1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * Functions for registration of I/O interruption subclasses on s390. 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Copyright IBM Corp. 2008 6*4882a593Smuzhiyun * Authors: Sebastian Ott <sebott@linux.vnet.ibm.com> 7*4882a593Smuzhiyun */ 8*4882a593Smuzhiyun 9*4882a593Smuzhiyun #include <linux/spinlock.h> 10*4882a593Smuzhiyun #include <linux/module.h> 11*4882a593Smuzhiyun #include <asm/isc.h> 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun static unsigned int isc_refs[MAX_ISC + 1]; 14*4882a593Smuzhiyun static DEFINE_SPINLOCK(isc_ref_lock); 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun /** 18*4882a593Smuzhiyun * isc_register - register an I/O interruption subclass. 19*4882a593Smuzhiyun * @isc: I/O interruption subclass to register 20*4882a593Smuzhiyun * 21*4882a593Smuzhiyun * The number of users for @isc is increased. If this is the first user to 22*4882a593Smuzhiyun * register @isc, the corresponding I/O interruption subclass mask is enabled. 23*4882a593Smuzhiyun * 24*4882a593Smuzhiyun * Context: 25*4882a593Smuzhiyun * This function must not be called in interrupt context. 26*4882a593Smuzhiyun */ isc_register(unsigned int isc)27*4882a593Smuzhiyunvoid isc_register(unsigned int isc) 28*4882a593Smuzhiyun { 29*4882a593Smuzhiyun if (isc > MAX_ISC) { 30*4882a593Smuzhiyun WARN_ON(1); 31*4882a593Smuzhiyun return; 32*4882a593Smuzhiyun } 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun spin_lock(&isc_ref_lock); 35*4882a593Smuzhiyun if (isc_refs[isc] == 0) 36*4882a593Smuzhiyun ctl_set_bit(6, 31 - isc); 37*4882a593Smuzhiyun isc_refs[isc]++; 38*4882a593Smuzhiyun spin_unlock(&isc_ref_lock); 39*4882a593Smuzhiyun } 40*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(isc_register); 41*4882a593Smuzhiyun 42*4882a593Smuzhiyun /** 43*4882a593Smuzhiyun * isc_unregister - unregister an I/O interruption subclass. 44*4882a593Smuzhiyun * @isc: I/O interruption subclass to unregister 45*4882a593Smuzhiyun * 46*4882a593Smuzhiyun * The number of users for @isc is decreased. If this is the last user to 47*4882a593Smuzhiyun * unregister @isc, the corresponding I/O interruption subclass mask is 48*4882a593Smuzhiyun * disabled. 49*4882a593Smuzhiyun * Note: This function must not be called if isc_register() hasn't been called 50*4882a593Smuzhiyun * before by the driver for @isc. 51*4882a593Smuzhiyun * 52*4882a593Smuzhiyun * Context: 53*4882a593Smuzhiyun * This function must not be called in interrupt context. 54*4882a593Smuzhiyun */ isc_unregister(unsigned int isc)55*4882a593Smuzhiyunvoid isc_unregister(unsigned int isc) 56*4882a593Smuzhiyun { 57*4882a593Smuzhiyun spin_lock(&isc_ref_lock); 58*4882a593Smuzhiyun /* check for misuse */ 59*4882a593Smuzhiyun if (isc > MAX_ISC || isc_refs[isc] == 0) { 60*4882a593Smuzhiyun WARN_ON(1); 61*4882a593Smuzhiyun goto out_unlock; 62*4882a593Smuzhiyun } 63*4882a593Smuzhiyun if (isc_refs[isc] == 1) 64*4882a593Smuzhiyun ctl_clear_bit(6, 31 - isc); 65*4882a593Smuzhiyun isc_refs[isc]--; 66*4882a593Smuzhiyun out_unlock: 67*4882a593Smuzhiyun spin_unlock(&isc_ref_lock); 68*4882a593Smuzhiyun } 69*4882a593Smuzhiyun EXPORT_SYMBOL_GPL(isc_unregister); 70