Re: [Linux-ia64] RTC support on ia64

[Alex Williamson <alex_williamson@hp.com>]

Joel,

   Does this provide more functionality than the EFI RTC?
Concerns I have w/ it on ia64 is that the rtc driver assumes
you have a legacy rtc at the legacy irq and port address.
This won't work on HP zx1 boxes, the legacy hardware doesn't
exist.  In the future, there's a possibility that the port
address could be allocated to non-legacy purposes.  Maybe
ACPI could tell you if you have a legacy RTC, it could at
least tell you if you support PC/AT compatible interrupts.
Thanks,

	Alex

Joel GUILLET wrote:
> 
> Hi,
> 
> Here is a patch to use the Real Time Clock (RTC) on ia64.
> It works on a tiger. It doesn't on early lion machines. (Why ?)
> I don't know about others ia64 machines. Please report me - if you test
> it.
> To see if it works, please check the /var/log/messages. The driver reports
> sometimes that "rtc losts some interrupts..." It usually means that the
> rtc doesn't work, and the interruptions that arrived were coming from a
> software-timer (see the driver code).
> 
> This patch is very simple.
> I changed the irq affected for the rtc as it is an "ex-i386" interruption.
> (an Ox20 offset)
> And copied some files from the asm-i386 to asm-ia64...
> The duplication of these files is a waste of disk space, but it's coherent
> with the way it has been made on i386.
> 
> You may want to try this patch and test it.
> There is a program test included in the Documentation/rtc.txt of the
> kernel tree.
> 
> The actual priority of the interruption is low but perhaps it might be
> changed (Do anyone know how to make it ?) for some usages.
> 
> For the kernel releases after 2.5.45, I've seen that the Kconfig will be
> modified so that the option will not be available (unless you activate it
> manually).
> 
> This can be used for example to run scheduler latencies tests (a way of
> using amlat) - I've got some more stuff for this, please mail me.
> 
> Here is the patch :
> 
> ********************************************
> diff -urN linux-2.5.45/arch/ia64/kernel/ia64_ksyms.c linux-2.5.45-clean/arch/ia64/kernel/ia64_ksyms.c
> --- linux-2.5.45/arch/ia64/kernel/ia64_ksyms.c  Thu Oct 31 01:42:54 2002
> +++ linux-2.5.45-clean/arch/ia64/kernel/ia64_ksyms.c    Tue Dec 17 15:08:19 2002
> @@ -143,3 +143,5 @@
>  #endif
>  EXPORT_SYMBOL(machvec_noop);
> 
> +extern spinlock_t rtc_lock;
> +EXPORT_SYMBOL(rtc_lock);
> diff -urN linux-2.5.45/arch/ia64/kernel/time.c linux-2.5.45-clean/arch/ia64/kernel/time.c
> --- linux-2.5.45/arch/ia64/kernel/time.c        Thu Oct 31 01:42:20 2002
> +++ linux-2.5.45-clean/arch/ia64/kernel/time.c  Tue Dec 17 15:08:19 2002
> @@ -27,6 +27,7 @@
>  extern rwlock_t xtime_lock;
>  extern unsigned long wall_jiffies;
>  extern unsigned long last_time_offset;
> +spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
> 
>  u64 jiffies_64;
> 
> diff -urN linux-2.5.45/include/asm-ia64/mc146818rtc.h linux-2.5.45-clean/include/asm-ia64/mc146818rtc.h
> --- linux-2.5.45/include/asm-ia64/mc146818rtc.h Thu Oct 31 01:43:38 2002
> +++ linux-2.5.45-clean/include/asm-ia64/mc146818rtc.h   Tue Dec 17 15:10:12 2002
> @@ -1,10 +1,29 @@
> +/*
> + * Machine dependent access functions for RTC registers.
> + */
>  #ifndef _ASM_IA64_MC146818RTC_H
>  #define _ASM_IA64_MC146818RTC_H
> 
> +#include <asm/io.h>
> +
> +#ifndef RTC_PORT
> +#define RTC_PORT(x)    (0x70 + (x))
> +#define RTC_ALWAYS_BCD 1       /* RTC operates in binary mode */
> +#endif
> +
>  /*
> - * Machine dependent access functions for RTC registers.
> + * The yet supported machines all access the RTC index register via
> + * an ISA port access but the way to access the date register differs ...
>   */
> +#define CMOS_READ(addr) ({ \
> +outb_p((addr),RTC_PORT(0)); \
> +inb_p(RTC_PORT(1)); \
> +})
> +#define CMOS_WRITE(val, addr) ({ \
> +outb_p((addr),RTC_PORT(0)); \
> +outb_p((val),RTC_PORT(1)); \
> +})
> 
> -/* empty include file to satisfy the include in genrtc.c */
> +#define RTC_IRQ 40 /* irq on a i386 + Ox20  */
> 
>  #endif /* _ASM_IA64_MC146818RTC_H */
> diff -urN linux-2.5.45/include/asm-ia64/rtc.h linux-2.5.45-clean/include/asm-ia64/rtc.h
> --- linux-2.5.45/include/asm-ia64/rtc.h Thu Jan  1 01:00:00 1970
> +++ linux-2.5.45-clean/include/asm-ia64/rtc.h   Tue Dec 17 15:09:03 2002
> @@ -0,0 +1,10 @@
> +#ifndef _IA64_RTC_H
> +#define _IA64_RTC_H
> +
> +/*
> + * ia64 uses the default access methods for the RTC.
> + */
> +
> +#include <asm-generic/rtc.h>
> +
> +#endif
> **************************************************************
> 
> --------------
> **  Joel
> 
> _______________________________________________
> Linux-IA64 mailing list
> Linux-IA64@linuxia64.org
> http://lists.linuxia64.org/lists/listinfo/linux-ia64

--
Alex Williamson                                  Linux Development Lab
alex_williamson@hp.com                                 Hewlett Packard
970-898-9173                                          Fort Collins, CO