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
61ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
62EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);
63
64static int ioei_check_exception_token;
65
66static 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 */
75static 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
121static 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
146static 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}
164machine_subsys_initcall(pseries, ioei_init);
165
166