xref: /openbmc/linux/arch/um/os-Linux/irq.c (revision 844f5ed5)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2017 - Cambridge Greys Ltd
4  * Copyright (C) 2011 - 2014 Cisco Systems Inc
5  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
6  */
7 
8 #include <stdlib.h>
9 #include <errno.h>
10 #include <sys/epoll.h>
11 #include <signal.h>
12 #include <string.h>
13 #include <irq_user.h>
14 #include <os.h>
15 #include <um_malloc.h>
16 
17 /* Epoll support */
18 
19 static int epollfd = -1;
20 
21 #define MAX_EPOLL_EVENTS 64
22 
23 static struct epoll_event epoll_events[MAX_EPOLL_EVENTS];
24 
25 /* Helper to return an Epoll data pointer from an epoll event structure.
26  * We need to keep this one on the userspace side to keep includes separate
27  */
28 
29 void *os_epoll_get_data_pointer(int index)
30 {
31 	return epoll_events[index].data.ptr;
32 }
33 
34 /* Helper to compare events versus the events in the epoll structure.
35  * Same as above - needs to be on the userspace side
36  */
37 
38 
39 int os_epoll_triggered(int index, int events)
40 {
41 	return epoll_events[index].events & events;
42 }
43 /* Helper to set the event mask.
44  * The event mask is opaque to the kernel side, because it does not have
45  * access to the right includes/defines for EPOLL constants.
46  */
47 
48 int os_event_mask(enum um_irq_type irq_type)
49 {
50 	if (irq_type == IRQ_READ)
51 		return EPOLLIN | EPOLLPRI | EPOLLERR | EPOLLHUP | EPOLLRDHUP;
52 	if (irq_type == IRQ_WRITE)
53 		return EPOLLOUT;
54 	return 0;
55 }
56 
57 /*
58  * Initial Epoll Setup
59  */
60 int os_setup_epoll(void)
61 {
62 	epollfd = epoll_create(MAX_EPOLL_EVENTS);
63 	return epollfd;
64 }
65 
66 /*
67  * Helper to run the actual epoll_wait
68  */
69 int os_waiting_for_events_epoll(void)
70 {
71 	int n, err;
72 
73 	n = epoll_wait(epollfd,
74 		(struct epoll_event *) &epoll_events, MAX_EPOLL_EVENTS, 0);
75 	if (n < 0) {
76 		err = -errno;
77 		if (errno != EINTR)
78 			printk(
79 				UM_KERN_ERR "os_waiting_for_events:"
80 				" epoll returned %d, error = %s\n", n,
81 				strerror(errno)
82 			);
83 		return err;
84 	}
85 	return n;
86 }
87 
88 
89 /*
90  * Helper to add a fd to epoll
91  */
92 int os_add_epoll_fd(int events, int fd, void *data)
93 {
94 	struct epoll_event event;
95 	int result;
96 
97 	event.data.ptr = data;
98 	event.events = events | EPOLLET;
99 	result = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);
100 	if ((result) && (errno == EEXIST))
101 		result = os_mod_epoll_fd(events, fd, data);
102 	if (result)
103 		printk("epollctl add err fd %d, %s\n", fd, strerror(errno));
104 	return result;
105 }
106 
107 /*
108  * Helper to mod the fd event mask and/or data backreference
109  */
110 int os_mod_epoll_fd(int events, int fd, void *data)
111 {
112 	struct epoll_event event;
113 	int result;
114 
115 	event.data.ptr = data;
116 	event.events = events;
117 	result = epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &event);
118 	if (result)
119 		printk(UM_KERN_ERR
120 			"epollctl mod err fd %d, %s\n", fd, strerror(errno));
121 	return result;
122 }
123 
124 /*
125  * Helper to delete the epoll fd
126  */
127 int os_del_epoll_fd(int fd)
128 {
129 	struct epoll_event event;
130 	/* This is quiet as we use this as IO ON/OFF - so it is often
131 	 * invoked on a non-existent fd
132 	 */
133 	return epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, &event);
134 }
135 
136 void os_set_ioignore(void)
137 {
138 	signal(SIGIO, SIG_IGN);
139 }
140 
141 void os_close_epoll_fd(void)
142 {
143 	/* Needed so we do not leak an fd when rebooting */
144 	os_close_file(epollfd);
145 }
146