[PATCH v1] irqchip/irq-sifive-plic: Add syscore callbacks for hibernation

[Mason Huo]

The priority and enable registers of plic will be reset
during hibernation power cycle in poweroff mode,
add the syscore callbacks to save/restore those registers.

Signed-off-by: Mason Huo <mason.huo at starfivetech.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan at starfivetech.com>
Reviewed-by: Sia Jee Heng <jeeheng.sia at starfivetech.com>
---
 drivers/irqchip/irq-sifive-plic.c | 93 ++++++++++++++++++++++++++++++-
 1 file changed, 91 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index ff47bd0dec45..80306de45d2b 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -17,6 +17,7 @@
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
+#include <linux/syscore_ops.h>
 #include <asm/smp.h>
 
 /*
@@ -67,6 +68,8 @@ struct plic_priv {
 	struct irq_domain *irqdomain;
 	void __iomem *regs;
 	unsigned long plic_quirks;
+	unsigned int nr_irqs;
+	u32 *priority_reg;
 };
 
 struct plic_handler {
@@ -79,10 +82,13 @@ struct plic_handler {
 	raw_spinlock_t		enable_lock;
 	void __iomem		*enable_base;
 	struct plic_priv	*priv;
+	/* To record interrupts that are enabled before suspend. */
+	u32 enable_reg[MAX_DEVICES / 32];
 };
 static int plic_parent_irq __ro_after_init;
 static bool plic_cpuhp_setup_done __ro_after_init;
 static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
+static struct plic_priv *priv_data;
 
 static int plic_irq_set_type(struct irq_data *d, unsigned int type);
 
@@ -229,6 +235,78 @@ static int plic_irq_set_type(struct irq_data *d, unsigned int type)
 	return IRQ_SET_MASK_OK;
 }
 
+static void plic_irq_resume(void)
+{
+	unsigned int i, cpu;
+	u32 __iomem *reg;
+
+	for (i = 0; i < priv_data->nr_irqs; i++)
+		writel(priv_data->priority_reg[i],
+				priv_data->regs + PRIORITY_BASE + i * PRIORITY_PER_ID);
+
+	for_each_cpu(cpu, cpu_present_mask) {
+		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
+
+		if (!handler->present)
+			continue;
+
+		for (i = 0; i < DIV_ROUND_UP(priv_data->nr_irqs, 32); i++) {
+			reg = handler->enable_base + i * sizeof(u32);
+			raw_spin_lock(&handler->enable_lock);
+			writel(handler->enable_reg[i], reg);
+			raw_spin_unlock(&handler->enable_lock);
+		}
+	}
+}
+
+static int plic_irq_suspend(void)
+{
+	unsigned int i, cpu;
+	u32 __iomem *reg;
+
+	for (i = 0; i < priv_data->nr_irqs; i++)
+		priv_data->priority_reg[i] =
+			readl(priv_data->regs + PRIORITY_BASE + i * PRIORITY_PER_ID);
+
+	for_each_cpu(cpu, cpu_present_mask) {
+		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
+
+		if (!handler->present)
+			continue;
+
+		for (i = 0; i < DIV_ROUND_UP(priv_data->nr_irqs, 32); i++) {
+			reg = handler->enable_base + i * sizeof(u32);
+			raw_spin_lock(&handler->enable_lock);
+			handler->enable_reg[i] = readl(reg);
+			raw_spin_unlock(&handler->enable_lock);
+		}
+	}
+
+	return 0;
+}
+
+static struct syscore_ops plic_irq_syscore_ops = {
+	.suspend	= plic_irq_suspend,
+	.resume		= plic_irq_resume,
+};
+
+static void plic_irq_pm_init(void)
+{
+	unsigned int cpu;
+
+	for_each_cpu(cpu, cpu_present_mask) {
+		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
+
+		if (!handler->present)
+			continue;
+
+		memset(&handler->enable_reg[0], 0,
+			sizeof(handler->enable_reg));
+	}
+
+	register_syscore_ops(&plic_irq_syscore_ops);
+}
+
 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			      irq_hw_number_t hwirq)
 {
@@ -351,6 +429,7 @@ static int __init __plic_init(struct device_node *node,
 		return -ENOMEM;
 
 	priv->plic_quirks = plic_quirks;
+	priv_data = priv;
 
 	priv->regs = of_iomap(node, 0);
 	if (WARN_ON(!priv->regs)) {
@@ -363,15 +442,21 @@ static int __init __plic_init(struct device_node *node,
 	if (WARN_ON(!nr_irqs))
 		goto out_iounmap;
 
+	priv->nr_irqs = nr_irqs;
+
+	priv->priority_reg = kcalloc(nr_irqs, sizeof(u32), GFP_KERNEL);
+	if (!priv->priority_reg)
+		goto out_free_priority_reg;
+
 	nr_contexts = of_irq_count(node);
 	if (WARN_ON(!nr_contexts))
-		goto out_iounmap;
+		goto out_free_priority_reg;
 
 	error = -ENOMEM;
 	priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
 			&plic_irqdomain_ops, priv);
 	if (WARN_ON(!priv->irqdomain))
-		goto out_iounmap;
+		goto out_free_priority_reg;
 
 	for (i = 0; i < nr_contexts; i++) {
 		struct of_phandle_args parent;
@@ -461,11 +546,15 @@ static int __init __plic_init(struct device_node *node,
 				  plic_starting_cpu, plic_dying_cpu);
 		plic_cpuhp_setup_done = true;
 	}
+	plic_irq_pm_init();
 
 	pr_info("%pOFP: mapped %d interrupts with %d handlers for"
 		" %d contexts.\n", node, nr_irqs, nr_handlers, nr_contexts);
 	return 0;
 
+out_free_priority_reg:
+	kfree(priv->priority_reg);
+
 out_iounmap:
 	iounmap(priv->regs);
 out_free_priv:
-- 
2.39.0