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