[patch 2.6.24-git] rtc: avoid legacy drivers with generic framework

[David Brownell <david-b@pacbell.net>]

Kconfig tweaks to help reduce RTC configuration bugs, by avoiding
legacy RTC drivers when the generic RTC framework is enabled:

 - If rtc-cmos is selected, disable the legacy rtc driver;

 - When using generic RTC on x86, enable rtc-cmos by default;

 - In the old "chardev RTC" section of Kconfig, add a comment
   warning people off these (seven) legacy RTC drivers when
   the generic framework is in use.

People can still use the legacy drivers if they want (or need) to.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
This doesn't fix the broken dependencies for the legacy "CMOS" RTC
driver.  Ideally it would be a full list of platforms where it works,
not a partial list of ones where it won't.  Or better yet, it would
depend on a "HAVE_CMOS_RTC" flag defined by various platforms ...
surely there's a Kconfig style guideline lurking there.

 drivers/char/Kconfig |    6 +++++-
 drivers/rtc/Kconfig  |    1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

--- g26.orig/drivers/char/Kconfig	2008-02-10 11:16:04.000000000 -0800
+++ g26/drivers/char/Kconfig	2008-02-10 11:30:21.000000000 -0800
@@ -704,9 +704,14 @@ config NVRAM
 	  To compile this driver as a module, choose M here: the
 	  module will be called nvram.
 
+comment "Avoid any legacy RTC drivers you may see here"
+	depends on RTC_LIB
+
 config RTC
 	tristate "Enhanced Real Time Clock Support"
-	depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV && !ARM && !SUPERH && !S390
+	depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV \
+			&& !ARM && !SUPERH && !S390 \
+			&& RTC_DRV_CMOS=n
 	---help---
 	  If you say Y here and create a character special file /dev/rtc with
 	  major number 10 and minor number 135 using mknod ("man mknod"), you
--- g26.orig/drivers/rtc/Kconfig	2008-02-10 11:16:04.000000000 -0800
+++ g26/drivers/rtc/Kconfig	2008-02-10 11:19:00.000000000 -0800
@@ -294,6 +294,7 @@ comment "Platform RTC drivers"
 config RTC_DRV_CMOS
 	tristate "PC-style 'CMOS'"
 	depends on X86 || ALPHA || ARM || M32R || ATARI || PPC || MIPS
+	default y if X86
 	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.