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, 10 insertions, 1 deletions

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 2906ee7bd298..929d4fa73fd9 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -732,9 +732,16 @@ config NVRAM
           To compile this driver as a module, choose M here: the
           module will be called nvram.
 
+#
+# These legacy RTC drivers just cause too many conflicts with the generic
+# RTC framework ... let's not even try to coexist any more.
+#
+if RTC_LIB=n
+
 config RTC
         tristate "Enhanced Real Time Clock Support"
-        depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV && !ARM && !SUPERH && !S390 && !AVR32
+        depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV \
+                        && !ARM && !SUPERH && !S390 && !AVR32
         ---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
@@ -840,6 +847,8 @@ config DS1302
           will get access to the real time clock (or hardware clock) built
           into your computer.
 
+endif # RTC_LIB
+
 config COBALT_LCD
         bool "Support for Cobalt LCD"
         depends on MIPS_COBALT