Added basic IRQ support

2 files changed, 263 insertions, 1 deletions

diff --git a/firmware/sieve.c b/firmware/sieve.c
index c3372f4..7f1c82e 100644
--- a/firmware/sieve.c
+++ b/firmware/sieve.c
@@ -18,6 +18,11 @@ static bool bitmap_get(int idx)
 	return (bitmap[idx/32] & (1 << (idx % 32))) != 0;
 }
 
+static void print_chr(char ch)
+{
+	*((volatile uint32_t*)OUTPORT) = ch;
+}
+
 static void print_str(const char *p)
 {
 	while (*p != 0)
@@ -37,6 +42,13 @@ static void print_dec(int val)
 	}
 }
 
+static void print_hex(unsigned int val)
+{
+	int i;
+	for (i = 32-4; i >= 0; i -= 4)
+		*((volatile uint32_t*)OUTPORT) = "0123456789ABCDEF"[(val >> i) % 16];
+}
+
 static void print_prime(int idx, int val)
 {
 	if (idx < 10)
@@ -76,3 +88,92 @@ void sieve()
 	}
 }
 
+void irq(uint32_t *regs, uint32_t irqnum)
+{
+	static int ext_irq_count = 0;
+	static int timer_irq_count = 0;
+
+	if (irqnum == 0) {
+		ext_irq_count++;
+		// print_str("[EXT-IRQ]");
+		return;
+	}
+
+	if (irqnum == 1) {
+		timer_irq_count++;
+		// print_str("[TIMER-IRQ]");
+		return;
+	}
+
+	if (irqnum == 2)
+	{
+		int i, k;
+		uint32_t pc = regs[0] - 4;
+		uint32_t instr = *(uint32_t*)pc;
+
+		print_str("\n");
+		print_str("------------------------------------------------------------\n");
+
+		if (instr == 0x00100073) {
+			print_str("SBREAK instruction at 0x");
+			print_hex(pc);
+			print_str("\n");
+		} else {
+			print_str("Illegal Instruction at 0x");
+			print_hex(pc);
+			print_str(": 0x");
+			print_hex(instr);
+			print_str("\n");
+		}
+
+		for (i = 0; i < 8; i++)
+		for (k = 0; k < 4; k++)
+		{
+			int r = i + k*8;
+
+			if (r == 0) {
+				print_str("pc  ");
+			} else
+			if (r < 10) {
+				print_chr('x');
+				print_chr('0' + r);
+				print_chr(' ');
+				print_chr(' ');
+			} else
+			if (r < 20) {
+				print_chr('x');
+				print_chr('1');
+				print_chr('0' + r - 10);
+				print_chr(' ');
+			} else
+			if (r < 30) {
+				print_chr('x');
+				print_chr('2');
+				print_chr('0' + r - 20);
+				print_chr(' ');
+			} else {
+				print_chr('x');
+				print_chr('3');
+				print_chr('0' + r - 30);
+				print_chr(' ');
+			}
+
+			print_hex(regs[r]);
+			print_str(k == 3 ? "\n" : "    ");
+		}
+
+		print_str("------------------------------------------------------------\n");
+
+		print_str("Number of external IRQs counted: ");
+		print_dec(ext_irq_count);
+		print_str("\n");
+
+		print_str("Number of timer IRQs counted: ");
+		print_dec(timer_irq_count);
+		print_str("\n");
+
+		__asm__("sbreak");
+		return;
+	}
+}
+
diff --git a/firmware/start.S b/firmware/start.S
index d9e0b3e..cdb8da0 100644
--- a/firmware/start.S
+++ b/firmware/start.S
@@ -1,13 +1,174 @@
 	.section .text
-	.global start
+	.global irq
 	.global sieve
 	.global stats
 
 #define TEST(n) \
 	.global n; .global n ## _ret; \
+	addi x1, zero, 1000; \
+	custom0 0,1,0,5; /* timer x1 */ \
 	jal zero,n; n ## _ret:
 
+reset_vec:
+	custom0 0,0,7,3 // maskirq 7
+	j start
+	nop
+	nop
+
+irq_vec:
+	/* save registers */
+
+	custom0 2,1,0,1 // setq q2, x1
+	custom0 3,2,0,1 // setq q3, x2
+
+	lui x1, %hi(irq_regs)
+	addi x1, x1, %lo(irq_regs)
+
+	custom0 2,0,0,0 // getq x2, q0
+	sw x2,   0*4(x1)
+
+	custom0 2,2,0,0 // getq x2, q2
+	sw x2,   1*4(x1)
+
+	custom0 2,3,0,0 // getq x2, q3
+	sw x2,   2*4(x1)
+
+	sw x3,   3*4(x1)
+	sw x4,   4*4(x1)
+	sw x5,   5*4(x1)
+	sw x6,   6*4(x1)
+	sw x7,   7*4(x1)
+	sw x8,   8*4(x1)
+	sw x9,   9*4(x1)
+	sw x10, 10*4(x1)
+	sw x11, 11*4(x1)
+	sw x12, 12*4(x1)
+	sw x13, 13*4(x1)
+	sw x14, 14*4(x1)
+	sw x15, 15*4(x1)
+	sw x16, 16*4(x1)
+	sw x17, 17*4(x1)
+	sw x18, 18*4(x1)
+	sw x19, 19*4(x1)
+	sw x20, 20*4(x1)
+	sw x21, 21*4(x1)
+	sw x22, 22*4(x1)
+	sw x23, 23*4(x1)
+	sw x24, 24*4(x1)
+	sw x25, 25*4(x1)
+	sw x26, 26*4(x1)
+	sw x27, 27*4(x1)
+	sw x28, 28*4(x1)
+	sw x29, 29*4(x1)
+	sw x30, 30*4(x1)
+	sw x31, 31*4(x1)
+
+	/* call interrupt handler */
+
+	lui sp, %hi(irq_stack_top)
+	addi sp, sp, %lo(irq_stack_top)
+
+	// arg0 = address of regs
+	lui a0, %hi(irq_regs)
+	addi a0, a0, %lo(irq_regs)
+
+	// arg1 = interrupt type
+	custom0 11,1,0,0 // getq x11, q1
+
+	// call to c function
+	jal ra, irq
+
+	/* restore registers */
+
+	lui x1, %hi(irq_regs)
+	addi x1, x1, %lo(irq_regs)
+
+	lw x2,   0*4(x1)
+	custom0 0,2,0,1 // setq q0, x2
+
+	lw x2,   1*4(x1)
+	custom0 1,2,0,1 // setq q1, x2
+
+	lw x2,   2*4(x1)
+	custom0 2,2,0,1 // setq q2, x2
+
+	lw x3,   3*4(x1)
+	lw x4,   4*4(x1)
+	lw x5,   5*4(x1)
+	lw x6,   6*4(x1)
+	lw x7,   7*4(x1)
+	lw x8,   8*4(x1)
+	lw x9,   9*4(x1)
+	lw x10, 10*4(x1)
+	lw x11, 11*4(x1)
+	lw x12, 12*4(x1)
+	lw x13, 13*4(x1)
+	lw x14, 14*4(x1)
+	lw x15, 15*4(x1)
+	lw x16, 16*4(x1)
+	lw x17, 17*4(x1)
+	lw x18, 18*4(x1)
+	lw x19, 19*4(x1)
+	lw x20, 20*4(x1)
+	lw x21, 21*4(x1)
+	lw x22, 22*4(x1)
+	lw x23, 23*4(x1)
+	lw x24, 24*4(x1)
+	lw x25, 25*4(x1)
+	lw x26, 26*4(x1)
+	lw x27, 27*4(x1)
+	lw x28, 28*4(x1)
+	lw x29, 29*4(x1)
+	lw x30, 30*4(x1)
+	lw x31, 31*4(x1)
+
+	custom0 1,1,0,0 // getq x1, q1
+	custom0 2,2,0,0 // getq x2, q2
+
+	custom0 0,0,0,2 // retirq
+
+irq_regs:
+	// registers are saved to this memory region
+	// the program counter is saved as register 0
+	.fill 32,4
+
+irq_stack:
+	.fill 128,4
+irq_stack_top:
+
 start:
+	addi x1, zero, 0
+	addi x2, zero, 0
+	addi x3, zero, 0
+	addi x4, zero, 0
+	addi x5, zero, 0
+	addi x6, zero, 0
+	addi x7, zero, 0
+	addi x8, zero, 0
+	addi x9, zero, 0
+	addi x10, zero, 0
+	addi x11, zero, 0
+	addi x12, zero, 0
+	addi x13, zero, 0
+	addi x14, zero, 0
+	addi x15, zero, 0
+	addi x16, zero, 0
+	addi x17, zero, 0
+	addi x18, zero, 0
+	addi x19, zero, 0
+	addi x20, zero, 0
+	addi x21, zero, 0
+	addi x22, zero, 0
+	addi x23, zero, 0
+	addi x24, zero, 0
+	addi x25, zero, 0
+	addi x26, zero, 0
+	addi x27, zero, 0
+	addi x28, zero, 0
+	addi x29, zero, 0
+	addi x30, zero, 0
+	addi x31, zero, 0
+
 	TEST(lui)
 	TEST(auipc)
 	TEST(j)