", 0,  1, -96,   0,   0)
+AUDIOHW_SETTING(RIGHT_GAIN,   "dB", 0,  1, -96,   0,   0)
+AUDIOHW_SETTING(MIC_GAIN,     "dB", 0,  1, -96,   0,   0, val + PGA_GAIN_DB)
+#endif /* HAVE_RECORDING */
+
+/* powered DSP modules */
+#define DSP_MODULE_TONE         (1 << 0)
+#define DSP_MODULE_MONITOR      (1 << 1)
 
 void audiohw_enable_lineout(bool enable);