The High Precision Event Timer (HPET) hardware follows a specification
by Intel and Microsoft which can be found at
- http://www.intel.com/technology/architecture/hpetspec.htm
+ http://www.intel.com/hardwaredesign/hpetspec_1.pdf
Each HPET has one fixed-rate counter (at 10+ MHz, hence "High Precision")
and up to 32 comparators. Normally three or more comparators are provided,
-each of which can generate oneshot interupts and at least one of which has
+each of which can generate oneshot interrupts and at least one of which has
additional hardware to support periodic interrupts. The comparators are
also called "timers", which can be misleading since usually timers are
independent of each other ... these share a counter, complicating resets.
arch/x86/kernel/hpet.c.
The driver provides a userspace API which resembles the API found in the
-RTC driver framework. An example user space program is provided below.
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <string.h>
-#include <memory.h>
-#include <malloc.h>
-#include <time.h>
-#include <ctype.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <signal.h>
-#include <fcntl.h>
-#include <errno.h>
-#include <sys/time.h>
-#include <linux/hpet.h>
-
-
-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 <sys/poll.h>
-#include <sys/ioctl.h>
-#include <signal.h>
-
-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;
-}
+RTC driver framework. An example user space program is provided in
+file:Documentation/timers/hpet_example.c
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff