diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/hpet.txt |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/hpet.txt')
-rw-r--r-- | Documentation/hpet.txt | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/Documentation/hpet.txt b/Documentation/hpet.txt new file mode 100644 index 000000000000..4e7cc8d3359b --- /dev/null +++ b/Documentation/hpet.txt | |||
@@ -0,0 +1,298 @@ | |||
1 | High Precision Event Timer Driver for Linux | ||
2 | |||
3 | The High Precision Event Timer (HPET) hardware is the future replacement for the 8254 and Real | ||
4 | Time Clock (RTC) periodic timer functionality. Each HPET can have up two 32 timers. It is possible | ||
5 | to configure the first two timers as legacy replacements for 8254 and RTC periodic. A specification | ||
6 | done by INTEL and Microsoft can be found at http://www.intel.com/labs/platcomp/hpet/hpetspec.htm. | ||
7 | |||
8 | The driver supports detection of HPET driver allocation and initialization of the HPET before the | ||
9 | driver module_init routine is called. This enables platform code which uses timer 0 or 1 as the | ||
10 | main timer to intercept HPET initialization. An example of this initialization can be found in | ||
11 | arch/i386/kernel/time_hpet.c. | ||
12 | |||
13 | The driver provides two APIs which are very similar to the API found in the rtc.c driver. | ||
14 | There is a user space API and a kernel space API. An example user space program is provided | ||
15 | below. | ||
16 | |||
17 | #include <stdio.h> | ||
18 | #include <stdlib.h> | ||
19 | #include <unistd.h> | ||
20 | #include <fcntl.h> | ||
21 | #include <string.h> | ||
22 | #include <memory.h> | ||
23 | #include <malloc.h> | ||
24 | #include <time.h> | ||
25 | #include <ctype.h> | ||
26 | #include <sys/types.h> | ||
27 | #include <sys/wait.h> | ||
28 | #include <signal.h> | ||
29 | #include <fcntl.h> | ||
30 | #include <errno.h> | ||
31 | #include <sys/time.h> | ||
32 | #include <linux/hpet.h> | ||
33 | |||
34 | |||
35 | extern void hpet_open_close(int, const char **); | ||
36 | extern void hpet_info(int, const char **); | ||
37 | extern void hpet_poll(int, const char **); | ||
38 | extern void hpet_fasync(int, const char **); | ||
39 | extern void hpet_read(int, const char **); | ||
40 | |||
41 | #include <sys/poll.h> | ||
42 | #include <sys/ioctl.h> | ||
43 | #include <signal.h> | ||
44 | |||
45 | struct hpet_command { | ||
46 | char *command; | ||
47 | void (*func)(int argc, const char ** argv); | ||
48 | } hpet_command[] = { | ||
49 | { | ||
50 | "open-close", | ||
51 | hpet_open_close | ||
52 | }, | ||
53 | { | ||
54 | "info", | ||
55 | hpet_info | ||
56 | }, | ||
57 | { | ||
58 | "poll", | ||
59 | hpet_poll | ||
60 | }, | ||
61 | { | ||
62 | "fasync", | ||
63 | hpet_fasync | ||
64 | }, | ||
65 | }; | ||
66 | |||
67 | int | ||
68 | main(int argc, const char ** argv) | ||
69 | { | ||
70 | int i; | ||
71 | |||
72 | argc--; | ||
73 | argv++; | ||
74 | |||
75 | if (!argc) { | ||
76 | fprintf(stderr, "-hpet: requires command\n"); | ||
77 | return -1; | ||
78 | } | ||
79 | |||
80 | |||
81 | for (i = 0; i < (sizeof (hpet_command) / sizeof (hpet_command[0])); i++) | ||
82 | if (!strcmp(argv[0], hpet_command[i].command)) { | ||
83 | argc--; | ||
84 | argv++; | ||
85 | fprintf(stderr, "-hpet: executing %s\n", | ||
86 | hpet_command[i].command); | ||
87 | hpet_command[i].func(argc, argv); | ||
88 | return 0; | ||
89 | } | ||
90 | |||
91 | fprintf(stderr, "do_hpet: command %s not implemented\n", argv[0]); | ||
92 | |||
93 | return -1; | ||
94 | } | ||
95 | |||
96 | void | ||
97 | hpet_open_close(int argc, const char **argv) | ||
98 | { | ||
99 | int fd; | ||
100 | |||
101 | if (argc != 1) { | ||
102 | fprintf(stderr, "hpet_open_close: device-name\n"); | ||
103 | return; | ||
104 | } | ||
105 | |||
106 | fd = open(argv[0], O_RDONLY); | ||
107 | if (fd < 0) | ||
108 | fprintf(stderr, "hpet_open_close: open failed\n"); | ||
109 | else | ||
110 | close(fd); | ||
111 | |||
112 | return; | ||
113 | } | ||
114 | |||
115 | void | ||
116 | hpet_info(int argc, const char **argv) | ||
117 | { | ||
118 | } | ||
119 | |||
120 | void | ||
121 | hpet_poll(int argc, const char **argv) | ||
122 | { | ||
123 | unsigned long freq; | ||
124 | int iterations, i, fd; | ||
125 | struct pollfd pfd; | ||
126 | struct hpet_info info; | ||
127 | struct timeval stv, etv; | ||
128 | struct timezone tz; | ||
129 | long usec; | ||
130 | |||
131 | if (argc != 3) { | ||
132 | fprintf(stderr, "hpet_poll: device-name freq iterations\n"); | ||
133 | return; | ||
134 | } | ||
135 | |||
136 | freq = atoi(argv[1]); | ||
137 | iterations = atoi(argv[2]); | ||
138 | |||
139 | fd = open(argv[0], O_RDONLY); | ||
140 | |||
141 | if (fd < 0) { | ||
142 | fprintf(stderr, "hpet_poll: open of %s failed\n", argv[0]); | ||
143 | return; | ||
144 | } | ||
145 | |||
146 | if (ioctl(fd, HPET_IRQFREQ, freq) < 0) { | ||
147 | fprintf(stderr, "hpet_poll: HPET_IRQFREQ failed\n"); | ||
148 | goto out; | ||
149 | } | ||
150 | |||
151 | if (ioctl(fd, HPET_INFO, &info) < 0) { | ||
152 | fprintf(stderr, "hpet_poll: failed to get info\n"); | ||
153 | goto out; | ||
154 | } | ||
155 | |||
156 | fprintf(stderr, "hpet_poll: info.hi_flags 0x%lx\n", info.hi_flags); | ||
157 | |||
158 | if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) { | ||
159 | fprintf(stderr, "hpet_poll: HPET_EPI failed\n"); | ||
160 | goto out; | ||
161 | } | ||
162 | |||
163 | if (ioctl(fd, HPET_IE_ON, 0) < 0) { | ||
164 | fprintf(stderr, "hpet_poll, HPET_IE_ON failed\n"); | ||
165 | goto out; | ||
166 | } | ||
167 | |||
168 | pfd.fd = fd; | ||
169 | pfd.events = POLLIN; | ||
170 | |||
171 | for (i = 0; i < iterations; i++) { | ||
172 | pfd.revents = 0; | ||
173 | gettimeofday(&stv, &tz); | ||
174 | if (poll(&pfd, 1, -1) < 0) | ||
175 | fprintf(stderr, "hpet_poll: poll failed\n"); | ||
176 | else { | ||
177 | long data; | ||
178 | |||
179 | gettimeofday(&etv, &tz); | ||
180 | usec = stv.tv_sec * 1000000 + stv.tv_usec; | ||
181 | usec = (etv.tv_sec * 1000000 + etv.tv_usec) - usec; | ||
182 | |||
183 | fprintf(stderr, | ||
184 | "hpet_poll: expired time = 0x%lx\n", usec); | ||
185 | |||
186 | fprintf(stderr, "hpet_poll: revents = 0x%x\n", | ||
187 | pfd.revents); | ||
188 | |||
189 | if (read(fd, &data, sizeof(data)) != sizeof(data)) { | ||
190 | fprintf(stderr, "hpet_poll: read failed\n"); | ||
191 | } | ||
192 | else | ||
193 | fprintf(stderr, "hpet_poll: data 0x%lx\n", | ||
194 | data); | ||
195 | } | ||
196 | } | ||
197 | |||
198 | out: | ||
199 | close(fd); | ||
200 | return; | ||
201 | } | ||
202 | |||
203 | static int hpet_sigio_count; | ||
204 | |||
205 | static void | ||
206 | hpet_sigio(int val) | ||
207 | { | ||
208 | fprintf(stderr, "hpet_sigio: called\n"); | ||
209 | hpet_sigio_count++; | ||
210 | } | ||
211 | |||
212 | void | ||
213 | hpet_fasync(int argc, const char **argv) | ||
214 | { | ||
215 | unsigned long freq; | ||
216 | int iterations, i, fd, value; | ||
217 | sig_t oldsig; | ||
218 | struct hpet_info info; | ||
219 | |||
220 | hpet_sigio_count = 0; | ||
221 | fd = -1; | ||
222 | |||
223 | if ((oldsig = signal(SIGIO, hpet_sigio)) == SIG_ERR) { | ||
224 | fprintf(stderr, "hpet_fasync: failed to set signal handler\n"); | ||
225 | return; | ||
226 | } | ||
227 | |||
228 | if (argc != 3) { | ||
229 | fprintf(stderr, "hpet_fasync: device-name freq iterations\n"); | ||
230 | goto out; | ||
231 | } | ||
232 | |||
233 | fd = open(argv[0], O_RDONLY); | ||
234 | |||
235 | if (fd < 0) { | ||
236 | fprintf(stderr, "hpet_fasync: failed to open %s\n", argv[0]); | ||
237 | return; | ||
238 | } | ||
239 | |||
240 | |||
241 | if ((fcntl(fd, F_SETOWN, getpid()) == 1) || | ||
242 | ((value = fcntl(fd, F_GETFL)) == 1) || | ||
243 | (fcntl(fd, F_SETFL, value | O_ASYNC) == 1)) { | ||
244 | fprintf(stderr, "hpet_fasync: fcntl failed\n"); | ||
245 | goto out; | ||
246 | } | ||
247 | |||
248 | freq = atoi(argv[1]); | ||
249 | iterations = atoi(argv[2]); | ||
250 | |||
251 | if (ioctl(fd, HPET_IRQFREQ, freq) < 0) { | ||
252 | fprintf(stderr, "hpet_fasync: HPET_IRQFREQ failed\n"); | ||
253 | goto out; | ||
254 | } | ||
255 | |||
256 | if (ioctl(fd, HPET_INFO, &info) < 0) { | ||
257 | fprintf(stderr, "hpet_fasync: failed to get info\n"); | ||
258 | goto out; | ||
259 | } | ||
260 | |||
261 | fprintf(stderr, "hpet_fasync: info.hi_flags 0x%lx\n", info.hi_flags); | ||
262 | |||
263 | if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) { | ||
264 | fprintf(stderr, "hpet_fasync: HPET_EPI failed\n"); | ||
265 | goto out; | ||
266 | } | ||
267 | |||
268 | if (ioctl(fd, HPET_IE_ON, 0) < 0) { | ||
269 | fprintf(stderr, "hpet_fasync, HPET_IE_ON failed\n"); | ||
270 | goto out; | ||
271 | } | ||
272 | |||
273 | for (i = 0; i < iterations; i++) { | ||
274 | (void) pause(); | ||
275 | fprintf(stderr, "hpet_fasync: count = %d\n", hpet_sigio_count); | ||
276 | } | ||
277 | |||
278 | out: | ||
279 | signal(SIGIO, oldsig); | ||
280 | |||
281 | if (fd >= 0) | ||
282 | close(fd); | ||
283 | |||
284 | return; | ||
285 | } | ||
286 | |||
287 | The kernel API has three interfaces exported from the driver: | ||
288 | |||
289 | hpet_register(struct hpet_task *tp, int periodic) | ||
290 | hpet_unregister(struct hpet_task *tp) | ||
291 | hpet_control(struct hpet_task *tp, unsigned int cmd, unsigned long arg) | ||
292 | |||
293 | The kernel module using this interface fills in the ht_func and ht_data members of the | ||
294 | hpet_task structure before calling hpet_register. hpet_control simply vectors to the hpet_ioctl | ||
295 | routine and has the same commands and respective arguments as the user API. hpet_unregister | ||
296 | is used to terminate usage of the HPET timer reserved by hpet_register. | ||
297 | |||
298 | |||