1/*
2 *   Channel report handling code
3 *
4 *    Copyright IBM Corp. 2000, 2009
5 *    Author(s): Ingo Adlung <adlung@de.ibm.com>,
6 *		 Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 *		 Cornelia Huck <cornelia.huck@de.ibm.com>,
8 *		 Heiko Carstens <heiko.carstens@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/crw.h>
16#include <asm/ctl_reg.h>
17
18static DEFINE_MUTEX(crw_handler_mutex);
19static crw_handler_t crw_handlers[NR_RSCS];
20static atomic_t crw_nr_req = ATOMIC_INIT(0);
21static DECLARE_WAIT_QUEUE_HEAD(crw_handler_wait_q);
22
23/**
24 * crw_register_handler() - register a channel report word handler
25 * @rsc: reporting source code to handle
26 * @handler: handler to be registered
27 *
28 * Returns %0 on success and a negative error value otherwise.
29 */
30int crw_register_handler(int rsc, crw_handler_t handler)
31{
32	int rc = 0;
33
34	if ((rsc < 0) || (rsc >= NR_RSCS))
35		return -EINVAL;
36	mutex_lock(&crw_handler_mutex);
37	if (crw_handlers[rsc])
38		rc = -EBUSY;
39	else
40		crw_handlers[rsc] = handler;
41	mutex_unlock(&crw_handler_mutex);
42	return rc;
43}
44
45/**
46 * crw_unregister_handler() - unregister a channel report word handler
47 * @rsc: reporting source code to handle
48 */
49void crw_unregister_handler(int rsc)
50{
51	if ((rsc < 0) || (rsc >= NR_RSCS))
52		return;
53	mutex_lock(&crw_handler_mutex);
54	crw_handlers[rsc] = NULL;
55	mutex_unlock(&crw_handler_mutex);
56}
57
58/*
59 * Retrieve CRWs and call function to handle event.
60 */
61static int crw_collect_info(void *unused)
62{
63	struct crw crw[2];
64	int ccode, signal;
65	unsigned int chain;
66
67repeat:
68	signal = wait_event_interruptible(crw_handler_wait_q,
69					  atomic_read(&crw_nr_req) > 0);
70	if (unlikely(signal))
71		atomic_inc(&crw_nr_req);
72	chain = 0;
73	while (1) {
74		crw_handler_t handler;
75
76		if (unlikely(chain > 1)) {
77			struct crw tmp_crw;
78
79			printk(KERN_WARNING"%s: Code does not support more "
80			       "than two chained crws; please report to "
81			       "linux390@de.ibm.com!\n", __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
135void crw_handle_channel_report(void)
136{
137	atomic_inc(&crw_nr_req);
138	wake_up(&crw_handler_wait_q);
139}
140
141void 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 */
151static 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	ctl_set_bit(14, 28);	/* enable channel report MCH */
159	return 0;
160}
161device_initcall(crw_machine_check_init);
162