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 #include <asm/tpi.h>
  19
  20 #include "cio.h"
  21 #include "ioasm.h"
  22 #include "qdio.h"
  23 #include "qdio_debug.h"
  24
  25 /*
  26  * Restriction: only 63 iqdio subchannels would have its own indicator,
  27  * after that, subsequent subchannels share one indicator
  28  */
  29 #define TIQDIO_NR_NONSHARED_IND         63
  30 #define TIQDIO_NR_INDICATORS            (TIQDIO_NR_NONSHARED_IND + 1)
  31 #define TIQDIO_SHARED_IND               63
  32
  33 /* device state change indicators */
  34 struct indicator_t {
  35         u32 ind;        /* u32 because of compare-and-swap performance */
  36         atomic_t count; /* use count, 0 or 1 for non-shared indicators */
  37 };
  38
  39 /* list of thin interrupt input queues */
  40 static LIST_HEAD(tiq_list);
  41 static DEFINE_MUTEX(tiq_list_lock);
  42
  43 static struct indicator_t *q_indicators;
  44
  45 u64 last_ai_time;
  46
  47 /* returns addr for the device state change indicator */
  48 static u32 *get_indicator(void)
  49 {
  50         int i;
  51
  52         for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
  53                 if (!atomic_cmpxchg(&q_indicators[i].count, 0, 1))
  54                         return &q_indicators[i].ind;
  55
  56         /* use the shared indicator */
  57         atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
  58         return &q_indicators[TIQDIO_SHARED_IND].ind;
  59 }
  60
  61 static void put_indicator(u32 *addr)
  62 {
  63         struct indicator_t *ind = container_of(addr, struct indicator_t, ind);
  64
  65         if (!addr)
  66                 return;
  67         atomic_dec(&ind->count);
  68 }
  69
  70 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
  71 {
  72         return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
  73 }
  74
  75 int test_nonshared_ind(struct qdio_irq *irq_ptr)
  76 {
  77         if (!is_thinint_irq(irq_ptr))
  78                 return 0;
  79         if (references_shared_dsci(irq_ptr))
  80                 return 0;
  81         if (*irq_ptr->dsci)
  82                 return 1;
  83         else
  84                 return 0;
  85 }
  86
  87 static inline u32 clear_shared_ind(void)
  88 {
  89         if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
  90                 return 0;
  91         return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
  92 }
  93
  94 /**
  95  * tiqdio_thinint_handler - thin interrupt handler for qdio
  96  * @airq: pointer to adapter interrupt descriptor
  97  * @tpi_info: interrupt information (e.g. floating vs directed -- unused)
  98  */
  99 static void tiqdio_thinint_handler(struct airq_struct *airq,
 100                                    struct tpi_info *tpi_info)
 101 {
 102         u64 irq_time = S390_lowcore.int_clock;
 103         u32 si_used = clear_shared_ind();
 104         struct qdio_irq *irq;
 105
 106         last_ai_time = irq_time;
 107         inc_irq_stat(IRQIO_QAI);
 108
 109         /* protect tiq_list entries, only changed in activate or shutdown */
 110         rcu_read_lock();
 111
 112         list_for_each_entry_rcu(irq, &tiq_list, entry) {
 113                 /* only process queues from changed sets */
 114                 if (unlikely(references_shared_dsci(irq))) {
 115                         if (!si_used)
 116                                 continue;
 117                 } else {
 118                         if (!*irq->dsci)
 119                                 continue;
 120
 121                         xchg(irq->dsci, 0);
 122                 }
 123
 124                 qdio_deliver_irq(irq);
 125                 irq->last_data_irq_time = irq_time;
 126
 127                 QDIO_PERF_STAT_INC(irq, adapter_int);
 128         }
 129         rcu_read_unlock();
 130 }
 131
 132 static struct airq_struct tiqdio_airq = {
 133         .handler = tiqdio_thinint_handler,
 134         .isc = QDIO_AIRQ_ISC,
 135 };
 136
 137 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 138 {
 139         struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
 140         u64 summary_indicator_addr, subchannel_indicator_addr;
 141         int rc;
 142
 143         if (reset) {
 144                 summary_indicator_addr = 0;
 145                 subchannel_indicator_addr = 0;
 146         } else {
 147                 summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 148                 subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 149         }
 150
 151         rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
 152                        subchannel_indicator_addr, tiqdio_airq.isc);
 153         if (rc) {
 154                 DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
 155                           scssc->response.code);
 156                 goto out;
 157         }
 158
 159         DBF_EVENT("setscind");
 160         DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
 161         DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
 162 out:
 163         return rc;
 164 }
 165
 166 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
 167 {
 168         int rc;
 169
 170         if (!is_thinint_irq(irq_ptr))
 171                 return 0;
 172
 173         irq_ptr->dsci = get_indicator();
 174         DBF_HEX(&irq_ptr->dsci, sizeof(void *));
 175
 176         rc = set_subchannel_ind(irq_ptr, 0);
 177         if (rc) {
 178                 put_indicator(irq_ptr->dsci);
 179                 return rc;
 180         }
 181
 182         mutex_lock(&tiq_list_lock);
 183         list_add_rcu(&irq_ptr->entry, &tiq_list);
 184         mutex_unlock(&tiq_list_lock);
 185         return 0;
 186 }
 187
 188 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
 189 {
 190         if (!is_thinint_irq(irq_ptr))
 191                 return;
 192
 193         mutex_lock(&tiq_list_lock);
 194         list_del_rcu(&irq_ptr->entry);
 195         mutex_unlock(&tiq_list_lock);
 196         synchronize_rcu();
 197
 198         /* reset adapter interrupt indicators */
 199         set_subchannel_ind(irq_ptr, 1);
 200         put_indicator(irq_ptr->dsci);
 201 }
 202
 203 int __init qdio_thinint_init(void)
 204 {
 205         int rc;
 206
 207         q_indicators = kcalloc(TIQDIO_NR_INDICATORS, sizeof(struct indicator_t),
 208                                GFP_KERNEL);
 209         if (!q_indicators)
 210                 return -ENOMEM;
 211
 212         rc = register_adapter_interrupt(&tiqdio_airq);
 213         if (rc) {
 214                 DBF_EVENT("RTI:%x", rc);
 215                 kfree(q_indicators);
 216                 return rc;
 217         }
 218         return 0;
 219 }
 220
 221 void __exit qdio_thinint_exit(void)
 222 {
 223         WARN_ON(!list_empty(&tiq_list));
 224         unregister_adapter_interrupt(&tiqdio_airq);
 225         kfree(q_indicators);
 226 }