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1da177e4 LT |
1 | High Precision Event Timer Driver for Linux |
2 | ||
64a76f66 DB |
3 | The High Precision Event Timer (HPET) hardware follows a specification |
4 | by Intel and Microsoft which can be found at | |
5 | ||
6 | http://www.intel.com/technology/architecture/hpetspec.htm | |
7 | ||
8 | Each HPET has one fixed-rate counter (at 10+ MHz, hence "High Precision") | |
9 | and up to 32 comparators. Normally three or more comparators are provided, | |
19f59460 | 10 | each of which can generate oneshot interrupts and at least one of which has |
64a76f66 DB |
11 | additional hardware to support periodic interrupts. The comparators are |
12 | also called "timers", which can be misleading since usually timers are | |
13 | independent of each other ... these share a counter, complicating resets. | |
14 | ||
15 | HPET devices can support two interrupt routing modes. In one mode, the | |
16 | comparators are additional interrupt sources with no particular system | |
17 | role. Many x86 BIOS writers don't route HPET interrupts at all, which | |
18 | prevents use of that mode. They support the other "legacy replacement" | |
19 | mode where the first two comparators block interrupts from 8254 timers | |
20 | and from the RTC. | |
8a0d4900 RD |
21 | |
22 | The driver supports detection of HPET driver allocation and initialization | |
23 | of the HPET before the driver module_init routine is called. This enables | |
24 | platform code which uses timer 0 or 1 as the main timer to intercept HPET | |
25 | initialization. An example of this initialization can be found in | |
64a76f66 | 26 | arch/x86/kernel/hpet.c. |
1da177e4 | 27 | |
64a76f66 DB |
28 | The driver provides a userspace API which resembles the API found in the |
29 | RTC driver framework. An example user space program is provided below. | |
1da177e4 LT |
30 | |
31 | #include <stdio.h> | |
32 | #include <stdlib.h> | |
33 | #include <unistd.h> | |
34 | #include <fcntl.h> | |
35 | #include <string.h> | |
36 | #include <memory.h> | |
37 | #include <malloc.h> | |
38 | #include <time.h> | |
39 | #include <ctype.h> | |
40 | #include <sys/types.h> | |
41 | #include <sys/wait.h> | |
42 | #include <signal.h> | |
43 | #include <fcntl.h> | |
44 | #include <errno.h> | |
45 | #include <sys/time.h> | |
46 | #include <linux/hpet.h> | |
47 | ||
48 | ||
49 | extern void hpet_open_close(int, const char **); | |
50 | extern void hpet_info(int, const char **); | |
51 | extern void hpet_poll(int, const char **); | |
52 | extern void hpet_fasync(int, const char **); | |
53 | extern void hpet_read(int, const char **); | |
54 | ||
55 | #include <sys/poll.h> | |
56 | #include <sys/ioctl.h> | |
57 | #include <signal.h> | |
58 | ||
59 | struct hpet_command { | |
60 | char *command; | |
61 | void (*func)(int argc, const char ** argv); | |
62 | } hpet_command[] = { | |
63 | { | |
64 | "open-close", | |
65 | hpet_open_close | |
66 | }, | |
67 | { | |
68 | "info", | |
69 | hpet_info | |
70 | }, | |
71 | { | |
72 | "poll", | |
73 | hpet_poll | |
74 | }, | |
75 | { | |
76 | "fasync", | |
77 | hpet_fasync | |
78 | }, | |
79 | }; | |
80 | ||
81 | int | |
82 | main(int argc, const char ** argv) | |
83 | { | |
84 | int i; | |
85 | ||
86 | argc--; | |
87 | argv++; | |
88 | ||
89 | if (!argc) { | |
90 | fprintf(stderr, "-hpet: requires command\n"); | |
91 | return -1; | |
92 | } | |
93 | ||
94 | ||
95 | for (i = 0; i < (sizeof (hpet_command) / sizeof (hpet_command[0])); i++) | |
96 | if (!strcmp(argv[0], hpet_command[i].command)) { | |
97 | argc--; | |
98 | argv++; | |
99 | fprintf(stderr, "-hpet: executing %s\n", | |
100 | hpet_command[i].command); | |
101 | hpet_command[i].func(argc, argv); | |
102 | return 0; | |
103 | } | |
104 | ||
105 | fprintf(stderr, "do_hpet: command %s not implemented\n", argv[0]); | |
106 | ||
107 | return -1; | |
108 | } | |
109 | ||
110 | void | |
111 | hpet_open_close(int argc, const char **argv) | |
112 | { | |
113 | int fd; | |
114 | ||
115 | if (argc != 1) { | |
116 | fprintf(stderr, "hpet_open_close: device-name\n"); | |
117 | return; | |
118 | } | |
119 | ||
120 | fd = open(argv[0], O_RDONLY); | |
121 | if (fd < 0) | |
122 | fprintf(stderr, "hpet_open_close: open failed\n"); | |
123 | else | |
124 | close(fd); | |
125 | ||
126 | return; | |
127 | } | |
128 | ||
129 | void | |
130 | hpet_info(int argc, const char **argv) | |
131 | { | |
132 | } | |
133 | ||
134 | void | |
135 | hpet_poll(int argc, const char **argv) | |
136 | { | |
137 | unsigned long freq; | |
138 | int iterations, i, fd; | |
139 | struct pollfd pfd; | |
140 | struct hpet_info info; | |
141 | struct timeval stv, etv; | |
142 | struct timezone tz; | |
143 | long usec; | |
144 | ||
145 | if (argc != 3) { | |
146 | fprintf(stderr, "hpet_poll: device-name freq iterations\n"); | |
147 | return; | |
148 | } | |
149 | ||
150 | freq = atoi(argv[1]); | |
151 | iterations = atoi(argv[2]); | |
152 | ||
153 | fd = open(argv[0], O_RDONLY); | |
154 | ||
155 | if (fd < 0) { | |
156 | fprintf(stderr, "hpet_poll: open of %s failed\n", argv[0]); | |
157 | return; | |
158 | } | |
159 | ||
160 | if (ioctl(fd, HPET_IRQFREQ, freq) < 0) { | |
161 | fprintf(stderr, "hpet_poll: HPET_IRQFREQ failed\n"); | |
162 | goto out; | |
163 | } | |
164 | ||
165 | if (ioctl(fd, HPET_INFO, &info) < 0) { | |
166 | fprintf(stderr, "hpet_poll: failed to get info\n"); | |
167 | goto out; | |
168 | } | |
169 | ||
170 | fprintf(stderr, "hpet_poll: info.hi_flags 0x%lx\n", info.hi_flags); | |
171 | ||
172 | if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) { | |
173 | fprintf(stderr, "hpet_poll: HPET_EPI failed\n"); | |
174 | goto out; | |
175 | } | |
176 | ||
177 | if (ioctl(fd, HPET_IE_ON, 0) < 0) { | |
178 | fprintf(stderr, "hpet_poll, HPET_IE_ON failed\n"); | |
179 | goto out; | |
180 | } | |
181 | ||
182 | pfd.fd = fd; | |
183 | pfd.events = POLLIN; | |
184 | ||
185 | for (i = 0; i < iterations; i++) { | |
186 | pfd.revents = 0; | |
187 | gettimeofday(&stv, &tz); | |
188 | if (poll(&pfd, 1, -1) < 0) | |
189 | fprintf(stderr, "hpet_poll: poll failed\n"); | |
190 | else { | |
191 | long data; | |
192 | ||
193 | gettimeofday(&etv, &tz); | |
194 | usec = stv.tv_sec * 1000000 + stv.tv_usec; | |
195 | usec = (etv.tv_sec * 1000000 + etv.tv_usec) - usec; | |
196 | ||
197 | fprintf(stderr, | |
198 | "hpet_poll: expired time = 0x%lx\n", usec); | |
199 | ||
200 | fprintf(stderr, "hpet_poll: revents = 0x%x\n", | |
201 | pfd.revents); | |
202 | ||
203 | if (read(fd, &data, sizeof(data)) != sizeof(data)) { | |
204 | fprintf(stderr, "hpet_poll: read failed\n"); | |
205 | } | |
206 | else | |
207 | fprintf(stderr, "hpet_poll: data 0x%lx\n", | |
208 | data); | |
209 | } | |
210 | } | |
211 | ||
212 | out: | |
213 | close(fd); | |
214 | return; | |
215 | } | |
216 | ||
217 | static int hpet_sigio_count; | |
218 | ||
219 | static void | |
220 | hpet_sigio(int val) | |
221 | { | |
222 | fprintf(stderr, "hpet_sigio: called\n"); | |
223 | hpet_sigio_count++; | |
224 | } | |
225 | ||
226 | void | |
227 | hpet_fasync(int argc, const char **argv) | |
228 | { | |
229 | unsigned long freq; | |
230 | int iterations, i, fd, value; | |
231 | sig_t oldsig; | |
232 | struct hpet_info info; | |
233 | ||
234 | hpet_sigio_count = 0; | |
235 | fd = -1; | |
236 | ||
237 | if ((oldsig = signal(SIGIO, hpet_sigio)) == SIG_ERR) { | |
238 | fprintf(stderr, "hpet_fasync: failed to set signal handler\n"); | |
239 | return; | |
240 | } | |
241 | ||
242 | if (argc != 3) { | |
243 | fprintf(stderr, "hpet_fasync: device-name freq iterations\n"); | |
244 | goto out; | |
245 | } | |
246 | ||
247 | fd = open(argv[0], O_RDONLY); | |
248 | ||
249 | if (fd < 0) { | |
250 | fprintf(stderr, "hpet_fasync: failed to open %s\n", argv[0]); | |
251 | return; | |
252 | } | |
253 | ||
254 | ||
255 | if ((fcntl(fd, F_SETOWN, getpid()) == 1) || | |
256 | ((value = fcntl(fd, F_GETFL)) == 1) || | |
257 | (fcntl(fd, F_SETFL, value | O_ASYNC) == 1)) { | |
258 | fprintf(stderr, "hpet_fasync: fcntl failed\n"); | |
259 | goto out; | |
260 | } | |
261 | ||
262 | freq = atoi(argv[1]); | |
263 | iterations = atoi(argv[2]); | |
264 | ||
265 | if (ioctl(fd, HPET_IRQFREQ, freq) < 0) { | |
266 | fprintf(stderr, "hpet_fasync: HPET_IRQFREQ failed\n"); | |
267 | goto out; | |
268 | } | |
269 | ||
270 | if (ioctl(fd, HPET_INFO, &info) < 0) { | |
271 | fprintf(stderr, "hpet_fasync: failed to get info\n"); | |
272 | goto out; | |
273 | } | |
274 | ||
275 | fprintf(stderr, "hpet_fasync: info.hi_flags 0x%lx\n", info.hi_flags); | |
276 | ||
277 | if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) { | |
278 | fprintf(stderr, "hpet_fasync: HPET_EPI failed\n"); | |
279 | goto out; | |
280 | } | |
281 | ||
282 | if (ioctl(fd, HPET_IE_ON, 0) < 0) { | |
283 | fprintf(stderr, "hpet_fasync, HPET_IE_ON failed\n"); | |
284 | goto out; | |
285 | } | |
286 | ||
287 | for (i = 0; i < iterations; i++) { | |
288 | (void) pause(); | |
289 | fprintf(stderr, "hpet_fasync: count = %d\n", hpet_sigio_count); | |
290 | } | |
291 | ||
292 | out: | |
293 | signal(SIGIO, oldsig); | |
294 | ||
295 | if (fd >= 0) | |
296 | close(fd); | |
297 | ||
298 | return; | |
299 | } |