linux-2.5.38_timer-change_A3

PATCH New john stultz 1 participant 1 message Sep 23, 2002

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john stultz

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2002-09-23 21:37 UTC #0 lore raw

PATCH 1/1 linux-2.5.38_timer-change_A3

Dave, Linus, all,
Here is a resync of the timer-change patch w/ 2.5.38. No major changes,
but a few cleanups. Again, this code breaks up the hardware specific time.c code into separate timer_pit.c and timer_tsc.c and creates an abstract interface (struct timer_opts) to be able to use either without caring/knowing about the lower level implementation. This should make it cleaner and easier to add new time sources to the kernel (such as the cyclone-timer, HPET, ACPI pm timer, etc).

I avoided any other cleanups to make the change as transparent and easy to follow as possible.

I may have mis-merged/dropped some of the recent #ifdef CONFIG_X86_TSC additions, but some of that didn't make sense to me, and I must have missed the dialog. Do we really want to have kernels forced to an either-or situation w/ regard to the TSC? Where kernels compiled for i386 won't use the TSC and kernels compiled for i686 must use it?

Any/all comments/nasty-grams welcome/accepted here/everywhere.

or something.
-john

arch/i386/kernel/Makefile +1 -1

diff -Nru a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
@@ -9,7 +9,7 @@
 obj-y	:= process.o semaphore.o signal.o entry.o traps.o irq.o vm86.o \
 		ptrace.o i8259.o ioport.o ldt.o setup.o time.o sys_i386.o \
 		pci-dma.o i386_ksyms.o i387.o bluesmoke.o dmi_scan.o \
-		bootflag.o
+		bootflag.o timer.o timer_tsc.o
 
 obj-y				+= cpu/
 obj-$(CONFIG_X86_BIOS_REBOOT)	+= reboot.o

arch/i386/kernel/time.c +9 ~~-291~~

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arch/i386/kernel/timer.c new file +32 -0

diff -Nru a/arch/i386/kernel/timer.c b/arch/i386/kernel/timer.c
@@ -0,0 +1,32 @@
+#include <linux/kernel.h>
+#include <asm/timer.h>
+
+/* list of externed timers */
+#ifndef CONFIG_X86_TSC
+extern struct timer_opts timer_pit;
+#endif
+extern struct timer_opts timer_tsc;
+
+/* list of timers, ordered by preference */
+struct timer_opts* timers[] = {
+	&timer_tsc
+#ifndef CONFIG_X86_TSC
+	,&timer_pit
+#endif
+};
+
+#define NR_TIMERS (sizeof(timers)/sizeof(timers[0]))
+
+/* iterates through the list of timers, returning the first 
+ * one that initializes successfully.
+ */
+struct timer_opts* select_timer(void)
+{
+	int i;
+	/* find most preferred working timer */
+	for(i=0; i < NR_TIMERS; i++)
+		if(timers[i]->init())
+			return timers[i];
+	panic("select_timer: Cannot find a suitable timer\n");
+	return 0;
+}

arch/i386/kernel/timer_pit.c new file +168 -0

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arch/i386/kernel/timer_tsc.c new file +215 -0

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include/asm-i386/timer.h new file +17 -0

diff -Nru a/include/asm-i386/timer.h b/include/asm-i386/timer.h
@@ -0,0 +1,17 @@
+#ifndef _ASMi386_TIMER_H
+#define _ASMi386_TIMER_H
+
+#include <asm/timer.h>
+
+struct timer_opts{
+	/* probes and initializes timer. returns 1 on sucess, 0 on failure */
+	int (*init)(void);
+	/* called by the timer interrupt */
+	void (*mark_offset)(void);
+	/* called by gettimeofday. returns # ms since the last timer interrupt */
+	unsigned long (*get_offset)(void);
+};
+
+#define TICK_SIZE (tick_nsec / 1000)
+struct timer_opts* select_timer(void);
+#endif