dspic: Timer bug fix (zephyrproject-rtos#29)

Fixed the issue in calculating the elapsed time

Signed-off-by: Udhayanandhan Jayakumar <[email protected]>

Author: Udhayanandhan-Jayakumar

drivers/timer/mchp_dspic33_timer.c

@@ -21,18 +21,25 @@ static struct k_spinlock lock;
 
 uint8_t map_prescaler_to_bits(uint32_t val)
 {
+	uint8_t ret_val;
 	switch (val) {
 	case 1:
-		return 0b00;
+		ret_val = 0b00;
+		break;
 	case 8:
-		return 0b01;
+		ret_val = 0b01;
+		break;
 	case 64:
-		return 0b10;
+		ret_val = 0b10;
+		break;
 	case 128:
-		return 0b11;
+		ret_val = 0b11;
+		break;
 	default:
-		return 0b00;
+		ret_val = 0b00;
+		break;
 	}
+	return ret_val;
 }
 
 static void configure_timer1(void)
@@ -78,7 +85,9 @@ uint32_t sys_clock_elapsed(void)
 		Since timer1 counter always starts from 0 when the sys_clock_announce
 		Call is made, the ticks elapsed is current timer1 count divided by
 		Number of cycles per tick */
-		ticks_elapsed = (uint32_t)TMR1 / (uint32_t)TIMER1_CYCLES_PER_TICK;
+		ticks_elapsed = (uint32_t)TMR1 < (uint32_t)TIMER1_CYCLES_PER_TICK
+					? 0
+					: (uint32_t)TMR1 / (uint32_t)TIMER1_CYCLES_PER_TICK;
 		k_spin_unlock(&lock, key);
 	} while (0);
 

dts/dspic/p33ak128mc106.dtsi

@@ -62,7 +62,7 @@
         timer1: timer@1E00 {
             compatible = "microchip,dspic33-timer";
             reg = <0x1E00 0xC>;
-            clock-frequency = <8000000>;
+            clock-frequency = <4000000>;
             prescalar = <8>;
             interrupt-parent = <&intc0>;
             interrupts = <48 1>;