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 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 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);