Fix the NVRAM access functions to work correctly for the

upper 128 bytes of NVRAM (if enabled).

For most chipsets this means using I/O ports 0x72/0x73, but at least
on some VIA chipsets (I tested the VIA VT8237R on actual hardware)
these ports won't work and you have to use 0x74/0x75. Thus, make this
a Kconfig option for now.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Jordan Crouse <jordan.crouse@amd.com>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3202 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

1 files changed, 16 insertions, 0 deletions

diff --git a/payloads/libpayload/Config.in b/payloads/libpayload/Config.in
index a1343f566b..fbb477ed7f 100644
--- a/payloads/libpayload/Config.in
+++ b/payloads/libpayload/Config.in
@@ -72,6 +72,22 @@ config NVRAM
 	bool "Support for reading/writing NVRAM bytes"
 	default y
 
+config RTC_PORT_EXTENDED_VIA
+	bool "Extended RTC ports are 0x74/0x75"
+	default n
+	help
+	  For recent chipsets with 256 NVRAM bytes, you have to access the
+	  upper 128 bytes (128-255) using two different I/O ports,
+	  usually 0x72/0x73.
+	
+	  On some chipsets this can be a different set of ports, though.
+	  The VIA VT8237R for example only recognizes the ports 0x74/0x75
+	  for accessing the high 128 NVRAM bytes (as seems to be the case for
+	  multiple VIA chipsets).
+	
+	  If you want to read or write CMOS bytes on computers with one of
+	  these chipsets, say 'y' here.
+
 endmenu
 
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