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authorRandy Dunlap <randy.dunlap@oracle.com>2008-07-22 09:46:13 -0700
committerThomas Gleixner <tglx@linutronix.de>2008-07-24 01:32:41 +0200
commita300bec952127d9a15e666b391bb35c9aecb3002 (patch)
tree9f2fea940cf7cb991c259f7f7fd71506337afc8c /Documentation/timers
parentf3561810b163aca5388ad550abbbc82ae5323189 (diff)
downloadlinaro-lsk-a300bec952127d9a15e666b391bb35c9aecb3002.tar.gz
documentation: move hpet.txt to timers/ subdirectory
Move hpet.txt to Documentation/timers/ subdirectory. Add 00-INDEX to Documentation/timers/ subdirectory. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: tglx <tglx@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/timers')
-rw-r--r--Documentation/timers/00-INDEX10
-rw-r--r--Documentation/timers/hpet.txt300
2 files changed, 310 insertions, 0 deletions
diff --git a/Documentation/timers/00-INDEX b/Documentation/timers/00-INDEX
new file mode 100644
index 00000000000..397dc35e132
--- /dev/null
+++ b/Documentation/timers/00-INDEX
@@ -0,0 +1,10 @@
+00-INDEX
+ - this file
+highres.txt
+ - High resolution timers and dynamic ticks design notes
+hpet.txt
+ - High Precision Event Timer Driver for Linux
+hrtimers.txt
+ - subsystem for high-resolution kernel timers
+timer_stats.txt
+ - timer usage statistics
diff --git a/Documentation/timers/hpet.txt b/Documentation/timers/hpet.txt
new file mode 100644
index 00000000000..6ad52d9dad6
--- /dev/null
+++ b/Documentation/timers/hpet.txt
@@ -0,0 +1,300 @@
+ 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
+<http://www.intel.com/technology/architecture/hpetspec.htm>.
+
+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 <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;
+}
+
+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.