1 files changed, 390 insertions, 0 deletions
diff --git a/drivers/irqchip/irq-riscv-imsic-platform.c b/drivers/irqchip/irq-riscv-imsic-platform.c
new file mode 100644
index 000000000000..1b9fbfce9581
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-imsic-platform.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ */
+
+#define pr_fmt(fmt) "riscv-imsic: " fmt
+#include <linux/acpi.h>
+#include <linux/bitmap.h>
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+
+#include <linux/irqchip/irq-msi-lib.h>
+#include "irq-riscv-imsic-state.h"
+
+static bool imsic_cpu_page_phys(unsigned int cpu, unsigned int guest_index,
+				phys_addr_t *out_msi_pa)
+{
+	struct imsic_global_config *global;
+	struct imsic_local_config *local;
+
+	global = &imsic->global;
+	local = per_cpu_ptr(global->local, cpu);
+
+	if (BIT(global->guest_index_bits) <= guest_index)
+		return false;
+
+	if (out_msi_pa)
+		*out_msi_pa = local->msi_pa + (guest_index * IMSIC_MMIO_PAGE_SZ);
+
+	return true;
+}
+
+static void imsic_irq_mask(struct irq_data *d)
+{
+	imsic_vector_mask(irq_data_get_irq_chip_data(d));
+}
+
+static void imsic_irq_unmask(struct irq_data *d)
+{
+	imsic_vector_unmask(irq_data_get_irq_chip_data(d));
+}
+
+static int imsic_irq_retrigger(struct irq_data *d)
+{
+	struct imsic_vector *vec = irq_data_get_irq_chip_data(d);
+	struct imsic_local_config *local;
+
+	if (WARN_ON(!vec))
+		return -ENOENT;
+
+	local = per_cpu_ptr(imsic->global.local, vec->cpu);
+	writel_relaxed(vec->local_id, local->msi_va);
+	return 0;
+}
+
+static void imsic_irq_ack(struct irq_data *d)
+{
+	irq_move_irq(d);
+}
+
+static void imsic_irq_compose_vector_msg(struct imsic_vector *vec, struct msi_msg *msg)
+{
+	phys_addr_t msi_addr;
+
+	if (WARN_ON(!vec))
+		return;
+
+	if (WARN_ON(!imsic_cpu_page_phys(vec->cpu, 0, &msi_addr)))
+		return;
+
+	msg->address_hi = upper_32_bits(msi_addr);
+	msg->address_lo = lower_32_bits(msi_addr);
+	msg->data = vec->local_id;
+}
+
+static void imsic_irq_compose_msg(struct irq_data *d, struct msi_msg *msg)
+{
+	imsic_irq_compose_vector_msg(irq_data_get_irq_chip_data(d), msg);
+}
+
+#ifdef CONFIG_SMP
+static void imsic_msi_update_msg(struct irq_data *d, struct imsic_vector *vec)
+{
+	struct msi_msg msg = { };
+
+	imsic_irq_compose_vector_msg(vec, &msg);
+	irq_data_get_irq_chip(d)->irq_write_msi_msg(d, &msg);
+}
+
+static int imsic_irq_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
+				  bool force)
+{
+	struct imsic_vector *old_vec, *new_vec;
+	struct imsic_vector tmp_vec;
+
+	/*
+	 * Requirements for the downstream irqdomains (or devices):
+	 *
+	 * 1) Downstream irqdomains (or devices) with atomic MSI update can
+	 *    happily do imsic_irq_set_affinity() in the process-context on
+	 *    any CPU so the irqchip of such irqdomains must not set the
+	 *    IRQCHIP_MOVE_DEFERRED flag.
+	 *
+	 * 2) Downstream irqdomains (or devices) with non-atomic MSI update
+	 *    must use imsic_irq_set_affinity() in nterrupt-context upon
+	 *    the next device interrupt so the irqchip of such irqdomains
+	 *    must set the IRQCHIP_MOVE_DEFERRED flag.
+	 */
+
+	old_vec = irq_data_get_irq_chip_data(d);
+	if (WARN_ON(!old_vec))
+		return -ENOENT;
+
+	/* If old vector cpu belongs to the target cpumask then do nothing */
+	if (cpumask_test_cpu(old_vec->cpu, mask_val))
+		return IRQ_SET_MASK_OK_DONE;
+
+	/* If move is already in-flight then return failure */
+	if (imsic_vector_get_move(old_vec))
+		return -EBUSY;
+
+	/* Get a new vector on the desired set of CPUs */
+	new_vec = imsic_vector_alloc(old_vec->irq, mask_val);
+	if (!new_vec)
+		return -ENOSPC;
+
+	/*
+	 * Device having non-atomic MSI update might see an intermediate
+	 * state when changing target IMSIC vector from one CPU to another.
+	 *
+	 * To avoid losing interrupt to such intermediate state, do the
+	 * following (just like x86 APIC):
+	 *
+	 * 1) First write a temporary IMSIC vector to the device which
+	 * has MSI address same as the old IMSIC vector but MSI data
+	 * matches the new IMSIC vector.
+	 *
+	 * 2) Next write the new IMSIC vector to the device.
+	 *
+	 * Based on the above, __imsic_local_sync() must check pending
+	 * status of both old MSI data and new MSI data on the old CPU.
+	 */
+	if (!irq_can_move_in_process_context(d) &&
+	    new_vec->local_id != old_vec->local_id) {
+		/* Setup temporary vector */
+		tmp_vec.cpu = old_vec->cpu;
+		tmp_vec.local_id = new_vec->local_id;
+
+		/* Point device to the temporary vector */
+		imsic_msi_update_msg(irq_get_irq_data(d->irq), &tmp_vec);
+	}
+
+	/* Point device to the new vector */
+	imsic_msi_update_msg(irq_get_irq_data(d->irq), new_vec);
+
+	/* Update irq descriptors with the new vector */
+	d->chip_data = new_vec;
+
+	/* Update effective affinity */
+	irq_data_update_effective_affinity(d, cpumask_of(new_vec->cpu));
+
+	/* Move state of the old vector to the new vector */
+	imsic_vector_move(old_vec, new_vec);
+
+	return IRQ_SET_MASK_OK_DONE;
+}
+
+static void imsic_irq_force_complete_move(struct irq_data *d)
+{
+	struct imsic_vector *mvec, *vec = irq_data_get_irq_chip_data(d);
+	unsigned int cpu = smp_processor_id();
+
+	if (WARN_ON(!vec))
+		return;
+
+	/* Do nothing if there is no in-flight move */
+	mvec = imsic_vector_get_move(vec);
+	if (!mvec)
+		return;
+
+	/* Do nothing if the old IMSIC vector does not belong to current CPU */
+	if (mvec->cpu != cpu)
+		return;
+
+	/*
+	 * The best we can do is force cleanup the old IMSIC vector.
+	 *
+	 * The challenges over here are same as x86 vector domain so
+	 * refer to the comments in irq_force_complete_move() function
+	 * implemented at arch/x86/kernel/apic/vector.c.
+	 */
+
+	/* Force cleanup in-flight move */
+	pr_info("IRQ fixup: irq %d move in progress, old vector cpu %d local_id %d\n",
+		d->irq, mvec->cpu, mvec->local_id);
+	imsic_vector_force_move_cleanup(vec);
+}
+#endif
+
+static struct irq_chip imsic_irq_base_chip = {
+	.name				= "IMSIC",
+	.irq_mask			= imsic_irq_mask,
+	.irq_unmask			= imsic_irq_unmask,
+#ifdef CONFIG_SMP
+	.irq_set_affinity		= imsic_irq_set_affinity,
+	.irq_force_complete_move	= imsic_irq_force_complete_move,
+#endif
+	.irq_retrigger			= imsic_irq_retrigger,
+	.irq_ack			= imsic_irq_ack,
+	.irq_compose_msi_msg		= imsic_irq_compose_msg,
+	.flags				= IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MASK_ON_SUSPEND,
+};
+
+static int imsic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				  unsigned int nr_irqs, void *args)
+{
+	struct imsic_vector *vec;
+
+	/* Multi-MSI is not supported yet. */
+	if (nr_irqs > 1)
+		return -EOPNOTSUPP;
+
+	vec = imsic_vector_alloc(virq, cpu_online_mask);
+	if (!vec)
+		return -ENOSPC;
+
+	irq_domain_set_info(domain, virq, virq, &imsic_irq_base_chip, vec,
+			    handle_edge_irq, NULL, NULL);
+	irq_set_noprobe(virq);
+	irq_set_affinity(virq, cpu_online_mask);
+	irq_data_update_effective_affinity(irq_get_irq_data(virq), cpumask_of(vec->cpu));
+
+	return 0;
+}
+
+static void imsic_irq_domain_free(struct irq_domain *domain, unsigned int virq,
+				  unsigned int nr_irqs)
+{
+	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+
+	imsic_vector_free(irq_data_get_irq_chip_data(d));
+	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+}
+
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+static void imsic_irq_debug_show(struct seq_file *m, struct irq_domain *d,
+				 struct irq_data *irqd, int ind)
+{
+	if (!irqd) {
+		imsic_vector_debug_show_summary(m, ind);
+		return;
+	}
+
+	imsic_vector_debug_show(m, irq_data_get_irq_chip_data(irqd), ind);
+}
+#endif
+
+static const struct irq_domain_ops imsic_base_domain_ops = {
+	.alloc		= imsic_irq_domain_alloc,
+	.free		= imsic_irq_domain_free,
+	.select		= msi_lib_irq_domain_select,
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+	.debug_show	= imsic_irq_debug_show,
+#endif
+};
+
+static bool imsic_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
+				    struct irq_domain *real_parent, struct msi_domain_info *info)
+{
+	if (!msi_lib_init_dev_msi_info(dev, domain, real_parent, info))
+		return false;
+
+	switch (info->bus_token) {
+	case DOMAIN_BUS_PCI_DEVICE_MSI:
+	case DOMAIN_BUS_PCI_DEVICE_MSIX:
+		info->chip->flags |= IRQCHIP_MOVE_DEFERRED;
+		break;
+	default:
+		break;
+	}
+
+	return true;
+}
+
+static const struct msi_parent_ops imsic_msi_parent_ops = {
+	.supported_flags	= MSI_GENERIC_FLAGS_MASK |
+				  MSI_FLAG_PCI_MSIX,
+	.required_flags		= MSI_FLAG_USE_DEF_DOM_OPS |
+				  MSI_FLAG_USE_DEF_CHIP_OPS |
+				  MSI_FLAG_PCI_MSI_MASK_PARENT,
+	.chip_flags		= MSI_CHIP_FLAG_SET_ACK,
+	.bus_select_token	= DOMAIN_BUS_NEXUS,
+	.bus_select_mask	= MATCH_PCI_MSI | MATCH_PLATFORM_MSI,
+	.init_dev_msi_info	= imsic_init_dev_msi_info,
+};
+
+int imsic_irqdomain_init(void)
+{
+	struct imsic_global_config *global;
+
+	if (!imsic || !imsic->fwnode) {
+		pr_err("early driver not probed\n");
+		return -ENODEV;
+	}
+
+	if (imsic->base_domain) {
+		pr_err("%pfwP: irq domain already created\n", imsic->fwnode);
+		return -ENODEV;
+	}
+
+	/* Create Base IRQ domain */
+	imsic->base_domain = irq_domain_create_tree(imsic->fwnode,
+						    &imsic_base_domain_ops, imsic);
+	if (!imsic->base_domain) {
+		pr_err("%pfwP: failed to create IMSIC base domain\n", imsic->fwnode);
+		return -ENOMEM;
+	}
+	imsic->base_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT;
+	imsic->base_domain->msi_parent_ops = &imsic_msi_parent_ops;
+
+	irq_domain_update_bus_token(imsic->base_domain, DOMAIN_BUS_NEXUS);
+
+	global = &imsic->global;
+	pr_info("%pfwP:  hart-index-bits: %d,  guest-index-bits: %d\n",
+		imsic->fwnode, global->hart_index_bits, global->guest_index_bits);
+	pr_info("%pfwP: group-index-bits: %d, group-index-shift: %d\n",
+		imsic->fwnode, global->group_index_bits, global->group_index_shift);
+	pr_info("%pfwP: per-CPU IDs %d at base address %pa\n",
+		imsic->fwnode, global->nr_ids, &global->base_addr);
+	pr_info("%pfwP: total %d interrupts available\n",
+		imsic->fwnode, num_possible_cpus() * (global->nr_ids - 1));
+
+	return 0;
+}
+
+static int imsic_platform_probe_common(struct fwnode_handle *fwnode)
+{
+	if (imsic && imsic->fwnode != fwnode) {
+		pr_err("%pfwP: fwnode mismatch\n", fwnode);
+		return -ENODEV;
+	}
+
+	return imsic_irqdomain_init();
+}
+
+static int imsic_platform_dt_probe(struct platform_device *pdev)
+{
+	return imsic_platform_probe_common(pdev->dev.fwnode);
+}
+
+#ifdef CONFIG_ACPI
+
+/*
+ *  On ACPI based systems, PCI enumeration happens early during boot in
+ *  acpi_scan_init(). PCI enumeration expects MSI domain setup before
+ *  it calls pci_set_msi_domain(). Hence, unlike in DT where
+ *  imsic-platform drive probe happens late during boot, ACPI based
+ *  systems need to setup the MSI domain early.
+ */
+int imsic_platform_acpi_probe(struct fwnode_handle *fwnode)
+{
+	return imsic_platform_probe_common(fwnode);
+}
+
+#endif
+
+static const struct of_device_id imsic_platform_match[] = {
+	{ .compatible = "riscv,imsics" },
+	{}
+};
+
+static struct platform_driver imsic_platform_driver = {
+	.driver = {
+		.name		= "riscv-imsic",
+		.of_match_table	= imsic_platform_match,
+	},
+	.probe = imsic_platform_dt_probe,
+};
+builtin_platform_driver(imsic_platform_driver);