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/semaphore.h>
  12 #include <linux/mutex.h>
  13 #include <linux/kthread.h>
  14 #include <linux/init.h>
  15 #include <asm/crw.h>
  16
  17 static struct semaphore crw_semaphore;
  18 static DEFINE_MUTEX(crw_handler_mutex);
  19 static crw_handler_t crw_handlers[NR_RSCS];
  20
  21 /**
  22  * crw_register_handler() - register a channel report word handler
  23  * @rsc: reporting source code to handle
  24  * @handler: handler to be registered
  25  *
  26  * Returns %0 on success and a negative error value otherwise.
  27  */
  28 int crw_register_handler(int rsc, crw_handler_t handler)
  29 {
  30         int rc = 0;
  31
  32         if ((rsc < 0) || (rsc >= NR_RSCS))
  33                 return -EINVAL;
  34         mutex_lock(&crw_handler_mutex);
  35         if (crw_handlers[rsc])
  36                 rc = -EBUSY;
  37         else
  38                 crw_handlers[rsc] = handler;
  39         mutex_unlock(&crw_handler_mutex);
  40         return rc;
  41 }
  42
  43 /**
  44  * crw_unregister_handler() - unregister a channel report word handler
  45  * @rsc: reporting source code to handle
  46  */
  47 void crw_unregister_handler(int rsc)
  48 {
  49         if ((rsc < 0) || (rsc >= NR_RSCS))
  50                 return;
  51         mutex_lock(&crw_handler_mutex);
  52         crw_handlers[rsc] = NULL;
  53         mutex_unlock(&crw_handler_mutex);
  54 }
  55
  56 /*
  57  * Retrieve CRWs and call function to handle event.
  58  */
  59 static int crw_collect_info(void *unused)
  60 {
  61         struct crw crw[2];
  62         int ccode;
  63         unsigned int chain;
  64         int ignore;
  65
  66 repeat:
  67         ignore = down_interruptible(&crw_semaphore);
  68         chain = 0;
  69         while (1) {
  70                 crw_handler_t handler;
  71
  72                 if (unlikely(chain > 1)) {
  73                         struct crw tmp_crw;
  74
  75                         printk(KERN_WARNING"%s: Code does not support more "
  76                                "than two chained crws; please report to "
  77                                "linux390@de.ibm.com!\n", __func__);
  78                         ccode = stcrw(&tmp_crw);
  79                         printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
  80                                "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
  81                                __func__, tmp_crw.slct, tmp_crw.oflw,
  82                                tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
  83                                tmp_crw.erc, tmp_crw.rsid);
  84                         printk(KERN_WARNING"%s: This was crw number %x in the "
  85                                "chain\n", __func__, chain);
  86                         if (ccode != 0)
  87                                 break;
  88                         chain = tmp_crw.chn ? chain + 1 : 0;
  89                         continue;
  90                 }
  91                 ccode = stcrw(&crw[chain]);
  92                 if (ccode != 0)
  93                         break;
  94                 printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
  95                        "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
  96                        crw[chain].slct, crw[chain].oflw, crw[chain].chn,
  97                        crw[chain].rsc, crw[chain].anc, crw[chain].erc,
  98                        crw[chain].rsid);
  99                 /* Check for overflows. */
 100                 if (crw[chain].oflw) {
 101                         int i;
 102
 103                         pr_debug("%s: crw overflow detected!\n", __func__);
 104                         mutex_lock(&crw_handler_mutex);
 105                         for (i = 0; i < NR_RSCS; i++) {
 106                                 if (crw_handlers[i])
 107                                         crw_handlers[i](NULL, NULL, 1);
 108                         }
 109                         mutex_unlock(&crw_handler_mutex);
 110                         chain = 0;
 111                         continue;
 112                 }
 113                 if (crw[0].chn && !chain) {
 114                         chain++;
 115                         continue;
 116                 }
 117                 mutex_lock(&crw_handler_mutex);
 118                 handler = crw_handlers[crw[chain].rsc];
 119                 if (handler)
 120                         handler(&crw[0], chain ? &crw[1] : NULL, 0);
 121                 mutex_unlock(&crw_handler_mutex);
 122                 /* chain is always 0 or 1 here. */
 123                 chain = crw[chain].chn ? chain + 1 : 0;
 124         }
 125         goto repeat;
 126         return 0;
 127 }
 128
 129 void crw_handle_channel_report(void)
 130 {
 131         up(&crw_semaphore);
 132 }
 133
 134 /*
 135  * Separate initcall needed for semaphore initialization since
 136  * crw_handle_channel_report might be called before crw_machine_check_init.
 137  */
 138 static int __init crw_init_semaphore(void)
 139 {
 140         init_MUTEX_LOCKED(&crw_semaphore);
 141         return 0;
 142 }
 143 pure_initcall(crw_init_semaphore);
 144
 145 /*
 146  * Machine checks for the channel subsystem must be enabled
 147  * after the channel subsystem is initialized
 148  */
 149 static int __init crw_machine_check_init(void)
 150 {
 151         struct task_struct *task;
 152
 153         task = kthread_run(crw_collect_info, NULL, "kmcheck");
 154         if (IS_ERR(task))
 155                 return PTR_ERR(task);
 156         ctl_set_bit(14, 28);    /* enable channel report MCH */
 157         return 0;
 158 }
 159 device_initcall(crw_machine_check_init);