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ARM: implement debug_ll_io_init()

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When using DEBUG_LL, the UART's (or other HW's) registers are mapped
into early page tables based on the results of assembly macro addruart.
Later, when the page tables are replaced, the same virtual address must
remain valid. Historically, this has been ensured by using defines from
<mach/iomap.h> in both the implementation of addruart, and the machine's
.map_io() function. However, with the move to single zImage, we wish to
remove <mach/iomap.h>. To enable this, the macro addruart may be used
when constructing the late page tables too; addruart is exposed as a
C function debug_ll_addr(), and used to set up the required mapping in
debug_ll_io_init(), which may called on an opt-in basis from a machine's
.map_io() function.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
[swarren: Mask map.virtual with PAGE_MASK. Checked for NULL results from
 debug_ll_addr (e.g. when selected UART isn't valid). Fixed compile when
 either !CONFIG_DEBUG_LL or CONFIG_DEBUG_SEMIHOSTING.]
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
This commit is contained in:
Rob Herring
2012-10-22 11:42:54 -06:00
committed by Olof Johansson
parent 3d70f8c617
commit e5c5f2adeb
3 changed files with 37 additions and 0 deletions
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14
arch/arm/kernel/debug.S
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@@ -100,6 +100,13 @@ ENTRY(printch)
b 1b
ENDPROC(printch)
ENTRY(debug_ll_addr)
addruart r2, r3, ip
str r2, [r0]
str r3, [r1]
mov pc, lr
ENDPROC(debug_ll_addr)
#else
ENTRY(printascii)
@@ -119,4 +126,11 @@ ENTRY(printch)
mov pc, lr
ENDPROC(printch)
ENTRY(debug_ll_addr)
mov r2, #0
str r2, [r0]
str r2, [r1]
mov pc, lr
ENDPROC(debug_ll_addr)
#endif