Blackfin: jtag-console: add debug markers

While we're in here, add some useful debug points.  We need custom debug
statements because we need the output to only go to the serial port.  If
we used the standard debug helpers, the output would also go to the stdout
(which would be the jtag console) and make it hard to figure out what is
going where exactly.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/cpu/jtag-console.c

@@ -10,6 +10,22 @@
 #include <stdio_dev.h>
 #include <asm/blackfin.h>
 
+#ifdef DEBUG
+# define dprintf(...) serial_printf(__VA_ARGS__)
+#else
+# define dprintf(...) do { if (0) printf(__VA_ARGS__); } while (0)
+#endif
+
+static inline void dprintf_decode(const char *s, uint32_t len)
+{
+	uint32_t i;
+	for (i = 0; i < len; ++i)
+		if (s[i] < 0x20 || s[i] >= 0x7f)
+			dprintf("\\%o", s[i]);
+		else
+			dprintf("%c", s[i]);
+}
+
 static inline uint32_t bfin_write_emudat(uint32_t emudat)
 {
 	__asm__ __volatile__("emudat = %0;" : : "d"(emudat));
@@ -52,6 +68,10 @@ static void jtag_send(const char *c, uint32_t len)
 	if (len == 0)
 		return;
 
+	dprintf("%s(\"", __func__);
+	dprintf_decode(c, len);
+	dprintf("\", %i)\n", len);
+
 	/* First send the length */
 	if (jtag_write_emudat(len))
 		return;
@@ -83,7 +103,10 @@ static size_t inbound_len, leftovers_len;
 /* Lower layers want to know when jtag has data */
 static int jtag_tstc_dbg(void)
 {
-	return (bfin_read_DBGSTAT() & 0x2);
+	int ret = (bfin_read_DBGSTAT() & 0x2);
+	if (ret)
+		dprintf("%s: ret:%i\n", __func__, ret);
+	return ret;
 }
 
 /* Higher layers want to know when any data is available */
@@ -101,6 +124,9 @@ static int jtag_getc(void)
 	int ret;
 	uint32_t emudat;
 
+	dprintf("%s: inlen:%zu leftlen:%zu left:%x\n", __func__,
+		inbound_len, leftovers_len, leftovers);
+
 	/* see if any data is left over */
 	if (leftovers_len) {
 		--leftovers_len;