[POWERPC] Add arch/powerpc driver for UIC, PPC4xx interrupt controller

This patch adds a driver to arch/powerpc/sysdev for the UIC, the
on-chip interrupt controller from IBM/AMCC 4xx chips. It uses the new
irq host mapping infrastructure.

Signed-off-by: David Gibson <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/sysdev/Makefile

···
 ifeq ($(CONFIG_PPC_MERGE),y)
 obj-$(CONFIG_PPC_I8259)		+= i8259.o
 obj-$(CONFIG_PPC_83xx)		+= ipic.o
+obj-$(CONFIG_4xx)		+= uic.o
 endif
 
 # Temporary hack until we have migrated to asm-powerpc

arch/powerpc/sysdev/uic.c

···
+/*
+ * arch/powerpc/sysdev/uic.c
+ *
+ * IBM PowerPC 4xx Universal Interrupt Controller
+ *
+ * Copyright 2007 David Gibson <[e-mail]>, IBM Corporation.
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/sysdev.h>
+#include <linux/device.h>
+#include <linux/bootmem.h>
+#include <linux/spinlock.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <asm/irq.h>
+#include <asm/io.h>
+#include <asm/prom.h>
+#include <asm/dcr.h>
+
+#define NR_UIC_INTS	32
+
+#define UIC_SR		0x0
+#define UIC_ER		0x2
+#define UIC_CR		0x3
+#define UIC_PR		0x4
+#define UIC_TR		0x5
+#define UIC_MSR		0x6
+#define UIC_VR		0x7
+#define UIC_VCR		0x8
+
+#define uic_irq_to_hw(virq)	(irq_map[virq].hwirq)
+
+struct uic *primary_uic;
+
+struct uic {
+	int index;
+	int dcrbase;
+
+	spinlock_t lock;
+
+	/* The remapper for this UIC */
+	struct irq_host	*irqhost;
+
+	/* For secondary UICs, the cascade interrupt's irqaction */
+	struct irqaction cascade;
+
+	/* The device node of the interrupt controller */
+	struct device_node *of_node;
+};
+
+static void uic_unmask_irq(unsigned int virq)
+{
+	struct uic *uic = get_irq_chip_data(virq);
+	unsigned int src = uic_irq_to_hw(virq);
+	unsigned long flags;
+	u32 er;
+
+	spin_lock_irqsave(&uic->lock, flags);
+	er = mfdcr(uic->dcrbase + UIC_ER);
+	er |= 1 << (31 - src);
+	mtdcr(uic->dcrbase + UIC_ER, er);
+	spin_unlock_irqrestore(&uic->lock, flags);
+}
+
+static void uic_mask_irq(unsigned int virq)
+{
+	struct uic *uic = get_irq_chip_data(virq);
+	unsigned int src = uic_irq_to_hw(virq);
+	unsigned long flags;
+	u32 er;
+
+	spin_lock_irqsave(&uic->lock, flags);
+	er = mfdcr(uic->dcrbase + UIC_ER);
+	er &= ~(1 << (31 - src));
+	mtdcr(uic->dcrbase + UIC_ER, er);
+	spin_unlock_irqrestore(&uic->lock, flags);
+}
+
+static void uic_ack_irq(unsigned int virq)
+{
+	struct uic *uic = get_irq_chip_data(virq);
+	unsigned int src = uic_irq_to_hw(virq);
+	unsigned long flags;
+
+	spin_lock_irqsave(&uic->lock, flags);
+	mtdcr(uic->dcrbase + UIC_SR, 1 << (31-src));
+	spin_unlock_irqrestore(&uic->lock, flags);
+}
+
+static int uic_set_irq_type(unsigned int virq, unsigned int flow_type)
+{
+	struct uic *uic = get_irq_chip_data(virq);
+	unsigned int src = uic_irq_to_hw(virq);
+	struct irq_desc *desc = get_irq_desc(virq);
+	unsigned long flags;
+	int trigger, polarity;
+	u32 tr, pr, mask;
+
+	switch (flow_type & IRQ_TYPE_SENSE_MASK) {
+	case IRQ_TYPE_NONE:
+		uic_mask_irq(virq);
+		return 0;
+
+	case IRQ_TYPE_EDGE_RISING:
+		trigger = 1; polarity = 1;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		trigger = 1; polarity = 0;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		trigger = 0; polarity = 1;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		trigger = 0; polarity = 0;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	mask = ~(1 << (31 - src));
+
+	spin_lock_irqsave(&uic->lock, flags);
+	tr = mfdcr(uic->dcrbase + UIC_TR);
+	pr = mfdcr(uic->dcrbase + UIC_PR);
+	tr = (tr & mask) | (trigger << (31-src));
+	pr = (pr & mask) | (polarity << (31-src));
+
+	mtdcr(uic->dcrbase + UIC_PR, pr);
+	mtdcr(uic->dcrbase + UIC_TR, tr);
+
+	desc->status &= ~(IRQ_TYPE_SENSE_MASK | IRQ_LEVEL);
+	desc->status |= flow_type & IRQ_TYPE_SENSE_MASK;
+	if (trigger)
+		desc->status |= IRQ_LEVEL;
+
+	spin_unlock_irqrestore(&uic->lock, flags);
+
+	return 0;
+}
+
+static struct irq_chip uic_irq_chip = {
+	.typename	= " UIC  ",
+	.unmask		= uic_unmask_irq,
+	.mask		= uic_mask_irq,
+/* 	.mask_ack	= uic_mask_irq_and_ack, */
+	.ack		= uic_ack_irq,
+	.set_type	= uic_set_irq_type,
+};
+
+static int uic_host_match(struct irq_host *h, struct device_node *node)
+{
+	struct uic *uic = h->host_data;
+	return uic->of_node == node;
+}
+
+static int uic_host_map(struct irq_host *h, unsigned int virq,
+			irq_hw_number_t hw)
+{
+	struct uic *uic = h->host_data;
+
+	set_irq_chip_data(virq, uic);
+	/* Despite the name, handle_level_irq() works for both level
+	 * and edge irqs on UIC.  FIXME: check this is correct */
+	set_irq_chip_and_handler(virq, &uic_irq_chip, handle_level_irq);
+
+	/* Set default irq type */
+	set_irq_type(virq, IRQ_TYPE_NONE);
+
+	return 0;
+}
+
+static int uic_host_xlate(struct irq_host *h, struct device_node *ct,
+			  u32 *intspec, unsigned int intsize,
+			  irq_hw_number_t *out_hwirq, unsigned int *out_type)
+
+{
+	/* UIC intspecs must have 2 cells */
+	BUG_ON(intsize != 2);
+	*out_hwirq = intspec[0];
+	*out_type = intspec[1];
+	return 0;
+}
+
+static struct irq_host_ops uic_host_ops = {
+	.match	= uic_host_match,
+	.map	= uic_host_map,
+	.xlate	= uic_host_xlate,
+};
+
+irqreturn_t uic_cascade(int virq, void *data)
+{
+	struct uic *uic = data;
+	u32 msr;
+	int src;
+	int subvirq;
+
+	msr = mfdcr(uic->dcrbase + UIC_MSR);
+	src = 32 - ffs(msr);
+
+	subvirq = irq_linear_revmap(uic->irqhost, src);
+	generic_handle_irq(subvirq);
+
+	return IRQ_HANDLED;
+}
+
+static struct uic * __init uic_init_one(struct device_node *node)
+{
+	struct uic *uic;
+	const u32 *indexp, *dcrreg;
+	int len;
+
+	BUG_ON(! device_is_compatible(node, "ibm,uic"));
+
+	uic = alloc_bootmem(sizeof(*uic));
+	if (! uic)
+		return NULL; /* FIXME: panic? */
+
+	memset(uic, 0, sizeof(*uic));
+	spin_lock_init(&uic->lock);
+	uic->of_node = of_node_get(node);
+	indexp = get_property(node, "cell-index", &len);
+	if (!indexp || (len != sizeof(u32))) {
+		printk(KERN_ERR "uic: Device node %s has missing or invalid "
+		       "cell-index property\n", node->full_name);
+		return NULL;
+	}
+	uic->index = *indexp;
+
+	dcrreg = get_property(node, "dcr-reg", &len);
+	if (!dcrreg || (len != 2*sizeof(u32))) {
+		printk(KERN_ERR "uic: Device node %s has missing or invalid "
+		       "dcr-reg property\n", node->full_name);
+		return NULL;
+	}
+	uic->dcrbase = *dcrreg;
+
+	uic->irqhost = irq_alloc_host(IRQ_HOST_MAP_LINEAR, NR_UIC_INTS,
+				      &uic_host_ops, -1);
+	if (! uic->irqhost) {
+		of_node_put(node);
+		return NULL; /* FIXME: panic? */
+	}
+
+	uic->irqhost->host_data = uic;
+
+	/* Start with all interrupts disabled, level and non-critical */
+	mtdcr(uic->dcrbase + UIC_ER, 0);
+	mtdcr(uic->dcrbase + UIC_CR, 0);
+	mtdcr(uic->dcrbase + UIC_TR, 0);
+	/* Clear any pending interrupts, in case the firmware left some */
+	mtdcr(uic->dcrbase + UIC_SR, 0xffffffff);
+
+	printk ("UIC%d (%d IRQ sources) at DCR 0x%x\n", uic->index,
+		NR_UIC_INTS, uic->dcrbase);
+
+	return uic;
+}
+
+void __init uic_init_tree(void)
+{
+	struct device_node *np;
+	struct uic *uic;
+	const u32 *interrupts;
+
+	/* First locate and initialize the top-level UIC */
+
+	np = of_find_compatible_node(NULL, NULL, "ibm,uic");
+	while (np) {
+		interrupts = get_property(np, "interrupts", NULL);
+		if (! interrupts)
+			break;
+
+		np = of_find_compatible_node(np, NULL, "ibm,uic");
+	}
+
+	BUG_ON(!np); /* uic_init_tree() assumes there's a UIC as the
+		      * top-level interrupt controller */
+	primary_uic = uic_init_one(np);
+	if (! primary_uic)
+		panic("Unable to initialize primary UIC %s\n", np->full_name);
+
+	irq_set_default_host(primary_uic->irqhost);
+	of_node_put(np);
+
+	/* The scan again for cascaded UICs */
+	np = of_find_compatible_node(NULL, NULL, "ibm,uic");
+	while (np) {
+		interrupts = get_property(np, "interrupts", NULL);
+		if (interrupts) {
+			/* Secondary UIC */
+			int cascade_virq;
+			int ret;
+
+			uic = uic_init_one(np);
+			if (! uic)
+				panic("Unable to initialize a secondary UIC %s\n",
+				      np->full_name);
+
+			cascade_virq = irq_of_parse_and_map(np, 0);
+
+			uic->cascade.handler = uic_cascade;
+			uic->cascade.name = "UIC cascade";
+			uic->cascade.dev_id = uic;
+
+			ret = setup_irq(cascade_virq, &uic->cascade);
+			if (ret)
+				printk(KERN_ERR "Failed to setup_irq(%d) for "
+				       "UIC%d cascade\n", cascade_virq,
+				       uic->index);
+
+			/* FIXME: setup critical cascade?? */
+		}
+
+		np = of_find_compatible_node(np, NULL, "ibm,uic");
+	}
+}
+
+/* Return an interrupt vector or NO_IRQ if no interrupt is pending. */
+unsigned int uic_get_irq(void)
+{
+	u32 msr;
+	int src;
+
+	BUG_ON(! primary_uic);
+
+	msr = mfdcr(primary_uic->dcrbase + UIC_MSR);
+	src = 32 - ffs(msr);
+
+	return irq_linear_revmap(primary_uic->irqhost, src);
+}

include/asm-powerpc/uic.h

···
+/*
+ * include/asm-powerpc/uic.h
+ *
+ * IBM PPC4xx UIC external definitions and structure.
+ *
+ * Maintainer: David Gibson <[e-mail]>
+ * Copyright 2007 IBM Corporation.
+ *
+ * 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.
+ */
+#ifndef _ASM_POWERPC_UIC_H
+#define _ASM_POWERPC_UIC_H
+
+#ifdef __KERNEL__
+
+extern void __init uic_init_tree(void);
+extern unsigned int uic_get_irq(void);
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_POWERPC_UIC_H */