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
12static unsigned int isc_refs[MAX_ISC + 1];
13static 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 */
26void 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}
39EXPORT_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 */
54void 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]--;
65out_unlock:
66	spin_unlock(&isc_ref_lock);
67}
68EXPORT_SYMBOL_GPL(isc_unregister);
69