text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   *  linux/arch/arm/kernel/irq.c
   *
   *  Copyright (C) 1992 Linus Torvalds
   *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
   *
   *  Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
   *  Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
   *  Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
   *
   *  This file contains the code used by various IRQ handling routines:
   *  asking for different IRQ's should be done through these routines
   *  instead of just grabbing them. Thus setups with different IRQ numbers
   *  shouldn't result in any weird surprises, and installing new handlers
   *  should be easier.
   *
   *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
   *  Naturally it's not a 1:1 relation, but there are similarities.
   */
  #include <linux/signal.h>
  #include <linux/ioport.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/irqchip.h>
  #include <linux/random.h>
  #include <linux/smp.h>
  #include <linux/init.h>
  #include <linux/seq_file.h>
  #include <linux/errno.h>
  #include <linux/list.h>
  #include <linux/kallsyms.h>
  #include <linux/proc_fs.h>
  #include <linux/export.h>
  
  #include <asm/hardware/cache-l2x0.h>
  #include <asm/hardware/cache-uniphier.h>
  #include <asm/outercache.h>
  #include <asm/exception.h>
  #include <asm/mach/arch.h>
  #include <asm/mach/irq.h>
  #include <asm/mach/time.h>
  
  unsigned long irq_err_count;
  
  int arch_show_interrupts(struct seq_file *p, int prec)
  {
  #ifdef CONFIG_FIQ
  	show_fiq_list(p, prec);
  #endif
  #ifdef CONFIG_SMP
  	show_ipi_list(p, prec);
  #endif
  	seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
  	return 0;
  }
  
  /*
   * handle_IRQ handles all hardware IRQ's.  Decoded IRQs should
   * not come via this function.  Instead, they should provide their
   * own 'handler'.  Used by platform code implementing C-based 1st
   * level decoding.
   */
  void handle_IRQ(unsigned int irq, struct pt_regs *regs)
  {
  	struct irq_desc *desc;
  
  	/*
  	 * Some hardware gives randomly wrong interrupts.  Rather
  	 * than crashing, do something sensible.
  	 */
  	if (unlikely(!irq || irq >= nr_irqs))
  		desc = NULL;
  	else
  		desc = irq_to_desc(irq);
  
  	if (likely(desc))
  		handle_irq_desc(desc);
  	else
  		ack_bad_irq(irq);
  }
  
  /*
   * asm_do_IRQ is the interface to be used from assembly code.
   */
  asmlinkage void __exception_irq_entry
  asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
  {
  	struct pt_regs *old_regs;
  
  	irq_enter();
  	old_regs = set_irq_regs(regs);
  
  	handle_IRQ(irq, regs);
  
  	set_irq_regs(old_regs);
  	irq_exit();
  }
  
  void __init init_IRQ(void)
  {
  	int ret;
  
  	if (IS_ENABLED(CONFIG_OF) && !machine_desc->init_irq)
  		irqchip_init();
  	else
  		machine_desc->init_irq();
  
  	if (IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_CACHE_L2X0) &&
  	    (machine_desc->l2c_aux_mask || machine_desc->l2c_aux_val)) {
  		if (!outer_cache.write_sec)
  			outer_cache.write_sec = machine_desc->l2c_write_sec;
  		ret = l2x0_of_init(machine_desc->l2c_aux_val,
  				   machine_desc->l2c_aux_mask);
  		if (ret && ret != -ENODEV)
  			pr_err("L2C: failed to init: %d\n", ret);
  	}
  
  	uniphier_cache_init();
  }
  
  #ifdef CONFIG_SPARSE_IRQ
  int __init arch_probe_nr_irqs(void)
  {
  	nr_irqs = machine_desc->nr_irqs ? machine_desc->nr_irqs : NR_IRQS;
  	return nr_irqs;
  }
  #endif
  