mirror of
git://projects.qi-hardware.com/openwrt-xburst.git
synced 2024-12-24 07:29:33 +02:00
0bf116e39e
git-svn-id: svn://svn.openwrt.org/openwrt/branches/buildroot-ng/openwrt@4951 3c298f89-4303-0410-b956-a3cf2f4a3e73
321 lines
12 KiB
Diff
321 lines
12 KiB
Diff
SCx200 High Resolution Timer Patch for Linux 2.6
|
|
http://www.gnusto.com/scx200-hr-timer.html
|
|
|
|
diff -Naurp linux-2.6.12-rc6.orig/arch/i386/Kconfig linux-2.6.12-rc6/arch/i386/Kconfig
|
|
--- linux-2.6.12-rc6.orig/arch/i386/Kconfig 2005-06-07 14:56:02.000000000 +0100
|
|
+++ linux-2.6.12-rc6/arch/i386/Kconfig 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -458,6 +458,17 @@ config HPET_EMULATE_RTC
|
|
bool "Provide RTC interrupt"
|
|
depends on HPET_TIMER && RTC=y
|
|
|
|
+config SCx200HR_TIMER
|
|
+ bool "NatSemi SCx200 27MHz High-Resolution Timer Support"
|
|
+ help
|
|
+ Some of the AMD (formerly National Semiconductor) Geode
|
|
+ processors, notably the SC1100, suffer from a buggy time
|
|
+ stamp counter which causes them to lose time when the
|
|
+ processor is sleeping. Enable this option to use the
|
|
+ on-board 27Mz high-resolution timer to keep time instead.
|
|
+ depends on (SCx200)
|
|
+ default n
|
|
+
|
|
config SMP
|
|
bool "Symmetric multi-processing support"
|
|
---help---
|
|
diff -Naurp linux-2.6.12-rc6.orig/arch/i386/kernel/scx200.c linux-2.6.12-rc6/arch/i386/kernel/scx200.c
|
|
--- linux-2.6.12-rc6.orig/arch/i386/kernel/scx200.c 2005-06-07 14:56:02.000000000 +0100
|
|
+++ linux-2.6.12-rc6/arch/i386/kernel/scx200.c 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -27,6 +27,10 @@ long scx200_gpio_shadow[2];
|
|
|
|
unsigned scx200_cb_base = 0;
|
|
|
|
+#ifdef CONFIG_SCx200HR_TIMER
|
|
+extern void __devinit scx200hr_timer_enable(void);
|
|
+#endif
|
|
+
|
|
static struct pci_device_id scx200_tbl[] = {
|
|
{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
|
|
{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
|
|
@@ -83,6 +87,9 @@ static int __devinit scx200_probe(struct
|
|
printk(KERN_INFO NAME ": Configuration Block base 0x%x\n", scx200_cb_base);
|
|
}
|
|
|
|
+#ifdef CONFIG_SCx200HR_TIMER
|
|
+ scx200hr_timer_enable();
|
|
+#endif
|
|
return 0;
|
|
}
|
|
|
|
diff -Naurp linux-2.6.12-rc6.orig/arch/i386/kernel/timers/Makefile linux-2.6.12-rc6/arch/i386/kernel/timers/Makefile
|
|
--- linux-2.6.12-rc6.orig/arch/i386/kernel/timers/Makefile 2004-03-11 18:21:13.000000000 +0000
|
|
+++ linux-2.6.12-rc6/arch/i386/kernel/timers/Makefile 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -5,5 +5,6 @@
|
|
obj-y := timer.o timer_none.o timer_tsc.o timer_pit.o common.o
|
|
|
|
obj-$(CONFIG_X86_CYCLONE_TIMER) += timer_cyclone.o
|
|
+obj-$(CONFIG_SCx200HR_TIMER) += timer_scx200hr.o
|
|
obj-$(CONFIG_HPET_TIMER) += timer_hpet.o
|
|
obj-$(CONFIG_X86_PM_TIMER) += timer_pm.o
|
|
diff -Naurp linux-2.6.12-rc6.orig/arch/i386/kernel/timers/timer.c linux-2.6.12-rc6/arch/i386/kernel/timers/timer.c
|
|
--- linux-2.6.12-rc6.orig/arch/i386/kernel/timers/timer.c 2004-12-26 14:07:37.000000000 +0000
|
|
+++ linux-2.6.12-rc6/arch/i386/kernel/timers/timer.c 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -13,6 +13,9 @@
|
|
#endif
|
|
/* list of timers, ordered by preference, NULL terminated */
|
|
static struct init_timer_opts* __initdata timers[] = {
|
|
+#ifdef CONFIG_SCx200HR_TIMER
|
|
+ &timer_scx200hr_init,
|
|
+#endif
|
|
#ifdef CONFIG_X86_CYCLONE_TIMER
|
|
&timer_cyclone_init,
|
|
#endif
|
|
diff -Naurp linux-2.6.12-rc6.orig/arch/i386/kernel/timers/timer_scx200hr.c linux-2.6.12-rc6/arch/i386/kernel/timers/timer_scx200hr.c
|
|
--- linux-2.6.12-rc6.orig/arch/i386/kernel/timers/timer_scx200hr.c 1970-01-01 01:00:00.000000000 +0100
|
|
+++ linux-2.6.12-rc6/arch/i386/kernel/timers/timer_scx200hr.c 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -0,0 +1,220 @@
|
|
+/*
|
|
+ * Copyright (C) 2005 Ted Phelps
|
|
+ *
|
|
+ * This is a clock driver for the Geode SCx200's 27MHz high-resolution
|
|
+ * timer as the system clock replacing its buggy time stamp counter.
|
|
+ *
|
|
+ * Based on parts of timer_hpet.c, timer_tsc.c and timer_pit.c.
|
|
+ *
|
|
+ * This program is free software; you can redistribute it and/or
|
|
+ * modify it under the terms of the GNU General Public License as
|
|
+ * published by the Free Software Foundation; either version 2 of the
|
|
+ * License, or (at your option) any later version.
|
|
+ */
|
|
+
|
|
+#include <asm/timer.h>
|
|
+#include <linux/init.h>
|
|
+#include <linux/pci.h>
|
|
+#include <linux/seq_file.h>
|
|
+#include <linux/scx200.h>
|
|
+
|
|
+#define NAME "scx200hr"
|
|
+
|
|
+/* Read the clock */
|
|
+#define SCx200HR_CLOCK() inl(scx200_cb_base + SCx200_TIMER_OFFSET)
|
|
+
|
|
+/* High-resolution timer configuration address */
|
|
+#define SCx200_TMCNFG_OFFSET (SCx200_TIMER_OFFSET + 5)
|
|
+
|
|
+/* Set this bit to disable the 27 MHz input clock */
|
|
+#define HR_TM27MPD (1 << 2)
|
|
+
|
|
+/* Set this bit to update the count-up timer once per cycle of the
|
|
+ * 27MHz timer, clear it to update the timer once every 27 cycles
|
|
+ * (effectively producing a 1MHz counter) */
|
|
+#define HR_TMCLKSEL (1 << 1)
|
|
+
|
|
+/* Set this bit to enable the high-resolution timer interrupt */
|
|
+#define HR_TMEN (1 << 0)
|
|
+
|
|
+/* The frequency of the timer. Change this to 27000000 and set
|
|
+ * HR_TMCLKSEL in scx200hr_enable to run at the faster clock rate. At
|
|
+ * this point in time there is no point in doing so since times are
|
|
+ * recorded in usec except for the monotonic clock, which is only used
|
|
+ * by the hangcheck-timer. */
|
|
+#define HR_FREQ 1000000
|
|
+
|
|
+/* The number of cycles of the high-resolution timer we expect to see
|
|
+ * in a single tick. Note that the result is <<8 for greater precision*/
|
|
+#define HR_CYCLES_PER_TICK \
|
|
+ (SH_DIV(HR_FREQ / 1000000 * TICK_NSEC, 1000, 8))
|
|
+
|
|
+/* The number of cycles of the high-resolution timer we expect to see
|
|
+ * in one microsecond, <<8 */
|
|
+#define HR_CYCLES_PER_US ((HR_FREQ / 1000000) << 8)
|
|
+
|
|
+
|
|
+/* The value of the timer at the last interrupt */
|
|
+static u32 clock_at_last_interrupt;
|
|
+
|
|
+/* The number of high-resolution clock cycles beyond what we would
|
|
+ have expected that the last tick occurred, <<8 for greater precision */
|
|
+static long clock_delay;
|
|
+
|
|
+/* The total number of timer nanoseconds between the time the timer
|
|
+ * went live and the most recent tick. */
|
|
+static unsigned long long total_ns;
|
|
+
|
|
+/* A lock to guard access to the monotonic clock-related variables
|
|
+ * (total_ns and clocal_at_last_interrupt). Note that these are also
|
|
+ * protected by the xtime lock. */
|
|
+static seqlock_t hr_lock = SEQLOCK_UNLOCKED;
|
|
+
|
|
+/* Nonzero if the timer has been selected */
|
|
+static int enable_scx200hr;
|
|
+
|
|
+static int __init scx200hr_init(char *override)
|
|
+{
|
|
+ /* Watch for a command-line clock= override */
|
|
+ if (override[0] && strncmp(override, NAME, sizeof(NAME) - 1) != 0) {
|
|
+ return -ENODEV;
|
|
+ }
|
|
+
|
|
+ /* Note that we should try to enable this timer once the
|
|
+ * configuration block address is known */
|
|
+ printk(KERN_WARNING NAME ": timer not yet accessible; will probe later.\n");
|
|
+ enable_scx200hr = 1;
|
|
+ return -EAGAIN;
|
|
+}
|
|
+
|
|
+/* Called by the timer interrupt. The xtime_lock will be held. */
|
|
+static void mark_offset_scx200hr(void)
|
|
+{
|
|
+ u32 now, delta;
|
|
+
|
|
+ /* Avoid races between the interrupt handler and monotonic_clock */
|
|
+ write_seqlock(&hr_lock);
|
|
+
|
|
+ /* Determine how many cycles have elapsed since the last interrupt */
|
|
+ now = SCx200HR_CLOCK();
|
|
+ delta = (now - clock_at_last_interrupt) << 8;
|
|
+ clock_at_last_interrupt = now;
|
|
+
|
|
+ /* Update the total us count and remainder */
|
|
+ total_ns += (delta * 1000) / HR_CYCLES_PER_US;
|
|
+
|
|
+ /* The monotonic clock is safe now */
|
|
+ write_sequnlock(&hr_lock);
|
|
+
|
|
+ /* Adjust for interrupt handling delay */
|
|
+ delta += clock_delay;
|
|
+
|
|
+ /* The high-resolution timer is driven by a different crystal
|
|
+ * to the main CPU, so there's no guarantee that the 1KHz
|
|
+ * interrupt rate will coincide with the timer. This keeps
|
|
+ * the jiffies count in line with the high-resolution timer,
|
|
+ * which makes it possible for NTP to do its magic */
|
|
+ if (delta < HR_CYCLES_PER_TICK) {
|
|
+#if 1
|
|
+ /* Didn't go over 1000us: decrement jiffies to balance
|
|
+ * out increment in do_timer. This will cause some
|
|
+ * jitter if the frequency offset is large, as that
|
|
+ * adjustment will be applied about 1ms late. */
|
|
+ jiffies_64--;
|
|
+ clock_delay = delta;
|
|
+#else /* !1 */
|
|
+ clock_delay = 0;
|
|
+#endif /* 1 */
|
|
+ } else if (delta < (HR_CYCLES_PER_TICK << 1) + (HR_CYCLES_PER_TICK >> 1)) {
|
|
+ clock_delay = delta - HR_CYCLES_PER_TICK;
|
|
+ } else {
|
|
+ jiffies_64 += delta / HR_CYCLES_PER_TICK - 2;
|
|
+ clock_delay = HR_CYCLES_PER_TICK + delta % HR_CYCLES_PER_TICK;
|
|
+ }
|
|
+}
|
|
+
|
|
+/* Called by gettimeofday(). Returns the number of microseconds since
|
|
+ * the last interrupt. This is called with the xtime_lock held.*/
|
|
+static unsigned long get_offset_scx200hr(void)
|
|
+{
|
|
+ u32 delta;
|
|
+
|
|
+ /* Get the time now and determine how many cycles have
|
|
+ * transpired since the interrupt, adjusting for timer
|
|
+ * interrupt jitter. */
|
|
+ delta = ((SCx200HR_CLOCK() - clock_at_last_interrupt) << 8) + clock_delay;
|
|
+
|
|
+ /* Convert from cycles<<8 to microseconds */
|
|
+ return delta / HR_CYCLES_PER_US;
|
|
+}
|
|
+
|
|
+/* Returns the number of nanoseconds since the init of the timer. */
|
|
+static unsigned long long monotonic_clock_scx200hr(void)
|
|
+{
|
|
+ u32 delta, seq;
|
|
+ unsigned long long ns;
|
|
+
|
|
+ /* This function is *not* called with xtime_lock held, so we
|
|
+ * need to get the hr_lock to ensure we're not competing with
|
|
+ * mark_offset_scx200hr. */
|
|
+ do {
|
|
+ seq = read_seqbegin(&hr_lock);
|
|
+ ns = total_ns;
|
|
+ delta = SCx200HR_CLOCK() - clock_at_last_interrupt;
|
|
+ } while (read_seqretry(&hr_lock, seq));
|
|
+
|
|
+ /* Convert cycles to microseconds and add. */
|
|
+ return ns + delta * 1000 / HR_CYCLES_PER_US;
|
|
+}
|
|
+
|
|
+/* scx200hr timer_opts struct */
|
|
+struct timer_opts timer_scx200hr = {
|
|
+ .name = NAME,
|
|
+ .mark_offset = mark_offset_scx200hr,
|
|
+ .get_offset = get_offset_scx200hr,
|
|
+ .monotonic_clock = monotonic_clock_scx200hr,
|
|
+ .delay = NULL
|
|
+};
|
|
+
|
|
+/* And the init_timer struct */
|
|
+struct init_timer_opts __devinitdata timer_scx200hr_init = {
|
|
+ .init = scx200hr_init,
|
|
+ .opts = &timer_scx200hr
|
|
+};
|
|
+
|
|
+
|
|
+/* Switch from the original timer to the high-resolution timer */
|
|
+void __devinit scx200hr_timer_enable(void)
|
|
+{
|
|
+ /* Make sure the timer was requested and that the
|
|
+ * configuration block is present */
|
|
+ if (!enable_scx200hr || !scx200_cb_present()) {
|
|
+ return;
|
|
+ }
|
|
+
|
|
+ /* Reserve the timer region for ourselves */
|
|
+ if (!request_region(scx200_cb_base + SCx200_TIMER_OFFSET,
|
|
+ SCx200_TIMER_SIZE,
|
|
+ "NatSemi SCx200 High-Resolution Timer")) {
|
|
+ printk(KERN_WARNING NAME ": unable to lock timer region\n");
|
|
+ return;
|
|
+ }
|
|
+
|
|
+ /* Configure the timer */
|
|
+ outb(0, scx200_cb_base + SCx200_TMCNFG_OFFSET);
|
|
+
|
|
+ /* Record the current value of the timer. */
|
|
+ clock_at_last_interrupt = SCx200HR_CLOCK();
|
|
+
|
|
+ /* Get the current value of the monotonic clock */
|
|
+ total_ns = cur_timer->monotonic_clock();
|
|
+
|
|
+ /* Switch from the original timer functions to ours, but keep
|
|
+ * the current delay function since loops_per_jiffy will have
|
|
+ * been computed using that */
|
|
+ timer_scx200hr.delay = cur_timer->delay;
|
|
+ cur_timer = &timer_scx200hr;
|
|
+
|
|
+ printk(KERN_INFO "switching to scx200 high-resolution timer (%lu cpt)\n",
|
|
+ HR_CYCLES_PER_TICK);
|
|
+}
|
|
diff -Naurp linux-2.6.12-rc6.orig/include/asm-i386/timer.h linux-2.6.12-rc6/include/asm-i386/timer.h
|
|
--- linux-2.6.12-rc6.orig/include/asm-i386/timer.h 2005-06-07 14:56:11.000000000 +0100
|
|
+++ linux-2.6.12-rc6/include/asm-i386/timer.h 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -50,6 +50,9 @@ extern struct init_timer_opts timer_tsc_
|
|
#ifdef CONFIG_X86_CYCLONE_TIMER
|
|
extern struct init_timer_opts timer_cyclone_init;
|
|
#endif
|
|
+#ifdef CONFIG_SCx200HR_TIMER
|
|
+extern struct init_timer_opts timer_scx200hr_init;
|
|
+#endif
|
|
|
|
extern unsigned long calibrate_tsc(void);
|
|
extern void init_cpu_khz(void);
|
|
diff -Naurp linux-2.6.12-rc6.orig/include/linux/scx200.h linux-2.6.12-rc6/include/linux/scx200.h
|
|
--- linux-2.6.12-rc6.orig/include/linux/scx200.h 2005-06-07 14:56:11.000000000 +0100
|
|
+++ linux-2.6.12-rc6/include/linux/scx200.h 2005-06-07 16:43:19.000000000 +0100
|
|
@@ -32,7 +32,7 @@ extern unsigned scx200_cb_base;
|
|
|
|
/* High Resolution Timer */
|
|
#define SCx200_TIMER_OFFSET 0x08
|
|
-#define SCx200_TIMER_SIZE 0x05
|
|
+#define SCx200_TIMER_SIZE 0x06
|
|
|
|
/* Clock Generators */
|
|
#define SCx200_CLOCKGEN_OFFSET 0x10
|