- Fix signal named priority, which is a keyword in SV

- Fix incorrect HIGHEST_WINS behaviour in one-hot selector
- Add test for asserting 32 IRQs at 16 priorities at once
- Add an entry counter to the soft dispatch code so tests can check
  the number of times hardware entered the vector

hdl/arith/hazard3_onehot_priority.v

@@ -21,7 +21,7 @@ always @ (*) begin: select
 	integer i;
 	for (i = 0; i < W_REQ; i = i + 1) begin
 		gnt[i] = req[i] && ~|(req & (
-			HIGHEST_WINS ? ~({W_REQ{1'b1}} >> i) : ~({W_REQ{1'b1}} << i)
+			HIGHEST_WINS ? ~({W_REQ{1'b1}} >> (W_REQ - 1 - i)) : ~({W_REQ{1'b1}} << i)
 		));
 	end
 end

hdl/arith/hazard3_onehot_priority_dynamic.v

@@ -19,7 +19,7 @@ module hazard3_onehot_priority_dynamic #(
 	// Do not modify:
 	parameter W_PRIORITY            = $clog2(N_PRIORITIES)
 ) (
-	input  wire [W_REQ*W_PRIORITY-1:0] priority,
+	input  wire [W_REQ*W_PRIORITY-1:0] pri,
 	input  wire [W_REQ-1:0]            req,
 	output wire [W_REQ-1:0]            gnt
 );
@@ -32,7 +32,7 @@ always @ (*) begin: stratify
 	integer i, j;
 	for (i = 0; i < N_PRIORITIES; i = i + 1) begin
 		for (j = 0; j < W_REQ; j = j + 1) begin
-			req_stratified[i][j] = req[j] && priority[W_PRIORITY * j +: W_PRIORITY] == i;
+			req_stratified[i][j] = req[j] && pri[W_PRIORITY * j +: W_PRIORITY] == i;
 		end
 		level_has_req[i] = |req_stratified[i];
 	end

hdl/hazard3_csr.v

@@ -313,7 +313,7 @@ end
 localparam MAX_IRQS = 512;
 localparam [MAX_IRQS-1:0] IRQ_IMPL_MASK = ~({MAX_IRQS{1'b1}} << NUM_IRQS);
 
-localparam IRQ_PRIORITY_MASK = ~(4'hf >> IRQ_PRIORITY_BITS);
+localparam [3:0] IRQ_PRIORITY_MASK = ~(4'hf >> IRQ_PRIORITY_BITS);
 
 // Assigned later:
 wire [MAX_IRQS-1:0]   meipa;
@@ -471,9 +471,9 @@ hazard3_onehot_priority_dynamic #(
 	.PRIORITY_HIGHEST_WINS (1),
 	.TIEBREAK_HIGHEST_WINS (0)
 ) eirq_priority_u (
-	.priority (meipra[NUM_IRQS-1:0] & {NUM_IRQS{IRQ_PRIORITY_MASK}}),
-	.req      (eirq_active_above_ppreempt),
-	.gnt      (highest_eirq_onehot)
+	.pri (meipra[4*NUM_IRQS-1:0] & {NUM_IRQS{IRQ_PRIORITY_MASK}}),
+	.req (eirq_active_above_ppreempt),
+	.gnt (highest_eirq_onehot)
 );
 
 always @ (*) begin: get_highest_eirq_priority

test/sim/common/irq_dispatch.S

@@ -23,6 +23,14 @@ isr_external_irq:
 	sw t5, 56(sp)
 	sw t6, 60(sp)
 
+	// Update a count of the number of external IRQ vector entries (just for
+	// use in tests)
+	la a0, _external_irq_entry_count
+	lw a1, (a0)
+	addi a1, a1, 1
+	sw a1, (a0)
+	// Make sure to delete the above ^^^ if you use this code for real!
+
 	csrr a0, mepc
 	sw a0, 64(sp)
 	// Make sure to set meicontext.clearts to clear and save mie.msie/mtie
@@ -117,3 +125,7 @@ _external_irq_table:
 ref_eirq i
 .equ i, i + 1
 .endr
+
+.global _external_irq_entry_count
+_external_irq_entry_count:
+.word 0

test/sim/sw_testcases/Makefile

@@ -5,5 +5,6 @@ MAX_CYCLES := 1000000
 INCDIR     := include ../common
 
 EXTRA_SRCS_irq_preempt_set_in_irq := ../common/irq_dispatch.S
+EXTRA_SRCS_irq_set_all_with_pri   := ../common/irq_dispatch.S
 
 include ../common/src_only_app.mk

test/sim/sw_testcases/irq_preempt_set_in_irq.c

@@ -36,7 +36,7 @@ Exiting IRQ 3
 Exiting IRQ 2
 Exiting IRQ 1
 Exiting IRQ 0
-Done.
+EIRQ vector was entered 16 times
 
 *******************************************************************************/
 
@@ -44,6 +44,7 @@ Done.
 #define NUM_IRQS 64
 
 extern uintptr_t _external_irq_table[NUM_IRQS];
+extern uint32_t _external_irq_entry_count;
 
 void handler(void);
 
@@ -64,7 +65,7 @@ int main() {
 	tb_set_irq_masked(0x1);
 	asm ("wfi");
 
-	tb_puts("Done.\n");
+	tb_printf("EIRQ vector was entered %d times\n", _external_irq_entry_count);
 	return 0;
 }
 

test/sim/sw_testcases/irq_set_all_with_pri.c

@@ -0,0 +1,91 @@
+#include "tb_cxxrtl_io.h"
+#include "hazard3_irq.h"
+
+// Similar to the irq_preempt_set_in_irq test, but there are two IRQs at each
+// priority level, and rather than posting the high-priority IRQs from within
+// lower priority IRQs, we post every single IRQ at once. Check that:
+//
+// - The IRQS run from highest to lowest priority order (which happens to be
+//   opposite to the default tiebreak order for these IRQs)
+//
+// - Within each priority level, the IRQs are tiebroken lowest-first
+//
+// - Each IRQ enters and exits before any lower IRQ enters
+//
+// - The EIRQ vector was entered exactly once (save/restore was shared between
+//   all the IRQs at their different priority levels)
+
+/*EXPECTED-OUTPUT***************************************************************
+
+Posting IRQs
+Entered IRQ 15
+Exiting IRQ 15
+Entered IRQ 14
+Exiting IRQ 14
+Entered IRQ 13
+Exiting IRQ 13
+Entered IRQ 12
+Exiting IRQ 12
+Entered IRQ 11
+Exiting IRQ 11
+Entered IRQ 10
+Exiting IRQ 10
+Entered IRQ 9
+Exiting IRQ 9
+Entered IRQ 8
+Exiting IRQ 8
+Entered IRQ 7
+Exiting IRQ 7
+Entered IRQ 6
+Exiting IRQ 6
+Entered IRQ 5
+Exiting IRQ 5
+Entered IRQ 4
+Exiting IRQ 4
+Entered IRQ 3
+Exiting IRQ 3
+Entered IRQ 2
+Exiting IRQ 2
+Entered IRQ 1
+Exiting IRQ 1
+Entered IRQ 0
+Exiting IRQ 0
+EIRQ vector was entered 1 times
+gstat
+*******************************************************************************/
+
+#define PRIORITY_LEVELS 16
+#define NUM_IRQS 32
+
+extern uintptr_t _external_irq_table[NUM_IRQS];
+extern uint32_t _external_irq_entry_count;
+
+void handler(void);
+
+int main() {
+	// Enable external IRQs globally
+	set_csr(mstatus, 0x8);
+	set_csr(mie, 0x800);
+	// Enable one external IRQ at each priority level
+	for (int i = 0; i < PRIORITY_LEVELS * 2; ++i) {
+		h3irq_enable(i, true);
+		h3irq_set_priority(i, i / 2);
+		_external_irq_table[i] = (uintptr_t)handler;
+	}
+	// Set off the lowest-priority IRQ. The IRQ handler will then set the
+	// next-lowest, which will preempt it. So on, up to the highest level,
+	// then return all the way back down through the nested frames.
+	tb_puts("Posting IRQs\n");
+	tb_set_irq_masked(0xffffffffu);
+	asm ("wfi");
+
+	tb_printf("EIRQ vector was entered %d times\n", _external_irq_entry_count);
+	return 0;
+}
+
+void handler(void) {
+	int irqnum = h3irq_get_current_irq();
+	tb_printf("Entered IRQ %d\n", irqnum);
+	tb_clr_irq_masked(1u << irqnum);
+	tb_printf("Exiting IRQ %d\n", irqnum);
+}