1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Channel report handling code
4 *
5 * Copyright IBM Corp. 2000, 2009
6 * Author(s): Ingo Adlung <adlung@de.ibm.com>,
7 * Martin Schwidefsky <schwidefsky@de.ibm.com>,
8 * Cornelia Huck <cornelia.huck@de.ibm.com>,
9 */
10
11 #include <linux/mutex.h>
12 #include <linux/kthread.h>
13 #include <linux/init.h>
14 #include <linux/wait.h>
15 #include <asm/ctlreg.h>
16 #include <asm/crw.h>
17 #include "ioasm.h"
18
19 static DEFINE_MUTEX(crw_handler_mutex);
20 static crw_handler_t crw_handlers[NR_RSCS];
21 static atomic_t crw_nr_req = ATOMIC_INIT(0);
22 static DECLARE_WAIT_QUEUE_HEAD(crw_handler_wait_q);
23
24 /**
25 * crw_register_handler() - register a channel report word handler
26 * @rsc: reporting source code to handle
27 * @handler: handler to be registered
28 *
29 * Returns %0 on success and a negative error value otherwise.
30 */
crw_register_handler(int rsc,crw_handler_t handler)31 int crw_register_handler(int rsc, crw_handler_t handler)
32 {
33 int rc = 0;
34
35 if ((rsc < 0) || (rsc >= NR_RSCS))
36 return -EINVAL;
37 mutex_lock(&crw_handler_mutex);
38 if (crw_handlers[rsc])
39 rc = -EBUSY;
40 else
41 crw_handlers[rsc] = handler;
42 mutex_unlock(&crw_handler_mutex);
43 return rc;
44 }
45
46 /**
47 * crw_unregister_handler() - unregister a channel report word handler
48 * @rsc: reporting source code to handle
49 */
crw_unregister_handler(int rsc)50 void crw_unregister_handler(int rsc)
51 {
52 if ((rsc < 0) || (rsc >= NR_RSCS))
53 return;
54 mutex_lock(&crw_handler_mutex);
55 crw_handlers[rsc] = NULL;
56 mutex_unlock(&crw_handler_mutex);
57 }
58
59 /*
60 * Retrieve CRWs and call function to handle event.
61 */
crw_collect_info(void * unused)62 static int crw_collect_info(void *unused)
63 {
64 struct crw crw[2];
65 int ccode, signal;
66 unsigned int chain;
67
68 repeat:
69 signal = wait_event_interruptible(crw_handler_wait_q,
70 atomic_read(&crw_nr_req) > 0);
71 if (unlikely(signal))
72 atomic_inc(&crw_nr_req);
73 chain = 0;
74 while (1) {
75 crw_handler_t handler;
76
77 if (unlikely(chain > 1)) {
78 struct crw tmp_crw;
79
80 printk(KERN_WARNING "%s: Code does not support more than two chained crws\n",
81 __func__);
82 ccode = stcrw(&tmp_crw);
83 printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
84 "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
85 __func__, tmp_crw.slct, tmp_crw.oflw,
86 tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
87 tmp_crw.erc, tmp_crw.rsid);
88 printk(KERN_WARNING"%s: This was crw number %x in the "
89 "chain\n", __func__, chain);
90 if (ccode != 0)
91 break;
92 chain = tmp_crw.chn ? chain + 1 : 0;
93 continue;
94 }
95 ccode = stcrw(&crw[chain]);
96 if (ccode != 0)
97 break;
98 printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
99 "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
100 crw[chain].slct, crw[chain].oflw, crw[chain].chn,
101 crw[chain].rsc, crw[chain].anc, crw[chain].erc,
102 crw[chain].rsid);
103 /* Check for overflows. */
104 if (crw[chain].oflw) {
105 int i;
106
107 pr_debug("%s: crw overflow detected!\n", __func__);
108 mutex_lock(&crw_handler_mutex);
109 for (i = 0; i < NR_RSCS; i++) {
110 if (crw_handlers[i])
111 crw_handlers[i](NULL, NULL, 1);
112 }
113 mutex_unlock(&crw_handler_mutex);
114 chain = 0;
115 continue;
116 }
117 if (crw[0].chn && !chain) {
118 chain++;
119 continue;
120 }
121 mutex_lock(&crw_handler_mutex);
122 handler = crw_handlers[crw[chain].rsc];
123 if (handler)
124 handler(&crw[0], chain ? &crw[1] : NULL, 0);
125 mutex_unlock(&crw_handler_mutex);
126 /* chain is always 0 or 1 here. */
127 chain = crw[chain].chn ? chain + 1 : 0;
128 }
129 if (atomic_dec_and_test(&crw_nr_req))
130 wake_up(&crw_handler_wait_q);
131 goto repeat;
132 return 0;
133 }
134
crw_handle_channel_report(void)135 void crw_handle_channel_report(void)
136 {
137 atomic_inc(&crw_nr_req);
138 wake_up(&crw_handler_wait_q);
139 }
140
crw_wait_for_channel_report(void)141 void crw_wait_for_channel_report(void)
142 {
143 crw_handle_channel_report();
144 wait_event(crw_handler_wait_q, atomic_read(&crw_nr_req) == 0);
145 }
146
147 /*
148 * Machine checks for the channel subsystem must be enabled
149 * after the channel subsystem is initialized
150 */
crw_machine_check_init(void)151 static int __init crw_machine_check_init(void)
152 {
153 struct task_struct *task;
154
155 task = kthread_run(crw_collect_info, NULL, "kmcheck");
156 if (IS_ERR(task))
157 return PTR_ERR(task);
158 system_ctl_set_bit(14, CR14_CHANNEL_REPORT_SUBMASK_BIT);
159 return 0;
160 }
161 device_initcall(crw_machine_check_init);
162