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  */
isc_register(unsigned int isc)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  */
isc_unregister(unsigned int isc)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);
70