On 10/17/2012 04:12 PM, Stephen Warren wrote:

On 10/17/2012 10:22 AM, Stephen Warren wrote:

snip

That implies we really do need to keep the two pieces of code completely
in sync, so a shared header is the right way to go. It also implies that
having duplicate mappings of the same physical address doesn't cause any
immediate obvious catastrophic problems.

Ways we might avoid files in arch/arm/include/debug having to use
relative include paths to pick up that header are:

a) Move mach-${mach}/include/mach/iomap.h to iomap-${mach}.h in some
standard include path.

Your goal should be to get rid of iomap.h though...

b) Rework debug-macro.S so that it isn't an include file, but rather a
regular top-level file. In other words, rather than compiling
arch/arm/kernel/debug.S, and having that #include DEBUG_LL_INCLUDE,
instead compile DEBUG_LL_SOURCE (i.e. arch/arm/mach-${mach}/debug.S by
default), and have that #include any common parts (e.g. implementation
of printhex8). This has benefits of:

b1) arch/arm/mach-${mach}/debug.S is in the mach directory that owns it,
rather than having them all dumped into a common location.

b2) Can use #include "iomap.h", a non-relative include, to pick up the
shared header

b3) Perhaps we can simplify the current debug.S e.g. have a common
debug-semihosting.S that contains the semihosting stuff, and only
include that from mach-*/debug.S if that machine uses semihosting, or
similar?

(b) seems like a lot of work. I don't see any advantage of (a) over just
using the relative include.

Agreed.

Here is what I mentioned previously. This removes the static mapping from 
the platforms. This is untested and probably breaks on different DEBUG_LL 
options. For now, platforms call debug_ll_io_init, but once all platforms 
are converted, this can be called from devicemaps_init.

diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h
index 195ac2f..2ece92c 100644
--- a/arch/arm/include/asm/mach/map.h
+++ b/arch/arm/include/asm/mach/map.h

@@ -40,6 +40,9 @@ extern void iotable_init(struct map_desc *, int);
 extern void vm_reserve_area_early(unsigned long addr, unsigned long size,
 				  void *caller);
 
+extern void debug_ll_addr(unsigned long *paddr, unsigned long *vaddr);
+extern void debug_ll_io_init(void);
+
 struct mem_type;
 extern const struct mem_type *get_mem_type(unsigned int type);
 /*

diff --git a/arch/arm/kernel/debug.S b/arch/arm/kernel/debug.S
index 66f711b..93883ed 100644
--- a/arch/arm/kernel/debug.S
+++ b/arch/arm/kernel/debug.S

@@ -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)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 941dfb9..1c8c7be 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c

@@ -876,6 +876,20 @@ static void __init pci_reserve_io(void)
 #define pci_reserve_io() do { } while (0)
 #endif
 
+void __init debug_ll_io_init(void)
+{
+	struct map_desc map;
+
+	if (!IS_ENABLED(CONFIG_DEBUG_LL))
+		return;
+
+	debug_ll_addr(&map.pfn, &map.virtual);
+	map.pfn = __phys_to_pfn(map.pfn);
+	map.length = PAGE_SIZE;
+	map.type = MT_DEVICE;
+	create_mapping(&map);
+}
+
 static void * __initdata vmalloc_min =
 	(void *)(VMALLOC_END - (240 << 20) - VMALLOC_OFFSET);