Forget all the nonsense with C delay loops. 'volatile' on the variable makes bloated code and a volatile, blank asm block inside may or may not be optimized out. Use asm delay loops instead for Coldfire. Radio i2c driver also needs NACK after reading last tuner byte. Get the volatile off the Ondio loops (not needed here now). Maybe this is straightened out now.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13725 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 27 insertions, 11 deletions

diff --git a/firmware/drivers/fmradio_i2c.c b/firmware/drivers/fmradio_i2c.c
index 1c9bc300c2..0a1d0c1fd7 100644
--- a/firmware/drivers/fmradio_i2c.c
+++ b/firmware/drivers/fmradio_i2c.c
@@ -80,7 +80,17 @@ int fmradio_i2c_read(unsigned char address, unsigned char* buf, int count)
 #endif
 
 /* delay loop to achieve 400kHz at 120MHz CPU frequency */
-#define DELAY   do { volatile int _x; for(_x=0;_x<22;_x++);} while (0)
+#define DELAY   \
+    ({                                \
+        int _x_;                      \
+        asm volatile (                \
+            "move.l #21, %[_x_] \r\n" \
+        "1:                     \r\n" \
+            "subq.l #1, %[_x_]  \r\n" \
+            "bhi.b  1b          \r\n" \
+            : [_x_]"=&d"(_x_)         \
+        );                            \
+    })
 
 static void fmradio_i2c_start(void)
 {
@@ -102,8 +112,8 @@ static void fmradio_i2c_stop(void)
    SDA_HI;
 }
 
-
-static void fmradio_i2c_ack(void)
+/* Generate ACK or NACK */
+static void fmradio_i2c_ack(bool nack)
 {
     /* Here's the deal. The slave is slow, and sometimes needs to wait
        before it can receive the acknowledge. Therefore it forces the clock
@@ -114,7 +124,11 @@ static void fmradio_i2c_ack(void)
        we have to drive the SCL high repeatedly to simulate a pullup. */
     
     SCL_LO;      /* Set the clock low */
-    SDA_LO;
+
+    if (nack)
+        SDA_HI;
+    else
+        SDA_LO;
     
     SCL_INPUT;   /* Set the clock to input */
     while(!SCL)  /* and wait for the slave to release it */
@@ -248,8 +262,7 @@ int fmradio_i2c_read(int address, unsigned char* buf, int count)
         for (i=count; i>0; i--)
         {
             *buf++ = fmradio_i2c_inb();
-            if (i != 1)
-                fmradio_i2c_ack();
+            fmradio_i2c_ack(i == 1);
         }
     }
     else
@@ -275,7 +288,7 @@ int fmradio_i2c_read(int address, unsigned char* buf, int count)
 #define SCL     (PBDR & 0x0002)
 
 /* arbitrary delay loop */
-#define DELAY   do { volatile int _x; for(_x=0;_x<20;_x++);} while (0)
+#define DELAY   do { int _x; for(_x=0;_x<20;_x++);} while (0)
 
 static void fmradio_i2c_start(void)
 {
@@ -296,7 +309,7 @@ static void fmradio_i2c_stop(void)
 }
 
 
-static void fmradio_i2c_ack(void)
+static void fmradio_i2c_ack(bool nack)
 {
     /* Here's the deal. The slave is slow, and sometimes needs to wait
        before it can receive the acknowledge. Therefore it forces the clock
@@ -304,7 +317,11 @@ static void fmradio_i2c_ack(void)
        high before we release the ack. */
     
     SCL_LO;      /* Set the clock low */
-    SDA_LO;
+
+    if (nack)
+        SDA_HI;
+    else
+        SDA_LO;
     
     SCL_INPUT;   /* Set the clock to input */
     while(!SCL)  /* and wait for the slave to release it */
@@ -416,8 +433,7 @@ int fmradio_i2c_read(int address, unsigned char* buf, int count)
         for (i=count; i>0; i--)
         {
             *buf++ = fmradio_i2c_inb();
-            if (i != 1)
-               fmradio_i2c_ack();
+            fmradio_i2c_ack(i == 1);
         }
     }
     else