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