[RFC PATCH kernel] powerpc: Fix early setup to make early_ioremap work

[Alexey Kardashevskiy]

The immediate problem is that after
0bd3f9e953bd ("powerpc/legacy_serial: Use early_ioremap()")
the kernel silently reboots. The reason is that early_ioremap() returns
broken addresses as it uses slot_virt[] array which initialized with
offsets from FIXADDR_TOP == IOREMAP_END+FIXADDR_SIZE ==
KERN_IO_END- FIXADDR_SIZ + FIXADDR_SIZE == __kernel_io_end which is 0
when early_ioremap_setup() is called. __kernel_io_end is initialized
little bit later in early_init_mmu().

This fixes the initialization by swapping early_ioremap_setup and
early_init_mmu.

This also fixes IOREMAP_END to use FIXADDR_SIZE defined just next to it,
seems to make sense, unless there is some weird logic with redefining
FIXADDR_SIZE as the compiling goes.

Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 2 +-
 arch/powerpc/kernel/setup_64.c               | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index a666d561b44d..54a06129794b 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -325,8 +325,8 @@ extern unsigned long pci_io_base;
 #define  PHB_IO_END	(KERN_IO_START + FULL_IO_SIZE)
 #define IOREMAP_BASE	(PHB_IO_END)
 #define IOREMAP_START	(ioremap_bot)
-#define IOREMAP_END	(KERN_IO_END - FIXADDR_SIZE)
 #define FIXADDR_SIZE	SZ_32M
+#define IOREMAP_END	(KERN_IO_END - FIXADDR_SIZE)
 
 /* Advertise special mapping type for AGP */
 #define HAVE_PAGE_AGP
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index b779d25761cf..ce09fe5debf4 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -369,11 +369,12 @@ void __init early_setup(unsigned long dt_ptr)
 	apply_feature_fixups();
 	setup_feature_keys();
 
-	early_ioremap_setup();
 
 	/* Initialize the hash table or TLB handling */
 	early_init_mmu();
 
+	early_ioremap_setup();
+
 	/*
 	 * After firmware and early platform setup code has set things up,
 	 * we note the SPR values for configurable control/performance
-- 
2.30.2