[U-Boot] [PATCH v1 20/21] sparc: leon3: Added busy wait function, made wait_ms() work when IRQ is disabled

[Francois Retief]

From: Daniel Hellstrom <daniel at gaisler.com>

Signed-off-by: Daniel Hellstrom <daniel at gaisler.com>
Signed-off-by: Francois Retief <fgretief at spaceteq.co.za>
---

 arch/sparc/cpu/leon3/cpu_init.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/cpu/leon3/cpu_init.c b/arch/sparc/cpu/leon3/cpu_init.c
index 88f82c9..9e294bf 100644
--- a/arch/sparc/cpu/leon3/cpu_init.c
+++ b/arch/sparc/cpu/leon3/cpu_init.c
@@ -11,6 +11,7 @@
 #include <asm/asi.h>
 #include <asm/leon.h>
 #include <asm/io.h>
+#include <asm/irq.h>
 #include <ambapp.h>
 #include <grlib/irqmp.h>
 #include <grlib/gptimer.h>
@@ -141,14 +142,41 @@ int cpu_init_r(void)
 	return 0;
 }
 
+/* Busy wait a number of ms */
+void cpu_wait_ms_busy(unsigned long ms)
+{
+	unsigned int ms_delay;
+	volatile unsigned int tmp;
+
+	/* ~10-20 cycles per decrement */
+	ms_delay = leon_cpu_freq / (1000 * 10);
+	do {
+		/* Wait ~1ms */
+		tmp = ms_delay;
+		while (tmp-- > 0)
+			;
+	} while (--ms > 0);
+}
+
 /* Uses Timer 0 to get accurate
  * pauses. Max 2 raised to 32 ticks
  *
  */
 void cpu_wait_ticks(unsigned long ticks)
 {
-	unsigned long start = get_timer(0);
-	while (get_timer(start) < ticks) ;
+	unsigned long start;
+
+	if (interrupt_is_enabled()) {
+		start = get_timer(0);
+		while (get_timer(start) < ticks)
+			;
+	} else {
+		/* Interrupts disabled, this means that we cannot
+		 * use get_timer(), it relies on IRQ. Instead the
+		 * CPU frequency is used.
+		 */
+		cpu_wait_ms_busy(ticks2usec(ticks) / 1000);
+	}
 }
 
 int timer_interrupt_init_cpu(void)
-- 
2.4.3