Branch data     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                 :            :