ipodnano3g: power, RTC, backlight, battery and audio

Fills in the stubs the Nano 3G port was left with, taking each from how
the original firmware drives the same hardware.

Testing evidence: firmware/target/arm/s5l8702/ipodnano3g/TESTING.md.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Change-Id: Iea5314769502f5941a176600869591756c5e3233

firmware/export/audiohw.h

@@ -169,7 +169,7 @@ struct sound_settings_info
 #include "wm8751.h"
 #elif defined(HAVE_WM8978)
 #include "wm8978.h"
-#elif defined(HAVE_WM8975)
+#elif defined(HAVE_WM8975) || defined(HAVE_WM1870)
 #include "wm8975.h"
 #elif defined(HAVE_WM8985)
 #include "wm8985.h"

firmware/export/config/ipodnano3g.h

@@ -138,22 +138,17 @@
 #define HAVE_MORSE_INPUT
 
 /* define this if you have a real-time clock */
-// TODO
-//#define CONFIG_RTC RTC_NANO3G
-#define CONFIG_RTC  0
+#define CONFIG_RTC RTC_NANO3G
 
 /* Define if the device can wake from an RTC alarm */
 //#define HAVE_RTC_ALARM
 
 #define CONFIG_LCD LCD_IPOD6GNANO3G4G
 
-// TODO
-#if 0
-/* Define the type of audio codec */
-#define HAVE_WM8975
-#endif
-// XXX: dummy for preliminary build, WRONG CODEC!!!
-#define HAVE_CS42L55
+/* Define the type of audio codec. The Nano 3G has a Wolfson WM1870 at I2C
+ * address 0x34, which the original firmware drives as a WM8975 plus a few
+ * registers above the WM8975's range, so wm8975.c covers it. */
+#define HAVE_WM1870
 
 #define HAVE_PCM_DMA_ADDRESS
 

firmware/export/wm8975.h

@@ -313,4 +313,7 @@ void audiohw_enable_lineout(bool enable);
 #define WM8975_88200HZ     0x7f
 #define WM8975_96000HZ     0x5d
 
+/* The WM1870 (HAVE_WM1870) answers these registers and a few above them */
+#define WM1870_R67         0x43
+
 #endif /* _WM8975_H */

firmware/export/wmcodec.h

@@ -20,3 +20,9 @@
 
 void wmcodec_write(int reg, int data);
 
+#ifdef HAVE_WM1870
+/* SAMPCTRL for a sample rate, which depends on the MCLK the target feeds
+ * the codec. Zero if the target cannot make that rate. */
+unsigned short wmcodec_sampctrl(unsigned long rate);
+#endif
+