1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
/*
* Copyright (C) 2012 by Alan Stern
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
/* This file is part of ehci-hcd.c */
/*-------------------------------------------------------------------------*/
/*
* EHCI timer support... Now using hrtimers.
*
* Lots of different events are triggered from ehci->hrtimer. Whenever
* the timer routine runs, it checks each possible event; events that are
* currently enabled and whose expiration time has passed get handled.
* The set of enabled events is stored as a collection of bitflags in
* ehci->enabled_hrtimer_events, and they are numbered in order of
* increasing delay values (ranging between 1 ms and 100 ms).
*
* Rather than implementing a sorted list or tree of all pending events,
* we keep track only of the lowest-numbered pending event, in
* ehci->next_hrtimer_event. Whenever ehci->hrtimer gets restarted, its
* expiration time is set to the timeout value for this event.
*
* As a result, events might not get handled right away; the actual delay
* could be anywhere up to twice the requested delay. This doesn't
* matter, because none of the events are especially time-critical. The
* ones that matter most all have a delay of 1 ms, so they will be
* handled after 2 ms at most, which is okay. In addition to this, we
* allow for an expiration range of 1 ms.
*/
/*
* Delay lengths for the hrtimer event types.
* Keep this list sorted by delay length, in the same order as
* the event types indexed by enum ehci_hrtimer_event in ehci.h.
*/
static unsigned event_delays_ns[] = {
};
/* Enable a pending hrtimer event */
static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
bool resched)
{
ktime_t *timeout = &ehci->hr_timeouts[event];
if (resched)
*timeout = ktime_add(ktime_get(),
ktime_set(0, event_delays_ns[event]));
ehci->enabled_hrtimer_events |= (1 << event);
/* Track only the lowest-numbered pending event */
if (event < ehci->next_hrtimer_event) {
ehci->next_hrtimer_event = event;
hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
NSEC_PER_MSEC, HRTIMER_MODE_ABS);
}
}
/*
* Handler functions for the hrtimer event types.
* Keep this array in the same order as the event types indexed by
* enum ehci_hrtimer_event in ehci.h.
*/
static void (*event_handlers[])(struct ehci_hcd *) = {
};
static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
{
struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
ktime_t now;
unsigned long events;
unsigned long flags;
unsigned e;
spin_lock_irqsave(&ehci->lock, flags);
events = ehci->enabled_hrtimer_events;
ehci->enabled_hrtimer_events = 0;
ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
/*
* Check each pending event. If its time has expired, handle
* the event; otherwise re-enable it.
*/
now = ktime_get();
for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
if (now.tv64 >= ehci->hr_timeouts[e].tv64)
event_handlers[e](ehci);
else
ehci_enable_event(ehci, e, false);
}
spin_unlock_irqrestore(&ehci->lock, flags);
return HRTIMER_NORESTART;
}
|
