[commit] r2400 - cpu/arm/mmp2

[repository service]

Author: wmb
Date: Tue Aug  2 05:55:57 2011
New Revision: 2400
URL: http://tracker.coreboot.org/trac/openfirmware/changeset/2400

Log:
OLPC XO-1.75 - trac #11089 - changed the SSP SPI driver to avoid glitches that confuse the SPI FLASH chip.

Modified:
   cpu/arm/mmp2/sspspi.fth

Modified: cpu/arm/mmp2/sspspi.fth
==============================================================================
--- cpu/arm/mmp2/sspspi.fth	Tue Aug  2 05:31:12 2011	(r2399)
+++ cpu/arm/mmp2/sspspi.fth	Tue Aug  2 05:55:57 2011	(r2400)
@@ -12,8 +12,11 @@
 : ssp-sssr   ( -- adr )  ssp-base  2 la+  ;
 : ssp-ssdr   ( -- adr )  ssp-base  4 la+  ;

-
 : ssp-spi-start  ( -- )
+   \ Avoid reinitializing the device after the first time, as that
+   \ seems to cause glitches that confuse the SPI FLASH chip
+   ssp-sscr1 io@ 0=  if  exit  then
+
    h# 07 ssp-sscr0 io!
    0 ssp-sscr1 io!
    h# 87 ssp-sscr0 io!   
@@ -127,16 +130,8 @@
 : ssp-spi-out  ( b -- )  ssp-spi-out-in drop  ;
 : ssp-spi-in  ( -- b )  0 ssp-spi-out-in  ;

-: safe-spi-start
-   ssp-spi-start
-   \ The following clears out some glitches so the chip will respond
-   \ to the ab-id command.
-   0 spi-cmd spi-cs-off
-   0 spi-cmd spi-cs-off
-;
-
 : use-ssp-spi  ( -- )
-   ['] safe-spi-start to spi-start
+   ['] ssp-spi-start  to spi-start
    ['] ssp-spi-in     to spi-in
    ['] ssp-spi-out    to spi-out
    ['] ssp-spi-cs-on  to spi-cs-on