rtc: avoid legacy drivers with generic framework

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.

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.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 02a4c8cf2b2d..6cc2c0330230 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -20,10 +20,6 @@ menuconfig RTC_CLASS
 
 if RTC_CLASS
 
-if GEN_RTC || RTC
-comment "Conflicting RTC option has been selected, check GEN_RTC and RTC"
-endif
-
 config RTC_HCTOSYS
         bool "Set system time from RTC on startup and resume"
         depends on RTC_CLASS = y
@@ -304,6 +300,7 @@ 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.