MIPS: Loongson-3: Fix CPU UART irq delivery problem

Masking/unmasking the CPU UART irq in CP0_Status (and redirecting it to
other CPUs) may cause interrupts be lost, especially in multi-package
machines (Package-0's UART irq cannot be delivered to others). So make
mask_loongson_irq() and unmask_loongson_irq() be no-ops.

The original problem (UART IRQ may deliver to any core) is also because
of masking/unmasking the CPU UART irq in CP0_Status. So it is safe to
remove all of the stuff.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/20433/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhuacai@gmail.com>

arch/mips/loongson64/loongson-3/irq.c

@@ -102,45 +102,8 @@ static struct irqaction cascade_irqaction = {
 	.name = "cascade",
 };
 
-static inline void mask_loongson_irq(struct irq_data *d)
-{
-	clear_c0_status(0x100 << (d->irq - MIPS_CPU_IRQ_BASE));
-	irq_disable_hazard();
-
-	/* Workaround: UART IRQ may deliver to any core */
-	if (d->irq == LOONGSON_UART_IRQ) {
-		int cpu = smp_processor_id();
-		int node_id = cpu_logical_map(cpu) / loongson_sysconf.cores_per_node;
-		int core_id = cpu_logical_map(cpu) % loongson_sysconf.cores_per_node;
-		u64 intenclr_addr = smp_group[node_id] |
-			(u64)(&LOONGSON_INT_ROUTER_INTENCLR);
-		u64 introuter_lpc_addr = smp_group[node_id] |
-			(u64)(&LOONGSON_INT_ROUTER_LPC);
-
-		*(volatile u32 *)intenclr_addr = 1 << 10;
-		*(volatile u8 *)introuter_lpc_addr = 0x10 + (1<<core_id);
-	}
-}
-
-static inline void unmask_loongson_irq(struct irq_data *d)
-{
-	/* Workaround: UART IRQ may deliver to any core */
-	if (d->irq == LOONGSON_UART_IRQ) {
-		int cpu = smp_processor_id();
-		int node_id = cpu_logical_map(cpu) / loongson_sysconf.cores_per_node;
-		int core_id = cpu_logical_map(cpu) % loongson_sysconf.cores_per_node;
-		u64 intenset_addr = smp_group[node_id] |
-			(u64)(&LOONGSON_INT_ROUTER_INTENSET);
-		u64 introuter_lpc_addr = smp_group[node_id] |
-			(u64)(&LOONGSON_INT_ROUTER_LPC);
-
-		*(volatile u32 *)intenset_addr = 1 << 10;
-		*(volatile u8 *)introuter_lpc_addr = 0x10 + (1<<core_id);
-	}
-
-	set_c0_status(0x100 << (d->irq - MIPS_CPU_IRQ_BASE));
-	irq_enable_hazard();
-}
+static inline void mask_loongson_irq(struct irq_data *d) { }
+static inline void unmask_loongson_irq(struct irq_data *d) { }
 
  /* For MIPS IRQs which shared by all cores */
 static struct irq_chip loongson_irq_chip = {
@@ -183,7 +146,7 @@ void __init mach_init_irq(void)
 	chip->irq_set_affinity = plat_set_irq_affinity;
 
 	irq_set_chip_and_handler(LOONGSON_UART_IRQ,
-			&loongson_irq_chip, handle_level_irq);
+			&loongson_irq_chip, handle_percpu_irq);
 
 	/* setup HT1 irq */
 	setup_irq(LOONGSON_HT1_IRQ, &cascade_irqaction);