C6X: interrupt handling

Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <msalter@redhat.com>
Signed-off-by: NAurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: NMark Salter <msalter@redhat.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NArnd Bergmann <arnd@arndb.de>

arch/c6x/include/asm/hardirq.h

+/*
+ *  Port on Texas Instruments TMS320C6x architecture
+ *
+ *  Copyright (C) 2004, 2009, 2010 Texas Instruments Incorporated
+ *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_C6X_HARDIRQ_H
+#define _ASM_C6X_HARDIRQ_H
+
+extern void ack_bad_irq(int irq);
+#define ack_bad_irq ack_bad_irq
+
+#include <asm-generic/hardirq.h>
+
+#endif /* _ASM_C6X_HARDIRQ_H */

arch/c6x/include/asm/irq.h

+/*
+ *  Port on Texas Instruments TMS320C6x architecture
+ *
+ *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
+ *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ *  Large parts taken directly from powerpc.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+#ifndef _ASM_C6X_IRQ_H
+#define _ASM_C6X_IRQ_H
+
+#include <linux/threads.h>
+#include <linux/list.h>
+#include <linux/radix-tree.h>
+#include <asm/percpu.h>
+
+#define irq_canonicalize(irq)  (irq)
+
+/*
+ * The C64X+ core has 16 IRQ vectors. One each is used by Reset and NMI. Two
+ * are reserved. The remaining 12 vectors are used to route SoC interrupts.
+ * These interrupt vectors are prioritized with IRQ 4 having the highest
+ * priority and IRQ 15 having the lowest.
+ *
+ * The C64x+ megamodule provides a PIC which combines SoC IRQ sources into a
+ * single core IRQ vector. There are four combined sources, each of which
+ * feed into one of the 12 general interrupt vectors. The remaining 8 vectors
+ * can each route a single SoC interrupt directly.
+ */
+#define NR_PRIORITY_IRQS 16
+
+#define NR_IRQS_LEGACY	NR_PRIORITY_IRQS
+
+/* Total number of virq in the platform */
+#define NR_IRQS		256
+
+/* This number is used when no interrupt has been assigned */
+#define NO_IRQ		0
+
+/* This type is the placeholder for a hardware interrupt number. It has to
+ * be big enough to enclose whatever representation is used by a given
+ * platform.
+ */
+typedef unsigned long irq_hw_number_t;
+
+/* Interrupt controller "host" data structure. This could be defined as a
+ * irq domain controller. That is, it handles the mapping between hardware
+ * and virtual interrupt numbers for a given interrupt domain. The host
+ * structure is generally created by the PIC code for a given PIC instance
+ * (though a host can cover more than one PIC if they have a flat number
+ * model). It's the host callbacks that are responsible for setting the
+ * irq_chip on a given irq_desc after it's been mapped.
+ *
+ * The host code and data structures are fairly agnostic to the fact that
+ * we use an open firmware device-tree. We do have references to struct
+ * device_node in two places: in irq_find_host() to find the host matching
+ * a given interrupt controller node, and of course as an argument to its
+ * counterpart host->ops->match() callback. However, those are treated as
+ * generic pointers by the core and the fact that it's actually a device-node
+ * pointer is purely a convention between callers and implementation. This
+ * code could thus be used on other architectures by replacing those two
+ * by some sort of arch-specific void * "token" used to identify interrupt
+ * controllers.
+ */
+struct irq_host;
+struct radix_tree_root;
+struct device_node;
+
+/* Functions below are provided by the host and called whenever a new mapping
+ * is created or an old mapping is disposed. The host can then proceed to
+ * whatever internal data structures management is required. It also needs
+ * to setup the irq_desc when returning from map().
+ */
+struct irq_host_ops {
+	/* Match an interrupt controller device node to a host, returns
+	 * 1 on a match
+	 */
+	int (*match)(struct irq_host *h, struct device_node *node);
+
+	/* Create or update a mapping between a virtual irq number and a hw
+	 * irq number. This is called only once for a given mapping.
+	 */
+	int (*map)(struct irq_host *h, unsigned int virq, irq_hw_number_t hw);
+
+	/* Dispose of such a mapping */
+	void (*unmap)(struct irq_host *h, unsigned int virq);
+
+	/* Translate device-tree interrupt specifier from raw format coming
+	 * from the firmware to a irq_hw_number_t (interrupt line number) and
+	 * type (sense) that can be passed to set_irq_type(). In the absence
+	 * of this callback, irq_create_of_mapping() and irq_of_parse_and_map()
+	 * will return the hw number in the first cell and IRQ_TYPE_NONE for
+	 * the type (which amount to keeping whatever default value the
+	 * interrupt controller has for that line)
+	 */
+	int (*xlate)(struct irq_host *h, struct device_node *ctrler,
+		     const u32 *intspec, unsigned int intsize,
+		     irq_hw_number_t *out_hwirq, unsigned int *out_type);
+};
+
+struct irq_host {
+	struct list_head	link;
+
+	/* type of reverse mapping technique */
+	unsigned int		revmap_type;
+#define IRQ_HOST_MAP_PRIORITY   0 /* core priority irqs, get irqs 1..15 */
+#define IRQ_HOST_MAP_NOMAP	1 /* no fast reverse mapping */
+#define IRQ_HOST_MAP_LINEAR	2 /* linear map of interrupts */
+#define IRQ_HOST_MAP_TREE	3 /* radix tree */
+	union {
+		struct {
+			unsigned int size;
+			unsigned int *revmap;
+		} linear;
+		struct radix_tree_root tree;
+	} revmap_data;
+	struct irq_host_ops	*ops;
+	void			*host_data;
+	irq_hw_number_t		inval_irq;
+
+	/* Optional device node pointer */
+	struct device_node	*of_node;
+};
+
+struct irq_data;
+extern irq_hw_number_t irqd_to_hwirq(struct irq_data *d);
+extern irq_hw_number_t virq_to_hw(unsigned int virq);
+extern bool virq_is_host(unsigned int virq, struct irq_host *host);
+
+/**
+ * irq_alloc_host - Allocate a new irq_host data structure
+ * @of_node: optional device-tree node of the interrupt controller
+ * @revmap_type: type of reverse mapping to use
+ * @revmap_arg: for IRQ_HOST_MAP_LINEAR linear only: size of the map
+ * @ops: map/unmap host callbacks
+ * @inval_irq: provide a hw number in that host space that is always invalid
+ *
+ * Allocates and initialize and irq_host structure. Note that in the case of
+ * IRQ_HOST_MAP_LEGACY, the map() callback will be called before this returns
+ * for all legacy interrupts except 0 (which is always the invalid irq for
+ * a legacy controller). For a IRQ_HOST_MAP_LINEAR, the map is allocated by
+ * this call as well. For a IRQ_HOST_MAP_TREE, the radix tree will be allocated
+ * later during boot automatically (the reverse mapping will use the slow path
+ * until that happens).
+ */
+extern struct irq_host *irq_alloc_host(struct device_node *of_node,
+				       unsigned int revmap_type,
+				       unsigned int revmap_arg,
+				       struct irq_host_ops *ops,
+				       irq_hw_number_t inval_irq);
+
+
+/**
+ * irq_find_host - Locates a host for a given device node
+ * @node: device-tree node of the interrupt controller
+ */
+extern struct irq_host *irq_find_host(struct device_node *node);
+
+
+/**
+ * irq_set_default_host - Set a "default" host
+ * @host: default host pointer
+ *
+ * For convenience, it's possible to set a "default" host that will be used
+ * whenever NULL is passed to irq_create_mapping(). It makes life easier for
+ * platforms that want to manipulate a few hard coded interrupt numbers that
+ * aren't properly represented in the device-tree.
+ */
+extern void irq_set_default_host(struct irq_host *host);
+
+
+/**
+ * irq_set_virq_count - Set the maximum number of virt irqs
+ * @count: number of linux virtual irqs, capped with NR_IRQS
+ *
+ * This is mainly for use by platforms like iSeries who want to program
+ * the virtual irq number in the controller to avoid the reverse mapping
+ */
+extern void irq_set_virq_count(unsigned int count);
+
+
+/**
+ * irq_create_mapping - Map a hardware interrupt into linux virq space
+ * @host: host owning this hardware interrupt or NULL for default host
+ * @hwirq: hardware irq number in that host space
+ *
+ * Only one mapping per hardware interrupt is permitted. Returns a linux
+ * virq number.
+ * If the sense/trigger is to be specified, set_irq_type() should be called
+ * on the number returned from that call.
+ */
+extern unsigned int irq_create_mapping(struct irq_host *host,
+				       irq_hw_number_t hwirq);
+
+
+/**
+ * irq_dispose_mapping - Unmap an interrupt
+ * @virq: linux virq number of the interrupt to unmap
+ */
+extern void irq_dispose_mapping(unsigned int virq);
+
+/**
+ * irq_find_mapping - Find a linux virq from an hw irq number.
+ * @host: host owning this hardware interrupt
+ * @hwirq: hardware irq number in that host space
+ *
+ * This is a slow path, for use by generic code. It's expected that an
+ * irq controller implementation directly calls the appropriate low level
+ * mapping function.
+ */
+extern unsigned int irq_find_mapping(struct irq_host *host,
+				     irq_hw_number_t hwirq);
+
+/**
+ * irq_create_direct_mapping - Allocate a virq for direct mapping
+ * @host: host to allocate the virq for or NULL for default host
+ *
+ * This routine is used for irq controllers which can choose the hardware
+ * interrupt numbers they generate. In such a case it's simplest to use
+ * the linux virq as the hardware interrupt number.
+ */
+extern unsigned int irq_create_direct_mapping(struct irq_host *host);
+
+/**
+ * irq_radix_revmap_insert - Insert a hw irq to linux virq number mapping.
+ * @host: host owning this hardware interrupt
+ * @virq: linux irq number
+ * @hwirq: hardware irq number in that host space
+ *
+ * This is for use by irq controllers that use a radix tree reverse
+ * mapping for fast lookup.
+ */
+extern void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
+				    irq_hw_number_t hwirq);
+
+/**
+ * irq_radix_revmap_lookup - Find a linux virq from a hw irq number.
+ * @host: host owning this hardware interrupt
+ * @hwirq: hardware irq number in that host space
+ *
+ * This is a fast path, for use by irq controller code that uses radix tree
+ * revmaps
+ */
+extern unsigned int irq_radix_revmap_lookup(struct irq_host *host,
+					    irq_hw_number_t hwirq);
+
+/**
+ * irq_linear_revmap - Find a linux virq from a hw irq number.
+ * @host: host owning this hardware interrupt
+ * @hwirq: hardware irq number in that host space
+ *
+ * This is a fast path, for use by irq controller code that uses linear
+ * revmaps. It does fallback to the slow path if the revmap doesn't exist
+ * yet and will create the revmap entry with appropriate locking
+ */
+
+extern unsigned int irq_linear_revmap(struct irq_host *host,
+				      irq_hw_number_t hwirq);
+
+
+
+/**
+ * irq_alloc_virt - Allocate virtual irq numbers
+ * @host: host owning these new virtual irqs
+ * @count: number of consecutive numbers to allocate
+ * @hint: pass a hint number, the allocator will try to use a 1:1 mapping
+ *
+ * This is a low level function that is used internally by irq_create_mapping()
+ * and that can be used by some irq controllers implementations for things
+ * like allocating ranges of numbers for MSIs. The revmaps are left untouched.
+ */
+extern unsigned int irq_alloc_virt(struct irq_host *host,
+				   unsigned int count,
+				   unsigned int hint);
+
+/**
+ * irq_free_virt - Free virtual irq numbers
+ * @virq: virtual irq number of the first interrupt to free
+ * @count: number of interrupts to free
+ *
+ * This function is the opposite of irq_alloc_virt. It will not clear reverse
+ * maps, this should be done previously by unmap'ing the interrupt. In fact,
+ * all interrupts covered by the range being freed should have been unmapped
+ * prior to calling this.
+ */
+extern void irq_free_virt(unsigned int virq, unsigned int count);
+
+extern void __init init_pic_c64xplus(void);
+
+extern void init_IRQ(void);
+
+struct pt_regs;
+
+extern asmlinkage void c6x_do_IRQ(unsigned int prio, struct pt_regs *regs);
+
+extern unsigned long irq_err_count;
+
+#endif /* _ASM_C6X_IRQ_H */

arch/c6x/include/asm/irqflags.h

+/*
+ *  C6X IRQ flag handling
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated
+ * Written by Mark Salter (msalter@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+#ifndef __ASSEMBLY__
+
+/* read interrupt enabled status */
+static inline unsigned long arch_local_save_flags(void)
+{
+	unsigned long flags;
+
+	asm volatile (" mvc .s2 CSR,%0\n" : "=b"(flags));
+	return flags;
+}
+
+/* set interrupt enabled status */
+static inline void arch_local_irq_restore(unsigned long flags)
+{
+	asm volatile (" mvc .s2 %0,CSR\n" : : "b"(flags));
+}
+
+/* unconditionally enable interrupts */
+static inline void arch_local_irq_enable(void)
+{
+	unsigned long flags = arch_local_save_flags();
+	flags |= 1;
+	arch_local_irq_restore(flags);
+}
+
+/* unconditionally disable interrupts */
+static inline void arch_local_irq_disable(void)
+{
+	unsigned long flags = arch_local_save_flags();
+	flags &= ~1;
+	arch_local_irq_restore(flags);
+}
+
+/* get status and disable interrupts */
+static inline unsigned long arch_local_irq_save(void)
+{
+	unsigned long flags;
+
+	flags = arch_local_save_flags();
+	arch_local_irq_restore(flags & ~1);
+	return flags;
+}
+
+/* test flags */
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+	return (flags & 1) == 0;
+}
+
+/* test hardware interrupt enable bit */
+static inline int arch_irqs_disabled(void)
+{
+	return arch_irqs_disabled_flags(arch_local_save_flags());
+}
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ASM_IRQFLAGS_H */

arch/c6x/include/asm/megamod-pic.h

+#ifndef _C6X_MEGAMOD_PIC_H
+#define _C6X_MEGAMOD_PIC_H
+
+#ifdef __KERNEL__
+
+extern void __init megamod_pic_init(void);
+
+#endif /* __KERNEL__ */
+#endif /* _C6X_MEGAMOD_PIC_H */

arch/c6x/kernel/irq.c

+/*
+ *  Copyright (C) 2011 Texas Instruments Incorporated
+ *
+ *  This borrows heavily from powerpc version, which is:
+ *
+ *  Derived from arch/i386/kernel/irq.c
+ *    Copyright (C) 1992 Linus Torvalds
+ *  Adapted from arch/i386 by Gary Thomas
+ *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *  Updated and modified by Cort Dougan <cort@fsmlabs.com>
+ *    Copyright (C) 1996-2001 Cort Dougan
+ *  Adapted for Power Macintosh by Paul Mackerras
+ *    Copyright (C) 1996 Paul Mackerras (paulus@cs.anu.edu.au)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/radix-tree.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
+
+#include <asm/megamod-pic.h>
+
+unsigned long irq_err_count;
+
+static DEFINE_RAW_SPINLOCK(core_irq_lock);
+
+static void mask_core_irq(struct irq_data *data)
+{
+	unsigned int prio = data->irq;
+
+	BUG_ON(prio < 4 || prio >= NR_PRIORITY_IRQS);
+
+	raw_spin_lock(&core_irq_lock);
+	and_creg(IER, ~(1 << prio));
+	raw_spin_unlock(&core_irq_lock);
+}
+
+static void unmask_core_irq(struct irq_data *data)
+{
+	unsigned int prio = data->irq;
+
+	raw_spin_lock(&core_irq_lock);
+	or_creg(IER, 1 << prio);
+	raw_spin_unlock(&core_irq_lock);
+}
+
+static struct irq_chip core_chip = {
+	.name		= "core",
+	.irq_mask	= mask_core_irq,
+	.irq_unmask	= unmask_core_irq,
+};
+
+asmlinkage void c6x_do_IRQ(unsigned int prio, struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	irq_enter();
+
+	BUG_ON(prio < 4 || prio >= NR_PRIORITY_IRQS);
+
+	generic_handle_irq(prio);
+
+	irq_exit();
+
+	set_irq_regs(old_regs);
+}
+
+static struct irq_host *core_host;
+
+static int core_host_map(struct irq_host *h, unsigned int virq,
+			 irq_hw_number_t hw)
+{
+	if (hw < 4 || hw >= NR_PRIORITY_IRQS)
+		return -EINVAL;
+
+	irq_set_status_flags(virq, IRQ_LEVEL);
+	irq_set_chip_and_handler(virq, &core_chip, handle_level_irq);
+	return 0;
+}
+
+static struct irq_host_ops core_host_ops = {
+	.map = core_host_map,
+};
+
+void __init init_IRQ(void)
+{
+	struct device_node *np;
+
+	/* Mask all priority IRQs */
+	and_creg(IER, ~0xfff0);
+
+	np = of_find_compatible_node(NULL, NULL, "ti,c64x+core-pic");
+	if (np != NULL) {
+		/* create the core host */
+		core_host = irq_alloc_host(np, IRQ_HOST_MAP_PRIORITY, 0,
+					   &core_host_ops, 0);
+		if (core_host)
+			irq_set_default_host(core_host);
+		of_node_put(np);
+	}
+
+	printk(KERN_INFO "Core interrupt controller initialized\n");
+
+	/* now we're ready for other SoC controllers */
+	megamod_pic_init();
+
+	/* Clear all general IRQ flags */
+	set_creg(ICR, 0xfff0);
+}
+
+void ack_bad_irq(int irq)
+{
+	printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
+	irq_err_count++;
+}
+
+int arch_show_interrupts(struct seq_file *p, int prec)
+{
+	seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
+	return 0;
+}
+
+/*
+ * IRQ controller and virtual interrupts
+ */
+
+/* The main irq map itself is an array of NR_IRQ entries containing the
+ * associate host and irq number. An entry with a host of NULL is free.
+ * An entry can be allocated if it's free, the allocator always then sets
+ * hwirq first to the host's invalid irq number and then fills ops.
+ */
+struct irq_map_entry {
+	irq_hw_number_t	hwirq;
+	struct irq_host	*host;
+};
+
+static LIST_HEAD(irq_hosts);
+static DEFINE_RAW_SPINLOCK(irq_big_lock);
+static DEFINE_MUTEX(revmap_trees_mutex);
+static struct irq_map_entry irq_map[NR_IRQS];
+static unsigned int irq_virq_count = NR_IRQS;
+static struct irq_host *irq_default_host;
+
+irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
+{
+	return irq_map[d->irq].hwirq;
+}
+EXPORT_SYMBOL_GPL(irqd_to_hwirq);
+
+irq_hw_number_t virq_to_hw(unsigned int virq)
+{
+	return irq_map[virq].hwirq;
+}
+EXPORT_SYMBOL_GPL(virq_to_hw);
+
+bool virq_is_host(unsigned int virq, struct irq_host *host)
+{
+	return irq_map[virq].host == host;
+}
+EXPORT_SYMBOL_GPL(virq_is_host);
+
+static int default_irq_host_match(struct irq_host *h, struct device_node *np)
+{
+	return h->of_node != NULL && h->of_node == np;
+}
+
+struct irq_host *irq_alloc_host(struct device_node *of_node,
+				unsigned int revmap_type,
+				unsigned int revmap_arg,
+				struct irq_host_ops *ops,
+				irq_hw_number_t inval_irq)
+{
+	struct irq_host *host;
+	unsigned int size = sizeof(struct irq_host);
+	unsigned int i;
+	unsigned int *rmap;
+	unsigned long flags;
+
+	/* Allocate structure and revmap table if using linear mapping */
+	if (revmap_type == IRQ_HOST_MAP_LINEAR)
+		size += revmap_arg * sizeof(unsigned int);
+	host = kzalloc(size, GFP_KERNEL);
+	if (host == NULL)
+		return NULL;
+
+	/* Fill structure */
+	host->revmap_type = revmap_type;
+	host->inval_irq = inval_irq;
+	host->ops = ops;
+	host->of_node = of_node_get(of_node);
+
+	if (host->ops->match == NULL)
+		host->ops->match = default_irq_host_match;
+
+	raw_spin_lock_irqsave(&irq_big_lock, flags);
+
+	/* Check for the priority controller. */
+	if (revmap_type == IRQ_HOST_MAP_PRIORITY) {
+		if (irq_map[0].host != NULL) {
+			raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+			of_node_put(host->of_node);
+			kfree(host);
+			return NULL;
+		}
+		irq_map[0].host = host;
+	}
+
+	list_add(&host->link, &irq_hosts);
+	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+
+	/* Additional setups per revmap type */
+	switch (revmap_type) {
+	case IRQ_HOST_MAP_PRIORITY:
+		/* 0 is always the invalid number for priority */
+		host->inval_irq = 0;
+		/* setup us as the host for all priority interrupts */
+		for (i = 1; i < NR_PRIORITY_IRQS; i++) {
+			irq_map[i].hwirq = i;
+			smp_wmb();
+			irq_map[i].host = host;
+			smp_wmb();
+
+			ops->map(host, i, i);
+		}
+		break;
+	case IRQ_HOST_MAP_LINEAR:
+		rmap = (unsigned int *)(host + 1);
+		for (i = 0; i < revmap_arg; i++)
+			rmap[i] = NO_IRQ;
+		host->revmap_data.linear.size = revmap_arg;
+		smp_wmb();
+		host->revmap_data.linear.revmap = rmap;
+		break;
+	case IRQ_HOST_MAP_TREE:
+		INIT_RADIX_TREE(&host->revmap_data.tree, GFP_KERNEL);
+		break;
+	default:
+		break;
+	}
+
+	pr_debug("irq: Allocated host of type %d @0x%p\n", revmap_type, host);
+
+	return host;
+}
+
+struct irq_host *irq_find_host(struct device_node *node)
+{
+	struct irq_host *h, *found = NULL;
+	unsigned long flags;
+
+	/* We might want to match the legacy controller last since
+	 * it might potentially be set to match all interrupts in
+	 * the absence of a device node. This isn't a problem so far
+	 * yet though...
+	 */
+	raw_spin_lock_irqsave(&irq_big_lock, flags);
+	list_for_each_entry(h, &irq_hosts, link)
+		if (h->ops->match(h, node)) {
+			found = h;
+			break;
+		}
+	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+	return found;
+}
+EXPORT_SYMBOL_GPL(irq_find_host);
+
+void irq_set_default_host(struct irq_host *host)
+{
+	pr_debug("irq: Default host set to @0x%p\n", host);
+
+	irq_default_host = host;
+}
+
+void irq_set_virq_count(unsigned int count)
+{
+	pr_debug("irq: Trying to set virq count to %d\n", count);
+
+	BUG_ON(count < NR_PRIORITY_IRQS);
+	if (count < NR_IRQS)
+		irq_virq_count = count;
+}
+
+static int irq_setup_virq(struct irq_host *host, unsigned int virq,
+			    irq_hw_number_t hwirq)
+{
+	int res;
+
+	res = irq_alloc_desc_at(virq, 0);
+	if (res != virq) {
+		pr_debug("irq: -> allocating desc failed\n");
+		goto error;
+	}
+
+	/* map it */
+	smp_wmb();
+	irq_map[virq].hwirq = hwirq;
+	smp_mb();
+
+	if (host->ops->map(host, virq, hwirq)) {
+		pr_debug("irq: -> mapping failed, freeing\n");
+		goto errdesc;
+	}
+
+	irq_clear_status_flags(virq, IRQ_NOREQUEST);
+
+	return 0;
+
+errdesc:
+	irq_free_descs(virq, 1);
+error:
+	irq_free_virt(virq, 1);
+	return -1;
+}
+
+unsigned int irq_create_direct_mapping(struct irq_host *host)
+{
+	unsigned int virq;
+
+	if (host == NULL)
+		host = irq_default_host;
+
+	BUG_ON(host == NULL);
+	WARN_ON(host->revmap_type != IRQ_HOST_MAP_NOMAP);
+
+	virq = irq_alloc_virt(host, 1, 0);
+	if (virq == NO_IRQ) {
+		pr_debug("irq: create_direct virq allocation failed\n");
+		return NO_IRQ;
+	}
+
+	pr_debug("irq: create_direct obtained virq %d\n", virq);
+
+	if (irq_setup_virq(host, virq, virq))
+		return NO_IRQ;
+
+	return virq;
+}
+
+unsigned int irq_create_mapping(struct irq_host *host,
+				irq_hw_number_t hwirq)
+{
+	unsigned int virq, hint;
+
+	pr_debug("irq: irq_create_mapping(0x%p, 0x%lx)\n", host, hwirq);
+
+	/* Look for default host if nececssary */
+	if (host == NULL)
+		host = irq_default_host;
+	if (host == NULL) {
+		printk(KERN_WARNING "irq_create_mapping called for"
+		       " NULL host, hwirq=%lx\n", hwirq);
+		WARN_ON(1);
+		return NO_IRQ;
+	}
+	pr_debug("irq: -> using host @%p\n", host);
+
+	/* Check if mapping already exists */
+	virq = irq_find_mapping(host, hwirq);
+	if (virq != NO_IRQ) {
+		pr_debug("irq: -> existing mapping on virq %d\n", virq);
+		return virq;
+	}
+
+	/* Allocate a virtual interrupt number */
+	hint = hwirq % irq_virq_count;
+	virq = irq_alloc_virt(host, 1, hint);
+	if (virq == NO_IRQ) {
+		pr_debug("irq: -> virq allocation failed\n");
+		return NO_IRQ;
+	}
+
+	if (irq_setup_virq(host, virq, hwirq))
+		return NO_IRQ;
+
+	pr_debug("irq: irq %lu on host %s mapped to virtual irq %u\n",
+		hwirq, host->of_node ? host->of_node->full_name : "null", virq);
+
+	return virq;
+}
+EXPORT_SYMBOL_GPL(irq_create_mapping);
+
+unsigned int irq_create_of_mapping(struct device_node *controller,
+				   const u32 *intspec, unsigned int intsize)
+{
+	struct irq_host *host;
+	irq_hw_number_t hwirq;
+	unsigned int type = IRQ_TYPE_NONE;
+	unsigned int virq;
+
+	if (controller == NULL)
+		host = irq_default_host;
+	else
+		host = irq_find_host(controller);
+	if (host == NULL) {
+		printk(KERN_WARNING "irq: no irq host found for %s !\n",
+		       controller->full_name);
+		return NO_IRQ;
+	}
+
+	/* If host has no translation, then we assume interrupt line */
+	if (host->ops->xlate == NULL)
+		hwirq = intspec[0];
+	else {
+		if (host->ops->xlate(host, controller, intspec, intsize,
+				     &hwirq, &type))
+			return NO_IRQ;
+	}
+
+	/* Create mapping */
+	virq = irq_create_mapping(host, hwirq);
+	if (virq == NO_IRQ)
+		return virq;
+
+	/* Set type if specified and different than the current one */
+	if (type != IRQ_TYPE_NONE &&
+	    type != (irqd_get_trigger_type(irq_get_irq_data(virq))))
+		irq_set_irq_type(virq, type);
+	return virq;
+}
+EXPORT_SYMBOL_GPL(irq_create_of_mapping);
+
+void irq_dispose_mapping(unsigned int virq)
+{
+	struct irq_host *host;
+	irq_hw_number_t hwirq;
+
+	if (virq == NO_IRQ)
+		return;
+
+	/* Never unmap priority interrupts */
+	if (virq < NR_PRIORITY_IRQS)
+		return;
+
+	host = irq_map[virq].host;
+	if (WARN_ON(host == NULL))
+		return;
+
+	irq_set_status_flags(virq, IRQ_NOREQUEST);
+
+	/* remove chip and handler */
+	irq_set_chip_and_handler(virq, NULL, NULL);
+
+	/* Make sure it's completed */
+	synchronize_irq(virq);
+
+	/* Tell the PIC about it */
+	if (host->ops->unmap)
+		host->ops->unmap(host, virq);
+	smp_mb();
+
+	/* Clear reverse map */
+	hwirq = irq_map[virq].hwirq;
+	switch (host->revmap_type) {
+	case IRQ_HOST_MAP_LINEAR:
+		if (hwirq < host->revmap_data.linear.size)
+			host->revmap_data.linear.revmap[hwirq] = NO_IRQ;
+		break;
+	case IRQ_HOST_MAP_TREE:
+		mutex_lock(&revmap_trees_mutex);
+		radix_tree_delete(&host->revmap_data.tree, hwirq);
+		mutex_unlock(&revmap_trees_mutex);
+		break;
+	}
+
+	/* Destroy map */
+	smp_mb();
+	irq_map[virq].hwirq = host->inval_irq;
+
+	irq_free_descs(virq, 1);
+	/* Free it */
+	irq_free_virt(virq, 1);
+}
+EXPORT_SYMBOL_GPL(irq_dispose_mapping);
+
+unsigned int irq_find_mapping(struct irq_host *host,
+			      irq_hw_number_t hwirq)
+{
+	unsigned int i;
+	unsigned int hint = hwirq % irq_virq_count;
+
+	/* Look for default host if nececssary */
+	if (host == NULL)
+		host = irq_default_host;
+	if (host == NULL)
+		return NO_IRQ;
+
+	/* Slow path does a linear search of the map */
+	i = hint;
+	do  {
+		if (irq_map[i].host == host &&
+		    irq_map[i].hwirq == hwirq)
+			return i;
+		i++;
+		if (i >= irq_virq_count)
+			i = 4;
+	} while (i != hint);
+	return NO_IRQ;
+}
+EXPORT_SYMBOL_GPL(irq_find_mapping);
+
+unsigned int irq_radix_revmap_lookup(struct irq_host *host,
+				     irq_hw_number_t hwirq)
+{
+	struct irq_map_entry *ptr;
+	unsigned int virq;
+
+	if (WARN_ON_ONCE(host->revmap_type != IRQ_HOST_MAP_TREE))
+		return irq_find_mapping(host, hwirq);
+
+	/*
+	 * The ptr returned references the static global irq_map.
+	 * but freeing an irq can delete nodes along the path to
+	 * do the lookup via call_rcu.
+	 */
+	rcu_read_lock();
+	ptr = radix_tree_lookup(&host->revmap_data.tree, hwirq);
+	rcu_read_unlock();
+
+	/*
+	 * If found in radix tree, then fine.
+	 * Else fallback to linear lookup - this should not happen in practice
+	 * as it means that we failed to insert the node in the radix tree.
+	 */
+	if (ptr)
+		virq = ptr - irq_map;
+	else
+		virq = irq_find_mapping(host, hwirq);
+
+	return virq;
+}
+
+void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
+			     irq_hw_number_t hwirq)
+{
+	if (WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE))
+		return;
+
+	if (virq != NO_IRQ) {
+		mutex_lock(&revmap_trees_mutex);
+		radix_tree_insert(&host->revmap_data.tree, hwirq,
+				  &irq_map[virq]);
+		mutex_unlock(&revmap_trees_mutex);
+	}
+}
+
+unsigned int irq_linear_revmap(struct irq_host *host,
+			       irq_hw_number_t hwirq)
+{
+	unsigned int *revmap;
+
+	if (WARN_ON_ONCE(host->revmap_type != IRQ_HOST_MAP_LINEAR))
+		return irq_find_mapping(host, hwirq);
+
+	/* Check revmap bounds */
+	if (unlikely(hwirq >= host->revmap_data.linear.size))
+		return irq_find_mapping(host, hwirq);
+
+	/* Check if revmap was allocated */
+	revmap = host->revmap_data.linear.revmap;
+	if (unlikely(revmap == NULL))
+		return irq_find_mapping(host, hwirq);
+
+	/* Fill up revmap with slow path if no mapping found */
+	if (unlikely(revmap[hwirq] == NO_IRQ))
+		revmap[hwirq] = irq_find_mapping(host, hwirq);
+
+	return revmap[hwirq];
+}
+
+unsigned int irq_alloc_virt(struct irq_host *host,
+			    unsigned int count,
+			    unsigned int hint)
+{
+	unsigned long flags;
+	unsigned int i, j, found = NO_IRQ;
+
+	if (count == 0 || count > (irq_virq_count - NR_PRIORITY_IRQS))
+		return NO_IRQ;
+
+	raw_spin_lock_irqsave(&irq_big_lock, flags);
+
+	/* Use hint for 1 interrupt if any */
+	if (count == 1 && hint >= NR_PRIORITY_IRQS &&
+	    hint < irq_virq_count && irq_map[hint].host == NULL) {
+		found = hint;
+		goto hint_found;
+	}
+
+	/* Look for count consecutive numbers in the allocatable
+	 * (non-legacy) space
+	 */
+	for (i = NR_PRIORITY_IRQS, j = 0; i < irq_virq_count; i++) {
+		if (irq_map[i].host != NULL)
+			j = 0;
+		else
+			j++;
+
+		if (j == count) {
+			found = i - count + 1;
+			break;
+		}
+	}
+	if (found == NO_IRQ) {
+		raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+		return NO_IRQ;
+	}
+ hint_found:
+	for (i = found; i < (found + count); i++) {
+		irq_map[i].hwirq = host->inval_irq;
+		smp_wmb();
+		irq_map[i].host = host;
+	}
+	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+	return found;
+}
+
+void irq_free_virt(unsigned int virq, unsigned int count)
+{
+	unsigned long flags;
+	unsigned int i;
+
+	WARN_ON(virq < NR_PRIORITY_IRQS);
+	WARN_ON(count == 0 || (virq + count) > irq_virq_count);
+
+	if (virq < NR_PRIORITY_IRQS) {
+		if (virq + count < NR_PRIORITY_IRQS)
+			return;
+		count  -= NR_PRIORITY_IRQS - virq;
+		virq = NR_PRIORITY_IRQS;
+	}
+
+	if (count > irq_virq_count || virq > irq_virq_count - count) {
+		if (virq > irq_virq_count)
+			return;
+		count = irq_virq_count - virq;
+	}
+
+	raw_spin_lock_irqsave(&irq_big_lock, flags);
+	for (i = virq; i < (virq + count); i++) {
+		struct irq_host *host;
+
+		host = irq_map[i].host;
+		irq_map[i].hwirq = host->inval_irq;
+		smp_wmb();
+		irq_map[i].host = NULL;
+	}
+	raw_spin_unlock_irqrestore(&irq_big_lock, flags);
+}
+
+#ifdef CONFIG_VIRQ_DEBUG
+static int virq_debug_show(struct seq_file *m, void *private)
+{
+	unsigned long flags;
+	struct irq_desc *desc;
+	const char *p;
+	static const char none[] = "none";
+	void *data;
+	int i;
+
+	seq_printf(m, "%-5s  %-7s  %-15s  %-18s  %s\n", "virq", "hwirq",
+		      "chip name", "chip data", "host name");
+
+	for (i = 1; i < nr_irqs; i++) {
+		desc = irq_to_desc(i);
+		if (!desc)
+			continue;
+
+		raw_spin_lock_irqsave(&desc->lock, flags);
+
+		if (desc->action && desc->action->handler) {
+			struct irq_chip *chip;
+
+			seq_printf(m, "%5d  ", i);
+			seq_printf(m, "0x%05lx  ", irq_map[i].hwirq);
+
+			chip = irq_desc_get_chip(desc);
+			if (chip && chip->name)
+				p = chip->name;
+			else
+				p = none;
+			seq_printf(m, "%-15s  ", p);
+
+			data = irq_desc_get_chip_data(desc);
+			seq_printf(m, "0x%16p  ", data);
+
+			if (irq_map[i].host && irq_map[i].host->of_node)
+				p = irq_map[i].host->of_node->full_name;
+			else
+				p = none;
+			seq_printf(m, "%s\n", p);
+		}
+
+		raw_spin_unlock_irqrestore(&desc->lock, flags);
+	}
+
+	return 0;
+}
+
+static int virq_debug_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, virq_debug_show, inode->i_private);
+}
+
+static const struct file_operations virq_debug_fops = {
+	.open = virq_debug_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int __init irq_debugfs_init(void)
+{
+	if (debugfs_create_file("virq_mapping", S_IRUGO, powerpc_debugfs_root,
+				 NULL, &virq_debug_fops) == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+device_initcall(irq_debugfs_init);
+#endif /* CONFIG_VIRQ_DEBUG */

arch/c6x/platforms/megamod-pic.c

+/*
+ *  Support for C64x+ Megamodule Interrupt Controller
+ *
+ *  Copyright (C) 2010, 2011 Texas Instruments Incorporated
+ *  Contributed by: Mark Salter <msalter@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <asm/soc.h>
+#include <asm/megamod-pic.h>
+
+#define NR_COMBINERS	4
+#define NR_MUX_OUTPUTS  12
+
+#define IRQ_UNMAPPED 0xffff
+
+/*
+ * Megamodule Interrupt Controller register layout
+ */
+struct megamod_regs {
+	u32	evtflag[8];
+	u32	evtset[8];
+	u32	evtclr[8];
+	u32	reserved0[8];
+	u32	evtmask[8];
+	u32	mevtflag[8];
+	u32	expmask[8];
+	u32	mexpflag[8];
+	u32	intmux_unused;
+	u32	intmux[7];
+	u32	reserved1[8];
+	u32	aegmux[2];
+	u32	reserved2[14];
+	u32	intxstat;
+	u32	intxclr;
+	u32	intdmask;
+	u32	reserved3[13];
+	u32	evtasrt;
+};
+
+struct megamod_pic {
+	struct irq_host	*irqhost;
+	struct megamod_regs __iomem *regs;
+	raw_spinlock_t lock;
+
+	/* hw mux mapping */
+	unsigned int output_to_irq[NR_MUX_OUTPUTS];
+};
+
+static struct megamod_pic *mm_pic;
+
+struct megamod_cascade_data {
+	struct megamod_pic *pic;
+	int index;
+};
+
+static struct megamod_cascade_data cascade_data[NR_COMBINERS];
+
+static void mask_megamod(struct irq_data *data)
+{
+	struct megamod_pic *pic = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t src = irqd_to_hwirq(data);
+	u32 __iomem *evtmask = &pic->regs->evtmask[src / 32];
+
+	raw_spin_lock(&pic->lock);
+	soc_writel(soc_readl(evtmask) | (1 << (src & 31)), evtmask);
+	raw_spin_unlock(&pic->lock);
+}
+
+static void unmask_megamod(struct irq_data *data)
+{
+	struct megamod_pic *pic = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t src = irqd_to_hwirq(data);
+	u32 __iomem *evtmask = &pic->regs->evtmask[src / 32];
+
+	raw_spin_lock(&pic->lock);
+	soc_writel(soc_readl(evtmask) & ~(1 << (src & 31)), evtmask);
+	raw_spin_unlock(&pic->lock);
+}
+
+static struct irq_chip megamod_chip = {
+	.name		= "megamod",
+	.irq_mask	= mask_megamod,
+	.irq_unmask	= unmask_megamod,
+};
+
+static void megamod_irq_cascade(unsigned int irq, struct irq_desc *desc)
+{
+	struct megamod_cascade_data *cascade;
+	struct megamod_pic *pic;
+	u32 events;
+	int n, idx;
+
+	cascade = irq_desc_get_handler_data(desc);
+
+	pic = cascade->pic;
+	idx = cascade->index;
+
+	while ((events = soc_readl(&pic->regs->mevtflag[idx])) != 0) {
+		n = __ffs(events);
+
+		irq = irq_linear_revmap(pic->irqhost, idx * 32 + n);
+
+		soc_writel(1 << n, &pic->regs->evtclr[idx]);
+
+		generic_handle_irq(irq);
+	}
+}
+
+static int megamod_map(struct irq_host *h, unsigned int virq,
+		       irq_hw_number_t hw)
+{
+	struct megamod_pic *pic = h->host_data;
+	int i;
+
+	/* We shouldn't see a hwirq which is muxed to core controller */
+	for (i = 0; i < NR_MUX_OUTPUTS; i++)
+		if (pic->output_to_irq[i] == hw)
+			return -1;
+
+	irq_set_chip_data(virq, pic);
+	irq_set_chip_and_handler(virq, &megamod_chip, handle_level_irq);
+
+	/* Set default irq type */
+	irq_set_irq_type(virq, IRQ_TYPE_NONE);
+
+	return 0;
+}
+
+static int megamod_xlate(struct irq_host *h, struct device_node *ct,
+			 const u32 *intspec, unsigned int intsize,
+			 irq_hw_number_t *out_hwirq, unsigned int *out_type)
+
+{
+	/* megamod intspecs must have 1 cell */
+	BUG_ON(intsize != 1);
+	*out_hwirq = intspec[0];
+	*out_type = IRQ_TYPE_NONE;
+	return 0;
+}
+
+static struct irq_host_ops megamod_host_ops = {
+	.map	= megamod_map,
+	.xlate	= megamod_xlate,
+};
+
+static void __init set_megamod_mux(struct megamod_pic *pic, int src, int output)
+{
+	int index, offset;
+	u32 val;
+
+	if (src < 0 || src >= (NR_COMBINERS * 32)) {
+		pic->output_to_irq[output] = IRQ_UNMAPPED;
+		return;
+	}
+
+	/* four mappings per mux register */
+	index = output / 4;
+	offset = (output & 3) * 8;
+
+	val = soc_readl(&pic->regs->intmux[index]);
+	val &= ~(0xff << offset);
+	val |= src << offset;
+	soc_writel(val, &pic->regs->intmux[index]);
+}
+
+/*
+ * Parse the MUX mapping, if one exists.
+ *
+ * The MUX map is an array of up to 12 cells; one for each usable core priority
+ * interrupt. The value of a given cell is the megamodule interrupt source
+ * which is to me MUXed to the output corresponding to the cell position
+ * withing the array. The first cell in the array corresponds to priority
+ * 4 and the last (12th) cell corresponds to priority 15. The allowed
+ * values are 4 - ((NR_COMBINERS * 32) - 1). Note that the combined interrupt
+ * sources (0 - 3) are not allowed to be mapped through this property. They
+ * are handled through the "interrupts" property. This allows us to use a
+ * value of zero as a "do not map" placeholder.
+ */
+static void __init parse_priority_map(struct megamod_pic *pic,
+				      int *mapping, int size)
+{
+	struct device_node *np = pic->irqhost->of_node;
+	const __be32 *map;
+	int i, maplen;
+	u32 val;
+
+	map = of_get_property(np, "ti,c64x+megamod-pic-mux", &maplen);
+	if (map) {
+		maplen /= 4;
+		if (maplen > size)
+			maplen = size;
+
+		for (i = 0; i < maplen; i++) {
+			val = be32_to_cpup(map);
+			if (val && val >= 4)
+				mapping[i] = val;
+			++map;
+		}
+	}
+}
+
+static struct megamod_pic * __init init_megamod_pic(struct device_node *np)
+{
+	struct megamod_pic *pic;
+	int i, irq;
+	int mapping[NR_MUX_OUTPUTS];
+
+	pr_info("Initializing C64x+ Megamodule PIC\n");
+
+	pic = kzalloc(sizeof(struct megamod_pic), GFP_KERNEL);
+	if (!pic) {
+		pr_err("%s: Could not alloc PIC structure.\n", np->full_name);
+		return NULL;
+	}
+
+	pic->irqhost = irq_alloc_host(np, IRQ_HOST_MAP_LINEAR,
+				      NR_COMBINERS * 32, &megamod_host_ops,
+				      IRQ_UNMAPPED);
+	if (!pic->irqhost) {
+		pr_err("%s: Could not alloc host.\n", np->full_name);
+		goto error_free;
+	}
+
+	pic->irqhost->host_data = pic;
+
+	raw_spin_lock_init(&pic->lock);
+
+	pic->regs = of_iomap(np, 0);
+	if (!pic->regs) {
+		pr_err("%s: Could not map registers.\n", np->full_name);
+		goto error_free;
+	}
+
+	/* Initialize MUX map */
+	for (i = 0; i < ARRAY_SIZE(mapping); i++)
+		mapping[i] = IRQ_UNMAPPED;
+
+	parse_priority_map(pic, mapping, ARRAY_SIZE(mapping));
+
+	/*
+	 * We can have up to 12 interrupts cascading to the core controller.
+	 * These cascades can be from the combined interrupt sources or for
+	 * individual interrupt sources. The "interrupts" property only
+	 * deals with the cascaded combined interrupts. The individual
+	 * interrupts muxed to the core controller use the core controller
+	 * as their interrupt parent.
+	 */
+	for (i = 0; i < NR_COMBINERS; i++) {
+
+		irq = irq_of_parse_and_map(np, i);
+		if (irq == NO_IRQ)
+			continue;
+
+		/*
+		 * We count on the core priority interrupts (4 - 15) being
+		 * direct mapped. Check that device tree provided something
+		 * in that range.
+		 */
+		if (irq < 4 || irq >= NR_PRIORITY_IRQS) {
+			pr_err("%s: combiner-%d virq %d out of range!\n",
+				 np->full_name, i, irq);
+			continue;
+		}
+
+		/* record the mapping */
+		mapping[irq - 4] = i;
+
+		pr_debug("%s: combiner-%d cascading to virq %d\n",
+			 np->full_name, i, irq);
+
+		cascade_data[i].pic = pic;
+		cascade_data[i].index = i;
+
+		/* mask and clear all events in combiner */
+		soc_writel(~0, &pic->regs->evtmask[i]);
+		soc_writel(~0, &pic->regs->evtclr[i]);
+
+		irq_set_handler_data(irq, &cascade_data[i]);
+		irq_set_chained_handler(irq, megamod_irq_cascade);
+	}
+
+	/* Finally, set up the MUX registers */
+	for (i = 0; i < NR_MUX_OUTPUTS; i++) {
+		if (mapping[i] != IRQ_UNMAPPED) {
+			pr_debug("%s: setting mux %d to priority %d\n",
+				 np->full_name, mapping[i], i + 4);
+			set_megamod_mux(pic, mapping[i], i);
+		}
+	}
+
+	return pic;
+
+error_free:
+	kfree(pic);
+
+	return NULL;
+}
+
+/*
+ * Return next active event after ACK'ing it.
+ * Return -1 if no events active.
+ */
+static int get_exception(void)
+{
+	int i, bit;
+	u32 mask;
+
+	for (i = 0; i < NR_COMBINERS; i++) {
+		mask = soc_readl(&mm_pic->regs->mexpflag[i]);
+		if (mask) {
+			bit = __ffs(mask);
+			soc_writel(1 << bit, &mm_pic->regs->evtclr[i]);
+			return (i * 32) + bit;
+		}
+	}
+	return -1;
+}
+
+static void assert_event(unsigned int val)
+{
+	soc_writel(val, &mm_pic->regs->evtasrt);
+}
+
+void __init megamod_pic_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "ti,c64x+megamod-pic");
+	if (!np)
+		return;
+
+	mm_pic = init_megamod_pic(np);
+	of_node_put(np);
+
+	soc_ops.get_exception = get_exception;
+	soc_ops.assert_event = assert_event;
+
+	return;
+}