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
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 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 */
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 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 */
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