drivers/s390/cio/airq.c

   1 /*
   2  *  drivers/s390/cio/airq.c
   3  *    Support for adapter interruptions
   4  *
   5  *    Copyright IBM Corp. 1999,2007
   6  *    Author(s): Ingo Adlung <adlung@de.ibm.com>
   7  *               Cornelia Huck <cornelia.huck@de.ibm.com>
   8  *               Arnd Bergmann <arndb@de.ibm.com>
   9  *               Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/rcupdate.h>
  16
  17 #include <asm/airq.h>
  18
  19 #include "cio.h"
  20 #include "cio_debug.h"
  21
  22 #define NR_AIRQS                32
  23 #define NR_AIRQS_PER_WORD       sizeof(unsigned long)
  24 #define NR_AIRQ_WORDS           (NR_AIRQS / NR_AIRQS_PER_WORD)
  25
  26 union indicator_t {
  27         unsigned long word[NR_AIRQ_WORDS];
  28         unsigned char byte[NR_AIRQS];
  29 } __attribute__((packed));
  30
  31 struct airq_t {
  32         adapter_int_handler_t handler;
  33         void *drv_data;
  34 };
  35
  36 static union indicator_t indicators;
  37 static struct airq_t *airqs[NR_AIRQS];
  38
  39 static int register_airq(struct airq_t *airq)
  40 {
  41         int i;
  42
  43         for (i = 0; i < NR_AIRQS; i++)
  44                 if (!cmpxchg(&airqs[i], NULL, airq))
  45                         return i;
  46         return -ENOMEM;
  47 }
  48
  49 /**
  50  * s390_register_adapter_interrupt() - register adapter interrupt handler
  51  * @handler: adapter handler to be registered
  52  * @drv_data: driver data passed with each call to the handler
  53  *
  54  * Returns:
  55  *  Pointer to the indicator to be used on success
  56  *  ERR_PTR() if registration failed
  57  */
  58 void *s390_register_adapter_interrupt(adapter_int_handler_t handler,
  59                                       void *drv_data)
  60 {
  61         struct airq_t *airq;
  62         char dbf_txt[16];
  63         int ret;
  64
  65         airq = kmalloc(sizeof(struct airq_t), GFP_KERNEL);
  66         if (!airq) {
  67                 ret = -ENOMEM;
  68                 goto out;
  69         }
  70         airq->handler = handler;
  71         airq->drv_data = drv_data;
  72         ret = register_airq(airq);
  73         if (ret < 0)
  74                 kfree(airq);
  75 out:
  76         snprintf(dbf_txt, sizeof(dbf_txt), "rairq:%d", ret);
  77         CIO_TRACE_EVENT(4, dbf_txt);
  78         if (ret < 0)
  79                 return ERR_PTR(ret);
  80         else
  81                 return &indicators.byte[ret];
  82 }
  83 EXPORT_SYMBOL(s390_register_adapter_interrupt);
  84
  85 /**
  86  * s390_unregister_adapter_interrupt - unregister adapter interrupt handler
  87  * @ind: indicator for which the handler is to be unregistered
  88  */
  89 void s390_unregister_adapter_interrupt(void *ind)
  90 {
  91         struct airq_t *airq;
  92         char dbf_txt[16];
  93         int i;
  94
  95         i = (int) ((addr_t) ind) - ((addr_t) &indicators.byte[0]);
  96         snprintf(dbf_txt, sizeof(dbf_txt), "urairq:%d", i);
  97         CIO_TRACE_EVENT(4, dbf_txt);
  98         indicators.byte[i] = 0;
  99         airq = xchg(&airqs[i], NULL);
 100         /*
 101          * Allow interrupts to complete. This will ensure that the airq handle
 102          * is no longer referenced by any interrupt handler.
 103          */
 104         synchronize_sched();
 105         kfree(airq);
 106 }
 107 EXPORT_SYMBOL(s390_unregister_adapter_interrupt);
 108
 109 #define INDICATOR_MASK  (0xffUL << ((NR_AIRQS_PER_WORD - 1) * 8))
 110
 111 void do_adapter_IO(void)
 112 {
 113         int w;
 114         int i;
 115         unsigned long word;
 116         struct airq_t *airq;
 117
 118         /*
 119          * Access indicator array in word-sized chunks to minimize storage
 120          * fetch operations.
 121          */
 122         for (w = 0; w < NR_AIRQ_WORDS; w++) {
 123                 word = indicators.word[w];
 124                 i = w * NR_AIRQS_PER_WORD;
 125                 /*
 126                  * Check bytes within word for active indicators.
 127                  */
 128                 while (word) {
 129                         if (word & INDICATOR_MASK) {
 130                                 airq = airqs[i];
 131                                 if (likely(airq))
 132                                         airq->handler(&indicators.byte[i],
 133                                                       airq->drv_data);
 134                                 else
 135                                         /*
 136                                          * Reset ill-behaved indicator.
 137                                          */
 138                                         indicators.byte[i] = 0;
 139                         }
 140                         word <<= 8;
 141                         i++;
 142                 }
 143         }
 144 }