[PATCH 3/5] irqchip: armada-370-xp: re-enable per-CPU interrupts at resume time

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Commit d17cab4451df1 ("irqchip: Kill off set_irq_flags usage") changed
the code of armada_370_xp_mpic_irq_map() from using set_irq_flags() to
irq_set_probe().

While the commit log seems to imply that there are no functional
changes, there are indeed functional changes introduced by this
commit: the IRQ_NOAUTOEN flag is no longer cleared. This functional
change causes a regression on Armada XP, which no longer works
properly after suspend/resume because per-CPU interrupts remain
disabled.

Due to how the hardware registers work, the irq-armada-370-xp cannot
simply save/restore a bunch of registers at suspend/resume to make
sure that the interrupts remain in the same state after
resuming. Therefore, it relies on the kernel to say whether the
interrupt is disabled or not, using the irqd_irq_disabled()
function. This was all working fine while the IRQ_NOAUTOEN flag was
cleared.

With the change introduced by Rob Herring in d17cab4451df1, the
IRQ_NOAUTOEN flag is now set for all interrupts. irqd_irq_disabled()
returns false for per-CPU interrupts, and therefore our per-CPU
interrupts are no longer re-enabled after resume.

This commit fixes that by using irqd_irq_disabled() only for global
interrupts, and using the newly introduced is_enabled_percpu_irq() for
per-CPU interrupts.

Also, it fixes a related problems that per-CPU interrupts were only
re-enabled on the boot CPU and not other CPUs. Until now this wasn't a
problem since on this platform, only the local timers are using
per-CPU interrupts and the local timers of secondary CPUs are turned
off/on during CPU hotplug before suspend, after after resume. However,
in Linux 4.4, we will also be using per-CPU interrupts for the network
controller, so we need to properly restore the per-CPU interrupts on
secondary CPUs as well.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 drivers/irqchip/irq-armada-370-xp.c | 45 ++++++++++++++++++++++++++++++++-----
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-armada-370-xp.c b/drivers/irqchip/irq-armada-370-xp.c
index f5afe81..106ac4c 100644
--- a/drivers/irqchip/irq-armada-370-xp.c
+++ b/drivers/irqchip/irq-armada-370-xp.c
@@ -311,7 +311,6 @@ static int armada_370_xp_mpic_irq_map(struct irq_domain *h,
 		irq_set_percpu_devid(virq);
 		irq_set_chip_and_handler(virq, &armada_370_xp_irq_chip,
 					handle_percpu_devid_irq);
-
 	} else {
 		irq_set_chip_and_handler(virq, &armada_370_xp_irq_chip,
 					handle_level_irq);
@@ -377,12 +376,35 @@ static void armada_mpic_send_doorbell(const struct cpumask *mask,
 static int armada_xp_mpic_secondary_init(struct notifier_block *nfb,
 					 unsigned long action, void *hcpu)
 {
+	unsigned int nirqs, irq;
+
 	if (action != CPU_STARTING && action != CPU_STARTING_FROZEN)
 		return NOTIFY_OK;
 
 	armada_xp_mpic_perf_init();
 	armada_xp_mpic_smp_cpu_init();
 
+	/* Re-enable per-CPU interrupts that were enabled before suspend */
+	nirqs = (readl(main_int_base + ARMADA_370_XP_INT_CONTROL) >> 2) & 0x3ff;
+	for (irq = 0; irq < nirqs; irq++) {
+		struct irq_data *data;
+		int virq;
+
+		virq = irq_linear_revmap(armada_370_xp_mpic_domain, irq);
+		if (virq == 0)
+			continue;
+
+		data = irq_get_irq_data(virq);
+
+		if (irq != ARMADA_370_XP_TIMER0_PER_CPU_IRQ)
+			continue;
+
+		if (!is_enabled_percpu_irq(virq))
+			continue;
+
+		armada_370_xp_irq_unmask(data);
+	}
+
 	return NOTIFY_OK;
 }
 
@@ -550,16 +572,27 @@ static void armada_370_xp_mpic_resume(void)
 		if (virq == 0)
 			continue;
 
-		if (irq != ARMADA_370_XP_TIMER0_PER_CPU_IRQ)
+		data = irq_get_irq_data(virq);
+
+		if (irq != ARMADA_370_XP_TIMER0_PER_CPU_IRQ) {
+			/* Non per-CPU interrupts */
 			writel(irq, per_cpu_int_base +
 			       ARMADA_370_XP_INT_CLEAR_MASK_OFFS);
-		else
+			if (!irqd_irq_disabled(data))
+				armada_370_xp_irq_unmask(data);
+		} else {
+			/* Per-CPU interrupts */
 			writel(irq, main_int_base +
 			       ARMADA_370_XP_INT_SET_ENABLE_OFFS);
 
-		data = irq_get_irq_data(virq);
-		if (!irqd_irq_disabled(data))
-			armada_370_xp_irq_unmask(data);
+			/*
+			 * Re-enable on the current CPU,
+			 * armada_xp_mpic_secondary_init() will take
+			 * care of secondary CPUs when they come up.
+			 */
+			if (is_enabled_percpu_irq(virq))
+				armada_370_xp_irq_unmask(data);
+		}
 	}
 
 	/* Reconfigure doorbells for IPIs and MSIs */
-- 
2.6.2