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Linux/arch/arm/kernel/irq.c

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  1 /*
  2  *  linux/arch/arm/kernel/irq.c
  3  *
  4  *  Copyright (C) 1992 Linus Torvalds
  5  *  Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
  6  *
  7  *  Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
  8  *  Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
  9  *  Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
 10  *
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License version 2 as
 13  * published by the Free Software Foundation.
 14  *
 15  *  This file contains the code used by various IRQ handling routines:
 16  *  asking for different IRQ's should be done through these routines
 17  *  instead of just grabbing them. Thus setups with different IRQ numbers
 18  *  shouldn't result in any weird surprises, and installing new handlers
 19  *  should be easier.
 20  *
 21  *  IRQ's are in fact implemented a bit like signal handlers for the kernel.
 22  *  Naturally it's not a 1:1 relation, but there are similarities.
 23  */
 24 #include <linux/kernel_stat.h>
 25 #include <linux/signal.h>
 26 #include <linux/ioport.h>
 27 #include <linux/interrupt.h>
 28 #include <linux/irq.h>
 29 #include <linux/irqchip.h>
 30 #include <linux/random.h>
 31 #include <linux/smp.h>
 32 #include <linux/init.h>
 33 #include <linux/seq_file.h>
 34 #include <linux/errno.h>
 35 #include <linux/list.h>
 36 #include <linux/kallsyms.h>
 37 #include <linux/proc_fs.h>
 38 #include <linux/export.h>
 39 
 40 #include <asm/exception.h>
 41 #include <asm/mach/arch.h>
 42 #include <asm/mach/irq.h>
 43 #include <asm/mach/time.h>
 44 
 45 unsigned long irq_err_count;
 46 
 47 int arch_show_interrupts(struct seq_file *p, int prec)
 48 {
 49 #ifdef CONFIG_FIQ
 50         show_fiq_list(p, prec);
 51 #endif
 52 #ifdef CONFIG_SMP
 53         show_ipi_list(p, prec);
 54 #endif
 55         seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count);
 56         return 0;
 57 }
 58 
 59 /*
 60  * handle_IRQ handles all hardware IRQ's.  Decoded IRQs should
 61  * not come via this function.  Instead, they should provide their
 62  * own 'handler'.  Used by platform code implementing C-based 1st
 63  * level decoding.
 64  */
 65 void handle_IRQ(unsigned int irq, struct pt_regs *regs)
 66 {
 67         struct pt_regs *old_regs = set_irq_regs(regs);
 68 
 69         irq_enter();
 70 
 71         /*
 72          * Some hardware gives randomly wrong interrupts.  Rather
 73          * than crashing, do something sensible.
 74          */
 75         if (unlikely(irq >= nr_irqs)) {
 76                 if (printk_ratelimit())
 77                         printk(KERN_WARNING "Bad IRQ%u\n", irq);
 78                 ack_bad_irq(irq);
 79         } else {
 80                 generic_handle_irq(irq);
 81         }
 82 
 83         irq_exit();
 84         set_irq_regs(old_regs);
 85 }
 86 
 87 /*
 88  * asm_do_IRQ is the interface to be used from assembly code.
 89  */
 90 asmlinkage void __exception_irq_entry
 91 asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
 92 {
 93         handle_IRQ(irq, regs);
 94 }
 95 
 96 void set_irq_flags(unsigned int irq, unsigned int iflags)
 97 {
 98         unsigned long clr = 0, set = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
 99 
100         if (irq >= nr_irqs) {
101                 printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
102                 return;
103         }
104 
105         if (iflags & IRQF_VALID)
106                 clr |= IRQ_NOREQUEST;
107         if (iflags & IRQF_PROBE)
108                 clr |= IRQ_NOPROBE;
109         if (!(iflags & IRQF_NOAUTOEN))
110                 clr |= IRQ_NOAUTOEN;
111         /* Order is clear bits in "clr" then set bits in "set" */
112         irq_modify_status(irq, clr, set & ~clr);
113 }
114 EXPORT_SYMBOL_GPL(set_irq_flags);
115 
116 void __init init_IRQ(void)
117 {
118         if (IS_ENABLED(CONFIG_OF) && !machine_desc->init_irq)
119                 irqchip_init();
120         else
121                 machine_desc->init_irq();
122 }
123 
124 #ifdef CONFIG_MULTI_IRQ_HANDLER
125 void __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
126 {
127         if (handle_arch_irq)
128                 return;
129 
130         handle_arch_irq = handle_irq;
131 }
132 #endif
133 
134 #ifdef CONFIG_SPARSE_IRQ
135 int __init arch_probe_nr_irqs(void)
136 {
137         nr_irqs = machine_desc->nr_irqs ? machine_desc->nr_irqs : NR_IRQS;
138         return nr_irqs;
139 }
140 #endif
141 
142 #ifdef CONFIG_HOTPLUG_CPU
143 
144 static bool migrate_one_irq(struct irq_desc *desc)
145 {
146         struct irq_data *d = irq_desc_get_irq_data(desc);
147         const struct cpumask *affinity = d->affinity;
148         struct irq_chip *c;
149         bool ret = false;
150 
151         /*
152          * If this is a per-CPU interrupt, or the affinity does not
153          * include this CPU, then we have nothing to do.
154          */
155         if (irqd_is_per_cpu(d) || !cpumask_test_cpu(smp_processor_id(), affinity))
156                 return false;
157 
158         if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
159                 affinity = cpu_online_mask;
160                 ret = true;
161         }
162 
163         c = irq_data_get_irq_chip(d);
164         if (!c->irq_set_affinity)
165                 pr_debug("IRQ%u: unable to set affinity\n", d->irq);
166         else if (c->irq_set_affinity(d, affinity, true) == IRQ_SET_MASK_OK && ret)
167                 cpumask_copy(d->affinity, affinity);
168 
169         return ret;
170 }
171 
172 /*
173  * The current CPU has been marked offline.  Migrate IRQs off this CPU.
174  * If the affinity settings do not allow other CPUs, force them onto any
175  * available CPU.
176  *
177  * Note: we must iterate over all IRQs, whether they have an attached
178  * action structure or not, as we need to get chained interrupts too.
179  */
180 void migrate_irqs(void)
181 {
182         unsigned int i;
183         struct irq_desc *desc;
184         unsigned long flags;
185 
186         local_irq_save(flags);
187 
188         for_each_irq_desc(i, desc) {
189                 bool affinity_broken;
190 
191                 raw_spin_lock(&desc->lock);
192                 affinity_broken = migrate_one_irq(desc);
193                 raw_spin_unlock(&desc->lock);
194 
195                 if (affinity_broken && printk_ratelimit())
196                         pr_warning("IRQ%u no longer affine to CPU%u\n", i,
197                                 smp_processor_id());
198         }
199 
200         local_irq_restore(flags);
201 }
202 #endif /* CONFIG_HOTPLUG_CPU */
203 

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