isc.c
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/*
* Functions for registration of I/O interruption subclasses on s390.
*
* Copyright IBM Corp. 2008
* Authors: Sebastian Ott <sebott@linux.vnet.ibm.com>
*/
#include <linux/spinlock.h>
#include <linux/module.h>
#include <asm/isc.h>
static unsigned int isc_refs[MAX_ISC + 1];
static DEFINE_SPINLOCK(isc_ref_lock);
/**
* isc_register - register an I/O interruption subclass.
* @isc: I/O interruption subclass to register
*
* The number of users for @isc is increased. If this is the first user to
* register @isc, the corresponding I/O interruption subclass mask is enabled.
*
* Context:
* This function must not be called in interrupt context.
*/
void isc_register(unsigned int isc)
{
if (isc > MAX_ISC) {
WARN_ON(1);
return;
}
spin_lock(&isc_ref_lock);
if (isc_refs[isc] == 0)
ctl_set_bit(6, 31 - isc);
isc_refs[isc]++;
spin_unlock(&isc_ref_lock);
}
EXPORT_SYMBOL_GPL(isc_register);
/**
* isc_unregister - unregister an I/O interruption subclass.
* @isc: I/O interruption subclass to unregister
*
* The number of users for @isc is decreased. If this is the last user to
* unregister @isc, the corresponding I/O interruption subclass mask is
* disabled.
* Note: This function must not be called if isc_register() hasn't been called
* before by the driver for @isc.
*
* Context:
* This function must not be called in interrupt context.
*/
void isc_unregister(unsigned int isc)
{
spin_lock(&isc_ref_lock);
/* check for misuse */
if (isc > MAX_ISC || isc_refs[isc] == 0) {
WARN_ON(1);
goto out_unlock;
}
if (isc_refs[isc] == 1)
ctl_clear_bit(6, 31 - isc);
isc_refs[isc]--;
out_unlock:
spin_unlock(&isc_ref_lock);
}
EXPORT_SYMBOL_GPL(isc_unregister);