drivers/irqchip/irq-vic.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *  linux/arch/arm/common/vic.c
  *
  *  Copyright (C) 1999 - 2003 ARM Limited
  *  Copyright (C) 2000 Deep Blue Solutions Ltd
  */

 #include <linux/export.h>
 #include <linux/init.h>
 #include <linux/list.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/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/syscore_ops.h>
 #include <linux/device.h>
 #include <linux/amba/bus.h>
 #include <linux/irqchip/arm-vic.h>

 #include <asm/exception.h>
 #include <asm/irq.h>

 #define VIC_IRQ_STATUS			0x00
 #define VIC_FIQ_STATUS			0x04
 #define VIC_RAW_STATUS			0x08
 #define VIC_INT_SELECT			0x0c	/* 1 = FIQ, 0 = IRQ */
 #define VIC_INT_ENABLE			0x10	/* 1 = enable, 0 = disable */
 #define VIC_INT_ENABLE_CLEAR		0x14
 #define VIC_INT_SOFT			0x18
 #define VIC_INT_SOFT_CLEAR		0x1c
 #define VIC_PROTECT			0x20
 #define VIC_PL190_VECT_ADDR		0x30	/* PL190 only */
 #define VIC_PL190_DEF_VECT_ADDR		0x34	/* PL190 only */

 #define VIC_VECT_ADDR0			0x100	/* 0 to 15 (0..31 PL192) */
 #define VIC_VECT_CNTL0			0x200	/* 0 to 15 (0..31 PL192) */
 #define VIC_ITCR			0x300	/* VIC test control register */

 #define VIC_VECT_CNTL_ENABLE		(1 << 5)

 #define VIC_PL192_VECT_ADDR		0xF00

 /**
  * struct vic_device - VIC PM device
  * @parent_irq: The parent IRQ number of the VIC if cascaded, or 0.
  * @irq: The IRQ number for the base of the VIC.
  * @base: The register base for the VIC.
  * @valid_sources: A bitmask of valid interrupts
  * @resume_sources: A bitmask of interrupts for resume.
  * @resume_irqs: The IRQs enabled for resume.
  * @int_select: Save for VIC_INT_SELECT.
  * @int_enable: Save for VIC_INT_ENABLE.
  * @soft_int: Save for VIC_INT_SOFT.
  * @protect: Save for VIC_PROTECT.
  * @domain: The IRQ domain for the VIC.
  */
 struct vic_device {
 	void __iomem	*base;
 	int		irq;
 	u32		valid_sources;
 	u32		resume_sources;
 	u32		resume_irqs;
 	u32		int_select;
 	u32		int_enable;
 	u32		soft_int;
 	u32		protect;
 	struct irq_domain *domain;
 };

 /* we cannot allocate memory when VICs are initially registered */
 static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];

 static int vic_id;

 static void vic_handle_irq(struct pt_regs *regs);

 /**
  * vic_init2 - common initialisation code
  * @base: Base of the VIC.
  *
  * Common initialisation code for registration
  * and resume.
 */
 static void vic_init2(void __iomem *base)
 {
 	int i;

 	for (i = 0; i < 16; i++) {
 		void __iomem *reg = base + VIC_VECT_CNTL0 + (i * 4);
 		writel(VIC_VECT_CNTL_ENABLE | i, reg);
 	}

 	writel(32, base + VIC_PL190_DEF_VECT_ADDR);
 }

 #ifdef CONFIG_PM
 static void resume_one_vic(struct vic_device *vic)
 {
 	void __iomem *base = vic->base;

 	printk(KERN_DEBUG "%s: resuming vic at %p\n", __func__, base);

 	/* re-initialise static settings */
 	vic_init2(base);

 	writel(vic->int_select, base + VIC_INT_SELECT);
 	writel(vic->protect, base + VIC_PROTECT);

 	/* set the enabled ints and then clear the non-enabled */
 	writel(vic->int_enable, base + VIC_INT_ENABLE);
 	writel(~vic->int_enable, base + VIC_INT_ENABLE_CLEAR);

 	/* and the same for the soft-int register */

 	writel(vic->soft_int, base + VIC_INT_SOFT);
 	writel(~vic->soft_int, base + VIC_INT_SOFT_CLEAR);
 }

 static void vic_resume(void)
 {
 	int id;

 	for (id = vic_id - 1; id >= 0; id--)
 		resume_one_vic(vic_devices + id);
 }

 static void suspend_one_vic(struct vic_device *vic)
 {
 	void __iomem *base = vic->base;

 	printk(KERN_DEBUG "%s: suspending vic at %p\n", __func__, base);

 	vic->int_select = readl(base + VIC_INT_SELECT);
 	vic->int_enable = readl(base + VIC_INT_ENABLE);
 	vic->soft_int = readl(base + VIC_INT_SOFT);
 	vic->protect = readl(base + VIC_PROTECT);

 	/* set the interrupts (if any) that are used for
 	 * resuming the system */

 	writel(vic->resume_irqs, base + VIC_INT_ENABLE);
 	writel(~vic->resume_irqs, base + VIC_INT_ENABLE_CLEAR);
 }

 static int vic_suspend(void)
 {
 	int id;

 	for (id = 0; id < vic_id; id++)
 		suspend_one_vic(vic_devices + id);

 	return 0;
 }

 static struct syscore_ops vic_syscore_ops = {
 	.suspend	= vic_suspend,
 	.resume		= vic_resume,
 };

 /**
  * vic_pm_init - initicall to register VIC pm
  *
  * This is called via late_initcall() to register
  * the resources for the VICs due to the early
  * nature of the VIC's registration.
 */
 static int __init vic_pm_init(void)
 {
 	if (vic_id > 0)
 		register_syscore_ops(&vic_syscore_ops);

 	return 0;
 }
 late_initcall(vic_pm_init);
 #endif /* CONFIG_PM */

 static struct irq_chip vic_chip;

 static int vic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			     irq_hw_number_t hwirq)
 {
 	struct vic_device *v = d->host_data;

 	/* Skip invalid IRQs, only register handlers for the real ones */
 	if (!(v->valid_sources & (1 << hwirq)))
 		return -EPERM;
 	irq_set_chip_and_handler(irq, &vic_chip, handle_level_irq);
 	irq_set_chip_data(irq, v->base);
 	irq_set_probe(irq);
 	return 0;
 }

 /*
  * Handle each interrupt in a single VIC.  Returns non-zero if we've
  * handled at least one interrupt.  This reads the status register
  * before handling each interrupt, which is necessary given that
  * handle_IRQ may briefly re-enable interrupts for soft IRQ handling.
  */
 static int handle_one_vic(struct vic_device *vic, struct pt_regs *regs)
 {
 	u32 stat, irq;
 	int handled = 0;

 	while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) {
 		irq = ffs(stat) - 1;
 		handle_domain_irq(vic->domain, irq, regs);
 		handled = 1;
 	}

 	return handled;
 }

 static void vic_handle_irq_cascaded(struct irq_desc *desc)
 {
 	u32 stat, hwirq;
 	struct irq_chip *host_chip = irq_desc_get_chip(desc);
 	struct vic_device *vic = irq_desc_get_handler_data(desc);

 	chained_irq_enter(host_chip, desc);

 	while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) {
 		hwirq = ffs(stat) - 1;
 		generic_handle_irq(irq_find_mapping(vic->domain, hwirq));
 	}

 	chained_irq_exit(host_chip, desc);
 }

 /*
  * Keep iterating over all registered VIC's until there are no pending
  * interrupts.
  */
 static void __exception_irq_entry vic_handle_irq(struct pt_regs *regs)
 {
 	int i, handled;

 	do {
 		for (i = 0, handled = 0; i < vic_id; ++i)
 			handled |= handle_one_vic(&vic_devices[i], regs);
 	} while (handled);
 }

 static const struct irq_domain_ops vic_irqdomain_ops = {
 	.map = vic_irqdomain_map,
 	.xlate = irq_domain_xlate_onetwocell,
 };

 /**
  * vic_register() - Register a VIC.
  * @base: The base address of the VIC.
  * @parent_irq: The parent IRQ if cascaded, else 0.
  * @irq: The base IRQ for the VIC.
  * @valid_sources: bitmask of valid interrupts
  * @resume_sources: bitmask of interrupts allowed for resume sources.
  * @node: The device tree node associated with the VIC.
  *
  * Register the VIC with the system device tree so that it can be notified
  * of suspend and resume requests and ensure that the correct actions are
  * taken to re-instate the settings on resume.
  *
  * This also configures the IRQ domain for the VIC.
  */
 static void __init vic_register(void __iomem *base, unsigned int parent_irq,
 				unsigned int irq,
 				u32 valid_sources, u32 resume_sources,
 				struct device_node *node)
 {
 	struct vic_device *v;
 	int i;

 	if (vic_id >= ARRAY_SIZE(vic_devices)) {
 		printk(KERN_ERR "%s: too few VICs, increase CONFIG_ARM_VIC_NR\n", __func__);
 		return;
 	}

 	v = &vic_devices[vic_id];
 	v->base = base;
 	v->valid_sources = valid_sources;
 	v->resume_sources = resume_sources;
 	set_handle_irq(vic_handle_irq);
 	vic_id++;

 	if (parent_irq) {
 		irq_set_chained_handler_and_data(parent_irq,
 						 vic_handle_irq_cascaded, v);
 	}

 	v->domain = irq_domain_add_simple(node, fls(valid_sources), irq,
 					  &vic_irqdomain_ops, v);
 	/* create an IRQ mapping for each valid IRQ */
 	for (i = 0; i < fls(valid_sources); i++)
 		if (valid_sources & (1 << i))
 			irq_create_mapping(v->domain, i);
 	/* If no base IRQ was passed, figure out our allocated base */
 	if (irq)
 		v->irq = irq;
 	else
 		v->irq = irq_find_mapping(v->domain, 0);
 }

 static void vic_ack_irq(struct irq_data *d)
 {
 	void __iomem *base = irq_data_get_irq_chip_data(d);
 	unsigned int irq = d->hwirq;
 	writel(1 << irq, base + VIC_INT_ENABLE_CLEAR);
 	/* moreover, clear the soft-triggered, in case it was the reason */
 	writel(1 << irq, base + VIC_INT_SOFT_CLEAR);
 }

 static void vic_mask_irq(struct irq_data *d)
 {
 	void __iomem *base = irq_data_get_irq_chip_data(d);
 	unsigned int irq = d->hwirq;
 	writel(1 << irq, base + VIC_INT_ENABLE_CLEAR);
 }

 static void vic_unmask_irq(struct irq_data *d)
 {
 	void __iomem *base = irq_data_get_irq_chip_data(d);
 	unsigned int irq = d->hwirq;
 	writel(1 << irq, base + VIC_INT_ENABLE);
 }

 #if defined(CONFIG_PM)
 static struct vic_device *vic_from_irq(unsigned int irq)
 {
         struct vic_device *v = vic_devices;
 	unsigned int base_irq = irq & ~31;
 	int id;

 	for (id = 0; id < vic_id; id++, v++) {
 		if (v->irq == base_irq)
 			return v;
 	}

 	return NULL;
 }

 static int vic_set_wake(struct irq_data *d, unsigned int on)
 {
 	struct vic_device *v = vic_from_irq(d->irq);
 	unsigned int off = d->hwirq;
 	u32 bit = 1 << off;

 	if (!v)
 		return -EINVAL;

 	if (!(bit & v->resume_sources))
 		return -EINVAL;

 	if (on)
 		v->resume_irqs |= bit;
 	else
 		v->resume_irqs &= ~bit;

 	return 0;
 }
 #else
 #define vic_set_wake NULL
 #endif /* CONFIG_PM */

 static struct irq_chip vic_chip = {
 	.name		= "VIC",
 	.irq_ack	= vic_ack_irq,
 	.irq_mask	= vic_mask_irq,
 	.irq_unmask	= vic_unmask_irq,
 	.irq_set_wake	= vic_set_wake,
 };

 static void __init vic_disable(void __iomem *base)
 {
 	writel(0, base + VIC_INT_SELECT);
 	writel(0, base + VIC_INT_ENABLE);
 	writel(~0, base + VIC_INT_ENABLE_CLEAR);
 	writel(0, base + VIC_ITCR);
 	writel(~0, base + VIC_INT_SOFT_CLEAR);
 }

 static void __init vic_clear_interrupts(void __iomem *base)
 {
 	unsigned int i;

 	writel(0, base + VIC_PL190_VECT_ADDR);
 	for (i = 0; i < 19; i++) {
 		unsigned int value;

 		value = readl(base + VIC_PL190_VECT_ADDR);
 		writel(value, base + VIC_PL190_VECT_ADDR);
 	}
 }

 /*
  * The PL190 cell from ARM has been modified by ST to handle 64 interrupts.
  * The original cell has 32 interrupts, while the modified one has 64,
  * replocating two blocks 0x00..0x1f in 0x20..0x3f. In that case
  * the probe function is called twice, with base set to offset 000
  *  and 020 within the page. We call this "second block".
  */
 static void __init vic_init_st(void __iomem *base, unsigned int irq_start,
 			       u32 vic_sources, struct device_node *node)
 {
 	unsigned int i;
 	int vic_2nd_block = ((unsigned long)base & ~PAGE_MASK) != 0;

 	/* Disable all interrupts initially. */
 	vic_disable(base);

 	/*
 	 * Make sure we clear all existing interrupts. The vector registers
 	 * in this cell are after the second block of general registers,
 	 * so we can address them using standard offsets, but only from
 	 * the second base address, which is 0x20 in the page
 	 */
 	if (vic_2nd_block) {
 		vic_clear_interrupts(base);

 		/* ST has 16 vectors as well, but we don't enable them by now */
 		for (i = 0; i < 16; i++) {
 			void __iomem *reg = base + VIC_VECT_CNTL0 + (i * 4);
 			writel(0, reg);
 		}

 		writel(32, base + VIC_PL190_DEF_VECT_ADDR);
 	}

 	vic_register(base, 0, irq_start, vic_sources, 0, node);
 }

 static void __init __vic_init(void __iomem *base, int parent_irq, int irq_start,
 			      u32 vic_sources, u32 resume_sources,
 			      struct device_node *node)
 {
 	unsigned int i;
 	u32 cellid = 0;
 	enum amba_vendor vendor;

 	/* Identify which VIC cell this one is, by reading the ID */
 	for (i = 0; i < 4; i++) {
 		void __iomem *addr;
 		addr = (void __iomem *)((u32)base & PAGE_MASK) + 0xfe0 + (i * 4);
 		cellid |= (readl(addr) & 0xff) << (8 * i);
 	}
 	vendor = (cellid >> 12) & 0xff;
 	printk(KERN_INFO "VIC @%p: id 0x%08x, vendor 0x%02x\n",
 	       base, cellid, vendor);

 	switch(vendor) {
 	case AMBA_VENDOR_ST:
 		vic_init_st(base, irq_start, vic_sources, node);
 		return;
 	default:
 		printk(KERN_WARNING "VIC: unknown vendor, continuing anyways\n");
 		/* fall through */
 	case AMBA_VENDOR_ARM:
 		break;
 	}

 	/* Disable all interrupts initially. */
 	vic_disable(base);

 	/* Make sure we clear all existing interrupts */
 	vic_clear_interrupts(base);

 	vic_init2(base);

 	vic_register(base, parent_irq, irq_start, vic_sources, resume_sources, node);
 }

 /**
  * vic_init() - initialise a vectored interrupt controller
  * @base: iomem base address
  * @irq_start: starting interrupt number, must be muliple of 32
  * @vic_sources: bitmask of interrupt sources to allow
  * @resume_sources: bitmask of interrupt sources to allow for resume
  */
 void __init vic_init(void __iomem *base, unsigned int irq_start,
 		     u32 vic_sources, u32 resume_sources)
 {
 	__vic_init(base, 0, irq_start, vic_sources, resume_sources, NULL);
 }

 #ifdef CONFIG_OF
 static int __init vic_of_init(struct device_node *node,
 			      struct device_node *parent)
 {
 	void __iomem *regs;
 	u32 interrupt_mask = ~0;
 	u32 wakeup_mask = ~0;
 	int parent_irq;

 	regs = of_iomap(node, 0);
 	if (WARN_ON(!regs))
 		return -EIO;

 	of_property_read_u32(node, "valid-mask", &interrupt_mask);
 	of_property_read_u32(node, "valid-wakeup-mask", &wakeup_mask);
 	parent_irq = of_irq_get(node, 0);
 	if (parent_irq < 0)
 		parent_irq = 0;

 	/*
 	 * Passing 0 as first IRQ makes the simple domain allocate descriptors
 	 */
 	__vic_init(regs, parent_irq, 0, interrupt_mask, wakeup_mask, node);

 	return 0;
 }
 IRQCHIP_DECLARE(arm_pl190_vic, "arm,pl190-vic", vic_of_init);
 IRQCHIP_DECLARE(arm_pl192_vic, "arm,pl192-vic", vic_of_init);
 IRQCHIP_DECLARE(arm_versatile_vic, "arm,versatile-vic", vic_of_init);
 #endif /* CONFIG OF */
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* linux/arch/arm/common/vic.c
	*
	* Copyright (C) 1999 - 2003 ARM Limited
	* Copyright (C) 2000 Deep Blue Solutions Ltd
	*/

	#include <linux/export.h>
	#include <linux/init.h>
	#include <linux/list.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/of.h>
	#include <linux/of_address.h>
	#include <linux/of_irq.h>
	#include <linux/syscore_ops.h>
	#include <linux/device.h>
	#include <linux/amba/bus.h>
	#include <linux/irqchip/arm-vic.h>

	#include <asm/exception.h>
	#include <asm/irq.h>

	#define VIC_IRQ_STATUS 0x00
	#define VIC_FIQ_STATUS 0x04
	#define VIC_RAW_STATUS 0x08
	#define VIC_INT_SELECT 0x0c /* 1 = FIQ, 0 = IRQ */
	#define VIC_INT_ENABLE 0x10 /* 1 = enable, 0 = disable */
	#define VIC_INT_ENABLE_CLEAR 0x14
	#define VIC_INT_SOFT 0x18
	#define VIC_INT_SOFT_CLEAR 0x1c
	#define VIC_PROTECT 0x20
	#define VIC_PL190_VECT_ADDR 0x30 /* PL190 only */
	#define VIC_PL190_DEF_VECT_ADDR 0x34 /* PL190 only */

	#define VIC_VECT_ADDR0 0x100 /* 0 to 15 (0..31 PL192) */
	#define VIC_VECT_CNTL0 0x200 /* 0 to 15 (0..31 PL192) */
	#define VIC_ITCR 0x300 /* VIC test control register */

	#define VIC_VECT_CNTL_ENABLE (1 << 5)

	#define VIC_PL192_VECT_ADDR 0xF00

	/**
	* struct vic_device - VIC PM device
	* @parent_irq: The parent IRQ number of the VIC if cascaded, or 0.
	* @irq: The IRQ number for the base of the VIC.
	* @base: The register base for the VIC.
	* @valid_sources: A bitmask of valid interrupts
	* @resume_sources: A bitmask of interrupts for resume.
	* @resume_irqs: The IRQs enabled for resume.
	* @int_select: Save for VIC_INT_SELECT.
	* @int_enable: Save for VIC_INT_ENABLE.
	* @soft_int: Save for VIC_INT_SOFT.
	* @protect: Save for VIC_PROTECT.
	* @domain: The IRQ domain for the VIC.
	*/
	struct vic_device {
	void __iomem *base;
	int irq;
	u32 valid_sources;
	u32 resume_sources;
	u32 resume_irqs;
	u32 int_select;
	u32 int_enable;
	u32 soft_int;
	u32 protect;
	struct irq_domain *domain;
	};

	/* we cannot allocate memory when VICs are initially registered */
	static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];

	static int vic_id;

	static void vic_handle_irq(struct pt_regs *regs);

	/**
	* vic_init2 - common initialisation code
	* @base: Base of the VIC.
	*
	* Common initialisation code for registration
	* and resume.
	*/
	static void vic_init2(void __iomem *base)
	{
	int i;

	for (i = 0; i < 16; i++) {
	void __iomem reg = base + VIC_VECT_CNTL0 + (i 4);
	writel(VIC_VECT_CNTL_ENABLE \| i, reg);
	}

	writel(32, base + VIC_PL190_DEF_VECT_ADDR);
	}

	#ifdef CONFIG_PM
	static void resume_one_vic(struct vic_device *vic)
	{
	void __iomem *base = vic->base;

	printk(KERN_DEBUG "%s: resuming vic at %p\n", __func__, base);

	/* re-initialise static settings */
	vic_init2(base);

	writel(vic->int_select, base + VIC_INT_SELECT);
	writel(vic->protect, base + VIC_PROTECT);

	/* set the enabled ints and then clear the non-enabled */
	writel(vic->int_enable, base + VIC_INT_ENABLE);
	writel(~vic->int_enable, base + VIC_INT_ENABLE_CLEAR);

	/* and the same for the soft-int register */

	writel(vic->soft_int, base + VIC_INT_SOFT);
	writel(~vic->soft_int, base + VIC_INT_SOFT_CLEAR);
	}

	static void vic_resume(void)
	{
	int id;

	for (id = vic_id - 1; id >= 0; id--)
	resume_one_vic(vic_devices + id);
	}

	static void suspend_one_vic(struct vic_device *vic)
	{
	void __iomem *base = vic->base;

	printk(KERN_DEBUG "%s: suspending vic at %p\n", __func__, base);

	vic->int_select = readl(base + VIC_INT_SELECT);
	vic->int_enable = readl(base + VIC_INT_ENABLE);
	vic->soft_int = readl(base + VIC_INT_SOFT);
	vic->protect = readl(base + VIC_PROTECT);

	/* set the interrupts (if any) that are used for
	* resuming the system */

	writel(vic->resume_irqs, base + VIC_INT_ENABLE);
	writel(~vic->resume_irqs, base + VIC_INT_ENABLE_CLEAR);
	}

	static int vic_suspend(void)
	{
	int id;

	for (id = 0; id < vic_id; id++)
	suspend_one_vic(vic_devices + id);

	return 0;
	}

	static struct syscore_ops vic_syscore_ops = {
	.suspend = vic_suspend,
	.resume = vic_resume,
	};

	/**
	* vic_pm_init - initicall to register VIC pm
	*
	* This is called via late_initcall() to register
	* the resources for the VICs due to the early
	* nature of the VIC's registration.
	*/
	static int __init vic_pm_init(void)
	{
	if (vic_id > 0)
	register_syscore_ops(&vic_syscore_ops);

	return 0;
	}
	late_initcall(vic_pm_init);
	#endif /* CONFIG_PM */

	static struct irq_chip vic_chip;

	static int vic_irqdomain_map(struct irq_domain *d, unsigned int irq,
	irq_hw_number_t hwirq)
	{
	struct vic_device *v = d->host_data;

	/* Skip invalid IRQs, only register handlers for the real ones */
	if (!(v->valid_sources & (1 << hwirq)))
	return -EPERM;
	irq_set_chip_and_handler(irq, &vic_chip, handle_level_irq);
	irq_set_chip_data(irq, v->base);
	irq_set_probe(irq);
	return 0;
	}

	/*
	* Handle each interrupt in a single VIC. Returns non-zero if we've
	* handled at least one interrupt. This reads the status register
	* before handling each interrupt, which is necessary given that
	* handle_IRQ may briefly re-enable interrupts for soft IRQ handling.
	*/
	static int handle_one_vic(struct vic_device vic, struct pt_regs regs)
	{
	u32 stat, irq;
	int handled = 0;

	while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) {
	irq = ffs(stat) - 1;
	handle_domain_irq(vic->domain, irq, regs);
	handled = 1;
	}

	return handled;
	}

	static void vic_handle_irq_cascaded(struct irq_desc *desc)
	{
	u32 stat, hwirq;
	struct irq_chip *host_chip = irq_desc_get_chip(desc);
	struct vic_device *vic = irq_desc_get_handler_data(desc);

	chained_irq_enter(host_chip, desc);

	while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) {
	hwirq = ffs(stat) - 1;
	generic_handle_irq(irq_find_mapping(vic->domain, hwirq));
	}

	chained_irq_exit(host_chip, desc);
	}

	/*
	* Keep iterating over all registered VIC's until there are no pending
	* interrupts.
	*/
	static void __exception_irq_entry vic_handle_irq(struct pt_regs *regs)
	{
	int i, handled;

	do {
	for (i = 0, handled = 0; i < vic_id; ++i)
	handled \|= handle_one_vic(&vic_devices[i], regs);
	} while (handled);
	}

	static const struct irq_domain_ops vic_irqdomain_ops = {
	.map = vic_irqdomain_map,
	.xlate = irq_domain_xlate_onetwocell,
	};

	/**
	* vic_register() - Register a VIC.
	* @base: The base address of the VIC.
	* @parent_irq: The parent IRQ if cascaded, else 0.
	* @irq: The base IRQ for the VIC.
	* @valid_sources: bitmask of valid interrupts
	* @resume_sources: bitmask of interrupts allowed for resume sources.
	* @node: The device tree node associated with the VIC.
	*
	* Register the VIC with the system device tree so that it can be notified
	* of suspend and resume requests and ensure that the correct actions are
	* taken to re-instate the settings on resume.
	*
	* This also configures the IRQ domain for the VIC.
	*/
	static void __init vic_register(void __iomem *base, unsigned int parent_irq,
	unsigned int irq,
	u32 valid_sources, u32 resume_sources,
	struct device_node *node)
	{
	struct vic_device *v;
	int i;

	if (vic_id >= ARRAY_SIZE(vic_devices)) {
	printk(KERN_ERR "%s: too few VICs, increase CONFIG_ARM_VIC_NR\n", __func__);
	return;
	}

	v = &vic_devices[vic_id];
	v->base = base;
	v->valid_sources = valid_sources;
	v->resume_sources = resume_sources;
	set_handle_irq(vic_handle_irq);
	vic_id++;

	if (parent_irq) {
	irq_set_chained_handler_and_data(parent_irq,
	vic_handle_irq_cascaded, v);
	}

	v->domain = irq_domain_add_simple(node, fls(valid_sources), irq,
	&vic_irqdomain_ops, v);
	/* create an IRQ mapping for each valid IRQ */
	for (i = 0; i < fls(valid_sources); i++)
	if (valid_sources & (1 << i))
	irq_create_mapping(v->domain, i);
	/* If no base IRQ was passed, figure out our allocated base */
	if (irq)
	v->irq = irq;
	else
	v->irq = irq_find_mapping(v->domain, 0);
	}

	static void vic_ack_irq(struct irq_data *d)
	{
	void __iomem *base = irq_data_get_irq_chip_data(d);
	unsigned int irq = d->hwirq;
	writel(1 << irq, base + VIC_INT_ENABLE_CLEAR);
	/* moreover, clear the soft-triggered, in case it was the reason */
	writel(1 << irq, base + VIC_INT_SOFT_CLEAR);
	}

	static void vic_mask_irq(struct irq_data *d)
	{
	void __iomem *base = irq_data_get_irq_chip_data(d);
	unsigned int irq = d->hwirq;
	writel(1 << irq, base + VIC_INT_ENABLE_CLEAR);
	}

	static void vic_unmask_irq(struct irq_data *d)
	{
	void __iomem *base = irq_data_get_irq_chip_data(d);
	unsigned int irq = d->hwirq;
	writel(1 << irq, base + VIC_INT_ENABLE);
	}

	#if defined(CONFIG_PM)
	static struct vic_device *vic_from_irq(unsigned int irq)
	{
	struct vic_device *v = vic_devices;
	unsigned int base_irq = irq & ~31;
	int id;

	for (id = 0; id < vic_id; id++, v++) {
	if (v->irq == base_irq)
	return v;
	}

	return NULL;
	}

	static int vic_set_wake(struct irq_data *d, unsigned int on)
	{
	struct vic_device *v = vic_from_irq(d->irq);
	unsigned int off = d->hwirq;
	u32 bit = 1 << off;

	if (!v)
	return -EINVAL;

	if (!(bit & v->resume_sources))
	return -EINVAL;

	if (on)
	v->resume_irqs \|= bit;
	else
	v->resume_irqs &= ~bit;

	return 0;
	}
	#else
	#define vic_set_wake NULL
	#endif /* CONFIG_PM */

	static struct irq_chip vic_chip = {
	.name = "VIC",
	.irq_ack = vic_ack_irq,
	.irq_mask = vic_mask_irq,
	.irq_unmask = vic_unmask_irq,
	.irq_set_wake = vic_set_wake,
	};

	static void __init vic_disable(void __iomem *base)
	{
	writel(0, base + VIC_INT_SELECT);
	writel(0, base + VIC_INT_ENABLE);
	writel(~0, base + VIC_INT_ENABLE_CLEAR);
	writel(0, base + VIC_ITCR);
	writel(~0, base + VIC_INT_SOFT_CLEAR);
	}

	static void __init vic_clear_interrupts(void __iomem *base)
	{
	unsigned int i;

	writel(0, base + VIC_PL190_VECT_ADDR);
	for (i = 0; i < 19; i++) {
	unsigned int value;

	value = readl(base + VIC_PL190_VECT_ADDR);
	writel(value, base + VIC_PL190_VECT_ADDR);
	}
	}

	/*
	* The PL190 cell from ARM has been modified by ST to handle 64 interrupts.
	* The original cell has 32 interrupts, while the modified one has 64,
	* replocating two blocks 0x00..0x1f in 0x20..0x3f. In that case
	* the probe function is called twice, with base set to offset 000
	* and 020 within the page. We call this "second block".
	*/
	static void __init vic_init_st(void __iomem *base, unsigned int irq_start,
	u32 vic_sources, struct device_node *node)
	{
	unsigned int i;
	int vic_2nd_block = ((unsigned long)base & ~PAGE_MASK) != 0;

	/* Disable all interrupts initially. */
	vic_disable(base);

	/*
	* Make sure we clear all existing interrupts. The vector registers
	* in this cell are after the second block of general registers,
	* so we can address them using standard offsets, but only from
	* the second base address, which is 0x20 in the page
	*/
	if (vic_2nd_block) {
	vic_clear_interrupts(base);

	/* ST has 16 vectors as well, but we don't enable them by now */
	for (i = 0; i < 16; i++) {
	void __iomem reg = base + VIC_VECT_CNTL0 + (i 4);
	writel(0, reg);
	}

	writel(32, base + VIC_PL190_DEF_VECT_ADDR);
	}

	vic_register(base, 0, irq_start, vic_sources, 0, node);
	}

	static void __init __vic_init(void __iomem *base, int parent_irq, int irq_start,
	u32 vic_sources, u32 resume_sources,
	struct device_node *node)
	{
	unsigned int i;
	u32 cellid = 0;
	enum amba_vendor vendor;

	/* Identify which VIC cell this one is, by reading the ID */
	for (i = 0; i < 4; i++) {
	void __iomem *addr;
	addr = (void __iomem )((u32)base & PAGE_MASK) + 0xfe0 + (i 4);
	cellid \|= (readl(addr) & 0xff) << (8 * i);
	}
	vendor = (cellid >> 12) & 0xff;
	printk(KERN_INFO "VIC @%p: id 0x%08x, vendor 0x%02x\n",
	base, cellid, vendor);

	switch(vendor) {
	case AMBA_VENDOR_ST:
	vic_init_st(base, irq_start, vic_sources, node);
	return;
	default:
	printk(KERN_WARNING "VIC: unknown vendor, continuing anyways\n");
	/* fall through */
	case AMBA_VENDOR_ARM:
	break;
	}

	/* Disable all interrupts initially. */
	vic_disable(base);

	/* Make sure we clear all existing interrupts */
	vic_clear_interrupts(base);

	vic_init2(base);

	vic_register(base, parent_irq, irq_start, vic_sources, resume_sources, node);
	}

	/**
	* vic_init() - initialise a vectored interrupt controller
	* @base: iomem base address
	* @irq_start: starting interrupt number, must be muliple of 32
	* @vic_sources: bitmask of interrupt sources to allow
	* @resume_sources: bitmask of interrupt sources to allow for resume
	*/
	void __init vic_init(void __iomem *base, unsigned int irq_start,
	u32 vic_sources, u32 resume_sources)
	{
	__vic_init(base, 0, irq_start, vic_sources, resume_sources, NULL);
	}

	#ifdef CONFIG_OF
	static int __init vic_of_init(struct device_node *node,
	struct device_node *parent)
	{
	void __iomem *regs;
	u32 interrupt_mask = ~0;
	u32 wakeup_mask = ~0;
	int parent_irq;

	regs = of_iomap(node, 0);
	if (WARN_ON(!regs))
	return -EIO;

	of_property_read_u32(node, "valid-mask", &interrupt_mask);
	of_property_read_u32(node, "valid-wakeup-mask", &wakeup_mask);
	parent_irq = of_irq_get(node, 0);
	if (parent_irq < 0)
	parent_irq = 0;

	/*
	* Passing 0 as first IRQ makes the simple domain allocate descriptors
	*/
	__vic_init(regs, parent_irq, 0, interrupt_mask, wakeup_mask, node);

	return 0;
	}
	IRQCHIP_DECLARE(arm_pl190_vic, "arm,pl190-vic", vic_of_init);
	IRQCHIP_DECLARE(arm_pl192_vic, "arm,pl192-vic", vic_of_init);
	IRQCHIP_DECLARE(arm_versatile_vic, "arm,versatile-vic", vic_of_init);
	#endif /* CONFIG OF */