kernel/drivers/s390/cio/qdio_thinint.c

   1 /*
   2  * Copyright IBM Corp. 2000, 2009
   3  * Author(s): Utz Bacher <utz.bacher@de.ibm.com>
   4  *            Cornelia Huck <cornelia.huck@de.ibm.com>
   5  *            Jan Glauber <jang@linux.vnet.ibm.com>
   6  */
   7 #include <linux/io.h>
   8 #include <linux/slab.h>
   9 #include <linux/kernel_stat.h>
  10 #include <linux/atomic.h>
  11 #include <asm/debug.h>
  12 #include <asm/qdio.h>
  13 #include <asm/airq.h>
  14 #include <asm/isc.h>
  15
  16 #include "cio.h"
  17 #include "ioasm.h"
  18 #include "qdio.h"
  19 #include "qdio_debug.h"
  20
  21 /*
  22  * Restriction: only 63 iqdio subchannels would have its own indicator,
  23  * after that, subsequent subchannels share one indicator
  24  */
  25 #define TIQDIO_NR_NONSHARED_IND         63
  26 #define TIQDIO_NR_INDICATORS            (TIQDIO_NR_NONSHARED_IND + 1)
  27 #define TIQDIO_SHARED_IND               63
  28
  29 /* device state change indicators */
  30 struct indicator_t {
  31         u32 ind;        /* u32 because of compare-and-swap performance */
  32         atomic_t count; /* use count, 0 or 1 for non-shared indicators */
  33 };
  34
  35 /* list of thin interrupt input queues */
  36 static LIST_HEAD(tiq_list);
  37 static DEFINE_MUTEX(tiq_list_lock);
  38
  39 /* Adapter interrupt definitions */
  40 static void tiqdio_thinint_handler(struct airq_struct *airq);
  41
  42 static struct airq_struct tiqdio_airq = {
  43         .handler = tiqdio_thinint_handler,
  44         .isc = QDIO_AIRQ_ISC,
  45 };
  46
  47 static struct indicator_t *q_indicators;
  48
  49 u64 last_ai_time;
  50
  51 /* returns addr for the device state change indicator */
  52 static u32 *get_indicator(void)
  53 {
  54         int i;
  55
  56         for (i = 0; i < TIQDIO_NR_NONSHARED_IND; i++)
  57                 if (!atomic_read(&q_indicators[i].count)) {
  58                         atomic_set(&q_indicators[i].count, 1);
  59                         return &q_indicators[i].ind;
  60                 }
  61
  62         /* use the shared indicator */
  63         atomic_inc(&q_indicators[TIQDIO_SHARED_IND].count);
  64         return &q_indicators[TIQDIO_SHARED_IND].ind;
  65 }
  66
  67 static void put_indicator(u32 *addr)
  68 {
  69         int i;
  70
  71         if (!addr)
  72                 return;
  73         i = ((unsigned long)addr - (unsigned long)q_indicators) /
  74                 sizeof(struct indicator_t);
  75         atomic_dec(&q_indicators[i].count);
  76 }
  77
  78 void tiqdio_add_input_queues(struct qdio_irq *irq_ptr)
  79 {
  80         mutex_lock(&tiq_list_lock);
  81         list_add_rcu(&irq_ptr->input_qs[0]->entry, &tiq_list);
  82         mutex_unlock(&tiq_list_lock);
  83         xchg(irq_ptr->dsci, 1 << 7);
  84 }
  85
  86 void tiqdio_remove_input_queues(struct qdio_irq *irq_ptr)
  87 {
  88         struct qdio_q *q;
  89
  90         q = irq_ptr->input_qs[0];
  91         /* if establish triggered an error */
  92         if (!q || !q->entry.prev || !q->entry.next)
  93                 return;
  94
  95         mutex_lock(&tiq_list_lock);
  96         list_del_rcu(&q->entry);
  97         mutex_unlock(&tiq_list_lock);
  98         synchronize_rcu();
  99 }
 100
 101 static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
 102 {
 103         return irq_ptr->nr_input_qs > 1;
 104 }
 105
 106 static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
 107 {
 108         return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
 109 }
 110
 111 static inline int shared_ind(struct qdio_irq *irq_ptr)
 112 {
 113         return references_shared_dsci(irq_ptr) ||
 114                 has_multiple_inq_on_dsci(irq_ptr);
 115 }
 116
 117 void clear_nonshared_ind(struct qdio_irq *irq_ptr)
 118 {
 119         if (!is_thinint_irq(irq_ptr))
 120                 return;
 121         if (shared_ind(irq_ptr))
 122                 return;
 123         xchg(irq_ptr->dsci, 0);
 124 }
 125
 126 int test_nonshared_ind(struct qdio_irq *irq_ptr)
 127 {
 128         if (!is_thinint_irq(irq_ptr))
 129                 return 0;
 130         if (shared_ind(irq_ptr))
 131                 return 0;
 132         if (*irq_ptr->dsci)
 133                 return 1;
 134         else
 135                 return 0;
 136 }
 137
 138 static inline u32 clear_shared_ind(void)
 139 {
 140         if (!atomic_read(&q_indicators[TIQDIO_SHARED_IND].count))
 141                 return 0;
 142         return xchg(&q_indicators[TIQDIO_SHARED_IND].ind, 0);
 143 }
 144
 145 static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
 146 {
 147         struct qdio_q *q;
 148         int i;
 149
 150         for_each_input_queue(irq, q, i) {
 151                 if (!references_shared_dsci(irq) &&
 152                     has_multiple_inq_on_dsci(irq))
 153                         xchg(q->irq_ptr->dsci, 0);
 154
 155                 if (q->u.in.queue_start_poll) {
 156                         /* skip if polling is enabled or already in work */
 157                         if (test_and_set_bit(QDIO_QUEUE_IRQS_DISABLED,
 158                                              &q->u.in.queue_irq_state)) {
 159                                 qperf_inc(q, int_discarded);
 160                                 continue;
 161                         }
 162
 163                         /* avoid dsci clear here, done after processing */
 164                         q->u.in.queue_start_poll(q->irq_ptr->cdev, q->nr,
 165                                                  q->irq_ptr->int_parm);
 166                 } else {
 167                         if (!shared_ind(q->irq_ptr))
 168                                 xchg(q->irq_ptr->dsci, 0);
 169
 170                         /*
 171                          * Call inbound processing but not directly
 172                          * since that could starve other thinint queues.
 173                          */
 174                         tasklet_schedule(&q->tasklet);
 175                 }
 176         }
 177 }
 178
 179 /**
 180  * tiqdio_thinint_handler - thin interrupt handler for qdio
 181  * @alsi: pointer to adapter local summary indicator
 182  * @data: NULL
 183  */
 184 static void tiqdio_thinint_handler(struct airq_struct *airq)
 185 {
 186         u32 si_used = clear_shared_ind();
 187         struct qdio_q *q;
 188
 189         last_ai_time = S390_lowcore.int_clock;
 190         inc_irq_stat(IRQIO_QAI);
 191
 192         /* protect tiq_list entries, only changed in activate or shutdown */
 193         rcu_read_lock();
 194
 195         /* check for work on all inbound thinint queues */
 196         list_for_each_entry_rcu(q, &tiq_list, entry) {
 197                 struct qdio_irq *irq;
 198
 199                 /* only process queues from changed sets */
 200                 irq = q->irq_ptr;
 201                 if (unlikely(references_shared_dsci(irq))) {
 202                         if (!si_used)
 203                                 continue;
 204                 } else if (!*irq->dsci)
 205                         continue;
 206
 207                 tiqdio_call_inq_handlers(irq);
 208
 209                 qperf_inc(q, adapter_int);
 210         }
 211         rcu_read_unlock();
 212 }
 213
 214 static int set_subchannel_ind(struct qdio_irq *irq_ptr, int reset)
 215 {
 216         struct chsc_scssc_area *scssc = (void *)irq_ptr->chsc_page;
 217         u64 summary_indicator_addr, subchannel_indicator_addr;
 218         int rc;
 219
 220         if (reset) {
 221                 summary_indicator_addr = 0;
 222                 subchannel_indicator_addr = 0;
 223         } else {
 224                 summary_indicator_addr = virt_to_phys(tiqdio_airq.lsi_ptr);
 225                 subchannel_indicator_addr = virt_to_phys(irq_ptr->dsci);
 226         }
 227
 228         rc = chsc_sadc(irq_ptr->schid, scssc, summary_indicator_addr,
 229                        subchannel_indicator_addr);
 230         if (rc) {
 231                 DBF_ERROR("%4x SSI r:%4x", irq_ptr->schid.sch_no,
 232                           scssc->response.code);
 233                 goto out;
 234         }
 235
 236         DBF_EVENT("setscind");
 237         DBF_HEX(&summary_indicator_addr, sizeof(summary_indicator_addr));
 238         DBF_HEX(&subchannel_indicator_addr, sizeof(subchannel_indicator_addr));
 239 out:
 240         return rc;
 241 }
 242
 243 /* allocate non-shared indicators and shared indicator */
 244 int __init tiqdio_allocate_memory(void)
 245 {
 246         q_indicators = kzalloc(sizeof(struct indicator_t) * TIQDIO_NR_INDICATORS,
 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 }