io_event_irq.c

  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
 57ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
 58EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);
 59
 60static int ioei_check_exception_token;
 61
 62static 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 */
 71static 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 *) &sect->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
117static 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
142static 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("/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}
160machine_subsys_initcall(pseries, ioei_init);
161