YP-CP3: Si4703 FM radio

The YP-CP3's tuner is a Silicon Labs Si470x at I2C address 0x20, an
Si4703 by the RDS the original firmware enables. The firmware drives it
the Si470x way - writes from register 2, reads from 0x0A - starts its
oscillator with TEST1 = 0x8100 and a 500 ms wait before ENABLE, and has
no power or reset line for it.

- config: CONFIG_TUNER SI4700 with RDS, polled (no interrupt line
  needed), and FM radio as an input source
- si4700.c: the YP-CP3 starts the oscillator as the Sansas do
- power-ypcp3.c: tuner power stubs - there is nothing to switch
- the rk27xx tuner I2C glue, and "radio" in the target's configure entry
- wm8751.c: audiohw_set_monitor() for a WM8750 target that plays the
  radio but cannot record (rk27xx has no recording yet). The tuner, on
  LINPUT1/RINPUT1, goes through the input PGA at +12 dB - as in the
  original firmware - into the output mixers, the DAC staying in the mix.
  The existing monitor routing lives in the recording code and switches
  OUT2 off, which is the YP-CP3's headphone output.

Tested on a YP-CP3: stations tune and play at a sane level.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Change-Id: Ic097fc85dbd7fb71fcc28c97a9d378fa09599e79

firmware/SOURCES

@@ -1739,6 +1739,9 @@ target/arm/rk27xx/ypcp3/lcd-ypcp3.c
 #ifndef BOOTLOADER
 target/arm/rk27xx/ypcp3/wmcodec-ypcp3.c
 #endif
+#if CONFIG_TUNER
+target/arm/rk27xx/rk27generic/fmradio-i2c-rk27generic.c
+#endif
 #endif
 
 #if CONFIG_CPU == JZ4732

firmware/drivers/audio/wm8751.c

@@ -427,6 +427,43 @@ void audiohw_set_depth_3d(int val)
 }
 #endif
 
+#if defined(HAVE_WM8750) && defined(HAVE_FMRADIO_IN) && !defined(HAVE_RECORDING)
+/* The FM tuner, on LINPUT1/RINPUT1, played through the analog bypass into
+ * the output mixers - for a target that plays the radio but cannot record
+ * it. As on the YP-CP3's original firmware, the signal goes through the
+ * input PGA at +12 dB, which the tuner's low line level needs. The DAC
+ * stays in the mix. */
+void audiohw_set_monitor(bool enable)
+{
+    if (enable)
+    {
+        wmcodec_set_masked(ADCL, ADCL_LINSEL_LINPUT1, ADCL_LINSEL_MASK);
+        wmcodec_set_masked(ADCR, ADCR_RINSEL_RINPUT1, ADCR_RINSEL_MASK);
+        wmcodec_set_reg(LINVOL, LINVOL_LIZC | LINVOL_LINVOL(0x27));
+        wmcodec_set_reg(RINVOL, RINVOL_RIVU | RINVOL_RIZC |
+                        RINVOL_RINVOL(0x27));
+        wmcodec_set_bits(PWRMGMT1, PWRMGMT1_AINL | PWRMGMT1_AINR);
+
+        wmcodec_set_masked(LEFTMIX1, LEFTMIX1_LMIXSEL_ADCLIN |
+                           LEFTMIX1_LI2LOVOL(0x20),
+                           0x7 | LEFTMIX1_LI2LOVOL_MASK);
+        wmcodec_set_bits(LEFTMIX1, LEFTMIX1_LI2LO);
+        wmcodec_set_masked(RIGHTMIX1, RIGHTMIX1_RMIXSEL_ADCRIN, 0x7);
+        wmcodec_set_masked(RIGHTMIX2, RIGHTMIX2_RI2ROVOL(0x20),
+                           RIGHTMIX2_RI2ROVOL_MASK);
+        wmcodec_set_bits(RIGHTMIX2, RIGHTMIX2_RI2RO);
+    }
+    else
+    {
+        wmcodec_clear_bits(LEFTMIX1, LEFTMIX1_LI2LO);
+        wmcodec_clear_bits(RIGHTMIX2, RIGHTMIX2_RI2RO);
+        wmcodec_set_bits(LINVOL, LINVOL_LINMUTE);
+        wmcodec_set_bits(RINVOL, RINVOL_RIVU | RINVOL_RINMUTE);
+        wmcodec_clear_bits(PWRMGMT1, PWRMGMT1_AINL | PWRMGMT1_AINR);
+    }
+}
+#endif
+
 #ifdef HAVE_RECORDING
 #if 0
 static void audiohw_set_ngat(int ngath, int type, bool enable)

firmware/drivers/tuner/si4700.c

@@ -34,7 +34,7 @@
 #include "backlight.h"
 
 #if defined(SANSA_CLIP) || defined(SANSA_E200V2) || defined(SANSA_FUZE) || defined(SANSA_C200V2) \
-    || defined(SANSA_FUZEPLUS)
+    || defined(SANSA_FUZEPLUS) || defined(SAMSUNG_YPCP3)
 /* some models use the internal 32 kHz oscillator which needs special attention
    during initialisation, power-up and power-down. */
 #define SI4700_USE_INTERNAL_OSCILLATOR

firmware/export/config/samsungypcp3.h

@@ -108,6 +108,15 @@
  * original firmware */
 #define CONFIG_RTC RTC_S35390A
 
+/* Silicon Labs Si4703 FM tuner on I2C, with RDS. It has no power control -
+ * the original firmware has none either - and its audio reaches the codec
+ * on LINPUT1/RINPUT1. RDS is polled, which needs no interrupt line. */
+#define CONFIG_TUNER SI4700
+#define HAVE_RDS_CAP
+#define CONFIG_RDS (RDS_CFG_POLL | RDS_CFG_PROCESS)
+#define CONFIG_RDS_POLL_TICKS 4
+#define INPUT_SRC_CAPS SRC_CAP_FMRADIO
+
 /* Define this for LCD backlight available */
 #define HAVE_BACKLIGHT
 #define HAVE_BACKLIGHT_BRIGHTNESS

firmware/target/arm/rk27xx/ypcp3/power-ypcp3.c

@@ -44,6 +44,21 @@ void power_off(void)
     }
 }
 
+#if CONFIG_TUNER
+/* The tuner has no power switch; the original firmware does not switch it
+ * either, it only puts the chip to sleep over I2C. */
+bool tuner_power(bool status)
+{
+    (void)status;
+    return true;
+}
+
+bool tuner_powered(void)
+{
+    return true;
+}
+#endif
+
 unsigned int power_input_status(void)
 {
     return (usb_detect() == USB_INSERTED) ? POWER_INPUT_MAIN_CHARGER : POWER_INPUT_NONE;