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 13 static unsigned int isc_refs[MAX_ISC + 1]; 14 static 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 */ 27 void 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 } 40 EXPORT_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 */ 55 void 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]--; 66 out_unlock: 67 spin_unlock(&isc_ref_lock); 68 } 69 EXPORT_SYMBOL_GPL(isc_unregister); 70