RFT: convert Gigabeat RDS to thread

This kind of reverts 7b596416bf ("Gigabeat S: Update RDS processing to
use asynchronous I2C rather than thread."). However, requiring RDS to
run in thread context will a) allow more upcoming features and b) remove
quite some complexity from the codebase (see the diffstat here) because
Gigabeat is the only user. iMX31 should be able to handle one more
thread, as it can even run Linux.

Change-Id: I46130034595ba66392c5417c275d036f4bd26943

1 files changed, 14 insertions, 35 deletions

diff --git a/firmware/target/arm/imx31/gigabeat-s/fmradio-i2c-gigabeat-s.c b/firmware/target/arm/imx31/gigabeat-s/fmradio-i2c-gigabeat-s.c
index 5b0c71110d..c84f1cf41c 100644
--- a/firmware/target/arm/imx31/gigabeat-s/fmradio-i2c-gigabeat-s.c
+++ b/firmware/target/arm/imx31/gigabeat-s/fmradio-i2c-gigabeat-s.c
@@ -125,53 +125,30 @@ bool si4700_st(void)
     return (GPIO1_DR & (1 << 28)) >> 28;
 }
 
-
 /* Low-level RDS Support */
-static bool int_restore;
-
-/* Called after I2C read cycle completes */
-static void si4700_rds_read_raw_async_callback(struct i2c_transfer_desc *xfer)
-{
-    if (xfer->rxcount == 0)
-        si4700_rds_process();
-    /* else read didn't finish */
-
-    if (int_restore)
-        gpio_int_enable(SI4700_EVENT_ID);
-}
-
-/* Called to read registers from ISR context */
-void si4700_rds_read_raw_async(unsigned char *buf, int count)
-{
-    /* transfer descriptor for RDS async operations */
-    static struct i2c_transfer_desc xfer = { .node = &si4700_i2c_node };
-
-    xfer.txdata = NULL;
-    xfer.txcount = 0;
-    xfer.rxdata = buf;
-    xfer.rxcount = count;
-    xfer.callback = si4700_rds_read_raw_async_callback;
-    xfer.next = NULL;
-
-    i2c_transfer(&xfer);
-}
+static struct semaphore rds_sema;
+static uint32_t rds_stack[DEFAULT_STACK_SIZE/sizeof(uint32_t)];
 
 /* RDS GPIO interrupt handler - start RDS data read */
 void INT_SI4700_RDS(void)
 {
-    /* mask and clear the interrupt until we're done */
-    gpio_int_disable(SI4700_EVENT_ID);
     gpio_int_clear(SI4700_EVENT_ID);
+    semaphore_release(&rds_sema);
+}
 
-    /* tell radio driver about it */
-    si4700_rds_interrupt();
+/* Captures RDS data and processes it */
+static void NORETURN_ATTR rds_thread(void)
+{
+    while (true) {
+        semaphore_wait(&rds_sema, TIMEOUT_BLOCK);
+        si4700_rds_process();
+    }
 }
 
 /* Called with on=true after full radio power up, and with on=false before
    powering down */
 void si4700_rds_powerup(bool on)
 {
-    int_restore = on;
     gpio_int_disable(SI4700_EVENT_ID);
     gpio_int_clear(SI4700_EVENT_ID);
     gpio_enable_event(SI4700_EVENT_ID, on);
@@ -180,5 +157,7 @@ void si4700_rds_powerup(bool on)
 /* One-time RDS init at startup */
 void si4700_rds_init(void)
 {
-    /* nothing to do */
+    semaphore_init(&rds_sema, 1, 0);
+    create_thread(rds_thread, rds_stack, sizeof(rds_stack), 0, "rds"
+                  IF_PRIO(, PRIORITY_REALTIME) IF_COP(, CPU));
 }