[openfirmware] [commit] r2942 - cpu/arm/olpc

[repository service]

Author: wmb
Date: Fri Apr 13 01:28:34 2012
New Revision: 2942
URL: http://tracker.coreboot.org/trac/openfirmware/changeset/2942

Log:
OLPC XO-1.75 and XO-3 - changed EDI (SPI interface to EC) timing to account for rise time issue on MISO.

Modified:
   cpu/arm/olpc/bbedi.fth

Modified: cpu/arm/olpc/bbedi.fth
==============================================================================
--- cpu/arm/olpc/bbedi.fth	Mon Apr  9 05:10:42 2012	(r2941)
+++ cpu/arm/olpc/bbedi.fth	Fri Apr 13 01:28:34 2012	(r2942)
@@ -103,7 +103,7 @@
    loop                      ( b )
 ;   
 [else]
-code edi-out0  ( byte -- )
+code edi-out  ( byte -- )
    mov   r2,#8
    mov   r0,#0x200           \ MOSI mask
    set   r1,`h# 19100 +io #` \ GPIO register address
@@ -112,7 +112,9 @@
       ands  r3,tos,#0x80   \ Test bit
 
       strne r0,[r1,#0x18]  \ Set MOSI if bit is non0
+      strne r0,[r1,#0x18]  \ Set MOSI if bit is non0  \ Twice for delay - setup time to CLK
       streq r0,[r1,#0x24]  \ Clr MOSI if bit is 0
+      streq r0,[r1,#0x24]  \ Clr MOSI if bit is 0  \ Twice for delay - setup time to CLK
 
       str   r4,[r1,#0x18]  \ Set CLK
       str   r4,[r1,#0x24]  \ Clr CLK
@@ -123,7 +125,7 @@
 
    pop tos,sp
 c;
-code edi-out  ( byte -- )
+code edi-out1  ( byte -- )
    mov   r2,#8
    mov   r0,#0x200           \ MOSI mask
    set   r1,`h# 19100 +io #` \ GPIO register address
@@ -158,7 +160,7 @@
 
       \ This delay is necessary to let the MMP2 GPIO pin clock in the
       \ data value.  Without the delay, bit values get lost.
-      mov   r7,#0x160      \ Delay spins
+      mov   r7,#0x400      \ Delay spins
       begin
          decs r7,#1
       0= until
@@ -166,6 +168,11 @@
       ldr   r0,[r1]        \ Read pin register
       str   r0,[r3],#4
       str   r4,[r1,#0x24]  \ Clr CLK
+      mov   r7,#0x400      \ Delay spins
+      begin
+         decs r7,#1
+      0= until
+
       ands  r0,r0,#0x80    \ Test MISO bit
       incne tos,1          \ Set bit in byte