[PATCH v2 1/1] irqchip: exynos-combiner: Save IRQ enable set on suspend

[Javier Martinez Canillas]

The Exynos interrupt combiner IP loses its state when the SoC enters
into a low power state during a Suspend-to-RAM. This means that if a
IRQ is used as a source, the interrupts for the devices are disabled
when the system is resumed from a sleep state so are not triggered.

Save the interrupt enable set register for each combiner group and
restore it after resume to make sure that the interrupts are enabled.

Signed-off-by: Javier Martinez Canillas <javier.martinez at collabora.co.uk>
---

Hello,

I noticed this issue because after a S2R, IRQs for some devices didn't
trigger anymore but others continued working and all of them had lines
from a GPIO chip as their interrupt source.

The only difference was that the GPIO pins that were not working after
a resume, were the ones that had the interrupt combiner as interrupt
parent.

With this patch now all perhiperals are working correctly after a resume.
Tested on an Exynos5250 Snow, Exynos5420 Peach Pit and Exynos5800 Peach Pi
Chromebooks.

Best regards,
Javier

Changes since v1:
 - Clear masking bits before of the COMBINER_ENABLE_CLEAR register before
   restore IRQ enable set the Suggested by Chanho Park.
 - Fixes a typo in the commit message. Suggested by Peter Chubb.

 drivers/irqchip/exynos-combiner.c | 64 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 59 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/exynos-combiner.c b/drivers/irqchip/exynos-combiner.c
index 5945223b73fa..639e59c8eed3 100644
--- a/drivers/irqchip/exynos-combiner.c
+++ b/drivers/irqchip/exynos-combiner.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/syscore_ops.h>
 #include <linux/irqdomain.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/interrupt.h>
@@ -34,9 +35,14 @@ struct combiner_chip_data {
 	unsigned int irq_mask;
 	void __iomem *base;
 	unsigned int parent_irq;
+#ifdef CONFIG_PM
+	u32 pm_save;
+#endif
 };
 
+static struct combiner_chip_data *combiner_data;
 static struct irq_domain *combiner_irq_domain;
+static unsigned int max_nr = 20;
 
 static inline void __iomem *combiner_base(struct irq_data *data)
 {
@@ -170,12 +176,10 @@ static struct irq_domain_ops combiner_irq_domain_ops = {
 };
 
 static void __init combiner_init(void __iomem *combiner_base,
-				 struct device_node *np,
-				 unsigned int max_nr)
+				 struct device_node *np)
 {
 	int i, irq;
 	unsigned int nr_irq;
-	struct combiner_chip_data *combiner_data;
 
 	nr_irq = max_nr * IRQ_IN_COMBINER;
 
@@ -201,11 +205,59 @@ static void __init combiner_init(void __iomem *combiner_base,
 	}
 }
 
+#ifdef CONFIG_PM
+
+/**
+ * combiner_suspend - save interrupt combiner state before suspend
+ *
+ * Save the interrupt enable set register for all combiner groups since
+ * the state is lost when the system enters into a sleep state.
+ *
+ */
+static int combiner_suspend(void)
+{
+	int i;
+
+	for (i = 0; i < max_nr; i++)
+		combiner_data[i].pm_save =
+			__raw_readl(combiner_data[i].base + COMBINER_ENABLE_SET);
+
+	return 0;
+}
+
+/**
+ * combiner_resume - restore interrupt combiner state after resume
+ *
+ * Restore the interrupt enable set register for all combiner groups since
+ * the state is lost when the system enters into a sleep state on suspend.
+ *
+ */
+static void combiner_resume(void)
+{
+	int i;
+
+	for (i = 0; i < max_nr; i++) {
+		__raw_writel(combiner_data[i].irq_mask,
+			     combiner_data[i].base + COMBINER_ENABLE_CLEAR);
+		__raw_writel(combiner_data[i].pm_save,
+			     combiner_data[i].base + COMBINER_ENABLE_SET);
+	}
+}
+
+#else
+#define combiner_suspend	NULL
+#define combiner_resume		NULL
+#endif
+
+static struct syscore_ops combiner_syscore_ops = {
+	.suspend	= combiner_suspend,
+	.resume		= combiner_resume,
+};
+
 static int __init combiner_of_init(struct device_node *np,
 				   struct device_node *parent)
 {
 	void __iomem *combiner_base;
-	unsigned int max_nr = 20;
 
 	combiner_base = of_iomap(np, 0);
 	if (!combiner_base) {
@@ -219,7 +271,9 @@ static int __init combiner_of_init(struct device_node *np,
 			__func__, max_nr);
 	}
 
-	combiner_init(combiner_base, np, max_nr);
+	combiner_init(combiner_base, np);
+
+	register_syscore_ops(&combiner_syscore_ops);
 
 	return 0;
 }
-- 
2.1.4