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(elog: (struct rtas_error_log *)ioei_rtas_buf); |
133 | if (!event) |
134 | continue; |
135 | |
136 | atomic_notifier_call_chain(nh: &pseries_ioei_notifier_list, |
137 | val: 0, v: 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_function_token(RTAS_FN_CHECK_EXCEPTION); |
147 | if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE) |
148 | return -ENODEV; |
149 | |
150 | np = of_find_node_by_path(path: "/event-sources/ibm,io-events" ); |
151 | if (np) { |
152 | request_event_sources_irqs(np, handler: ioei_interrupt, name: "IO_EVENT" ); |
153 | pr_info("IBM I/O event interrupts enabled\n" ); |
154 | of_node_put(node: np); |
155 | } else { |
156 | return -ENODEV; |
157 | } |
158 | return 0; |
159 | } |
160 | machine_subsys_initcall(pseries, ioei_init); |
161 | |
162 | |