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 */
ioei_find_event(struct rtas_error_log * elog)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 *) §->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 the event.
119 */
120
ioei_interrupt(int irq,void * dev_id)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
ioei_init(void)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