Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0
       2             : /*
       3             :  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
       4             :  *
       5             :  * This file contains the interrupt probing code and driver APIs.
       6             :  */
       7             : 
       8             : #include <linux/irq.h>
       9             : #include <linux/module.h>
      10             : #include <linux/interrupt.h>
      11             : #include <linux/delay.h>
      12             : #include <linux/async.h>
      13             : 
      14             : #include "internals.h"
      15             : 
      16             : /*
      17             :  * Autodetection depends on the fact that any interrupt that
      18             :  * comes in on to an unassigned handler will get stuck with
      19             :  * "IRQS_WAITING" cleared and the interrupt disabled.
      20             :  */
      21             : static DEFINE_MUTEX(probing_active);
      22             : 
      23             : /**
      24             :  *      probe_irq_on    - begin an interrupt autodetect
      25             :  *
      26             :  *      Commence probing for an interrupt. The interrupts are scanned
      27             :  *      and a mask of potential interrupt lines is returned.
      28             :  *
      29             :  */
      30           0 : unsigned long probe_irq_on(void)
      31             : {
      32           0 :         struct irq_desc *desc;
      33           0 :         unsigned long mask = 0;
      34           0 :         int i;
      35             : 
      36             :         /*
      37             :          * quiesce the kernel, or at least the asynchronous portion
      38             :          */
      39           0 :         async_synchronize_full();
      40           0 :         mutex_lock(&probing_active);
      41             :         /*
      42             :          * something may have generated an irq long ago and we want to
      43             :          * flush such a longstanding irq before considering it as spurious.
      44             :          */
      45           0 :         for_each_irq_desc_reverse(i, desc) {
      46           0 :                 raw_spin_lock_irq(&desc->lock);
      47           0 :                 if (!desc->action && irq_settings_can_probe(desc)) {
      48             :                         /*
      49             :                          * Some chips need to know about probing in
      50             :                          * progress:
      51             :                          */
      52           0 :                         if (desc->irq_data.chip->irq_set_type)
      53           0 :                                 desc->irq_data.chip->irq_set_type(&desc->irq_data,
      54             :                                                          IRQ_TYPE_PROBE);
      55           0 :                         irq_activate_and_startup(desc, IRQ_NORESEND);
      56             :                 }
      57           0 :                 raw_spin_unlock_irq(&desc->lock);
      58             :         }
      59             : 
      60             :         /* Wait for longstanding interrupts to trigger. */
      61           0 :         msleep(20);
      62             : 
      63             :         /*
      64             :          * enable any unassigned irqs
      65             :          * (we must startup again here because if a longstanding irq
      66             :          * happened in the previous stage, it may have masked itself)
      67             :          */
      68           0 :         for_each_irq_desc_reverse(i, desc) {
      69           0 :                 raw_spin_lock_irq(&desc->lock);
      70           0 :                 if (!desc->action && irq_settings_can_probe(desc)) {
      71           0 :                         desc->istate |= IRQS_AUTODETECT | IRQS_WAITING;
      72           0 :                         if (irq_activate_and_startup(desc, IRQ_NORESEND))
      73           0 :                                 desc->istate |= IRQS_PENDING;
      74             :                 }
      75           0 :                 raw_spin_unlock_irq(&desc->lock);
      76             :         }
      77             : 
      78             :         /*
      79             :          * Wait for spurious interrupts to trigger
      80             :          */
      81           0 :         msleep(100);
      82             : 
      83             :         /*
      84             :          * Now filter out any obviously spurious interrupts
      85             :          */
      86           0 :         for_each_irq_desc(i, desc) {
      87           0 :                 raw_spin_lock_irq(&desc->lock);
      88             : 
      89           0 :                 if (desc->istate & IRQS_AUTODETECT) {
      90             :                         /* It triggered already - consider it spurious. */
      91           0 :                         if (!(desc->istate & IRQS_WAITING)) {
      92           0 :                                 desc->istate &= ~IRQS_AUTODETECT;
      93           0 :                                 irq_shutdown_and_deactivate(desc);
      94             :                         } else
      95           0 :                                 if (i < 32)
      96           0 :                                         mask |= 1 << i;
      97             :                 }
      98           0 :                 raw_spin_unlock_irq(&desc->lock);
      99             :         }
     100             : 
     101           0 :         return mask;
     102             : }
     103             : EXPORT_SYMBOL(probe_irq_on);
     104             : 
     105             : /**
     106             :  *      probe_irq_mask - scan a bitmap of interrupt lines
     107             :  *      @val:   mask of interrupts to consider
     108             :  *
     109             :  *      Scan the interrupt lines and return a bitmap of active
     110             :  *      autodetect interrupts. The interrupt probe logic state
     111             :  *      is then returned to its previous value.
     112             :  *
     113             :  *      Note: we need to scan all the irq's even though we will
     114             :  *      only return autodetect irq numbers - just so that we reset
     115             :  *      them all to a known state.
     116             :  */
     117           0 : unsigned int probe_irq_mask(unsigned long val)
     118             : {
     119           0 :         unsigned int mask = 0;
     120           0 :         struct irq_desc *desc;
     121           0 :         int i;
     122             : 
     123           0 :         for_each_irq_desc(i, desc) {
     124           0 :                 raw_spin_lock_irq(&desc->lock);
     125           0 :                 if (desc->istate & IRQS_AUTODETECT) {
     126           0 :                         if (i < 16 && !(desc->istate & IRQS_WAITING))
     127           0 :                                 mask |= 1 << i;
     128             : 
     129           0 :                         desc->istate &= ~IRQS_AUTODETECT;
     130           0 :                         irq_shutdown_and_deactivate(desc);
     131             :                 }
     132           0 :                 raw_spin_unlock_irq(&desc->lock);
     133             :         }
     134           0 :         mutex_unlock(&probing_active);
     135             : 
     136           0 :         return mask & val;
     137             : }
     138             : EXPORT_SYMBOL(probe_irq_mask);
     139             : 
     140             : /**
     141             :  *      probe_irq_off   - end an interrupt autodetect
     142             :  *      @val: mask of potential interrupts (unused)
     143             :  *
     144             :  *      Scans the unused interrupt lines and returns the line which
     145             :  *      appears to have triggered the interrupt. If no interrupt was
     146             :  *      found then zero is returned. If more than one interrupt is
     147             :  *      found then minus the first candidate is returned to indicate
     148             :  *      their is doubt.
     149             :  *
     150             :  *      The interrupt probe logic state is returned to its previous
     151             :  *      value.
     152             :  *
     153             :  *      BUGS: When used in a module (which arguably shouldn't happen)
     154             :  *      nothing prevents two IRQ probe callers from overlapping. The
     155             :  *      results of this are non-optimal.
     156             :  */
     157           0 : int probe_irq_off(unsigned long val)
     158             : {
     159           0 :         int i, irq_found = 0, nr_of_irqs = 0;
     160           0 :         struct irq_desc *desc;
     161             : 
     162           0 :         for_each_irq_desc(i, desc) {
     163           0 :                 raw_spin_lock_irq(&desc->lock);
     164             : 
     165           0 :                 if (desc->istate & IRQS_AUTODETECT) {
     166           0 :                         if (!(desc->istate & IRQS_WAITING)) {
     167           0 :                                 if (!nr_of_irqs)
     168           0 :                                         irq_found = i;
     169           0 :                                 nr_of_irqs++;
     170             :                         }
     171           0 :                         desc->istate &= ~IRQS_AUTODETECT;
     172           0 :                         irq_shutdown_and_deactivate(desc);
     173             :                 }
     174           0 :                 raw_spin_unlock_irq(&desc->lock);
     175             :         }
     176           0 :         mutex_unlock(&probing_active);
     177             : 
     178           0 :         if (nr_of_irqs > 1)
     179           0 :                 irq_found = -irq_found;
     180             : 
     181           0 :         return irq_found;
     182             : }
     183             : EXPORT_SYMBOL(probe_irq_off);
     184             :