LXR linux/drivers/s390/cio/qdio

   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 */
  33struct 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 */
  39static LIST_HEAD(tiq_list);
  40static DEFINE_MUTEX(tiq_list_lock);
  41
  42/* Adapter interrupt definitions */
  43static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating);
  44
  45static struct airq_struct tiqdio_airq = {
  46        .handler = tiqdio_thinint_handler,
  47        .isc = QDIO_AIRQ_ISC,
  48};
  49
  50static struct indicator_t *q_indicators;
  51
  52u64 last_ai_time;
  53
  54/* returns addr for the device state change indicator */
  55static 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
  68static 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
  77void 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
  84void 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
  99static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
 100{
 101        return irq_ptr->nr_input_qs > 1;
 102}
 103
 104static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
 105{
 106        return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
 107}
 108
 109static 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
 115void 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
 124int 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
 136static 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
 143static 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 * @floating: flag to recognize floating vs. directed interrupts (unused)
 181 */
 182static void tiqdio_thinint_handler(struct airq_struct *airq, bool floating)
 183{
 184        u32 si_used = clear_shared_ind();
 185        struct qdio_q *q;
 186
 187        last_ai_time = S390_lowcore.int_clock;
 188        inc_irq_stat(IRQIO_QAI);
 189
 190        /* protect tiq_list entries, only changed in activate or shutdown */
 191        rcu_read_lock();
 192
 193        /* check for work on all inbound thinint queues */
 194        list_for_each_entry_rcu(q, &tiq_list, entry) {
 195                struct qdio_irq *irq;
 196
 197                /* only process queues from changed sets */
 198                irq = q->irq_ptr;
 199                if (unlikely(references_shared_dsci(irq))) {
 200                        if (!si_used)
 201                                continue;
 202                } else if (!*irq->dsci)
 203                        continue;
 204
 205                tiqdio_call_inq_handlers(irq);
 206
 207                qperf_inc(q, adapter_int);
 208        }
 209        rcu_read_unlock();
 210}
 211
 212static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 213{
 214        struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
 215        u64 summary_indicator_addr, subchannel_indicator_addr;
 216        int rc;
 217
 218        if (reset) {
 219                summary_indicator_addr = 0;
 220                subchannel_indicator_addr = 0;
 221        } else {
 222                summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 223                subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 224        }
 225
 226        rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
 227                       subchannel_indicator_addr);
 228        if (rc) {
 229                DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
 230                          scssc->response.code);
 231                goto out;
 232        }
 233
 234        DBF_EVENT("setscind");
 235        DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
 236        DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
 237out:
 238        return rc;
 239}
 240
 241/* allocate non-shared indicators and shared indicator */
 242int __init tiqdio_allocate_memory(void)
 243{
 244        q_indicators = kcalloc(TIQDIO_NR_INDICATORS,
 245                               sizeof(struct indicator_t),
 246                               GFP_KERNEL);
 247        if (!q_indicators)
 248                return -ENOMEM;
 249        return 0;
 250}
 251
 252void tiqdio_free_memory(void)
 253{
 254        kfree(q_indicators);
 255}
 256
 257int __init tiqdio_register_thinints(void)
 258{
 259        int rc;
 260
 261        rc = register_adapter_interrupt(&tiqdio_airq);
 262        if (rc) {
 263                DBF_EVENT("RTI:%x", rc);
 264                return rc;
 265        }
 266        return 0;
 267}
 268
 269int qdio_establish_thinint(struct qdio_irq *irq_ptr)
 270{
 271        if (!is_thinint_irq(irq_ptr))
 272                return 0;
 273        return set_subchannel_ind(irq_ptr, 0);
 274}
 275
 276void qdio_setup_thinint(struct qdio_irq *irq_ptr)
 277{
 278        if (!is_thinint_irq(irq_ptr))
 279                return;
 280        irq_ptr->dsci = get_indicator();
 281        DBF_HEX(&irq_ptr->dsci, sizeof(void *));
 282}
 283
 284void qdio_shutdown_thinint(struct qdio_irq *irq_ptr)
 285{
 286        if (!is_thinint_irq(irq_ptr))
 287                return;
 288
 289        /* reset adapter interrupt indicators */
 290        set_subchannel_ind(irq_ptr, 1);
 291        put_indicator(irq_ptr->dsci);
 292}
 293
 294void __exit tiqdio_unregister_thinints(void)
 295{
 296        WARN_ON(!list_empty(&tiq_list));
 297        unregister_adapter_interrupt(&tiqdio_airq);
 298}
 299