irqchip/sifive-plic: Convert PLIC driver into a platform driver

The PLIC driver does not require very early initialization so convert
it into a platform driver.

After conversion, the PLIC driver is probed after CPUs are brought-up
so setup cpuhp state after context handler of all online CPUs are
initialized otherwise PLIC driver crashes for platforms with multiple
PLIC instances.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240222094006.1030709-2-apatel@ventanamicro.com

Author: avpatel

drivers/irqchip/irq-sifive-plic.c

@@ -64,6 +64,7 @@
 #define PLIC_QUIRK_EDGE_INTERRUPT	0
 
 struct plic_priv {
+	struct device *dev;
 	struct cpumask lmask;
 	struct irq_domain *irqdomain;
 	void __iomem *regs;
@@ -406,30 +407,50 @@ static int plic_starting_cpu(unsigned int cpu)
 	return 0;
 }
 
-static int __init __plic_init(struct device_node *node,
-			      struct device_node *parent,
-			      unsigned long plic_quirks)
+static const struct of_device_id plic_match[] = {
+	{ .compatible = "sifive,plic-1.0.0" },
+	{ .compatible = "riscv,plic0" },
+	{ .compatible = "andestech,nceplic100",
+	  .data = (const void *)BIT(PLIC_QUIRK_EDGE_INTERRUPT) },
+	{ .compatible = "thead,c900-plic",
+	  .data = (const void *)BIT(PLIC_QUIRK_EDGE_INTERRUPT) },
+	{}
+};
+
+static int plic_probe(struct platform_device *pdev)
 {
 	int error = 0, nr_contexts, nr_handlers = 0, i;
-	u32 nr_irqs;
-	struct plic_priv *priv;
+	struct device *dev = &pdev->dev;
+	unsigned long plic_quirks = 0;
 	struct plic_handler *handler;
+	struct plic_priv *priv;
+	bool cpuhp_setup;
 	unsigned int cpu;
+	u32 nr_irqs;
+
+	if (is_of_node(dev->fwnode)) {
+		const struct of_device_id *id;
+
+		id = of_match_node(plic_match, to_of_node(dev->fwnode));
+		if (id)
+			plic_quirks = (unsigned long)id->data;
+	}
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
 
+	priv->dev = dev;
 	priv->plic_quirks = plic_quirks;
 
-	priv->regs = of_iomap(node, 0);
+	priv->regs = of_iomap(to_of_node(dev->fwnode), 0);
 	if (WARN_ON(!priv->regs)) {
 		error = -EIO;
 		goto out_free_priv;
 	}
 
 	error = -EINVAL;
-	of_property_read_u32(node, "riscv,ndev", &nr_irqs);
+	of_property_read_u32(to_of_node(dev->fwnode), "riscv,ndev", &nr_irqs);
 	if (WARN_ON(!nr_irqs))
 		goto out_iounmap;
 
@@ -439,13 +460,13 @@ static int __init __plic_init(struct device_node *node,
 	if (!priv->prio_save)
 		goto out_free_priority_reg;
 
-	nr_contexts = of_irq_count(node);
+	nr_contexts = of_irq_count(to_of_node(dev->fwnode));
 	if (WARN_ON(!nr_contexts))
 		goto out_free_priority_reg;
 
 	error = -ENOMEM;
-	priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
-			&plic_irqdomain_ops, priv);
+	priv->irqdomain = irq_domain_add_linear(to_of_node(dev->fwnode), nr_irqs + 1,
+						&plic_irqdomain_ops, priv);
 	if (WARN_ON(!priv->irqdomain))
 		goto out_free_priority_reg;
 
@@ -455,7 +476,7 @@ static int __init __plic_init(struct device_node *node,
 		int cpu;
 		unsigned long hartid;
 
-		if (of_irq_parse_one(node, i, &parent)) {
+		if (of_irq_parse_one(to_of_node(dev->fwnode), i, &parent)) {
 			pr_err("failed to parse parent for context %d.\n", i);
 			continue;
 		}
@@ -491,7 +512,7 @@ static int __init __plic_init(struct device_node *node,
 
 		/* Find parent domain and register chained handler */
 		if (!plic_parent_irq && irq_find_host(parent.np)) {
-			plic_parent_irq = irq_of_parse_and_map(node, i);
+			plic_parent_irq = irq_of_parse_and_map(to_of_node(dev->fwnode), i);
 			if (plic_parent_irq)
 				irq_set_chained_handler(plic_parent_irq,
 							plic_handle_irq);
@@ -533,20 +554,29 @@ static int __init __plic_init(struct device_node *node,
 
 	/*
 	 * We can have multiple PLIC instances so setup cpuhp state
-	 * and register syscore operations only when context handler
-	 * for current/boot CPU is present.
+	 * and register syscore operations only once after context
+	 * handlers of all online CPUs are initialized.
 	 */
-	handler = this_cpu_ptr(&plic_handlers);
-	if (handler->present && !plic_cpuhp_setup_done) {
-		cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
-				  "irqchip/sifive/plic:starting",
-				  plic_starting_cpu, plic_dying_cpu);
-		register_syscore_ops(&plic_irq_syscore_ops);
-		plic_cpuhp_setup_done = true;
+	if (!plic_cpuhp_setup_done) {
+		cpuhp_setup = true;
+		for_each_online_cpu(cpu) {
+			handler = per_cpu_ptr(&plic_handlers, cpu);
+			if (!handler->present) {
+				cpuhp_setup = false;
+				break;
+			}
+		}
+		if (cpuhp_setup) {
+			cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
+					  "irqchip/sifive/plic:starting",
+					  plic_starting_cpu, plic_dying_cpu);
+			register_syscore_ops(&plic_irq_syscore_ops);
+			plic_cpuhp_setup_done = true;
+		}
 	}
 
-	pr_info("%pOFP: mapped %d interrupts with %d handlers for"
-		" %d contexts.\n", node, nr_irqs, nr_handlers, nr_contexts);
+	pr_info("%pOFP: mapped %d interrupts with %d handlers for %d contexts.\n",
+		to_of_node(dev->fwnode), nr_irqs, nr_handlers, nr_contexts);
 	return 0;
 
 out_free_enable_reg:
@@ -563,20 +593,11 @@ static int __init __plic_init(struct device_node *node,
 	return error;
 }
 
-static int __init plic_init(struct device_node *node,
-			    struct device_node *parent)
-{
-	return __plic_init(node, parent, 0);
-}
-
-IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
-IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */
-
-static int __init plic_edge_init(struct device_node *node,
-				 struct device_node *parent)
-{
-	return __plic_init(node, parent, BIT(PLIC_QUIRK_EDGE_INTERRUPT));
-}
-
-IRQCHIP_DECLARE(andestech_nceplic100, "andestech,nceplic100", plic_edge_init);
-IRQCHIP_DECLARE(thead_c900_plic, "thead,c900-plic", plic_edge_init);
+static struct platform_driver plic_driver = {
+	.driver = {
+		.name		= "riscv-plic",
+		.of_match_table	= plic_match,
+	},
+	.probe = plic_probe,
+};
+builtin_platform_driver(plic_driver);