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