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 /* Adapter interrupt definitions */
  43 static void tiqdio_thinint_handler(struct airq_struct *airq);
  44
  45 static struct airq_struct tiqdio_airq = {
  46         .handler = tiqdio_thinint_handler,
  47         .isc = QDIO_AIRQ_ISC,
  48 };
  49
  50 static struct indicator_t *q_indicators;
  51
  52 u64 last_ai_time;
  53
  54 /* returns addr for the device state change indicator */
  55 static u32 *get_indicator(void)
  56 {
  57         int i;
  58
  59         for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
  60                 if (!atomic_read(&q_indicators[i].count)) {
  61                         atomic_set(&q_indicators[i].count, 1);
  62                         return &q_indicators[i].ind;
  63                 }
  64
  65         /* use the shared indicator */
  66         atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
  67         return &q_indicators[TIQDIO_SHARED_IND].ind;
  68 }
  69
  70 static void put_indicator(u32 *addr)
  71 {
  72         int i;
  73
  74         if (!addr)
  75                 return;
  76         i = ((unsigned long)addr - (unsigned long)q_indicators) /
  77                 sizeof(struct indicator_t);
  78         atomic_dec(&q_indicators[i].count);
  79 }
  80
  81 void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
  82 {
  83         mutex_lock(&tiq_list_lock);
  84         list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
  85         mutex_unlock(&tiq_list_lock);
  86         xchg(irq_ptr->dsci, 1 << 7);
  87 }
  88
  89 void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
  90 {
  91         struct qdio_q *q;
  92
  93         q = irq_ptr->input_qs[0];
  94         /* if establish triggered an error */
  95         if (!q || !q->entry.prev || !q->entry.next)
  96                 return;
  97
  98         mutex_lock(&tiq_list_lock);
  99         list_del_rcu(&q->entry);
 100         mutex_unlock(&tiq_list_lock);
 101         synchronize_rcu();
 102 }
 103
 104 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
 105 {
 106         return irq_ptr->nr_input_qs > 1;
 107 }
 108
 109 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
 110 {
 111         return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
 112 }
 113
 114 static inline int shared_ind(struct qdio_irq *irq_ptr)
 115 {
 116         return references_shared_dsci(irq_ptr) ||
 117                 has_multiple_inq_on_dsci(irq_ptr);
 118 }
 119
 120 void clear_nonshared_ind(struct qdio_irq *irq_ptr)
 121 {
 122         if (!is_thinint_irq(irq_ptr))
 123                 return;
 124         if (shared_ind(irq_ptr))
 125                 return;
 126         xchg(irq_ptr->dsci, 0);
 127 }
 128
 129 int test_nonshared_ind(struct qdio_irq *irq_ptr)
 130 {
 131         if (!is_thinint_irq(irq_ptr))
 132                 return 0;
 133         if (shared_ind(irq_ptr))
 134                 return 0;
 135         if (*irq_ptr->dsci)
 136                 return 1;
 137         else
 138                 return 0;
 139 }
 140
 141 static inline u32 clear_shared_ind(void)
 142 {
 143         if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
 144                 return 0;
 145         return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
 146 }
 147
 148 static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
 149 {
 150         struct qdio_q *q;
 151         int i;
 152
 153         if (!references_shared_dsci(irq) &&
 154             has_multiple_inq_on_dsci(irq))
 155                 xchg(irq->dsci, 0);
 156
 157         for_each_input_queue(irq, q, i) {
 158                 if (q->u.in.queue_start_poll) {
 159                         /* skip if polling is enabled or already in work */
 160                         if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
 161                                              &q->u.in.queue_irq_state)) {
 162                                 qperf_inc(q, int_discarded);
 163                                 continue;
 164                         }
 165
 166                         /* avoid dsci clear here, done after processing */
 167                         q->u.in.queue_start_poll(irq->cdev, q->nr,
 168                                                  irq->int_parm);
 169                 } else {
 170                         if (!shared_ind(irq))
 171                                 xchg(irq->dsci, 0);
 172
 173                         /*
 174                          * Call inbound processing but not directly
 175                          * since that could starve other thinint queues.
 176                          */
 177                         tasklet_schedule(&q->tasklet);
 178                 }
 179         }
 180 }
 181
 182 /**
 183  * tiqdio_thinint_handler - thin interrupt handler for qdio
 184  * @airq: pointer to adapter interrupt descriptor
 185  */
 186 static void tiqdio_thinint_handler(struct airq_struct *airq)
 187 {
 188         u32 si_used = clear_shared_ind();
 189         struct qdio_q *q;
 190
 191         last_ai_time = S390_lowcore.int_clock;
 192         inc_irq_stat(IRQIO_QAI);
 193
 194         /* protect tiq_list entries, only changed in activate or shutdown */
 195         rcu_read_lock();
 196
 197         /* check for work on all inbound thinint queues */
 198         list_for_each_entry_rcu(q, &tiq_list, entry) {
 199                 struct qdio_irq *irq;
 200
 201                 /* only process queues from changed sets */
 202                 irq = q->irq_ptr;
 203                 if (unlikely(references_shared_dsci(irq))) {
 204                         if (!si_used)
 205                                 continue;
 206                 } else if (!*irq->dsci)
 207                         continue;
 208
 209                 tiqdio_call_inq_handlers(irq);
 210
 211                 qperf_inc(q, adapter_int);
 212         }
 213         rcu_read_unlock();
 214 }
 215
 216 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 217 {
 218         struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
 219         u64 summary_indicator_addr, subchannel_indicator_addr;
 220         int rc;
 221
 222         if (reset) {
 223                 summary_indicator_addr = 0;
 224                 subchannel_indicator_addr = 0;
 225         } else {
 226                 summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 227                 subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 228         }
 229
 230         rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
 231                        subchannel_indicator_addr);
 232         if (rc) {
 233                 DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
 234                           scssc->response.code);
 235                 goto out;
 236         }
 237
 238         DBF_EVENT("setscind");
 239         DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
 240         DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
 241 out:
 242         return rc;
 243 }
 244
 245 /* allocate non-shared indicators and shared indicator */
 246 int __init tiqdio_allocate_memory(void)
 247 {
 248         q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
 249                              GFP_KERNEL);
 250         if (!q_indicators)
 251                 return -ENOMEM;
 252         return 0;
 253 }
 254
 255 void tiqdio_free_memory(void)
 256 {
 257         kfree(q_indicators);
 258 }
 259
 260 int __init tiqdio_register_thinints(void)
 261 {
 262         int rc;
 263
 264         rc = register_adapter_interrupt(&tiqdio_airq);
 265         if (rc) {
 266                 DBF_EVENT("RTI:%x", rc);
 267                 return rc;
 268         }
 269         return 0;
 270 }
 271
 272 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
 273 {
 274         if (!is_thinint_irq(irq_ptr))
 275                 return 0;
 276         return set_subchannel_ind(irq_ptr, 0);
 277 }
 278
 279 void qdio_setup_thinint(struct qdio_irq *irq_ptr)
 280 {
 281         if (!is_thinint_irq(irq_ptr))
 282                 return;
 283         irq_ptr->dsci = get_indicator();
 284         DBF_HEX(&irq_ptr->dsci, sizeof(void *));
 285 }
 286
 287 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
 288 {
 289         if (!is_thinint_irq(irq_ptr))
 290                 return;
 291
 292         /* reset adapter interrupt indicators */
 293         set_subchannel_ind(irq_ptr, 1);
 294         put_indicator(irq_ptr->dsci);
 295 }
 296
 297 void __exit tiqdio_unregister_thinints(void)
 298 {
 299         WARN_ON(!list_empty(&tiq_list));
 300         unregister_adapter_interrupt(&tiqdio_airq);
 301 }