MIPS: Lantiq: Fix cascaded IRQ setup

With the IRQ stack changes integrated, the XRX200 devices started
emitting a constant stream of kernel messages like this:

[  565.415310] Spurious IRQ: CAUSE=0x1100c300

This is caused by IP0 getting handled by plat_irq_dispatch() rather than
its vectored interrupt handler, which is fixed by commit de856416e714
("MIPS: IRQ Stack: Fix erroneous jal to plat_irq_dispatch").

Fix plat_irq_dispatch() to handle non-vectored IPI interrupts correctly
by setting up IP2-6 as proper chained IRQ handlers and calling do_IRQ
for all MIPS CPU interrupts.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: John Crispin <john@phrozen.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15077/
[james.hogan@imgtec.com: tweaked commit message]
Signed-off-by: James Hogan <james.hogan@imgtec.com>

diff --git a/arch/mips/lantiq/irq.c b/arch/mips/lantiq/irq.c
index 8ac0e5994ed2926548e3da44b158b7a8aff4aa12..0ddf3698b85dac2ebf8bc03e1bf8a089258b8b41 100644 (file)
--- a/arch/mips/lantiq/irq.c
+++ b/arch/mips/lantiq/irq.c
@@ -269,6 +269,11 @@ static void ltq_hw5_irqdispatch(void)
 DEFINE_HWx_IRQDISPATCH(5)
 #endif
 
+static void ltq_hw_irq_handler(struct irq_desc *desc)
+{
+       ltq_hw_irqdispatch(irq_desc_get_irq(desc) - 2);
+}
+
 #ifdef CONFIG_MIPS_MT_SMP
 void __init arch_init_ipiirq(int irq, struct irqaction *action)
 {
@@ -313,23 +318,19 @@ static struct irqaction irq_call = {
 asmlinkage void plat_irq_dispatch(void)
 {
        unsigned int pending = read_c0_status() & read_c0_cause() & ST0_IM;
-       unsigned int i;
-
-       if ((MIPS_CPU_TIMER_IRQ == 7) && (pending & CAUSEF_IP7)) {
-               do_IRQ(MIPS_CPU_TIMER_IRQ);
-               goto out;
-       } else {
-               for (i = 0; i < MAX_IM; i++) {
-                       if (pending & (CAUSEF_IP2 << i)) {
-                               ltq_hw_irqdispatch(i);
-                               goto out;
-                       }
-               }
+       int irq;
+
+       if (!pending) {
+               spurious_interrupt();
+               return;
        }
-       pr_alert("Spurious IRQ: CAUSE=0x%08x\n", read_c0_status());
 
-out:
-       return;
+       pending >>= CAUSEB_IP;
+       while (pending) {
+               irq = fls(pending) - 1;
+               do_IRQ(MIPS_CPU_IRQ_BASE + irq);
+               pending &= ~BIT(irq);
+       }
 }
 
 static int icu_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
@@ -354,11 +355,6 @@ static const struct irq_domain_ops irq_domain_ops = {
        .map = icu_map,
 };
 
-static struct irqaction cascade = {
-       .handler = no_action,
-       .name = "cascade",
-};
-
 int __init icu_of_init(struct device_node *node, struct device_node *parent)
 {
        struct device_node *eiu_node;
@@ -390,7 +386,7 @@ int __init icu_of_init(struct device_node *node, struct device_node *parent)
        mips_cpu_irq_init();
 
        for (i = 0; i < MAX_IM; i++)
-               setup_irq(i + 2, &cascade);
+               irq_set_chained_handler(i + 2, ltq_hw_irq_handler);
 
        if (cpu_has_vint) {
                pr_info("Setting up vectored interrupts\n");