[OpenBIOS] r640 - cpu/x86/pc/olpc

Author: wmb
Date: 2007-09-28 00:06:12 +0200 (Fri, 28 Sep 2007)
New Revision: 640

Modified:
   cpu/x86/pc/olpc/resume.bth
Log:
OLPC resume - added code to bitbang the DCON SMBUS, generating 8 clock
pulses with DATA held high, in order to clear the DCON in case it sees
a false start condition.  This is per a suggestion from HiMax.
To enable this code, uncomment the "create reset-smbus-bitbang" line.

Modified: cpu/x86/pc/olpc/resume.bth
===================================================================
--- cpu/x86/pc/olpc/resume.bth	2007-09-27 17:25:13 UTC (rev 639)
+++ cpu/x86/pc/olpc/resume.bth	2007-09-27 22:06:12 UTC (rev 640)
@@ -20,7 +20,8 @@
 \ This code will be copied to RAM at suspend-base

\ create save-display
-create reset-smbus
+\ create reset-smbus
+\ create reset-smbus-bitbang
 \ create restore-usb-power

h# fe00.0000 constant gp-pa
@@ -336,6 +337,40 @@
    ax lods  ax dx xchg  ax lods  ax dx xchg  h# c000.2001 wmsr  \ Video output format
    ax lods  ax dx xchg  ax lods  ax dx xchg  h# c000.2011 wmsr  \ TFTP pad select

+[ifdef] reset-smbus-bitbang
+   \ GPIO15 is SMB_DATA
+   \ GPIO14 is SMB_CLOCK
+   h# c0000000 # ax mov         \ Mask to clear SMB_DATA and SMB_CLOCK
+   h# 1010 # dx mov  ax dx out  \ Deselect OUT AUX1
+   h# 1014 # dx mov  ax dx out  \ Deselect OUT AUX2
+   h# 1034 # dx mov  ax dx out  \ Deselect IN AUX1
+   h#     c000 # ax mov         \ Mask to set SMB_DATA and SMB_CLOCK
+   h# 1000 # dx mov  ax dx out  \ Set output values to high
+   h# 1004 # dx mov  ax dx out  \ Set pins to output
+
+   h# 1000 # dx mov             \ Output value register
+
+   8 # cx mov  \ Generate 8 low pulses on SMB_CLOCK
+   begin
+      \ 50 uS delay (slightly longer for GX)
+      rdtsc  ax bx mov  d# 50 d# 500 * #  bx  add
+      begin  rdtsc  bx ax sub  0>= until
+
+      h# 40000000 # ax mov  ax dx out    \ Clear SMB_CLOCK
+
+      \ 50 uS delay (slightly longer for GX)
+      rdtsc  ax bx mov  d# 50 d# 500 * #  bx  add
+      begin  rdtsc  bx ax sub  0>= until
+
+      h#     4000 # ax mov  ax dx out    \ Set SMB_CLOCK
+
+   loopa
+
+   \ 50 uS delay (slightly longer for GX)
+   rdtsc  ax bx mov  d# 50 d# 500 * #  bx  add
+   begin  rdtsc  bx ax sub  0>= until
+[then]
+
    h# 1038 #     dx  mov  \ Low bank - first contiguous GPIO register
    h# 3c /l / #  cx  mov  \ Register count (stop at lock register)
    begin