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 #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  */
  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  */
  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  */
  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 "
  81                                "than two chained crws; please report to "
  82                                "linux390@de.ibm.com!\n", __func__);
  83                         ccode = stcrw(&tmp_crw);
  84                         printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
  85                                "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
  86                                __func__, tmp_crw.slct, tmp_crw.oflw,
  87                                tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
  88                                tmp_crw.erc, tmp_crw.rsid);
  89                         printk(KERN_WARNING"%s: This was crw number %x in the "
  90                                "chain\n", __func__, chain);
  91                         if (ccode != 0)
  92                                 break;
  93                         chain = tmp_crw.chn ? chain + 1 : 0;
  94                         continue;
  95                 }
  96                 ccode = stcrw(&crw[chain]);
  97                 if (ccode != 0)
  98                         break;
  99                 printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
 100                        "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 101                        crw[chain].slct, crw[chain].oflw, crw[chain].chn,
 102                        crw[chain].rsc, crw[chain].anc, crw[chain].erc,
 103                        crw[chain].rsid);
 104                 /* Check for overflows. */
 105                 if (crw[chain].oflw) {
 106                         int i;
 107
 108                         pr_debug("%s: crw overflow detected!\n", __func__);
 109                         mutex_lock(&crw_handler_mutex);
 110                         for (i = 0; i < NR_RSCS; i++) {
 111                                 if (crw_handlers[i])
 112                                         crw_handlers[i](NULL, NULL, 1);
 113                         }
 114                         mutex_unlock(&crw_handler_mutex);
 115                         chain = 0;
 116                         continue;
 117                 }
 118                 if (crw[0].chn && !chain) {
 119                         chain++;
 120                         continue;
 121                 }
 122                 mutex_lock(&crw_handler_mutex);
 123                 handler = crw_handlers[crw[chain].rsc];
 124                 if (handler)
 125                         handler(&crw[0], chain ? &crw[1] : NULL, 0);
 126                 mutex_unlock(&crw_handler_mutex);
 127                 /* chain is always 0 or 1 here. */
 128                 chain = crw[chain].chn ? chain + 1 : 0;
 129         }
 130         if (atomic_dec_and_test(&crw_nr_req))
 131                 wake_up(&crw_handler_wait_q);
 132         goto repeat;
 133         return 0;
 134 }
 135
 136 void crw_handle_channel_report(void)
 137 {
 138         atomic_inc(&crw_nr_req);
 139         wake_up(&crw_handler_wait_q);
 140 }
 141
 142 void crw_wait_for_channel_report(void)
 143 {
 144         crw_handle_channel_report();
 145         wait_event(crw_handler_wait_q, atomic_read(&crw_nr_req) == 0);
 146 }
 147
 148 /*
 149  * Machine checks for the channel subsystem must be enabled
 150  * after the channel subsystem is initialized
 151  */
 152 static int __init crw_machine_check_init(void)
 153 {
 154         struct task_struct *task;
 155
 156         task = kthread_run(crw_collect_info, NULL, "kmcheck");
 157         if (IS_ERR(task))
 158                 return PTR_ERR(task);
 159         ctl_set_bit(14, 28);    /* enable channel report MCH */
 160         return 0;
 161 }
 162 device_initcall(crw_machine_check_init);