kernel/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 #include <asm/ctl_reg.h>
  17
  18 static DEFINE_MUTEX(crw_handler_mutex);
  19 static crw_handler_t crw_handlers[NR_RSCS];
  20 static atomic_t crw_nr_req = ATOMIC_INIT(0);
  21 static 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  */
  30 int 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  */
  49 void 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  */
  61 static int crw_collect_info(void *unused)
  62 {
  63         struct crw crw[2];
  64         int ccode, signal;
  65         unsigned int chain;
  66
  67 repeat:
  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
 135 void crw_handle_channel_report(void)
 136 {
 137         atomic_inc(&crw_nr_req);
 138         wake_up(&crw_handler_wait_q);
 139 }
 140
 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  */
 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         ctl_set_bit(14, 28);    /* enable channel report MCH */
 159         return 0;
 160 }
 161 device_initcall(crw_machine_check_init);