arch/powerpc/platforms/pseries/io_event_irq.c

   1 /*
   2  * Copyright 2010 2011 Mark Nelson and Tseng-Hui (Frank) Lin, IBM Corporation
   3  *
   4  *  This program is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU General Public License
   6  *  as published by the Free Software Foundation; either version
   7  *  2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/errno.h>
  11 #include <linux/slab.h>
  12 #include <linux/export.h>
  13 #include <linux/irq.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/of.h>
  16 #include <linux/list.h>
  17 #include <linux/notifier.h>
  18
  19 #include <asm/machdep.h>
  20 #include <asm/rtas.h>
  21 #include <asm/irq.h>
  22 #include <asm/io_event_irq.h>
  23
  24 #include "pseries.h"
  25
  26 /*
  27  * IO event interrupt is a mechanism provided by RTAS to return
  28  * information about hardware error and non-error events. Device
  29  * drivers can register their event handlers to receive events.
  30  * Device drivers are expected to use atomic_notifier_chain_register()
  31  * and atomic_notifier_chain_unregister() to register and unregister
  32  * their event handlers. Since multiple IO event types and scopes
  33  * share an IO event interrupt, the event handlers are called one
  34  * by one until the IO event is claimed by one of the handlers.
  35  * The event handlers are expected to return NOTIFY_OK if the
  36  * event is handled by the event handler or NOTIFY_DONE if the
  37  * event does not belong to the handler.
  38  *
  39  * Usage:
  40  *
  41  * Notifier function:
  42  * #include <asm/io_event_irq.h>
  43  * int event_handler(struct notifier_block *nb, unsigned long val, void *data) {
  44  *      p = (struct pseries_io_event_sect_data *) data;
  45  *      if (! is_my_event(p->scope, p->event_type)) return NOTIFY_DONE;
  46  *              :
  47  *              :
  48  *      return NOTIFY_OK;
  49  * }
  50  * struct notifier_block event_nb = {
  51  *      .notifier_call = event_handler,
  52  * }
  53  *
  54  * Registration:
  55  * atomic_notifier_chain_register(&pseries_ioei_notifier_list, &event_nb);
  56  *
  57  * Unregistration:
  58  * atomic_notifier_chain_unregister(&pseries_ioei_notifier_list, &event_nb);
  59  */
  60
  61 ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
  62 EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);
  63
  64 static int ioei_check_exception_token;
  65
  66 static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
  67
  68 /**
  69  * Find the data portion of an IO Event section from event log.
  70  * @elog: RTAS error/event log.
  71  *
  72  * Return:
  73  *      pointer to a valid IO event section data. NULL if not found.
  74  */
  75 static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog)
  76 {
  77         struct pseries_errorlog *sect;
  78
  79         /* We should only ever get called for io-event interrupts, but if
  80          * we do get called for another type then something went wrong so
  81          * make some noise about it.
  82          * RTAS_TYPE_IO only exists in extended event log version 6 or later.
  83          * No need to check event log version.
  84          */
  85         if (unlikely(elog->type != RTAS_TYPE_IO)) {
  86                 printk_once(KERN_WARNING "io_event_irq: Unexpected event type %d",
  87                             elog->type);
  88                 return NULL;
  89         }
  90
  91         sect = get_pseries_errorlog(elog, PSERIES_ELOG_SECT_ID_IO_EVENT);
  92         if (unlikely(!sect)) {
  93                 printk_once(KERN_WARNING "io_event_irq: RTAS extended event "
  94                             "log does not contain an IO Event section. "
  95                             "Could be a bug in system firmware!\n");
  96                 return NULL;
  97         }
  98         return (struct pseries_io_event *) &sect->data;
  99 }
 100
 101 /*
 102  * PAPR:
 103  * - check-exception returns the first found error or event and clear that
 104  *   error or event so it is reported once.
 105  * - Each interrupt returns one event. If a plateform chooses to report
 106  *   multiple events through a single interrupt, it must ensure that the
 107  *   interrupt remains asserted until check-exception has been used to
 108  *   process all out-standing events for that interrupt.
 109  *
 110  * Implementation notes:
 111  * - Events must be processed in the order they are returned. Hence,
 112  *   sequential in nature.
 113  * - The owner of an event is determined by combinations of scope,
 114  *   event type, and sub-type. There is no easy way to pre-sort clients
 115  *   by scope or event type alone. For example, Torrent ISR route change
 116  *   event is reported with scope 0x00 (Not Applicatable) rather than
 117  *   0x3B (Torrent-hub). It is better to let the clients to identify
 118  *   who owns the event.
 119  */
 120
 121 static irqreturn_t ioei_interrupt(int irq, void *dev_id)
 122 {
 123         struct pseries_io_event *event;
 124         int rtas_rc;
 125
 126         for (;;) {
 127                 rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL,
 128                                     RTAS_VECTOR_EXTERNAL_INTERRUPT,
 129                                     virq_to_hw(irq),
 130                                     RTAS_IO_EVENTS, 1 /* Time Critical */,
 131                                     __pa(ioei_rtas_buf),
 132                                     RTAS_DATA_BUF_SIZE);
 133                 if (rtas_rc != 0)
 134                         break;
 135
 136                 event = ioei_find_event((struct rtas_error_log *)ioei_rtas_buf);
 137                 if (!event)
 138                         continue;
 139
 140                 atomic_notifier_call_chain(&pseries_ioei_notifier_list,
 141                                            0, event);
 142         }
 143         return IRQ_HANDLED;
 144 }
 145
 146 static int __init ioei_init(void)
 147 {
 148         struct device_node *np;
 149
 150         ioei_check_exception_token = rtas_token("check-exception");
 151         if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE)
 152                 return -ENODEV;
 153
 154         np = of_find_node_by_path("/event-sources/ibm,io-events");
 155         if (np) {
 156                 request_event_sources_irqs(np, ioei_interrupt, "IO_EVENT");
 157                 pr_info("IBM I/O event interrupts enabled\n");
 158                 of_node_put(np);
 159         } else {
 160                 return -ENODEV;
 161         }
 162         return 0;
 163 }
 164 machine_subsys_initcall(pseries, ioei_init);
 165