1 files changed, 490 insertions, 0 deletions

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
new file mode 100644
index 000000000..2f4784860
--- /dev/null
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -0,0 +1,490 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 SiFive
+ * Copyright (C) 2018 Christoph Hellwig
+ */
+#define pr_fmt(fmt) "plic: " fmt
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <asm/smp.h>
+
+/*
+ * This driver implements a version of the RISC-V PLIC with the actual layout
+ * specified in chapter 8 of the SiFive U5 Coreplex Series Manual:
+ *
+ *     https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf
+ *
+ * The largest number supported by devices marked as 'sifive,plic-1.0.0', is
+ * 1024, of which device 0 is defined as non-existent by the RISC-V Privileged
+ * Spec.
+ */
+
+#define MAX_DEVICES			1024
+#define MAX_CONTEXTS			15872
+
+/*
+ * Each interrupt source has a priority register associated with it.
+ * We always hardwire it to one in Linux.
+ */
+#define PRIORITY_BASE			0
+#define     PRIORITY_PER_ID		4
+
+/*
+ * Each hart context has a vector of interrupt enable bits associated with it.
+ * There's one bit for each interrupt source.
+ */
+#define CONTEXT_ENABLE_BASE		0x2000
+#define     CONTEXT_ENABLE_SIZE		0x80
+
+/*
+ * 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
+ * take an interrupt, and a register to claim interrupts.
+ */
+#define CONTEXT_BASE			0x200000
+#define     CONTEXT_SIZE		0x1000
+#define     CONTEXT_THRESHOLD		0x00
+#define     CONTEXT_CLAIM		0x04
+
+#define	PLIC_DISABLE_THRESHOLD		0x7
+#define	PLIC_ENABLE_THRESHOLD		0
+
+#define PLIC_QUIRK_EDGE_INTERRUPT	0
+
+struct plic_priv {
+	struct cpumask lmask;
+	struct irq_domain *irqdomain;
+	void __iomem *regs;
+	unsigned long plic_quirks;
+};
+
+struct plic_handler {
+	bool			present;
+	void __iomem		*hart_base;
+	/*
+	 * Protect mask operations on the registers given that we can't
+	 * assume atomic memory operations work on them.
+	 */
+	raw_spinlock_t		enable_lock;
+	void __iomem		*enable_base;
+	struct plic_priv	*priv;
+};
+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 int plic_irq_set_type(struct irq_data *d, unsigned int type);
+
+static void __plic_toggle(void __iomem *enable_base, int hwirq, int enable)
+{
+	u32 __iomem *reg = enable_base + (hwirq / 32) * sizeof(u32);
+	u32 hwirq_mask = 1 << (hwirq % 32);
+
+	if (enable)
+		writel(readl(reg) | hwirq_mask, reg);
+	else
+		writel(readl(reg) & ~hwirq_mask, reg);
+}
+
+static void plic_toggle(struct plic_handler *handler, int hwirq, int enable)
+{
+	raw_spin_lock(&handler->enable_lock);
+	__plic_toggle(handler->enable_base, hwirq, enable);
+	raw_spin_unlock(&handler->enable_lock);
+}
+
+static inline void plic_irq_toggle(const struct cpumask *mask,
+				   struct irq_data *d, int enable)
+{
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
+
+		plic_toggle(handler, d->hwirq, enable);
+	}
+}
+
+static void plic_irq_enable(struct irq_data *d)
+{
+	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 1);
+}
+
+static void plic_irq_disable(struct irq_data *d)
+{
+	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
+}
+
+static void plic_irq_unmask(struct irq_data *d)
+{
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
+
+	writel(1, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
+}
+
+static void plic_irq_mask(struct irq_data *d)
+{
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
+
+	writel(0, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
+}
+
+static void plic_irq_eoi(struct irq_data *d)
+{
+	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
+
+	writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
+}
+
+#ifdef CONFIG_SMP
+static int plic_set_affinity(struct irq_data *d,
+			     const struct cpumask *mask_val, bool force)
+{
+	unsigned int cpu;
+	struct cpumask amask;
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
+
+	cpumask_and(&amask, &priv->lmask, mask_val);
+
+	if (force)
+		cpu = cpumask_first(&amask);
+	else
+		cpu = cpumask_any_and(&amask, cpu_online_mask);
+
+	if (cpu >= nr_cpu_ids)
+		return -EINVAL;
+
+	plic_irq_disable(d);
+
+	irq_data_update_effective_affinity(d, cpumask_of(cpu));
+
+	if (!irqd_irq_disabled(d))
+		plic_irq_enable(d);
+
+	return IRQ_SET_MASK_OK_DONE;
+}
+#endif
+
+static struct irq_chip plic_edge_chip = {
+	.name		= "SiFive PLIC",
+	.irq_enable	= plic_irq_enable,
+	.irq_disable	= plic_irq_disable,
+	.irq_ack	= plic_irq_eoi,
+	.irq_mask	= plic_irq_mask,
+	.irq_unmask	= plic_irq_unmask,
+#ifdef CONFIG_SMP
+	.irq_set_affinity = plic_set_affinity,
+#endif
+	.irq_set_type	= plic_irq_set_type,
+	.flags		= IRQCHIP_AFFINITY_PRE_STARTUP,
+};
+
+static struct irq_chip plic_chip = {
+	.name		= "SiFive PLIC",
+	.irq_enable	= plic_irq_enable,
+	.irq_disable	= plic_irq_disable,
+	.irq_mask	= plic_irq_mask,
+	.irq_unmask	= plic_irq_unmask,
+	.irq_eoi	= plic_irq_eoi,
+#ifdef CONFIG_SMP
+	.irq_set_affinity = plic_set_affinity,
+#endif
+	.irq_set_type	= plic_irq_set_type,
+	.flags		= IRQCHIP_AFFINITY_PRE_STARTUP,
+};
+
+static int plic_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
+
+	if (!test_bit(PLIC_QUIRK_EDGE_INTERRUPT, &priv->plic_quirks))
+		return IRQ_SET_MASK_OK_NOCOPY;
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		irq_set_chip_handler_name_locked(d, &plic_edge_chip,
+						 handle_edge_irq, NULL);
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		irq_set_chip_handler_name_locked(d, &plic_chip,
+						 handle_fasteoi_irq, NULL);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return IRQ_SET_MASK_OK;
+}
+
+static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
+			      irq_hw_number_t hwirq)
+{
+	struct plic_priv *priv = d->host_data;
+
+	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
+			    handle_fasteoi_irq, NULL, NULL);
+	irq_set_noprobe(irq);
+	irq_set_affinity(irq, &priv->lmask);
+	return 0;
+}
+
+static int plic_irq_domain_translate(struct irq_domain *d,
+				     struct irq_fwspec *fwspec,
+				     unsigned long *hwirq,
+				     unsigned int *type)
+{
+	struct plic_priv *priv = d->host_data;
+
+	if (test_bit(PLIC_QUIRK_EDGE_INTERRUPT, &priv->plic_quirks))
+		return irq_domain_translate_twocell(d, fwspec, hwirq, type);
+
+	return irq_domain_translate_onecell(d, fwspec, hwirq, type);
+}
+
+static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				 unsigned int nr_irqs, void *arg)
+{
+	int i, ret;
+	irq_hw_number_t hwirq;
+	unsigned int type;
+	struct irq_fwspec *fwspec = arg;
+
+	ret = plic_irq_domain_translate(domain, fwspec, &hwirq, &type);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < nr_irqs; i++) {
+		ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct irq_domain_ops plic_irqdomain_ops = {
+	.translate	= plic_irq_domain_translate,
+	.alloc		= plic_irq_domain_alloc,
+	.free		= irq_domain_free_irqs_top,
+};
+
+/*
+ * Handling an interrupt is a two-step process: first you claim the interrupt
+ * by reading the claim register, then you complete the interrupt by writing
+ * that source ID back to the same claim register.  This automatically enables
+ * and disables the interrupt, so there's nothing else to do.
+ */
+static void plic_handle_irq(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 = readl(claim))) {
+		int err = generic_handle_domain_irq(handler->priv->irqdomain,
+						    hwirq);
+		if (unlikely(err))
+			pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
+					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 */
+	writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
+}
+
+static int plic_dying_cpu(unsigned int cpu)
+{
+	if (plic_parent_irq)
+		disable_percpu_irq(plic_parent_irq);
+
+	return 0;
+}
+
+static int plic_starting_cpu(unsigned int cpu)
+{
+	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
+
+	if (plic_parent_irq)
+		enable_percpu_irq(plic_parent_irq,
+				  irq_get_trigger_type(plic_parent_irq));
+	else
+		pr_warn("cpu%d: parent irq not available\n", cpu);
+	plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);
+
+	return 0;
+}
+
+static int __init __plic_init(struct device_node *node,
+			      struct device_node *parent,
+			      unsigned long plic_quirks)
+{
+	int error = 0, nr_contexts, nr_handlers = 0, i;
+	u32 nr_irqs;
+	struct plic_priv *priv;
+	struct plic_handler *handler;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->plic_quirks = plic_quirks;
+
+	priv->regs = of_iomap(node, 0);
+	if (WARN_ON(!priv->regs)) {
+		error = -EIO;
+		goto out_free_priv;
+	}
+
+	error = -EINVAL;
+	of_property_read_u32(node, "riscv,ndev", &nr_irqs);
+	if (WARN_ON(!nr_irqs))
+		goto out_iounmap;
+
+	nr_contexts = of_irq_count(node);
+	if (WARN_ON(!nr_contexts))
+		goto out_iounmap;
+
+	error = -ENOMEM;
+	priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
+			&plic_irqdomain_ops, priv);
+	if (WARN_ON(!priv->irqdomain))
+		goto out_iounmap;
+
+	for (i = 0; i < nr_contexts; i++) {
+		struct of_phandle_args parent;
+		irq_hw_number_t hwirq;
+		int cpu;
+		unsigned long hartid;
+
+		if (of_irq_parse_one(node, i, &parent)) {
+			pr_err("failed to parse parent for context %d.\n", i);
+			continue;
+		}
+
+		/*
+		 * Skip contexts other than external interrupts for our
+		 * privilege level.
+		 */
+		if (parent.args[0] != 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;
+
+				for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
+					__plic_toggle(enable_base, hwirq, 0);
+			}
+			continue;
+		}
+
+		error = riscv_of_parent_hartid(parent.np, &hartid);
+		if (error < 0) {
+			pr_warn("failed to parse hart ID for context %d.\n", i);
+			continue;
+		}
+
+		cpu = riscv_hartid_to_cpuid(hartid);
+		if (cpu < 0) {
+			pr_warn("Invalid cpuid for context %d\n", i);
+			continue;
+		}
+
+		/* 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);
+			if (plic_parent_irq)
+				irq_set_chained_handler(plic_parent_irq,
+							plic_handle_irq);
+		}
+
+		/*
+		 * When running in M-mode we need to ignore the S-mode handler.
+		 * Here we assume it always comes later, but that might be a
+		 * little fragile.
+		 */
+		handler = per_cpu_ptr(&plic_handlers, cpu);
+		if (handler->present) {
+			pr_warn("handler already present for context %d.\n", i);
+			plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
+			goto done;
+		}
+
+		cpumask_set_cpu(cpu, &priv->lmask);
+		handler->present = true;
+		handler->hart_base = priv->regs + CONTEXT_BASE +
+			i * CONTEXT_SIZE;
+		raw_spin_lock_init(&handler->enable_lock);
+		handler->enable_base = priv->regs + CONTEXT_ENABLE_BASE +
+			i * CONTEXT_ENABLE_SIZE;
+		handler->priv = priv;
+done:
+		for (hwirq = 1; hwirq <= nr_irqs; hwirq++) {
+			plic_toggle(handler, hwirq, 0);
+			writel(1, priv->regs + PRIORITY_BASE +
+				  hwirq * PRIORITY_PER_ID);
+		}
+		nr_handlers++;
+	}
+
+	/*
+	 * We can have multiple PLIC instances so setup cpuhp state only
+	 * when context handler for current/boot CPU is present.
+	 */
+	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);
+		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);
+	return 0;
+
+out_iounmap:
+	iounmap(priv->regs);
+out_free_priv:
+	kfree(priv);
+	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);