LXR linux/drivers/s390/cio/isc.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Functions for registration of I/O interruption subclasses on s390.
   4 *
   5 * Copyright IBM Corp. 2008
   6 * Authors: Sebastian Ott <sebott@linux.vnet.ibm.com>
   7 */
   8
   9#include <linux/spinlock.h>
  10#include <linux/module.h>
  11#include <asm/isc.h>
  12
  13static unsigned int isc_refs[MAX_ISC + 1];
  14static DEFINE_SPINLOCK(isc_ref_lock);
  15
  16
  17/**
  18 * isc_register - register an I/O interruption subclass.
  19 * @isc: I/O interruption subclass to register
  20 *
  21 * The number of users for @isc is increased. If this is the first user to
  22 * register @isc, the corresponding I/O interruption subclass mask is enabled.
  23 *
  24 * Context:
  25 *   This function must not be called in interrupt context.
  26 */
  27void isc_register(unsigned int isc)
  28{
  29        if (isc > MAX_ISC) {
  30                WARN_ON(1);
  31                return;
  32        }
  33
  34        spin_lock(&isc_ref_lock);
  35        if (isc_refs[isc] == 0)
  36                ctl_set_bit(6, 31 - isc);
  37        isc_refs[isc]++;
  38        spin_unlock(&isc_ref_lock);
  39}
  40EXPORT_SYMBOL_GPL(isc_register);
  41
  42/**
  43 * isc_unregister - unregister an I/O interruption subclass.
  44 * @isc: I/O interruption subclass to unregister
  45 *
  46 * The number of users for @isc is decreased. If this is the last user to
  47 * unregister @isc, the corresponding I/O interruption subclass mask is
  48 * disabled.
  49 * Note: This function must not be called if isc_register() hasn't been called
  50 * before by the driver for @isc.
  51 *
  52 * Context:
  53 *   This function must not be called in interrupt context.
  54 */
  55void isc_unregister(unsigned int isc)
  56{
  57        spin_lock(&isc_ref_lock);
  58        /* check for misuse */
  59        if (isc > MAX_ISC || isc_refs[isc] == 0) {
  60                WARN_ON(1);
  61                goto out_unlock;
  62        }
  63        if (isc_refs[isc] == 1)
  64                ctl_clear_bit(6, 31 - isc);
  65        isc_refs[isc]--;
  66out_unlock:
  67        spin_unlock(&isc_ref_lock);
  68}
  69EXPORT_SYMBOL_GPL(isc_unregister);
  70