/*
   * drivers/irq/irq-nvic.c
   *
   * Copyright (C) 2008 ARM Limited, All Rights Reserved.
   * Copyright (C) 2013 Pengutronix
   *
   * 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.
   *
   * Support for the Nested Vectored Interrupt Controller found on the
   * ARMv7-M CPUs (Cortex-M3/M4)
   */
  #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
  
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/irq.h>

  #include <linux/irqchip.h>

  #include <linux/irqdomain.h>
  
  #include <asm/v7m.h>
  #include <asm/exception.h>

  #define NVIC_ISER		0x000
  #define NVIC_ICER		0x080
  #define NVIC_IPR		0x300
  
  #define NVIC_MAX_BANKS		16
  /*
   * Each bank handles 32 irqs. Only the 16th (= last) bank handles only
   * 16 irqs.
   */
  #define NVIC_MAX_IRQ		((NVIC_MAX_BANKS - 1) * 32 + 16)
  
  static struct irq_domain *nvic_irq_domain;
  
  asmlinkage void __exception_irq_entry
  nvic_handle_irq(irq_hw_number_t hwirq, struct pt_regs *regs)
  {
  	unsigned int irq = irq_linear_revmap(nvic_irq_domain, hwirq);
  
  	handle_IRQ(irq, regs);
  }

  static int nvic_irq_domain_translate(struct irq_domain *d,
  				     struct irq_fwspec *fwspec,
  				     unsigned long *hwirq, unsigned int *type)
  {
  	if (WARN_ON(fwspec->param_count < 1))
  		return -EINVAL;
  	*hwirq = fwspec->param[0];
  	*type = IRQ_TYPE_NONE;
  	return 0;
  }

  static int nvic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
  				unsigned int nr_irqs, void *arg)
  {
  	int i, ret;
  	irq_hw_number_t hwirq;
  	unsigned int type = IRQ_TYPE_NONE;

  	struct irq_fwspec *fwspec = arg;

  	ret = nvic_irq_domain_translate(domain, fwspec, &hwirq, &type);

  	if (ret)
  		return ret;
  
  	for (i = 0; i < nr_irqs; i++)
  		irq_map_generic_chip(domain, virq + i, hwirq + i);
  
  	return 0;
  }
  
  static const struct irq_domain_ops nvic_irq_domain_ops = {

  	.translate = nvic_irq_domain_translate,

  	.alloc = nvic_irq_domain_alloc,
  	.free = irq_domain_free_irqs_top,
  };

  static int __init nvic_of_init(struct device_node *node,
  			       struct device_node *parent)
  {
  	unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
  	unsigned int irqs, i, ret, numbanks;
  	void __iomem *nvic_base;
  
  	numbanks = (readl_relaxed(V7M_SCS_ICTR) &
  		    V7M_SCS_ICTR_INTLINESNUM_MASK) + 1;
  
  	nvic_base = of_iomap(node, 0);
  	if (!nvic_base) {
  		pr_warn("unable to map nvic registers
  ");
  		return -ENOMEM;
  	}
  
  	irqs = numbanks * 32;
  	if (irqs > NVIC_MAX_IRQ)
  		irqs = NVIC_MAX_IRQ;
  
  	nvic_irq_domain =

  		irq_domain_add_linear(node, irqs, &nvic_irq_domain_ops, NULL);

  	if (!nvic_irq_domain) {
  		pr_warn("Failed to allocate irq domain
  ");
  		return -ENOMEM;
  	}

  	ret = irq_alloc_domain_generic_chips(nvic_irq_domain, 32, 1,

  					     "nvic_irq", handle_fasteoi_irq,
  					     clr, 0, IRQ_GC_INIT_MASK_CACHE);
  	if (ret) {
  		pr_warn("Failed to allocate irq chips
  ");
  		irq_domain_remove(nvic_irq_domain);
  		return ret;
  	}
  
  	for (i = 0; i < numbanks; ++i) {
  		struct irq_chip_generic *gc;
  
  		gc = irq_get_domain_generic_chip(nvic_irq_domain, 32 * i);
  		gc->reg_base = nvic_base + 4 * i;
  		gc->chip_types[0].regs.enable = NVIC_ISER;
  		gc->chip_types[0].regs.disable = NVIC_ICER;
  		gc->chip_types[0].chip.irq_mask = irq_gc_mask_disable_reg;
  		gc->chip_types[0].chip.irq_unmask = irq_gc_unmask_enable_reg;

  		/* This is a no-op as end of interrupt is signaled by the
  		 * exception return sequence.
  		 */
  		gc->chip_types[0].chip.irq_eoi = irq_gc_noop;

  
  		/* disable interrupts */
  		writel_relaxed(~0, gc->reg_base + NVIC_ICER);
  	}
  
  	/* Set priority on all interrupts */
  	for (i = 0; i < irqs; i += 4)
  		writel_relaxed(0, nvic_base + NVIC_IPR + i);
  
  	return 0;
  }
  IRQCHIP_DECLARE(armv7m_nvic, "arm,armv7m-nvic", nvic_of_init);