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 }
  87
  88 void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
  89 {
  90         struct qdio_q *q;
  91
  92         q = irq_ptr->input_qs[0];
  93         if (!q)
  94                 return;
  95
  96         mutex_lock(&tiq_list_lock);
  97         list_del_rcu(&q->entry);
  98         mutex_unlock(&tiq_list_lock);
  99         synchronize_rcu();
 100         INIT_LIST_HEAD(&q->entry);
 101 }
 102
 103 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
 104 {
 105         return irq_ptr->nr_input_qs > 1;
 106 }
 107
 108 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
 109 {
 110         return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
 111 }
 112
 113 static inline int shared_ind(struct qdio_irq *irq_ptr)
 114 {
 115         return references_shared_dsci(irq_ptr) ||
 116                 has_multiple_inq_on_dsci(irq_ptr);
 117 }
 118
 119 void clear_nonshared_ind(struct qdio_irq *irq_ptr)
 120 {
 121         if (!is_thinint_irq(irq_ptr))
 122                 return;
 123         if (shared_ind(irq_ptr))
 124                 return;
 125         xchg(irq_ptr->dsci, 0);
 126 }
 127
 128 int test_nonshared_ind(struct qdio_irq *irq_ptr)
 129 {
 130         if (!is_thinint_irq(irq_ptr))
 131                 return 0;
 132         if (shared_ind(irq_ptr))
 133                 return 0;
 134         if (*irq_ptr->dsci)
 135                 return 1;
 136         else
 137                 return 0;
 138 }
 139
 140 static inline u32 clear_shared_ind(void)
 141 {
 142         if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
 143                 return 0;
 144         return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
 145 }
 146
 147 static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
 148 {
 149         struct qdio_q *q;
 150         int i;
 151
 152         if (!references_shared_dsci(irq) &&
 153             has_multiple_inq_on_dsci(irq))
 154                 xchg(irq->dsci, 0);
 155
 156         for_each_input_queue(irq, q, i) {
 157                 if (q->u.in.queue_start_poll) {
 158                         /* skip if polling is enabled or already in work */
 159                         if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
 160                                              &q->u.in.queue_irq_state)) {
 161                                 qperf_inc(q, int_discarded);
 162                                 continue;
 163                         }
 164
 165                         /* avoid dsci clear here, done after processing */
 166                         q->u.in.queue_start_poll(irq->cdev, q->nr,
 167                                                  irq->int_parm);
 168                 } else {
 169                         if (!shared_ind(irq))
 170                                 xchg(irq->dsci, 0);
 171
 172                         /*
 173                          * Call inbound processing but not directly
 174                          * since that could starve other thinint queues.
 175                          */
 176                         tasklet_schedule(&q->tasklet);
 177                 }
 178         }
 179 }
 180
 181 /**
 182  * tiqdio_thinint_handler - thin interrupt handler for qdio
 183  * @airq: pointer to adapter interrupt descriptor
 184  */
 185 static void tiqdio_thinint_handler(struct airq_struct *airq)
 186 {
 187         u32 si_used = clear_shared_ind();
 188         struct qdio_q *q;
 189
 190         last_ai_time = S390_lowcore.int_clock;
 191         inc_irq_stat(IRQIO_QAI);
 192
 193         /* protect tiq_list entries, only changed in activate or shutdown */
 194         rcu_read_lock();
 195
 196         /* check for work on all inbound thinint queues */
 197         list_for_each_entry_rcu(q, &tiq_list, entry) {
 198                 struct qdio_irq *irq;
 199
 200                 /* only process queues from changed sets */
 201                 irq = q->irq_ptr;
 202                 if (unlikely(references_shared_dsci(irq))) {
 203                         if (!si_used)
 204                                 continue;
 205                 } else if (!*irq->dsci)
 206                         continue;
 207
 208                 tiqdio_call_inq_handlers(irq);
 209
 210                 qperf_inc(q, adapter_int);
 211         }
 212         rcu_read_unlock();
 213 }
 214
 215 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 216 {
 217         struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
 218         u64 summary_indicator_addr, subchannel_indicator_addr;
 219         int rc;
 220
 221         if (reset) {
 222                 summary_indicator_addr = 0;
 223                 subchannel_indicator_addr = 0;
 224         } else {
 225                 summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 226                 subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 227         }
 228
 229         rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
 230                        subchannel_indicator_addr);
 231         if (rc) {
 232                 DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
 233                           scssc->response.code);
 234                 goto out;
 235         }
 236
 237         DBF_EVENT("setscind");
 238         DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
 239         DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
 240 out:
 241         return rc;
 242 }
 243
 244 /* allocate non-shared indicators and shared indicator */
 245 int __init tiqdio_allocate_memory(void)
 246 {
 247         q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
 248                              GFP_KERNEL);
 249         if (!q_indicators)
 250                 return -ENOMEM;
 251         return 0;
 252 }
 253
 254 void tiqdio_free_memory(void)
 255 {
 256         kfree(q_indicators);
 257 }
 258
 259 int __init tiqdio_register_thinints(void)
 260 {
 261         int rc;
 262
 263         rc = register_adapter_interrupt(&tiqdio_airq);
 264         if (rc) {
 265                 DBF_EVENT("RTI:%x", rc);
 266                 return rc;
 267         }
 268         return 0;
 269 }
 270
 271 int qdio_establish_thinint(struct qdio_irq *irq_ptr)
 272 {
 273         int rc;
 274
 275         if (!is_thinint_irq(irq_ptr))
 276                 return 0;
 277
 278         irq_ptr->dsci = get_indicator();
 279         DBF_HEX(&irq_ptr->dsci, sizeof(void *));
 280
 281         rc = set_subchannel_ind(irq_ptr, 0);
 282         if (rc)
 283                 put_indicator(irq_ptr->dsci);
 284
 285         return rc;
 286 }
 287
 288 void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
 289 {
 290         if (!is_thinint_irq(irq_ptr))
 291                 return;
 292
 293         /* reset adapter interrupt indicators */
 294         set_subchannel_ind(irq_ptr, 1);
 295         put_indicator(irq_ptr->dsci);
 296 }
 297
 298 void __exit tiqdio_unregister_thinints(void)
 299 {
 300         WARN_ON(!list_empty(&tiq_list));
 301         unregister_adapter_interrupt(&tiqdio_airq);
 302 }