Hexagon: add support for ARCH_PFN_OFFSET

Add support for loading the kernel at a physical offset.  The
offset should still be 4M aligned.

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>

3 files changed, 22 insertions, 12 deletions

diff --git a/arch/hexagon/kernel/head.S b/arch/hexagon/kernel/head.S
index d859402c73ba..477320c455f7 100644
--- a/arch/hexagon/kernel/head.S
+++ b/arch/hexagon/kernel/head.S
@@ -43,14 +43,21 @@ ENTRY(stext)
          * Symbol is kernel segment address, but we need
          * the logical/physical address.
          */
-        r24 = asl(r24, #2)
-        r24 = lsr(r24, #2)
+        r25 = pc;
+        r2.h = #0xffc0;
+        r2.l = #0x0000;
+        r25 = and(r2,r25);      /*  R25 holds PHYS_OFFSET now  */
+        r1.h = #HI(PAGE_OFFSET);
+        r1.l = #LO(PAGE_OFFSET);
+        r24 = sub(r24,r1);      /* swapper_pg_dir - PAGE_OFFSET */
+        r24 = add(r24,r25);     /* + PHYS_OFFSET */
 
-        r0 = r24
+        r0 = r24;  /* aka __pa(swapper_pg_dir)  */
 
         /*
-         * Initialize a 16MB PTE to make the virtual and physical
+         * Initialize page dir to make the virtual and physical
          * addresses where the kernel was loaded be identical.
+         * Done in 4MB chunks.
          */
 #define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X      \
                   | __HEXAGON_C_WB_L2 << 6                      \
@@ -143,6 +150,13 @@ __head_s_vaddr_target:
         r2 = sub(r2,r0);
         call memset;
 
+        /*  Set PHYS_OFFSET; should still be in R25 */
+#ifdef CONFIG_HEXAGON_PHYS_OFFSET
+        r0.l = #LO(__phys_offset);
+        r0.h = #HI(__phys_offset);
+        memw(r0) = r25;
+#endif
+
         /* Time to make the doughnuts.   */
         call start_kernel
 
diff --git a/arch/hexagon/kernel/setup.c b/arch/hexagon/kernel/setup.c
index 94a387835008..2e2304f7b7ee 100644
--- a/arch/hexagon/kernel/setup.c
+++ b/arch/hexagon/kernel/setup.c
@@ -68,6 +68,8 @@ void __init setup_arch(char **cmdline_p)
          */
         __vmsetvec(_K_VM_event_vector);
 
+        printk(KERN_INFO "PHYS_OFFSET=0x%08x\n", PHYS_OFFSET);
+
         /*
          * Simulator has a few differences from the hardware.
          * For now, check uninitialized-but-mapped memory
diff --git a/arch/hexagon/kernel/vmlinux.lds.S b/arch/hexagon/kernel/vmlinux.lds.S
index 14e793f6abbf..fafb886511e3 100644
--- a/arch/hexagon/kernel/vmlinux.lds.S
+++ b/arch/hexagon/kernel/vmlinux.lds.S
@@ -18,8 +18,6 @@
  * 02110-1301, USA.
  */
 
-#define LOAD_OFFSET PAGE_OFFSET
-
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/asm-offsets.h>    /*  Most of the kernel defines are here  */
 #include <asm/mem-layout.h>     /*  except for page_offset  */
@@ -36,13 +34,9 @@ See asm-generic/sections.h for seemingly required labels.
 
 #define PAGE_SIZE _PAGE_SIZE
 
-/*  This LOAD_OFFSET is temporary for debugging on the simulator; it may change
-    for hypervisor pseudo-physical memory.  */
-
-
 SECTIONS
 {
-        . = PAGE_OFFSET + LOAD_ADDRESS;
+        . = PAGE_OFFSET;
 
         __init_begin = .;
         HEAD_TEXT_SECTION
@@ -52,7 +46,7 @@ SECTIONS
 
         . = ALIGN(_PAGE_SIZE);
         _stext = .;
-        .text : AT(ADDR(.text) - LOAD_OFFSET) {
+        .text : AT(ADDR(.text)) {
                 _text = .;
                 TEXT_TEXT
                 SCHED_TEXT