ARM: implement debug_ll_io_init()

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>

diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h
index 195ac2f9d3d3b1eaaebca8a2b5260fb41f4e27e0..2fe141fcc8d63311b63a2be06a0289a31b0174a3 100644 (file)
--- a/arch/arm/include/asm/mach/map.h
+++ b/arch/arm/include/asm/mach/map.h
@@ -40,6 +40,13 @@ extern void iotable_init(struct map_desc *, int);
 extern void vm_reserve_area_early(unsigned long addr, unsigned long size,
                                  void *caller);
 
+#ifdef CONFIG_DEBUG_LL
+extern void debug_ll_addr(unsigned long *paddr, unsigned long *vaddr);
+extern void debug_ll_io_init(void);
+#else
+static inline void debug_ll_io_init(void) {}
+#endif
+
 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 66f711b2e0e856fa6485f96bc26f32f3c661c767..6809200c31fb73349df3af95cd737c0e70293ada 100644 (file)
--- 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)
@@ -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

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 941dfb9e9a78635680d85225169d0edd187aea8c..39719bb93caab493bc2e71ab5c86c20b955d6b13 100644 (file)
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -876,6 +876,22 @@ static void __init pci_reserve_io(void)
 #define pci_reserve_io() do { } while (0)
 #endif
 
+#ifdef CONFIG_DEBUG_LL
+void __init debug_ll_io_init(void)
+{
+       struct map_desc map;
+
+       debug_ll_addr(&map.pfn, &map.virtual);
+       if (!map.pfn || !map.virtual)
+               return;
+       map.pfn = __phys_to_pfn(map.pfn);
+       map.virtual &= PAGE_MASK;
+       map.length = PAGE_SIZE;
+       map.type = MT_DEVICE;
+       create_mapping(&map);
+}
+#endif
+
 static void * __initdata vmalloc_min =
        (void *)(VMALLOC_END - (240 << 20) - VMALLOC_OFFSET);