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1// SPDX-License-Identifier: GPL-2.02/*3 * Functions for registration of I/O interruption subclasses on s390.4 *5 * Copyright IBM Corp. 20086 * 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 register20 *21 * The number of users for @isc is increased. If this is the first user to22 * 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 system_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 unregister45 *46 * The number of users for @isc is decreased. If this is the last user to47 * unregister @isc, the corresponding I/O interruption subclass mask is48 * disabled.49 * Note: This function must not be called if isc_register() hasn't been called50 * 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 system_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