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