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