I'm just trying to support the save_and_sleep() support into u-boot for an au1100 based board.
Into u-boot I added the following code:
Index: cpu/mips/start.S =================================================================== RCS file: /home/develop/cvs_private/uboot-mips-exadron/cpu/mips/start.S,v retrieving revision 1.2 diff -u -r1.2 start.S --- cpu/mips/start.S 12 Oct 2005 12:55:54 -0000 1.2 +++ cpu/mips/start.S 16 Dec 2005 15:29:22 -0000 @@ -26,6 +26,7 @@ #include <config.h> #include <version.h> #include <asm/regdef.h> +#include <asm/au1x00.h> #include <asm/mipsregs.h>
@@ -273,6 +274,33 @@ li t0, CONF_CM_CACHABLE_NONCOHERENT mtc0 t0, CP0_CONFIG
+ /* Now check the wakeup cause + */ + li t0, SYS_WAKESRC + lw t1, 0(t0) + andi t1, t1, 0x00000002 /* check the SW bit */ + beq zero, t1, 1f + nop + + li t0, SYS_SCRATCH0 + lw t1, 0(t0) + move sp, t1 + li t0, SYS_SCRATCH1 + lw t1, 0(t0) + j t1 /* this cause a jump into already + nop frozen Linux (brr! :) */ + + /* If we reach this point we come from a normal system power up, + so just clear the wakeup cause registers + */ + +1: li t0, SYS_WAKEMSK + li t1, 0x00000000 + sw t1, 0(t0) + + li t0, SYS_WAKESRC + li t1, 0x00000000 + sw t1, 0(t0)
/* Set up temporary stack. */
in order to restore the scratch registers contents as descibed into file "linux/arch/mips/au1000/common/sleeper.S":
/* Now set up the scratch registers so the boot rom will * return to this point upon wakeup. */ la k0, 1f lui k1, 0xb190 ori k1, 0x18 sw sp, 0(k1) ori k1, 0x1c sw k0, 0(k1)
However it seems something is wrong since the system at the end of save_and_sleep() does not correctly continue its execution...
Unlikely my JTAG do not allow me to follow the code after the save_and_sleep()'s return (I definitely have to buy a better one), however I noticed that when the system tryes to resume the register 29 (the sp) doing:
lw $29, PT_R29(sp)
something goes wrong!
Suggestions? :)
Thanks in advance,
Rodolfo