setup_timer_irq: check that we handle the correct IRQ

1 files changed, 10 insertions, 4 deletions

diff --git a/software/first/setup_timer_irq.S b/software/first/setup_timer_irq.S
index 6c75d67..8ca0370 100644
--- a/software/first/setup_timer_irq.S
+++ b/software/first/setup_timer_irq.S
@@ -60,6 +60,11 @@ irq_handler:
 	sw t3, 8(sp)     # save temporary
 	sw a0, 4(sp)     # save first argument to function
 
+	li t0, 0x80000007 # irqcause + 7 (machine timer interrupt)
+	csrr t1, mcause   # load cause CSR
+	and t1, t1, t0    # check if it's a timer interrupt
+	bne t1, t0, exit
+
 	li t0, GPIO_CTRL_ADDR      # load base GPIO address
 	lw t1, GPIO_OUTPUT_VAL(t0) # load state
 
@@ -74,22 +79,23 @@ irq_handler:
 
 switchOnRed:
 	li t2, GPIO_RED_LED   # load value indicating red LED
-	j exit
+	j setAndexit
 
 switchOnBlue:
 	li t2, GPIO_BLUE_LED   # load value indicating blue LED
-	j exit
+	j setAndexit
 
 switchOnGreen:
 	li t2, GPIO_GREEN_LED   # load value indicating green LED
-	j exit
+	j setAndexit
 
 
-exit:
+setAndexit:
 	sw t2, GPIO_OUTPUT_VAL(t0)   # write new LED values to the right address
 	li a0, 200      # load the desired delay value (in ms) as the first arg to the function
 	jal delay       # call delay function to set new delay
 
+exit:
 	lw ra, 24(sp)   # load return address
 	lw t0, 20(sp)   # restore temporary
 	lw t1, 16(sp)   # restore temporary