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Subject[RFC PATCH] x86: Add safe_udelay() and safe_msleep()

We need to use those function in early-quirk stage with code that is shared with
later stage.

for x86, normal udelay() will need to wait per_cpu(cpu_info) is allocated... that i
after smp_prepare_cpus(), because it need to use percpu.loops_per_jiffy.

Also msleep() will need to wait schedular is ready.

Try to have one early version udelay that use loops_per_jiffy directly.
and early msleep is just early delay.

This patch will set safe_udelay to early in x86 early arch code, and then init/main.c
will set them back.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
arch/x86/include/asm/delay.h | 3 +++
arch/x86/kernel/setup.c | 4 ++++
arch/x86/lib/delay.c | 28 ++++++++++++++++++++++++++++
include/linux/delay.h | 2 ++
init/main.c | 6 ++++++
5 files changed, 43 insertions(+)

Index: linux-2.6/arch/x86/include/asm/delay.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/delay.h
+++ linux-2.6/arch/x86/include/asm/delay.h
@@ -28,4 +28,7 @@ extern void __delay(unsigned long loops)

void use_tsc_delay(void);

+extern void __early_udelay(unsigned long usecs);
+extern void __early_msleep(unsigned int msecs);
+
#endif /* _ASM_X86_DELAY_H */
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -853,6 +853,10 @@ void __init setup_arch(char **cmdline_p)

dmi_scan_machine();

+ /* for early using */
+ safe_udelay = __early_udelay;
+ safe_msleep = __early_msleep;
+
/*
* VMware detection requires dmi to be available, so this
* needs to be done after dmi_scan_machine, for the BP.
Index: linux-2.6/arch/x86/lib/delay.c
===================================================================
--- linux-2.6.orig/arch/x86/lib/delay.c
+++ linux-2.6/arch/x86/lib/delay.c
@@ -138,3 +138,31 @@ void __ndelay(unsigned long nsecs)
__const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
}
EXPORT_SYMBOL(__ndelay);
+
+/* before cpu_info.loops_per_jiffy get set */
+static inline void __early_const_udelay(unsigned long xloops)
+{
+ int d0;
+
+ xloops *= 4;
+ asm("mull %%edx"
+ : "=d" (xloops), "=&a" (d0)
+ : "1" (xloops), "0"
+ (loops_per_jiffy * (HZ/4)));
+
+ delay_loop(++xloops);
+}
+
+/* usecs need to < 2000 */
+void __init __early_udelay(unsigned long usecs)
+{
+ /* 2**32 / 1000000 (rounded up) */
+ __early_const_udelay(usecs * 0x000010c7);
+}
+
+/* before schedular is there */
+void __init __early_msleep(unsigned int msecs)
+{
+ while (msecs--)
+ __early_udelay(1000);
+}
Index: linux-2.6/include/linux/delay.h
===================================================================
--- linux-2.6.orig/include/linux/delay.h
+++ linux-2.6/include/linux/delay.h
@@ -52,4 +52,6 @@ static inline void ssleep(unsigned int s
msleep(seconds * 1000);
}

+extern void (*safe_udelay)(unsigned long);
+extern void (*safe_msleep)(unsigned int);
#endif /* defined(_LINUX_DELAY_H) */
Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c
+++ linux-2.6/init/main.c
@@ -240,6 +240,9 @@ unsigned long loops_per_jiffy = (1<<12);

EXPORT_SYMBOL(loops_per_jiffy);

+void (*safe_udelay)(unsigned long) = __udelay;
+void (*safe_msleep)(unsigned int) = msleep;
+
static int __init debug_kernel(char *str)
{
console_loglevel = 10;
@@ -879,6 +882,9 @@ static int __init kernel_init(void * unu
cad_pid = task_pid(current);

smp_prepare_cpus(setup_max_cpus);
+ /* set them back, x86 use it for early delay*/
+ safe_udelay = __udelay;
+ safe_msleep = msleep;

do_pre_smp_initcalls();
lockup_detector_init();

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