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authorDavid Brownell <david-b@pacbell.net>2007-02-10 01:46:02 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-11 10:51:32 -0800
commit7be2c7c96aff2871240d61fef508c41176c688b5 (patch)
tree37d39d2869b99021d0157f2ac3982a03901e0943 /drivers/rtc/Kconfig
parentf1f8810cf48dd88ee70e974924f2dd76e5669dd5 (diff)
downloadop-kernel-dev-7be2c7c96aff2871240d61fef508c41176c688b5.zip
op-kernel-dev-7be2c7c96aff2871240d61fef508c41176c688b5.tar.gz
[PATCH] RTC framework driver for CMOS RTCs
This is an "RTC framework" driver for the "CMOS" RTCs which are standard on PCs and some other platforms. That's MC146818 compatible silicon. Advantages of this vs. drivers/char/rtc.c (use one _or_ the other, only one will be able to claim the RTC irq) include: - This leverages both the new RTC framework and the driver model; both PNPACPI and platform device modes are supported. (A separate patch creates a platform device on PCs where PNPACPI isn't configured.) - It supports common extensions like longer alarms. (A separate patch exports that information from ACPI through platform_data.) - Likewise, system wakeup events use "real driver model support", with policy control via sysfs "wakeup" attributes and and using normal rtc ioctls to manage wakeup. (Patch in the works. The ACPI hooks are known; /proc/acpi/alarm can vanish. Making it work with EFI will be a minor challenge to someone with e.g. a MiniMac.) It's not yet been tested on non-x86 systems, without ACPI, or with HPET. And the RTC framework will surely have teething pains on "mainstream" PC-based systems (though must embedded Linux systems use it heavily), not limited to sorting out the "/dev/rtc0" issue (udev easily tweaked). Also, the ALSA rtctimer code doesn't use the new RTC API. Otherwise, this should be a no-known-regressions replacement for the old drivers/char/rtc.c driver, and should help the non-embedded distros (and the new timekeeping code) start to switch to the framework. Note also that any systems using "rtc-m48t86" are candidates to switch over to this more functional driver; the platform data is different, and the way bytes are read is different, but otherwise those chips should be compatible. [akpm@osdl.org: sparc32 fix] [akpm@osdl.org: sparc64 fix] Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Cc: Woody Suwalski <woodys@xandros.com> Cc: Alessandro Zummo <alessandro.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/rtc/Kconfig')
-rw-r--r--drivers/rtc/Kconfig25
1 files changed, 24 insertions, 1 deletions
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 09660e2..4bbca50 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1,4 +1,4 @@
-\#
+#
# RTC class/drivers configuration
#
@@ -95,6 +95,29 @@ config RTC_INTF_DEV_UIE_EMUL
comment "RTC drivers"
depends on RTC_CLASS
+# this 'CMOS' RTC driver is arch dependent because <asm-generic/rtc.h>
+# requires <asm/mc146818rtc.h> defining CMOS_READ/CMOS_WRITE, and a
+# global rtc_lock ... it's not yet just another platform_device.
+
+config RTC_DRV_CMOS
+ tristate "PC-style 'CMOS' real time clock"
+ depends on RTC_CLASS && (X86_PC || ALPHA || ARM26 || ARM \
+ || M32R || ATARI || POWERPC)
+ help
+ Say "yes" here to get direct support for the real time clock
+ found in every PC or ACPI-based system, and some other boards.
+ Specifically the original MC146818, compatibles like those in
+ PC south bridges, the DS12887 or M48T86, some multifunction
+ or LPC bus chips, and so on.
+
+ Your system will need to define the platform device used by
+ this driver, otherwise it won't be accessible. This means
+ you can safely enable this driver if you don't know whether
+ or not your board has this kind of hardware.
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-cmos.
+
config RTC_DRV_X1205
tristate "Xicor/Intersil X1205"
depends on RTC_CLASS && I2C
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