drivers/s390/cio/qdio_thinint.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright IBM Corp. 2000, 2009
   4  * Author(s): Utz Bacher <utz.bacher@de.ibm.com>
   5  *            Cornelia Huck <cornelia.huck@de.ibm.com>
   6  *            Jan Glauber <jang@linux.vnet.ibm.com>
   7  */
   8 #include <linux/io.h>
   9 #include <linux/slab.h>
  10 #include <linux/kernel_stat.h>
  11 #include <linux/atomic.h>
  12 #include <linux/rculist.h>
  13
  14 #include <asm/debug.h>
  15 #include <asm/qdio.h>
  16 #include <asm/airq.h>
  17 #include <asm/isc.h>
  18
  19 #include "cio.h"
  20 #include "ioasm.h"
  21 #include "qdio.h"
  22 #include "qdio_debug.h"
  23
  24 /*
  25  * Restriction: only 63 iqdio subchannels would have its own indicator,
  26  * after that, subsequent subchannels share one indicator
  27  */
  28 #define TIQDIO_NR_NONSHARED_IND         63
  29 #define TIQDIO_NR_INDICATORS            (TIQDIO_NR_NONSHARED_IND + 1)
  30 #define TIQDIO_SHARED_IND               63
  31
  32 /* device state change indicators */
  33 struct indicator_t {
  34         u32 ind;        /* u32 because of compare-and-swap performance */
  35         atomic_t count; /* use count, 0 or 1 for non-shared indicators */
  36 };
  37
  38 /* list of thin interrupt input queues */
  39 static LIST_HEAD(tiq_list);
  40 static DEFINE_MUTEX(tiq_list_lock);
  41
  42 static struct indicator_t *q_indicators;
  43
  44 u64 last_ai_time;
  45
  46 /* returns addr for the device state change indicator */
  47 static u32 *get_indicator(void)
  48 {
  49         int i;
  50
  51         for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
  52                 if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
  53                         return &q_indicators[i].ind;
  54
  55         /* use the shared indicator */
  56         atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
  57         return &q_indicators[TIQDIO_SHARED_IND].ind;
  58 }
  59
  60 static void put_indicator(u32 *addr)
  61 {
  62         struct indicator_t *ind = container_of(addr, struct indicator_t, ind);
  63
  64         if (!addr)
  65                 return;
  66         atomic_dec(&ind->count);
  67 }
  68
  69 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
  70 {
  71         return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
  72 }
  73
  74 int test_nonshared_ind(struct qdio_irq *irq_ptr)
  75 {
  76         if (!is_thinint_irq(irq_ptr))
  77                 return 0;
  78         if (references_shared_dsci(irq_ptr))
  79                 return 0;
  80         if (*irq_ptr->dsci)
  81                 return 1;
  82         else
  83                 return 0;
  84 }
  85
  86 static inline u32 clear_shared_ind(void)
  87 {
  88         if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
  89                 return 0;
  90         return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
  91 }
  92
  93 /**
  94  * tiqdio_thinint_handler - thin interrupt handler for qdio
  95  * @airq: pointer to adapter interrupt descriptor
  96  * @floating: flag to recognize floating vs. directed interrupts (unused)
  97  */
  98 static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
  99 {
 100         u32 si_used = clear_shared_ind();
 101         struct qdio_irq *irq;
 102
 103         last_ai_time = S390_lowcore.int_clock;
 104         inc_irq_stat(IRQIO_QAI);
 105
 106         /* protect tiq_list entries, only changed in activate or shutdown */
 107         rcu_read_lock();
 108
 109         list_for_each_entry_rcu(irq, &tiq_list, entry) {
 110                 /* only process queues from changed sets */
 111                 if (unlikely(references_shared_dsci(irq))) {
 112                         if (!si_used)
 113                                 continue;
 114                 } else {
 115                         if (!*irq->dsci)
 116                                 continue;
 117
 118                         xchg(irq->dsci, 0);
 119                 }
 120
 121                 qdio_deliver_irq(irq);
 122
 123                 QDIO_PERF_STAT_INC(irq, adapter_int);
 124         }
 125         rcu_read_unlock();
 126 }
 127
 128 static struct airq_struct tiqdio_airq = {
 129         .handler = tiqdio_thinint_handler,
 130         .isc = QDIO_AIRQ_ISC,
 131 };
 132
 133 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 134 {
 135         struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
 136         u64 summary_indicator_addr, subchannel_indicator_addr;
 137         int rc;
 138
 139         if (reset) {
 140                 summary_indicator_addr = 0;
 141                 subchannel_indicator_addr = 0;
 142         } else {
 143                 summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 144                 subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 145         }
 146
 147         rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
 148                        subchannel_indicator_addr, tiqdio_airq.isc);
 149         if (rc) {
 150                 DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
 151                           scssc->response.code);
 152                 goto out;
 153         }
 154
 155         DBF_EVENT("setscind");
 156         DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
 157         DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
 158 out:
 159         return rc;
 160 }
 161
 162 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
 163 {
 164         int rc;
 165
 166         if (!is_thinint_irq(irq_ptr))
 167                 return 0;
 168
 169         irq_ptr->dsci = get_indicator();
 170         DBF_HEX(&irq_ptr->dsci, sizeof(void *));
 171
 172         rc = set_subchannel_ind(irq_ptr, 0);
 173         if (rc) {
 174                 put_indicator(irq_ptr->dsci);
 175                 return rc;
 176         }
 177
 178         mutex_lock(&tiq_list_lock);
 179         list_add_rcu(&irq_ptr->entry, &tiq_list);
 180         mutex_unlock(&tiq_list_lock);
 181         return 0;
 182 }
 183
 184 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
 185 {
 186         if (!is_thinint_irq(irq_ptr))
 187                 return;
 188
 189         mutex_lock(&tiq_list_lock);
 190         list_del_rcu(&irq_ptr->entry);
 191         mutex_unlock(&tiq_list_lock);
 192         synchronize_rcu();
 193
 194         /* reset adapter interrupt indicators */
 195         set_subchannel_ind(irq_ptr, 1);
 196         put_indicator(irq_ptr->dsci);
 197 }
 198
 199 int __init qdio_thinint_init(void)
 200 {
 201         int rc;
 202
 203         q_indicators = kcalloc(TIQDIO_NR_INDICATORS, sizeof(struct indicator_t),
 204                                GFP_KERNEL);
 205         if (!q_indicators)
 206                 return -ENOMEM;
 207
 208         rc = register_adapter_interrupt(&tiqdio_airq);
 209         if (rc) {
 210                 DBF_EVENT("RTI:%x", rc);
 211                 kfree(q_indicators);
 212                 return rc;
 213         }
 214         return 0;
 215 }
 216
 217 void __exit qdio_thinint_exit(void)
 218 {
 219         WARN_ON(!list_empty(&tiq_list));
 220         unregister_adapter_interrupt(&tiqdio_airq);
 221         kfree(q_indicators);
 222 }