release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/s390/cio/crw.c

   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
  17 static DEFINE_MUTEX(crw_handler_mutex);
  18 static crw_handler_t crw_handlers[NR_RSCS];
  19 static atomic_t crw_nr_req = ATOMIC_INIT(0);
  20 static DECLARE_WAIT_QUEUE_HEAD(crw_handler_wait_q);
  21
  22 /**
  23  * crw_register_handler() - register a channel report word handler
  24  * @rsc: reporting source code to handle
  25  * @handler: handler to be registered
  26  *
  27  * Returns %0 on success and a negative error value otherwise.
  28  */
  29 int crw_register_handler(int rsc, crw_handler_t handler)
  30 {
  31         int rc = 0;
  32
  33         if ((rsc < 0) || (rsc >= NR_RSCS))
  34                 return -EINVAL;
  35         mutex_lock(&crw_handler_mutex);
  36         if (crw_handlers[rsc])
  37                 rc = -EBUSY;
  38         else
  39                 crw_handlers[rsc] = handler;
  40         mutex_unlock(&crw_handler_mutex);
  41         return rc;
  42 }
  43
  44 /**
  45  * crw_unregister_handler() - unregister a channel report word handler
  46  * @rsc: reporting source code to handle
  47  */
  48 void crw_unregister_handler(int rsc)
  49 {
  50         if ((rsc < 0) || (rsc >= NR_RSCS))
  51                 return;
  52         mutex_lock(&crw_handler_mutex);
  53         crw_handlers[rsc] = NULL;
  54         mutex_unlock(&crw_handler_mutex);
  55 }
  56
  57 /*
  58  * Retrieve CRWs and call function to handle event.
  59  */
  60 static int crw_collect_info(void *unused)
  61 {
  62         struct crw crw[2];
  63         int ccode, signal;
  64         unsigned int chain;
  65
  66 repeat:
  67         signal = wait_event_interruptible(crw_handler_wait_q,
  68                                           atomic_read(&crw_nr_req) > 0);
  69         if (unlikely(signal))
  70                 atomic_inc(&crw_nr_req);
  71         chain = 0;
  72         while (1) {
  73                 crw_handler_t handler;
  74
  75                 if (unlikely(chain > 1)) {
  76                         struct crw tmp_crw;
  77
  78                         printk(KERN_WARNING"%s: Code does not support more "
  79                                "than two chained crws; please report to "
  80                                "linux390@de.ibm.com!\n", __func__);
  81                         ccode = stcrw(&tmp_crw);
  82                         printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
  83                                "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
  84                                __func__, tmp_crw.slct, tmp_crw.oflw,
  85                                tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
  86                                tmp_crw.erc, tmp_crw.rsid);
  87                         printk(KERN_WARNING"%s: This was crw number %x in the "
  88                                "chain\n", __func__, chain);
  89                         if (ccode != 0)
  90                                 break;
  91                         chain = tmp_crw.chn ? chain + 1 : 0;
  92                         continue;
  93                 }
  94                 ccode = stcrw(&crw[chain]);
  95                 if (ccode != 0)
  96                         break;
  97                 printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
  98                        "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
  99                        crw[chain].slct, crw[chain].oflw, crw[chain].chn,
 100                        crw[chain].rsc, crw[chain].anc, crw[chain].erc,
 101                        crw[chain].rsid);
 102                 /* Check for overflows. */
 103                 if (crw[chain].oflw) {
 104                         int i;
 105
 106                         pr_debug("%s: crw overflow detected!\n", __func__);
 107                         mutex_lock(&crw_handler_mutex);
 108                         for (i = 0; i < NR_RSCS; i++) {
 109                                 if (crw_handlers[i])
 110                                         crw_handlers[i](NULL, NULL, 1);
 111                         }
 112                         mutex_unlock(&crw_handler_mutex);
 113                         chain = 0;
 114                         continue;
 115                 }
 116                 if (crw[0].chn && !chain) {
 117                         chain++;
 118                         continue;
 119                 }
 120                 mutex_lock(&crw_handler_mutex);
 121                 handler = crw_handlers[crw[chain].rsc];
 122                 if (handler)
 123                         handler(&crw[0], chain ? &crw[1] : NULL, 0);
 124                 mutex_unlock(&crw_handler_mutex);
 125                 /* chain is always 0 or 1 here. */
 126                 chain = crw[chain].chn ? chain + 1 : 0;
 127         }
 128         if (atomic_dec_and_test(&crw_nr_req))
 129                 wake_up(&crw_handler_wait_q);
 130         goto repeat;
 131         return 0;
 132 }
 133
 134 void crw_handle_channel_report(void)
 135 {
 136         atomic_inc(&crw_nr_req);
 137         wake_up(&crw_handler_wait_q);
 138 }
 139
 140 void crw_wait_for_channel_report(void)
 141 {
 142         crw_handle_channel_report();
 143         wait_event(crw_handler_wait_q, atomic_read(&crw_nr_req) == 0);
 144 }
 145
 146 /*
 147  * Machine checks for the channel subsystem must be enabled
 148  * after the channel subsystem is initialized
 149  */
 150 static int __init crw_machine_check_init(void)
 151 {
 152         struct task_struct *task;
 153
 154         task = kthread_run(crw_collect_info, NULL, "kmcheck");
 155         if (IS_ERR(task))
 156                 return PTR_ERR(task);
 157         ctl_set_bit(14, 28);    /* enable channel report MCH */
 158         return 0;
 159 }
 160 device_initcall(crw_machine_check_init);