Boot code now works properly in both kernel and bare-metal mode.

--HG--
branch : dtrg-videocore

diff --git a/plat/rpi/boot.s b/plat/rpi/boot.s
index 523cf40..71081d2 100644 (file)
--- a/plat/rpi/boot.s
+++ b/plat/rpi/boot.s
@@ -23,13 +23,15 @@
 begtext:
        ! This empty space is required by the boot loader.
 
-       b start
-       .space 508 ! 512 minus space needed for branch instruction
+kernel_start:
+       ! When running as a kernel, we need to preserve all registers. We save
+       ! them onto the default stack.
+       push r0-r24
+       b baremetal_start
+       .space 506 ! first 512 bytes are ignored by the boot loader
+baremetal_start:
+       ! Wipe the bss (including the new stack).
 
-       ! Wipe the bss. This must happen absolutely first, because we need
-       ! to store the old system registers into it.
-
-start:
        lea r6, begbss
        lea r7, endbss
        mov r8, #0
@@ -37,35 +39,23 @@ _1:
        stb r8, (r6)
        addcmpb.lt r6, #1, r7, _1
 
-       ! Set up system registers.
+       ! Save system registers.
 
-       lea gp, begtext
        st fp, .returnfp
        st sp, .returnsp
        st lr, .returnlr
 
-       ! Set up the new stack and save the kernel parameters to it.
-
-       lea sp, .stack + STACKSIZE - 6*4
-
-       sub r0, gp ! pointer
-       st r0, 0 (sp)
-
-       sub r1, gp ! pointer
-       st r1, 4 (sp)
-
-       sub r2, gp ! pointer
-       st r2, 8 (sp)
-
-       sub r3, gp ! pointer
-       st r3, 12 (sp)
+       lea gp, begtext
 
-       ! r4-r5 are not pointers and don't need adjusting
-       st r4, 16 (sp)
-       st r5, 20 (sp)
+       ! Save the kernel parameters.
 
+       sub r0, gp ! fix up pointer
+       sub r1, gp ! fix up pointer
+       sub r2, gp ! fix up pointer
+       sub r3, gp ! fix up pointer
+       push r0-r5
        sub r0, sp, gp
-       st r0, _gpu_parameters
+       st r0, _pi_kernel_parameters
 
        ! Push standard parameters onto the stack and go.
        
@@ -82,10 +72,16 @@ _1:
 
 .define __exit
 __exit:
+       ! It only makes sense to get here if we're in kernel mode. If we're in
+       ! bare-metal mode, we'll just crash, but that's fine.
+
+       st r0, _pi_kernel_parameters ! save return value
        mov r0, sr
        ld fp, .returnfp
        ld sp, .returnsp
        ld lr, .returnlr
+       pop r0-r24
+       ld r0, _pi_kernel_parameters ! restore return value
        b lr
 
 ! Define symbols at the beginning of our various segments, so that we can find
@@ -110,10 +106,8 @@ __exit:
 .comm .returnsp, 4
 .comm .returnlr, 4
 
-! User pointer to the GPU kernel parameter block.
-
-.define _gpu_parameters
-.comm _gpu_parameters, 4
+.define _pi_kernel_parameters
+.comm _pi_kernel_parameters, 4
 
 ! User stack.
 

diff --git a/plat/rpi/include/pi.h b/plat/rpi/include/pi.h
index b5c5428..656543b 100644 (file)
--- a/plat/rpi/include/pi.h
+++ b/plat/rpi/include/pi.h
@@ -8,6 +8,21 @@
 #ifndef PI_H
 #define PI_H
 
+/* When running in kernel mode, this structure gets the incoming parameters.
+ * In bare metal mode, it's gibberish. */
+
+struct pi_kernel_parameters
+{
+       int r5;
+       int r4;
+       void* r3;
+       void* r2;
+       void* r1;
+       void* r0;
+};
+
+extern struct pi_kernel_parameters* pi_kernel_parameters;
+
 /* Initialise the mini UART (only do this if running on bare metal! */
 extern void pi_init_uart(void);