Sansa Clip+: add RDS support

Based on a patch by Amaury Pouly which was based on a patch from Ryan
Hitchman.

I mainly moved the code for polling into the tuner driver so it can be
reused by other targets. I added the CONFIG parameter for the polling
frequency (in ticks) to save energy. Also, I did some minor cleanups.

Change-Id: I95a62e7e1e42c62dbf47ecb27a3b312a42be62aa

firmware/drivers/tuner/si4700.c

@@ -587,12 +587,67 @@ void si4700_rds_process(void)
     if (tuner_powered())
     {
         si4700_read_reg(RDSD);
+#if (CONFIG_RDS & RDS_CFG_POLL)
+	/* we need to keep track of the ready bit because it stays set for 80ms
+	 * and we must avoid processing it twice */
+
+        static bool old_rdsr = false;
+        bool rdsr = (cache[STATUSRSSI] & STATUSRSSI_RDSR);
+        if (rdsr && !old_rdsr)
+            rds_process(&cache[RDSA]);
+        old_rdsr = rdsr;
+#else
         rds_process(&cache[RDSA]);
+#endif /* !(CONFIG_RDS & RDS_CFG_POLL) */
     }
 
     mutex_unlock(&fmr_mutex);
 }
 #endif /* (CONFIG_RDS & RDS_CFG_ISR) */
 
+#if (CONFIG_RDS & RDS_CFG_POLL)
+static struct event_queue rds_queue;
+static uint32_t rds_stack[DEFAULT_STACK_SIZE / sizeof(uint32_t)];
+
+enum {
+    Q_POWERUP,
+};
+
+static void NORETURN_ATTR rds_thread(void)
+{
+    /* start up frozen */
+    int timeout = TIMEOUT_BLOCK;
+    struct queue_event ev;
+
+    while (true) {
+        queue_wait_w_tmo(&rds_queue, &ev, timeout);
+        switch (ev.id) {
+            case Q_POWERUP:
+                /* power up: timeout after 1 tick, else block indefinitely */
+                timeout = ev.data ? CONFIG_RDS_POLL_TICKS : TIMEOUT_BLOCK;
+                break;
+            case SYS_TIMEOUT:;
+                /* Captures RDS data and processes it */
+                si4700_rds_process();
+                break;
+        }
+    }
+}
+
+/* true after full radio power up, and false before powering down */
+void si4700_rds_powerup(bool on)
+{
+    queue_post(&rds_queue, Q_POWERUP, on);
+}
+
+/* One-time RDS init at startup */
+void si4700_rds_init(void)
+{
+    queue_init(&rds_queue, false);
+    create_thread(rds_thread, rds_stack, sizeof(rds_stack), 0, "rds"
+        IF_PRIO(, PRIORITY_PLAYBACK) IF_COP(, CPU));
+}
+#endif /* !(CONFIG_RDS & RDS_CFG_POLL) */
+
 #endif /* HAVE_RDS_CAP */
 

firmware/export/config.h

@@ -718,6 +718,7 @@ Lyre prototype 1 */
 #define RDS_CFG_ISR     0x1 /* uses ISR to process packets */
 #define RDS_CFG_PROCESS 0x2 /* uses raw packet processing */
 #define RDS_CFG_PUSH    0x4 /* pushes processed information */
+#define RDS_CFG_POLL    0x8 /* tuner driver provides a polling function */
 #ifndef CONFIG_RDS
 #define CONFIG_RDS  RDS_CFG_PROCESS /* thread processing+raw processing */
 #endif /* CONFIG_RDS */

firmware/export/config/sansaclipplus.h

@@ -17,6 +17,9 @@
 
 #ifndef BOOTLOADER
 #define HAVE_HOTSWAP
+#define HAVE_RDS_CAP
+#define CONFIG_RDS (RDS_CFG_POLL | RDS_CFG_PROCESS)
+#define CONFIG_RDS_POLL_TICKS 4
 #endif
 
 #define HW_SAMPR_CAPS       SAMPR_CAP_ALL_96
@@ -146,6 +149,9 @@
 /* define this if the flash memory uses the SecureDigital Memory Card protocol */
 #define CONFIG_STORAGE STORAGE_SD
 
+/* Define this if target has an additional number of threads specific to it */
+#define TARGET_EXTRA_THREADS 1  /* RDS thread */
+
 #define BATTERY_CAPACITY_DEFAULT 290    /* default battery capacity */
 #define BATTERY_CAPACITY_MIN 290        /* min. capacity selectable */
 #define BATTERY_CAPACITY_MAX 290        /* max. capacity selectable */

firmware/export/si4700.h

@@ -55,7 +55,13 @@ void si4700_rds_read_raw_async(unsigned char *buf, int count); /* implemented by
 void si4700_rds_interrupt(void);
 #endif /* (CONFIG_RDS & RDS_CFG_ISR) */
 
-/* Read raw RDS info for processing */
+/* Read raw RDS info for processing.
+ * - If RDS_CFG_ISR is set, the tuner driver will call si4700_rds_read_raw_async() which should
+ *   perform an asynchronous read and call this function when the data has been read.
+ * - If RDS_CFG_POLL is set, this function will read status and RDS data and process it if a new
+ *   packet is available.
+ * - Otherwise this function will read a RDS packet and process it under the assumption that it is
+ *   new. */
 void si4700_rds_process(void);
 
 #endif /* HAVE_RDS_CAP */

firmware/target/arm/as3525/fmradio-i2c-as3525.c

@@ -185,6 +185,11 @@ int fmradio_i2c_read(unsigned char address, unsigned char* buf, int count)
 }
 
 #ifdef HAVE_RDS_CAP
+/* On the Sansa Clip Zip, the tuner interrupt line is routed to the SoC so we
+ * can use to detect when a RDS packet is ready. On the Clip+, we have to
+ * regularly poll. */
+
+#if !(CONFIG_RDS & RDS_CFG_POLL)
 /* Low-level RDS Support */
 static struct semaphore rds_sema;
 static uint32_t rds_stack[DEFAULT_STACK_SIZE/sizeof(uint32_t)];
@@ -231,4 +236,5 @@ void si4700_rds_init(void)
     create_thread(rds_thread, rds_stack, sizeof(rds_stack), 0, "rds"
                   IF_PRIO(, PRIORITY_REALTIME) IF_COP(, CPU));
 }
+#endif /* !(CONFIG_RDS & RDS_CFG_POLL) */
 #endif /* HAVE_RDS_CAP */

firmware/target/arm/as3525/system-as3525.c

@@ -180,7 +180,7 @@ void INT_GPIOA(void)
     void button_gpioa_isr(void);
     button_gpioa_isr();
 #endif
-#ifdef HAVE_RDS_CAP
+#if defined(HAVE_RDS_CAP) && !(CONFIG_RDS & RDS_CFG_POLL)
     void tuner_isr(void);
     tuner_isr();
 #endif