1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 2010 2011 Mark Nelson and Tseng-Hui (Frank) Lin, IBM Corporation
4 */
5
6 #include <linux/errno.h>
7 #include <linux/slab.h>
8 #include <linux/export.h>
9 #include <linux/irq.h>
10 #include <linux/interrupt.h>
11 #include <linux/of.h>
12 #include <linux/list.h>
13 #include <linux/notifier.h>
14
15 #include <asm/machdep.h>
16 #include <asm/rtas.h>
17 #include <asm/irq.h>
18 #include <asm/io_event_irq.h>
19
20 #include "pseries.h"
21
22 /*
23 * IO event interrupt is a mechanism provided by RTAS to return
24 * information about hardware error and non-error events. Device
25 * drivers can register their event handlers to receive events.
26 * Device drivers are expected to use atomic_notifier_chain_register()
27 * and atomic_notifier_chain_unregister() to register and unregister
28 * their event handlers. Since multiple IO event types and scopes
29 * share an IO event interrupt, the event handlers are called one
30 * by one until the IO event is claimed by one of the handlers.
31 * The event handlers are expected to return NOTIFY_OK if the
32 * event is handled by the event handler or NOTIFY_DONE if the
33 * event does not belong to the handler.
34 *
35 * Usage:
36 *
37 * Notifier function:
38 * #include <asm/io_event_irq.h>
39 * int event_handler(struct notifier_block *nb, unsigned long val, void *data) {
40 * p = (struct pseries_io_event_sect_data *) data;
41 * if (! is_my_event(p->scope, p->event_type)) return NOTIFY_DONE;
42 * :
43 * :
44 * return NOTIFY_OK;
45 * }
46 * struct notifier_block event_nb = {
47 * .notifier_call = event_handler,
48 * }
49 *
50 * Registration:
51 * atomic_notifier_chain_register(&pseries_ioei_notifier_list, &event_nb);
52 *
53 * Unregistration:
54 * atomic_notifier_chain_unregister(&pseries_ioei_notifier_list, &event_nb);
55 */
56
57 ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
58 EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);
59
60 static int ioei_check_exception_token;
61
62 static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
63
64 /**
65 * Find the data portion of an IO Event section from event log.
66 * @elog: RTAS error/event log.
67 *
68 * Return:
69 * pointer to a valid IO event section data. NULL if not found.
70 */
71 static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog)
72 {
73 struct pseries_errorlog *sect;
74
75 /* We should only ever get called for io-event interrupts, but if
76 * we do get called for another type then something went wrong so
77 * make some noise about it.
78 * RTAS_TYPE_IO only exists in extended event log version 6 or later.
79 * No need to check event log version.
80 */
81 if (unlikely(rtas_error_type(elog) != RTAS_TYPE_IO)) {
82 printk_once(KERN_WARNING"io_event_irq: Unexpected event type %d",
83 rtas_error_type(elog));
84 return NULL;
85 }
86
87 sect = get_pseries_errorlog(elog, PSERIES_ELOG_SECT_ID_IO_EVENT);
88 if (unlikely(!sect)) {
89 printk_once(KERN_WARNING "io_event_irq: RTAS extended event "
90 "log does not contain an IO Event section. "
91 "Could be a bug in system firmware!\n");
92 return NULL;
93 }
94 return (struct pseries_io_event *) §->data;
95 }
96
97 /*
98 * PAPR:
99 * - check-exception returns the first found error or event and clear that
100 * error or event so it is reported once.
101 * - Each interrupt returns one event. If a plateform chooses to report
102 * multiple events through a single interrupt, it must ensure that the
103 * interrupt remains asserted until check-exception has been used to
104 * process all out-standing events for that interrupt.
105 *
106 * Implementation notes:
107 * - Events must be processed in the order they are returned. Hence,
108 * sequential in nature.
109 * - The owner of an event is determined by combinations of scope,
110 * event type, and sub-type. There is no easy way to pre-sort clients
111 * by scope or event type alone. For example, Torrent ISR route change
112 * event is reported with scope 0x00 (Not Applicable) rather than
113 * 0x3B (Torrent-hub). It is better to let the clients to identify
114 * who owns the event.
115 */
116
117 static irqreturn_t ioei_interrupt(int irq, void *dev_id)
118 {
119 struct pseries_io_event *event;
120 int rtas_rc;
121
122 for (;;) {
123 rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL,
124 RTAS_VECTOR_EXTERNAL_INTERRUPT,
125 virq_to_hw(irq),
126 RTAS_IO_EVENTS, 1 /* Time Critical */,
127 __pa(ioei_rtas_buf),
128 RTAS_DATA_BUF_SIZE);
129 if (rtas_rc != 0)
130 break;
131
132 event = ioei_find_event((struct rtas_error_log *)ioei_rtas_buf);
133 if (!event)
134 continue;
135
136 atomic_notifier_call_chain(&pseries_ioei_notifier_list,
137 0, event);
138 }
139 return IRQ_HANDLED;
140 }
141
142 static int __init ioei_init(void)
143 {
144 struct device_node *np;
145
146 ioei_check_exception_token = rtas_token("check-exception");
147 if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE)
148 return -ENODEV;
149
150 np = of_find_node_by_path("/event-sources/ibm,io-events");
151 if (np) {
152 request_event_sources_irqs(np, ioei_interrupt, "IO_EVENT");
153 pr_info("IBM I/O event interrupts enabled\n");
154 of_node_put(np);
155 } else {
156 return -ENODEV;
157 }
158 return 0;
159 }
160 machine_subsys_initcall(pseries, ioei_init);
161