irqchip/irq-sifive-plic: Add syscore callbacks for hibernation

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 <[e-mail]>
Reviewed-by: Ley Foon Tan <[e-mail]>
Reviewed-by: Sia Jee Heng <[e-mail]>
Reported-by: Dan Carpenter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]/
Signed-off-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/irqchip/irq-sifive-plic.c

···
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
+#include <linux/syscore_ops.h>
 #include <asm/smp.h>
 
 /*
···
 	struct irq_domain *irqdomain;
 	void __iomem *regs;
 	unsigned long plic_quirks;
+	unsigned int nr_irqs;
+	unsigned long *prio_save;
 };
 
 struct plic_handler {
···
 	 */
 	raw_spinlock_t		enable_lock;
 	void __iomem		*enable_base;
+	u32			*enable_save;
 	struct plic_priv	*priv;
 };
 static int plic_parent_irq __ro_after_init;
···
 	return IRQ_SET_MASK_OK;
 }
 
+static int plic_irq_suspend(void)
+{
+	unsigned int i, cpu;
+	u32 __iomem *reg;
+	struct plic_priv *priv;
+
+	priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;
+
+	for (i = 0; i < priv->nr_irqs; i++)
+		if (readl(priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID))
+			__set_bit(i, priv->prio_save);
+		else
+			__clear_bit(i, priv->prio_save);
+
+	for_each_cpu(cpu, cpu_present_mask) {
+		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
+
+		if (!handler->present)
+			continue;
+
+		raw_spin_lock(&handler->enable_lock);
+		for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
+			reg = handler->enable_base + i * sizeof(u32);
+			handler->enable_save[i] = readl(reg);
+		}
+		raw_spin_unlock(&handler->enable_lock);
+	}
+
+	return 0;
+}
+
+static void plic_irq_resume(void)
+{
+	unsigned int i, index, cpu;
+	u32 __iomem *reg;
+	struct plic_priv *priv;
+
+	priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;
+
+	for (i = 0; i < priv->nr_irqs; i++) {
+		index = BIT_WORD(i);
+		writel((priv->prio_save[index] & BIT_MASK(i)) ? 1 : 0,
+		       priv->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;
+
+		raw_spin_lock(&handler->enable_lock);
+		for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) {
+			reg = handler->enable_base + i * sizeof(u32);
+			writel(handler->enable_save[i], reg);
+		}
+		raw_spin_unlock(&handler->enable_lock);
+	}
+}
+
+static struct syscore_ops plic_irq_syscore_ops = {
+	.suspend	= plic_irq_suspend,
+	.resume		= plic_irq_resume,
+};
+
 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			      irq_hw_number_t hwirq)
 {
···
 	u32 nr_irqs;
 	struct plic_priv *priv;
 	struct plic_handler *handler;
+	unsigned int cpu;
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv)
···
 	if (WARN_ON(!nr_irqs))
 		goto out_iounmap;
 
+	priv->nr_irqs = nr_irqs;
+
+	priv->prio_save = bitmap_alloc(nr_irqs, GFP_KERNEL);
+	if (!priv->prio_save)
+		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;
···
 		handler->enable_base = priv->regs + CONTEXT_ENABLE_BASE +
 			i * CONTEXT_ENABLE_SIZE;
 		handler->priv = priv;
+
+		handler->enable_save =  kcalloc(DIV_ROUND_UP(nr_irqs, 32),
+						sizeof(*handler->enable_save), GFP_KERNEL);
+		if (!handler->enable_save)
+			goto out_free_enable_reg;
 done:
 		for (hwirq = 1; hwirq <= nr_irqs; hwirq++) {
 			plic_toggle(handler, hwirq, 0);
···
 				  plic_starting_cpu, plic_dying_cpu);
 		plic_cpuhp_setup_done = true;
 	}
+	register_syscore_ops(&plic_irq_syscore_ops);
 
 	pr_info("%pOFP: mapped %d interrupts with %d handlers for"
 		" %d contexts.\n", node, nr_irqs, nr_handlers, nr_contexts);
 	return 0;
 
+out_free_enable_reg:
+	for_each_cpu(cpu, cpu_present_mask) {
+		handler = per_cpu_ptr(&plic_handlers, cpu);
+		kfree(handler->enable_save);
+	}
+out_free_priority_reg:
+	kfree(priv->prio_save);
 out_iounmap:
 	iounmap(priv->regs);
 out_free_priv: