1 files changed, 120 insertions, 29 deletions

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index cbd7697bc148..c5db7d6e3f7c 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -49,6 +49,8 @@
 #define CONTEXT_ENABLE_BASE		0x2000
 #define     CONTEXT_ENABLE_SIZE		0x80
 
+#define PENDING_BASE			0x1000
+
 /*
  * Each hart context has a set of control registers associated with it.  Right
  * now there's only two: a source priority threshold over which the hart will
@@ -63,6 +65,7 @@
 #define	PLIC_ENABLE_THRESHOLD		0
 
 #define PLIC_QUIRK_EDGE_INTERRUPT	0
+#define PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM	1
 
 struct plic_priv {
 	struct fwnode_handle *fwnode;
@@ -94,15 +97,22 @@ static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
 
 static int plic_irq_set_type(struct irq_data *d, unsigned int type);
 
-static void __plic_toggle(void __iomem *enable_base, int hwirq, int enable)
+static void __plic_toggle(struct plic_handler *handler, int hwirq, int enable)
 {
-	u32 __iomem *reg = enable_base + (hwirq / 32) * sizeof(u32);
+	u32 __iomem *base = handler->enable_base;
 	u32 hwirq_mask = 1 << (hwirq % 32);
+	int group = hwirq / 32;
+	u32 value;
+
+	value = readl(base + group);
 
 	if (enable)
-		writel(readl(reg) | hwirq_mask, reg);
+		value |= hwirq_mask;
 	else
-		writel(readl(reg) & ~hwirq_mask, reg);
+		value &= ~hwirq_mask;
+
+	handler->enable_save[group] = value;
+	writel(value, base + group);
 }
 
 static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
@@ -110,7 +120,7 @@ static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
 	unsigned long flags;
 
 	raw_spin_lock_irqsave(&handler->enable_lock, flags);
-	__plic_toggle(handler->enable_base, hwirq, enable);
+	__plic_toggle(handler, hwirq, enable);
 	raw_spin_unlock_irqrestore(&handler->enable_lock, flags);
 }
 
@@ -247,33 +257,16 @@ static int plic_irq_set_type(struct irq_data *d, unsigned int type)
 
 static int plic_irq_suspend(void)
 {
-	unsigned int i, cpu;
-	unsigned long flags;
-	u32 __iomem *reg;
 	struct plic_priv *priv;
 
 	priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv;
 
 	/* irq ID 0 is reserved */
-	for (i = 1; i < priv->nr_irqs; i++) {
+	for (unsigned int i = 1; i < priv->nr_irqs; i++) {
 		__assign_bit(i, priv->prio_save,
 			     readl(priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID));
 	}
 
-	for_each_present_cpu(cpu) {
-		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
-
-		if (!handler->present)
-			continue;
-
-		raw_spin_lock_irqsave(&handler->enable_lock, flags);
-		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_irqrestore(&handler->enable_lock, flags);
-	}
-
 	return 0;
 }
 
@@ -398,6 +391,98 @@ static void plic_handle_irq(struct irq_desc *desc)
 	chained_irq_exit(chip, desc);
 }
 
+static u32 cp100_isolate_pending_irq(int nr_irq_groups, struct plic_handler *handler)
+{
+	u32 __iomem *pending = handler->priv->regs + PENDING_BASE;
+	u32 __iomem *enable = handler->enable_base;
+	u32 pending_irqs = 0;
+	int i, j;
+
+	/* Look for first pending interrupt */
+	for (i = 0; i < nr_irq_groups; i++) {
+		/* Any pending interrupts would be annihilated, so skip checking them */
+		if (!handler->enable_save[i])
+			continue;
+
+		pending_irqs = handler->enable_save[i] & readl_relaxed(pending + i);
+		if (pending_irqs)
+			break;
+	}
+
+	if (!pending_irqs)
+		return 0;
+
+	/* Isolate lowest set bit */
+	pending_irqs &= -pending_irqs;
+
+	/* Disable all interrupts but the first pending one */
+	for (j = 0; j < nr_irq_groups; j++) {
+		u32 new_mask = j == i ? pending_irqs : 0;
+
+		if (new_mask != handler->enable_save[j])
+			writel_relaxed(new_mask, enable + j);
+	}
+	return pending_irqs;
+}
+
+static irq_hw_number_t cp100_get_hwirq(struct plic_handler *handler, void __iomem *claim)
+{
+	int nr_irq_groups = DIV_ROUND_UP(handler->priv->nr_irqs, 32);
+	u32 __iomem *enable = handler->enable_base;
+	irq_hw_number_t hwirq = 0;
+	u32 iso_mask;
+	int i;
+
+	guard(raw_spinlock)(&handler->enable_lock);
+
+	/* Existing enable state is already cached in enable_save */
+	iso_mask = cp100_isolate_pending_irq(nr_irq_groups, handler);
+	if (!iso_mask)
+		return 0;
+
+	/*
+	 * Interrupts delievered to hardware still become pending, but only
+	 * interrupts that are both pending and enabled can be claimed.
+	 * Clearing the enable bit for all interrupts but the first pending
+	 * one avoids a hardware bug that occurs during read from the claim
+	 * register with more than one eligible interrupt.
+	 */
+	hwirq = readl(claim);
+
+	/* Restore previous state */
+	for (i = 0; i < nr_irq_groups; i++) {
+		u32 written = i == hwirq / 32 ? iso_mask : 0;
+		u32 stored = handler->enable_save[i];
+
+		if (stored != written)
+			writel_relaxed(stored, enable + i);
+	}
+	return hwirq;
+}
+
+static void plic_handle_irq_cp100(struct irq_desc *desc)
+{
+	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
+	irq_hw_number_t hwirq;
+
+	WARN_ON_ONCE(!handler->present);
+
+	chained_irq_enter(chip, desc);
+
+	while ((hwirq = cp100_get_hwirq(handler, claim))) {
+		int err = generic_handle_domain_irq(handler->priv->irqdomain, hwirq);
+
+		if (unlikely(err)) {
+			pr_warn_ratelimited("%pfwP: can't find mapping for hwirq %lu\n",
+					    handler->priv->fwnode, hwirq);
+		}
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
 static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
 {
 	/* priority must be > threshold to trigger an interrupt */
@@ -434,6 +519,8 @@ static const struct of_device_id plic_match[] = {
 	  .data = (const void *)BIT(PLIC_QUIRK_EDGE_INTERRUPT) },
 	{ .compatible = "thead,c900-plic",
 	  .data = (const void *)BIT(PLIC_QUIRK_EDGE_INTERRUPT) },
+	{ .compatible = "ultrarisc,cp100-plic",
+	  .data = (const void *)BIT(PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM) },
 	{}
 };
 
@@ -592,12 +679,11 @@ static int plic_probe(struct fwnode_handle *fwnode)
 		if (parent_hwirq != RV_IRQ_EXT) {
 			/* Disable S-mode enable bits if running in M-mode. */
 			if (IS_ENABLED(CONFIG_RISCV_M_MODE)) {
-				void __iomem *enable_base = priv->regs +
-					CONTEXT_ENABLE_BASE +
-					i * CONTEXT_ENABLE_SIZE;
+				u32 __iomem *enable_base = priv->regs +	CONTEXT_ENABLE_BASE +
+							   i * CONTEXT_ENABLE_SIZE;
 
-				for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
-					__plic_toggle(enable_base, hwirq, 0);
+				for (int j = 0; j <= nr_irqs / 32; j++)
+					writel(0, enable_base + j);
 			}
 			continue;
 		}
@@ -668,12 +754,17 @@ done:
 		}
 
 		if (global_setup) {
+			void (*handler_fn)(struct irq_desc *) = plic_handle_irq;
+
+			if (test_bit(PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM, &handler->priv->plic_quirks))
+				handler_fn = plic_handle_irq_cp100;
+
 			/* Find parent domain and register chained handler */
 			domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), DOMAIN_BUS_ANY);
 			if (domain)
 				plic_parent_irq = irq_create_mapping(domain, RV_IRQ_EXT);
 			if (plic_parent_irq)
-				irq_set_chained_handler(plic_parent_irq, plic_handle_irq);
+				irq_set_chained_handler(plic_parent_irq, handler_fn);
 
 			cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
 					  "irqchip/sifive/plic:starting",