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Linux/arch/powerpc/platforms/pseries/io_event_irq.c

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  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(rtas_error_type(elog) != RTAS_TYPE_IO)) {
 86                 printk_once(KERN_WARNING"io_event_irq: Unexpected event type %d",
 87                             rtas_error_type(elog));
 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 
166 

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