[PATCH 2/9] irqchip/sun6i-r: Add wakeup support

[Samuel Holland <samuel@xxxxxxxxxxxx>]

We maintain a mask of wake-enabled IRQs, and enable them in hardware
during the syscore phase of suspend (once IRQs are globally turned off).
We restore the original mask (either nothing or NMI only) during resume.

This serves two purposes. First, it lets power management firmware
running on the ARISC coprocessor know which wakeup sources Linux wants
to have enabled. That way, it can avoid turning them off when it shuts
down the remainder of the clock tree. Second, it preconfigures the
ARISC coprocessor's interrupt controller, so the firmware's wakeup logic
is as simple as waiting for an interrupt to arrive.

Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>
---
 drivers/irqchip/irq-sun6i-r.c | 53 +++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/irqchip/irq-sun6i-r.c b/drivers/irqchip/irq-sun6i-r.c
index 37b6e9c60bf8..f4a4e335061b 100644
--- a/drivers/irqchip/irq-sun6i-r.c
+++ b/drivers/irqchip/irq-sun6i-r.c
@@ -3,12 +3,14 @@
 // Allwinner A31 and newer SoCs R_INTC driver
 //
 
+#include <linux/atomic.h>
 #include <linux/irq.h>
 #include <linux/irqchip.h>
 #include <linux/irqdomain.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/syscore_ops.h>
 
 #include <dt-bindings/interrupt-controller/arm-gic.h>
 
@@ -31,6 +33,9 @@ enum {
 static void __iomem *base;
 static irq_hw_number_t parent_offset;
 static u32 parent_type;
+#ifdef CONFIG_PM_SLEEP
+static atomic_t wake_mask;
+#endif
 
 static void sun6i_r_intc_irq_enable(struct irq_data *data)
 {
@@ -108,6 +113,21 @@ static int sun6i_r_intc_irq_set_type(struct irq_data *data, unsigned int type)
 	return irq_chip_set_type_parent(data, type);
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int sun6i_r_intc_irq_set_wake(struct irq_data *data, unsigned int on)
+{
+	if (on)
+		atomic_or(BIT(data->hwirq), &wake_mask);
+	else
+		atomic_andnot(BIT(data->hwirq), &wake_mask);
+
+	/* GIC cannot wake, so there is no need to call the parent hook. */
+	return 0;
+}
+#else
+#define sun6i_r_intc_irq_set_wake NULL
+#endif
+
 static struct irq_chip sun6i_r_intc_chip = {
 	.name			= "sun6i-r-intc",
 	.irq_enable		= sun6i_r_intc_irq_enable,
@@ -118,6 +138,7 @@ static struct irq_chip sun6i_r_intc_chip = {
 	.irq_set_affinity	= irq_chip_set_affinity_parent,
 	.irq_retrigger		= irq_chip_retrigger_hierarchy,
 	.irq_set_type		= sun6i_r_intc_irq_set_type,
+	.irq_set_wake		= sun6i_r_intc_irq_set_wake,
 	.irq_set_vcpu_affinity	= irq_chip_set_vcpu_affinity_parent,
 };
 
@@ -171,6 +192,36 @@ static const struct irq_domain_ops sun6i_r_intc_domain_ops = {
 	.free		= irq_domain_free_irqs_common,
 };
 
+#ifdef CONFIG_PM_SLEEP
+static int sun6i_r_intc_suspend(void)
+{
+	/* All wake IRQs are enabled during suspend. */
+	writel(atomic_read(&wake_mask), base + SUN6I_R_INTC_ENABLE);
+
+	return 0;
+}
+
+static void sun6i_r_intc_resume(void)
+{
+	u32 mask = atomic_read(&wake_mask) & BIT(NMI_HWIRQ);
+
+	/* Only the NMI is relevant during normal operation. */
+	writel(mask, base + SUN6I_R_INTC_ENABLE);
+}
+
+static struct syscore_ops sun6i_r_intc_syscore_ops = {
+	.suspend	= sun6i_r_intc_suspend,
+	.resume		= sun6i_r_intc_resume,
+};
+
+static void sun6i_r_intc_syscore_init(void)
+{
+	register_syscore_ops(&sun6i_r_intc_syscore_ops);
+}
+#else
+static inline void sun6i_r_intc_syscore_init(void) {}
+#endif
+
 static int __init sun6i_r_intc_init(struct device_node *node,
 				    struct device_node *parent)
 {
@@ -215,6 +266,8 @@ static int __init sun6i_r_intc_init(struct device_node *node,
 	/* Clear any pending interrupts. */
 	writel(~0, base + SUN6I_R_INTC_PENDING);
 
+	sun6i_r_intc_syscore_init();
+
 	return 0;
 }
 IRQCHIP_DECLARE(sun6i_r_intc, "allwinner,sun6i-a31-r-intc", sun6i_r_intc_init);
-- 
2.23.0