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                High Precision Event Timer Driver for Linux
 
The High Precision Event Timer (HPET) hardware is the future replacement
for the 8254 and Real Time Clock (RTC) periodic timer functionality.
Each HPET can have up to 32 timers.  It is possible to configure the
first two timers as legacy replacements for 8254 and RTC periodic timers.
A specification done by Intel and Microsoft can be found at
.
 
The driver supports detection of HPET driver allocation and initialization
of the HPET before the driver module_init routine is called.  This enables
platform code which uses timer 0 or 1 as the main timer to intercept HPET
initialization.  An example of this initialization can be found in
arch/i386/kernel/time_hpet.c.
 
The driver provides two APIs which are very similar to the API found in
the rtc.c driver.  There is a user space API and a kernel space API.
An example user space program is provided below.
 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
 
 
extern void hpet_open_close(int, const char **);
extern void hpet_info(int, const char **);
extern void hpet_poll(int, const char **);
extern void hpet_fasync(int, const char **);
extern void hpet_read(int, const char **);
 
#include 
#include 
#include 
 
struct hpet_command {
        char            *command;
        void            (*func)(int argc, const char ** argv);
} hpet_command[] = {
        {
                "open-close",
                hpet_open_close
        },
        {
                "info",
                hpet_info
        },
        {
                "poll",
                hpet_poll
        },
        {
                "fasync",
                hpet_fasync
        },
};
 
int
main(int argc, const char ** argv)
{
        int     i;
 
        argc--;
        argv++;
 
        if (!argc) {
                fprintf(stderr, "-hpet: requires command\n");
                return -1;
        }
 
 
        for (i = 0; i < (sizeof (hpet_command) / sizeof (hpet_command[0])); i++)
                if (!strcmp(argv[0], hpet_command[i].command)) {
                        argc--;
                        argv++;
                        fprintf(stderr, "-hpet: executing %s\n",
                                hpet_command[i].command);
                        hpet_command[i].func(argc, argv);
                        return 0;
                }
 
        fprintf(stderr, "do_hpet: command %s not implemented\n", argv[0]);
 
        return -1;
}
 
void
hpet_open_close(int argc, const char **argv)
{
        int     fd;
 
        if (argc != 1) {
                fprintf(stderr, "hpet_open_close: device-name\n");
                return;
        }
 
        fd = open(argv[0], O_RDONLY);
        if (fd < 0)
                fprintf(stderr, "hpet_open_close: open failed\n");
        else
                close(fd);
 
        return;
}
 
void
hpet_info(int argc, const char **argv)
{
}
 
void
hpet_poll(int argc, const char **argv)
{
        unsigned long           freq;
        int                     iterations, i, fd;
        struct pollfd           pfd;
        struct hpet_info        info;
        struct timeval          stv, etv;
        struct timezone         tz;
        long                    usec;
 
        if (argc != 3) {
                fprintf(stderr, "hpet_poll: device-name freq iterations\n");
                return;
        }
 
        freq = atoi(argv[1]);
        iterations = atoi(argv[2]);
 
        fd = open(argv[0], O_RDONLY);
 
        if (fd < 0) {
                fprintf(stderr, "hpet_poll: open of %s failed\n", argv[0]);
                return;
        }
 
        if (ioctl(fd, HPET_IRQFREQ, freq) < 0) {
                fprintf(stderr, "hpet_poll: HPET_IRQFREQ failed\n");
                goto out;
        }
 
        if (ioctl(fd, HPET_INFO, &info) < 0) {
                fprintf(stderr, "hpet_poll: failed to get info\n");
                goto out;
        }
 
        fprintf(stderr, "hpet_poll: info.hi_flags 0x%lx\n", info.hi_flags);
 
        if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) {
                fprintf(stderr, "hpet_poll: HPET_EPI failed\n");
                goto out;
        }
 
        if (ioctl(fd, HPET_IE_ON, 0) < 0) {
                fprintf(stderr, "hpet_poll, HPET_IE_ON failed\n");
                goto out;
        }
 
        pfd.fd = fd;
        pfd.events = POLLIN;
 
        for (i = 0; i < iterations; i++) {
                pfd.revents = 0;
                gettimeofday(&stv, &tz);
                if (poll(&pfd, 1, -1) < 0)
                        fprintf(stderr, "hpet_poll: poll failed\n");
                else {
                        long    data;
 
                        gettimeofday(&etv, &tz);
                        usec = stv.tv_sec * 1000000 + stv.tv_usec;
                        usec = (etv.tv_sec * 1000000 + etv.tv_usec) - usec;
 
                        fprintf(stderr,
                                "hpet_poll: expired time = 0x%lx\n", usec);
 
                        fprintf(stderr, "hpet_poll: revents = 0x%x\n",
                                pfd.revents);
 
                        if (read(fd, &data, sizeof(data)) != sizeof(data)) {
                                fprintf(stderr, "hpet_poll: read failed\n");
                        }
                        else
                                fprintf(stderr, "hpet_poll: data 0x%lx\n",
                                        data);
                }
        }
 
out:
        close(fd);
        return;
}
 
static int hpet_sigio_count;
 
static void
hpet_sigio(int val)
{
        fprintf(stderr, "hpet_sigio: called\n");
        hpet_sigio_count++;
}
 
void
hpet_fasync(int argc, const char **argv)
{
        unsigned long           freq;
        int                     iterations, i, fd, value;
        sig_t                   oldsig;
        struct hpet_info        info;
 
        hpet_sigio_count = 0;
        fd = -1;
 
        if ((oldsig = signal(SIGIO, hpet_sigio)) == SIG_ERR) {
                fprintf(stderr, "hpet_fasync: failed to set signal handler\n");
                return;
        }
 
        if (argc != 3) {
                fprintf(stderr, "hpet_fasync: device-name freq iterations\n");
                goto out;
        }
 
        fd = open(argv[0], O_RDONLY);
 
        if (fd < 0) {
                fprintf(stderr, "hpet_fasync: failed to open %s\n", argv[0]);
                return;
        }
 
 
        if ((fcntl(fd, F_SETOWN, getpid()) == 1) ||
                ((value = fcntl(fd, F_GETFL)) == 1) ||
                (fcntl(fd, F_SETFL, value | O_ASYNC) == 1)) {
                fprintf(stderr, "hpet_fasync: fcntl failed\n");
                goto out;
        }
 
        freq = atoi(argv[1]);
        iterations = atoi(argv[2]);
 
        if (ioctl(fd, HPET_IRQFREQ, freq) < 0) {
                fprintf(stderr, "hpet_fasync: HPET_IRQFREQ failed\n");
                goto out;
        }
 
        if (ioctl(fd, HPET_INFO, &info) < 0) {
                fprintf(stderr, "hpet_fasync: failed to get info\n");
                goto out;
        }
 
        fprintf(stderr, "hpet_fasync: info.hi_flags 0x%lx\n", info.hi_flags);
 
        if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) {
                fprintf(stderr, "hpet_fasync: HPET_EPI failed\n");
                goto out;
        }
 
        if (ioctl(fd, HPET_IE_ON, 0) < 0) {
                fprintf(stderr, "hpet_fasync, HPET_IE_ON failed\n");
                goto out;
        }
 
        for (i = 0; i < iterations; i++) {
                (void) pause();
                fprintf(stderr, "hpet_fasync: count = %d\n", hpet_sigio_count);
        }
 
out:
        signal(SIGIO, oldsig);
 
        if (fd >= 0)
                close(fd);
 
        return;
}
 
The kernel API has three interfaces exported from the driver:
 
        hpet_register(struct hpet_task *tp, int periodic)
        hpet_unregister(struct hpet_task *tp)
        hpet_control(struct hpet_task *tp, unsigned int cmd, unsigned long arg)
 
The kernel module using this interface fills in the ht_func and ht_data
members of the hpet_task structure before calling hpet_register.
hpet_control simply vectors to the hpet_ioctl routine and has the same
commands and respective arguments as the user API.  hpet_unregister
is used to terminate usage of the HPET timer reserved by hpet_register.

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[/] [or1k_soc_on_altera_embedded_dev_kit/] [trunk/] [linux-2.6/] [linux-2.6.24/] [Documentation/] [hpet.txt] - Blame information for rev 3

Line No.	Rev	Author	Line
1	3	xianfeng	`High Precision Event Timer Driver for Linux`
2
3			`The High Precision Event Timer (HPET) hardware is the future replacement`
4			`for the 8254 and Real Time Clock (RTC) periodic timer functionality.`
5			`Each HPET can have up to 32 timers. It is possible to configure the`
6			`first two timers as legacy replacements for 8254 and RTC periodic timers.`
7			`A specification done by Intel and Microsoft can be found at`
8			`.`
9
10			`The driver supports detection of HPET driver allocation and initialization`
11			`of the HPET before the driver module_init routine is called. This enables`
12			`platform code which uses timer 0 or 1 as the main timer to intercept HPET`
13			`initialization. An example of this initialization can be found in`
14			`arch/i386/kernel/time_hpet.c.`
15
16			`The driver provides two APIs which are very similar to the API found in`
17			`the rtc.c driver. There is a user space API and a kernel space API.`
18			`An example user space program is provided below.`
19
20			`#include`
21			`#include`
22			`#include`
23			`#include`
24			`#include`
25			`#include`
26			`#include`
27			`#include`
28			`#include`
29			`#include`
30			`#include`
31			`#include`
32			`#include`
33			`#include`
34			`#include`
35			`#include`
36
37
38			`extern void hpet_open_close(int, const char **);`
39			`extern void hpet_info(int, const char **);`
40			`extern void hpet_poll(int, const char **);`
41			`extern void hpet_fasync(int, const char **);`
42			`extern void hpet_read(int, const char **);`
43
44			`#include`
45			`#include`
46			`#include`
47
48			`struct hpet_command {`
49			`char *command;`
50			`void (func)(int argc, const char * argv);`
51			`} hpet_command[] = {`
52			`{`
53			`"open-close",`
54			`hpet_open_close`
55			`},`
56			`{`
57			`"info",`
58			`hpet_info`
59			`},`
60			`{`
61			`"poll",`
62			`hpet_poll`
63			`},`
64			`{`
65			`"fasync",`
66			`hpet_fasync`
67			`},`
68			`};`
69
70			`int`
71			`main(int argc, const char ** argv)`
72			`{`
73			`int i;`
74
75			`argc--;`
76			`argv++;`
77
78			`if (!argc) {`
79			`fprintf(stderr, "-hpet: requires command\n");`
80			`return -1;`
81			`}`
82
83
84			`for (i = 0; i < (sizeof (hpet_command) / sizeof (hpet_command[0])); i++)`
85			`if (!strcmp(argv[0], hpet_command[i].command)) {`
86			`argc--;`
87			`argv++;`
88			`fprintf(stderr, "-hpet: executing %s\n",`
89			`hpet_command[i].command);`
90			`hpet_command[i].func(argc, argv);`
91			`return 0;`
92			`}`
93
94			`fprintf(stderr, "do_hpet: command %s not implemented\n", argv[0]);`
95
96			`return -1;`
97			`}`
98
99			`void`
100			`hpet_open_close(int argc, const char **argv)`
101			`{`
102			`int fd;`
103
104			`if (argc != 1) {`
105			`fprintf(stderr, "hpet_open_close: device-name\n");`
106			`return;`
107			`}`
108
109			`fd = open(argv[0], O_RDONLY);`
110			`if (fd < 0)`
111			`fprintf(stderr, "hpet_open_close: open failed\n");`
112			`else`
113			`close(fd);`
114
115			`return;`
116			`}`
117
118			`void`
119			`hpet_info(int argc, const char **argv)`
120			`{`
121			`}`
122
123			`void`
124			`hpet_poll(int argc, const char **argv)`
125			`{`
126			`unsigned long freq;`
127			`int iterations, i, fd;`
128			`struct pollfd pfd;`
129			`struct hpet_info info;`
130			`struct timeval stv, etv;`
131			`struct timezone tz;`
132			`long usec;`
133
134			`if (argc != 3) {`
135			`fprintf(stderr, "hpet_poll: device-name freq iterations\n");`
136			`return;`
137			`}`
138
139			`freq = atoi(argv[1]);`
140			`iterations = atoi(argv[2]);`
141
142			`fd = open(argv[0], O_RDONLY);`
143
144			`if (fd < 0) {`
145			`fprintf(stderr, "hpet_poll: open of %s failed\n", argv[0]);`
146			`return;`
147			`}`
148
149			`if (ioctl(fd, HPET_IRQFREQ, freq) < 0) {`
150			`fprintf(stderr, "hpet_poll: HPET_IRQFREQ failed\n");`
151			`goto out;`
152			`}`
153
154			`if (ioctl(fd, HPET_INFO, &info) < 0) {`
155			`fprintf(stderr, "hpet_poll: failed to get info\n");`
156			`goto out;`
157			`}`
158
159			`fprintf(stderr, "hpet_poll: info.hi_flags 0x%lx\n", info.hi_flags);`
160
161			`if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) {`
162			`fprintf(stderr, "hpet_poll: HPET_EPI failed\n");`
163			`goto out;`
164			`}`
165
166			`if (ioctl(fd, HPET_IE_ON, 0) < 0) {`
167			`fprintf(stderr, "hpet_poll, HPET_IE_ON failed\n");`
168			`goto out;`
169			`}`
170
171			`pfd.fd = fd;`
172			`pfd.events = POLLIN;`
173
174			`for (i = 0; i < iterations; i++) {`
175			`pfd.revents = 0;`
176			`gettimeofday(&stv, &tz);`
177			`if (poll(&pfd, 1, -1) < 0)`
178			`fprintf(stderr, "hpet_poll: poll failed\n");`
179			`else {`
180			`long data;`
181
182			`gettimeofday(&etv, &tz);`
183			`usec = stv.tv_sec * 1000000 + stv.tv_usec;`
184			`usec = (etv.tv_sec * 1000000 + etv.tv_usec) - usec;`
185
186			`fprintf(stderr,`
187			`"hpet_poll: expired time = 0x%lx\n", usec);`
188
189			`fprintf(stderr, "hpet_poll: revents = 0x%x\n",`
190			`pfd.revents);`
191
192			`if (read(fd, &data, sizeof(data)) != sizeof(data)) {`
193			`fprintf(stderr, "hpet_poll: read failed\n");`
194			`}`
195			`else`
196			`fprintf(stderr, "hpet_poll: data 0x%lx\n",`
197			`data);`
198			`}`
199			`}`
200
201			`out:`
202			`close(fd);`
203			`return;`
204			`}`
205
206			`static int hpet_sigio_count;`
207
208			`static void`
209			`hpet_sigio(int val)`
210			`{`
211			`fprintf(stderr, "hpet_sigio: called\n");`
212			`hpet_sigio_count++;`
213			`}`
214
215			`void`
216			`hpet_fasync(int argc, const char **argv)`
217			`{`
218			`unsigned long freq;`
219			`int iterations, i, fd, value;`
220			`sig_t oldsig;`
221			`struct hpet_info info;`
222
223			`hpet_sigio_count = 0;`
224			`fd = -1;`
225
226			`if ((oldsig = signal(SIGIO, hpet_sigio)) == SIG_ERR) {`
227			`fprintf(stderr, "hpet_fasync: failed to set signal handler\n");`
228			`return;`
229			`}`
230
231			`if (argc != 3) {`
232			`fprintf(stderr, "hpet_fasync: device-name freq iterations\n");`
233			`goto out;`
234			`}`
235
236			`fd = open(argv[0], O_RDONLY);`
237
238			`if (fd < 0) {`
239			`fprintf(stderr, "hpet_fasync: failed to open %s\n", argv[0]);`
240			`return;`
241			`}`
242
243
244			`if ((fcntl(fd, F_SETOWN, getpid()) == 1) \|\|`
245			`((value = fcntl(fd, F_GETFL)) == 1) \|\|`
246			`(fcntl(fd, F_SETFL, value \| O_ASYNC) == 1)) {`
247			`fprintf(stderr, "hpet_fasync: fcntl failed\n");`
248			`goto out;`
249			`}`
250
251			`freq = atoi(argv[1]);`
252			`iterations = atoi(argv[2]);`
253
254			`if (ioctl(fd, HPET_IRQFREQ, freq) < 0) {`
255			`fprintf(stderr, "hpet_fasync: HPET_IRQFREQ failed\n");`
256			`goto out;`
257			`}`
258
259			`if (ioctl(fd, HPET_INFO, &info) < 0) {`
260			`fprintf(stderr, "hpet_fasync: failed to get info\n");`
261			`goto out;`
262			`}`
263
264			`fprintf(stderr, "hpet_fasync: info.hi_flags 0x%lx\n", info.hi_flags);`
265
266			`if (info.hi_flags && (ioctl(fd, HPET_EPI, 0) < 0)) {`
267			`fprintf(stderr, "hpet_fasync: HPET_EPI failed\n");`
268			`goto out;`
269			`}`
270
271			`if (ioctl(fd, HPET_IE_ON, 0) < 0) {`
272			`fprintf(stderr, "hpet_fasync, HPET_IE_ON failed\n");`
273			`goto out;`
274			`}`
275
276			`for (i = 0; i < iterations; i++) {`
277			`(void) pause();`
278			`fprintf(stderr, "hpet_fasync: count = %d\n", hpet_sigio_count);`
279			`}`
280
281			`out:`
282			`signal(SIGIO, oldsig);`
283
284			`if (fd >= 0)`
285			`close(fd);`
286
287			`return;`
288			`}`
289
290			`The kernel API has three interfaces exported from the driver:`
291
292			`hpet_register(struct hpet_task *tp, int periodic)`
293			`hpet_unregister(struct hpet_task *tp)`
294			`hpet_control(struct hpet_task *tp, unsigned int cmd, unsigned long arg)`
295
296			`The kernel module using this interface fills in the ht_func and ht_data`
297			`members of the hpet_task structure before calling hpet_register.`
298			`hpet_control simply vectors to the hpet_ioctl routine and has the same`
299			`commands and respective arguments as the user API. hpet_unregister`
300			`is used to terminate usage of the HPET timer reserved by hpet_register.`