1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
15 *
16 * Copyright (c) 2005 Linas Vepstas <linas@linas.org>
17 */
18
19#include <linux/delay.h>
20#include <linux/list.h>
21#include <linux/sched.h>
22#include <linux/semaphore.h>
23#include <linux/pci.h>
24#include <linux/slab.h>
25#include <linux/kthread.h>
26#include <asm/eeh_event.h>
27#include <asm/ppc-pci.h>
28
29/** Overview:
30 *  EEH error states may be detected within exception handlers;
31 *  however, the recovery processing needs to occur asynchronously
32 *  in a normal kernel context and not an interrupt context.
33 *  This pair of routines creates an event and queues it onto a
34 *  work-queue, where a worker thread can drive recovery.
35 */
36
37static DEFINE_SPINLOCK(eeh_eventlist_lock);
38static struct semaphore eeh_eventlist_sem;
39LIST_HEAD(eeh_eventlist);
40
41/**
42 * eeh_event_handler - Dispatch EEH events.
43 * @dummy - unused
44 *
45 * The detection of a frozen slot can occur inside an interrupt,
46 * where it can be hard to do anything about it.  The goal of this
47 * routine is to pull these detection events out of the context
48 * of the interrupt handler, and re-dispatch them for processing
49 * at a later time in a normal context.
50 */
51static int eeh_event_handler(void * dummy)
52{
53	unsigned long flags;
54	struct eeh_event *event;
55	struct eeh_pe *pe;
56
57	while (!kthread_should_stop()) {
58		if (down_interruptible(&eeh_eventlist_sem))
59			break;
60
61		/* Fetch EEH event from the queue */
62		spin_lock_irqsave(&eeh_eventlist_lock, flags);
63		event = NULL;
64		if (!list_empty(&eeh_eventlist)) {
65			event = list_entry(eeh_eventlist.next,
66					   struct eeh_event, list);
67			list_del(&event->list);
68		}
69		spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
70		if (!event)
71			continue;
72
73		/* We might have event without binding PE */
74		pe = event->pe;
75		if (pe) {
76			eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
77			if (pe->type & EEH_PE_PHB)
78				pr_info("EEH: Detected error on PHB#%d\n",
79					 pe->phb->global_number);
80			else
81				pr_info("EEH: Detected PCI bus error on "
82					"PHB#%d-PE#%x\n",
83					pe->phb->global_number, pe->addr);
84			eeh_handle_event(pe);
85			eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
86		} else {
87			eeh_handle_event(NULL);
88		}
89
90		kfree(event);
91	}
92
93	return 0;
94}
95
96/**
97 * eeh_event_init - Start kernel thread to handle EEH events
98 *
99 * This routine is called to start the kernel thread for processing
100 * EEH event.
101 */
102int eeh_event_init(void)
103{
104	struct task_struct *t;
105	int ret = 0;
106
107	/* Initialize semaphore */
108	sema_init(&eeh_eventlist_sem, 0);
109
110	t = kthread_run(eeh_event_handler, NULL, "eehd");
111	if (IS_ERR(t)) {
112		ret = PTR_ERR(t);
113		pr_err("%s: Failed to start EEH daemon (%d)\n",
114			__func__, ret);
115		return ret;
116	}
117
118	return 0;
119}
120
121/**
122 * eeh_send_failure_event - Generate a PCI error event
123 * @pe: EEH PE
124 *
125 * This routine can be called within an interrupt context;
126 * the actual event will be delivered in a normal context
127 * (from a workqueue).
128 */
129int eeh_send_failure_event(struct eeh_pe *pe)
130{
131	unsigned long flags;
132	struct eeh_event *event;
133
134	event = kzalloc(sizeof(*event), GFP_ATOMIC);
135	if (!event) {
136		pr_err("EEH: out of memory, event not handled\n");
137		return -ENOMEM;
138	}
139	event->pe = pe;
140
141	/* We may or may not be called in an interrupt context */
142	spin_lock_irqsave(&eeh_eventlist_lock, flags);
143	list_add(&event->list, &eeh_eventlist);
144	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
145
146	/* For EEH deamon to knick in */
147	up(&eeh_eventlist_sem);
148
149	return 0;
150}
151
152/**
153 * eeh_remove_event - Remove EEH event from the queue
154 * @pe: Event binding to the PE
155 * @force: Event will be removed unconditionally
156 *
157 * On PowerNV platform, we might have subsequent coming events
158 * is part of the former one. For that case, those subsequent
159 * coming events are totally duplicated and unnecessary, thus
160 * they should be removed.
161 */
162void eeh_remove_event(struct eeh_pe *pe, bool force)
163{
164	unsigned long flags;
165	struct eeh_event *event, *tmp;
166
167	/*
168	 * If we have NULL PE passed in, we have dead IOC
169	 * or we're sure we can report all existing errors
170	 * by the caller.
171	 *
172	 * With "force", the event with associated PE that
173	 * have been isolated, the event won't be removed
174	 * to avoid event lost.
175	 */
176	spin_lock_irqsave(&eeh_eventlist_lock, flags);
177	list_for_each_entry_safe(event, tmp, &eeh_eventlist, list) {
178		if (!force && event->pe &&
179		    (event->pe->state & EEH_PE_ISOLATED))
180			continue;
181
182		if (!pe) {
183			list_del(&event->list);
184			kfree(event);
185		} else if (pe->type & EEH_PE_PHB) {
186			if (event->pe && event->pe->phb == pe->phb) {
187				list_del(&event->list);
188				kfree(event);
189			}
190		} else if (event->pe == pe) {
191			list_del(&event->list);
192			kfree(event);
193		}
194	}
195	spin_unlock_irqrestore(&eeh_eventlist_lock, flags);
196}
197