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: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arnd 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/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/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;
+}