drivers/s390/cio/airq.c

   1 /*
   2  *    Support for adapter interruptions
   3  *
   4  *    Copyright IBM Corp. 1999, 2007
   5  *    Author(s): Ingo Adlung <adlung@de.ibm.com>
   6  *               Cornelia Huck <cornelia.huck@de.ibm.com>
   7  *               Arnd Bergmann <arndb@de.ibm.com>
   8  *               Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
   9  */
  10
  11 #include <linux/init.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/rcupdate.h>
  15
  16 #include <asm/airq.h>
  17 #include <asm/isc.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[MAX_ISC+1];
  37 static struct airq_t *airqs[MAX_ISC+1][NR_AIRQS];
  38
  39 static int register_airq(struct airq_t *airq, u8 isc)
  40 {
  41         int i;
  42
  43         for (i = 0; i < NR_AIRQS; i++)
  44                 if (!cmpxchg(&airqs[isc][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  * @isc: isc for which the handler should be called
  54  *
  55  * Returns:
  56  *  Pointer to the indicator to be used on success
  57  *  ERR_PTR() if registration failed
  58  */
  59 void *s390_register_adapter_interrupt(adapter_int_handler_t handler,
  60                                       void *drv_data, u8 isc)
  61 {
  62         struct airq_t *airq;
  63         char dbf_txt[16];
  64         int ret;
  65
  66         if (isc > MAX_ISC)
  67                 return ERR_PTR(-EINVAL);
  68         airq = kmalloc(sizeof(struct airq_t), GFP_KERNEL);
  69         if (!airq) {
  70                 ret = -ENOMEM;
  71                 goto out;
  72         }
  73         airq->handler = handler;
  74         airq->drv_data = drv_data;
  75
  76         ret = register_airq(airq, isc);
  77 out:
  78         snprintf(dbf_txt, sizeof(dbf_txt), "rairq:%d", ret);
  79         CIO_TRACE_EVENT(4, dbf_txt);
  80         if (ret < 0) {
  81                 kfree(airq);
  82                 return ERR_PTR(ret);
  83         } else
  84                 return &indicators[isc].byte[ret];
  85 }
  86 EXPORT_SYMBOL(s390_register_adapter_interrupt);
  87
  88 /**
  89  * s390_unregister_adapter_interrupt - unregister adapter interrupt handler
  90  * @ind: indicator for which the handler is to be unregistered
  91  * @isc: interruption subclass
  92  */
  93 void s390_unregister_adapter_interrupt(void *ind, u8 isc)
  94 {
  95         struct airq_t *airq;
  96         char dbf_txt[16];
  97         int i;
  98
  99         i = (int) ((addr_t) ind) - ((addr_t) &indicators[isc].byte[0]);
 100         snprintf(dbf_txt, sizeof(dbf_txt), "urairq:%d", i);
 101         CIO_TRACE_EVENT(4, dbf_txt);
 102         indicators[isc].byte[i] = 0;
 103         airq = xchg(&airqs[isc][i], NULL);
 104         /*
 105          * Allow interrupts to complete. This will ensure that the airq handle
 106          * is no longer referenced by any interrupt handler.
 107          */
 108         synchronize_sched();
 109         kfree(airq);
 110 }
 111 EXPORT_SYMBOL(s390_unregister_adapter_interrupt);
 112
 113 #define INDICATOR_MASK  (0xffUL << ((NR_AIRQS_PER_WORD - 1) * 8))
 114
 115 void do_adapter_IO(u8 isc)
 116 {
 117         int w;
 118         int i;
 119         unsigned long word;
 120         struct airq_t *airq;
 121
 122         /*
 123          * Access indicator array in word-sized chunks to minimize storage
 124          * fetch operations.
 125          */
 126         for (w = 0; w < NR_AIRQ_WORDS; w++) {
 127                 word = indicators[isc].word[w];
 128                 i = w * NR_AIRQS_PER_WORD;
 129                 /*
 130                  * Check bytes within word for active indicators.
 131                  */
 132                 while (word) {
 133                         if (word & INDICATOR_MASK) {
 134                                 airq = airqs[isc][i];
 135                                 /* Make sure gcc reads from airqs only once. */
 136                                 barrier();
 137                                 if (likely(airq))
 138                                         airq->handler(&indicators[isc].byte[i],
 139                                                       airq->drv_data);
 140                                 else
 141                                         /*
 142                                          * Reset ill-behaved indicator.
 143                                          */
 144                                         indicators[isc].byte[i] = 0;
 145                         }
 146                         word <<= 8;
 147                         i++;
 148                 }
 149         }
 150 }