[3.16.y-ckt stable] Patch "irqchip: armada-370-xp: Fix chained per-cpu interrupts" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    irqchip: armada-370-xp: Fix chained per-cpu interrupts

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 5a8b9eaa1c4e9b41a013393b45138bbe97f8d7bd Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime.ripard at free-electrons.com>
Date: Tue, 3 Mar 2015 11:27:23 +0100
Subject: irqchip: armada-370-xp: Fix chained per-cpu interrupts

commit 5724be8464dceac047c1eaddaa3651cea0ec16ca upstream.

On the Cortex-A9-based Armada SoCs, the MPIC is not the primary interrupt
controller. Yet, it still has to handle some per-cpu interrupt.

To do so, it is chained with the GIC using a per-cpu interrupt. However, the
current code only call irq_set_chained_handler, which is called and enable that
interrupt only on the boot CPU, which means that the parent per-CPU interrupt
is never unmasked on the secondary CPUs, preventing the per-CPU interrupt to
actually work as expected.

This was not seen until now since the only MPIC PPI users were the Marvell
timers that were not working, but not used either since the system use the ARM
TWD by default, and the ethernet controllers, that are faking there interrupts
as SPI, and don't really expect to have interrupts on the secondary cores
anyway.

Add a CPU notifier that will enable the PPI on the secondary cores when they
are brought up.

Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
Link: https://lkml.kernel.org/r/1425378443-28822-1-git-send-email-maxime.ripard@free-electrons.com
Signed-off-by: Jason Cooper <jason at lakedaemon.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/irqchip/irq-armada-370-xp.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-armada-370-xp.c b/drivers/irqchip/irq-armada-370-xp.c
index 1cb538fd85e9..f9597b75fa3d 100644
--- a/drivers/irqchip/irq-armada-370-xp.c
+++ b/drivers/irqchip/irq-armada-370-xp.c
@@ -67,6 +67,7 @@
 static void __iomem *per_cpu_int_base;
 static void __iomem *main_int_base;
 static struct irq_domain *armada_370_xp_mpic_domain;
+static int parent_irq;
 #ifdef CONFIG_PCI_MSI
 static struct irq_domain *armada_370_xp_msi_domain;
 static DECLARE_BITMAP(msi_used, PCI_MSI_DOORBELL_NR);
@@ -360,6 +361,7 @@ static int armada_xp_mpic_secondary_init(struct notifier_block *nfb,
 {
 	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
 		armada_xp_mpic_smp_cpu_init();
+
 	return NOTIFY_OK;
 }

@@ -368,6 +370,20 @@ static struct notifier_block armada_370_xp_mpic_cpu_notifier = {
 	.priority = 100,
 };

+static int mpic_cascaded_secondary_init(struct notifier_block *nfb,
+					unsigned long action, void *hcpu)
+{
+	if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
+		enable_percpu_irq(parent_irq, IRQ_TYPE_NONE);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block mpic_cascaded_cpu_notifier = {
+	.notifier_call = mpic_cascaded_secondary_init,
+	.priority = 100,
+};
+
 #endif /* CONFIG_SMP */

 static struct irq_domain_ops armada_370_xp_mpic_irq_ops = {
@@ -494,7 +510,7 @@ static int __init armada_370_xp_mpic_of_init(struct device_node *node,
 					     struct device_node *parent)
 {
 	struct resource main_int_res, per_cpu_int_res;
-	int parent_irq, nr_irqs, i;
+	int nr_irqs, i;
 	u32 control;

 	BUG_ON(of_address_to_resource(node, 0, &main_int_res));
@@ -542,6 +558,9 @@ static int __init armada_370_xp_mpic_of_init(struct device_node *node,
 		register_cpu_notifier(&armada_370_xp_mpic_cpu_notifier);
 #endif
 	} else {
+#ifdef CONFIG_SMP
+		register_cpu_notifier(&mpic_cascaded_cpu_notifier);
+#endif
 		irq_set_chained_handler(parent_irq,
 					armada_370_xp_mpic_handle_cascade_irq);
 	}