sh: Tidy up the sh bios VBR handling.

This moves the VBR handling out of the main trap handling code and in to
the sh-bios helper code. A couple of accessors are added in order to
permit other kernel code to get at the VBR value for state save/restore
paths.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/sh_bios.h

@@ -1,18 +1,28 @@
 #ifndef __ASM_SH_BIOS_H
 #define __ASM_SH_BIOS_H
 
+#ifdef CONFIG_SH_STANDARD_BIOS
+
 /*
  * Copyright (C) 2000 Greg Banks, Mitch Davis
  * C API to interface to the standard LinuxSH BIOS
  * usually from within the early stages of kernel boot.
  */
-
-
 extern void sh_bios_console_write(const char *buf, unsigned int len);
 extern void sh_bios_char_out(char ch);
 extern void sh_bios_gdb_detach(void);
 
 extern void sh_bios_get_node_addr(unsigned char *node_addr);
 extern void sh_bios_shutdown(unsigned int how);
 
+extern void sh_bios_vbr_init(void);
+extern void sh_bios_vbr_reload(void);
+
+#else
+
+static inline void sh_bios_vbr_init(void) { }
+static inline void sh_bios_vbr_reload(void) { }
+
+#endif /* CONFIG_SH_STANDARD_BIOS */
+
 #endif /* __ASM_SH_BIOS_H */

arch/sh/kernel/machine_kexec.c

@@ -21,14 +21,14 @@
 #include <asm/mmu_context.h>
 #include <asm/io.h>
 #include <asm/cacheflush.h>
+#include <asm/sh_bios.h>
 
 typedef void (*relocate_new_kernel_t)(unsigned long indirection_page,
 				      unsigned long reboot_code_buffer,
 				      unsigned long start_address);
 
 extern const unsigned char relocate_new_kernel[];
 extern const unsigned int relocate_new_kernel_size;
-extern void *gdb_vbr_vector;
 extern void *vbr_base;
 
 void machine_shutdown(void)
@@ -117,11 +117,7 @@ void machine_kexec(struct kimage *image)
 	kexec_info(image);
 	flush_cache_all();
 
-#if defined(CONFIG_SH_STANDARD_BIOS)
-	asm volatile("ldc %0, vbr" :
-		     : "r" (((unsigned long) gdb_vbr_vector) - 0x100)
-		     : "memory");
-#endif
+	sh_bios_vbr_reload();
 
 	/* now call it */
 	rnk = (relocate_new_kernel_t) reboot_code_buffer;

arch/sh/kernel/sh_bios.c

@@ -55,3 +55,40 @@ void sh_bios_shutdown(unsigned int how)
 {
 	sh_bios_call(BIOS_CALL_SHUTDOWN, how, 0, 0, 0);
 }
+
+void *gdb_vbr_vector = NULL;
+
+/*
+ * Read the old value of the VBR register to initialise the vector
+ * through which debug and BIOS traps are delegated by the Linux trap
+ * handler.
+ */
+void sh_bios_vbr_init(void)
+{
+	unsigned long vbr;
+
+	if (unlikely(gdb_vbr_vector))
+		return;
+
+	__asm__ __volatile__ ("stc vbr, %0" : "=r" (vbr));
+
+	gdb_vbr_vector = (void *)(vbr + 0x100);
+	printk(KERN_NOTICE "Setting GDB trap vector to %p\n", gdb_vbr_vector);
+}
+
+/**
+ * sh_bios_vbr_reload - Re-load the system VBR from the BIOS vector.
+ *
+ * This can be used by save/restore code to reinitialize the system VBR
+ * from the fixed BIOS VBR. A no-op if no BIOS VBR is known.
+ */
+void sh_bios_vbr_reload(void)
+{
+	if (gdb_vbr_vector)
+		__asm__ __volatile__ (
+			"ldc %0, vbr"
+			:
+			: "r" (((unsigned long) gdb_vbr_vector) - 0x100)
+			: "memory"
+		);
+}

arch/sh/kernel/traps_32.c

@@ -31,6 +31,7 @@
 #include <asm/uaccess.h>
 #include <asm/fpu.h>
 #include <asm/kprobes.h>
+#include <asm/sh_bios.h>
 
 #ifdef CONFIG_CPU_SH2
 # define TRAP_RESERVED_INST	4
@@ -876,35 +877,10 @@ asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
 	die_if_kernel("exception", regs, ex);
 }
 
-#if defined(CONFIG_SH_STANDARD_BIOS)
-void *gdb_vbr_vector;
-
-static inline void __init gdb_vbr_init(void)
-{
-	register unsigned long vbr;
-
-	/*
-	 * Read the old value of the VBR register to initialise
-	 * the vector through which debug and BIOS traps are
-	 * delegated by the Linux trap handler.
-	 */
-	asm volatile("stc vbr, %0" : "=r" (vbr));
-
-	gdb_vbr_vector = (void *)(vbr + 0x100);
-	printk("Setting GDB trap vector to 0x%08lx\n",
-	       (unsigned long)gdb_vbr_vector);
-}
-#endif
-
 void __cpuinit per_cpu_trap_init(void)
 {
 	extern void *vbr_base;
 
-#ifdef CONFIG_SH_STANDARD_BIOS
-	if (raw_smp_processor_id() == 0)
-		gdb_vbr_init();
-#endif
-
 	/* NOTE: The VBR value should be at P1
 	   (or P2, virtural "fixed" address space).
 	   It's definitely should not in physical address.  */
@@ -959,6 +935,9 @@ void __init trap_init(void)
 	set_exception_table_vec(TRAP_UBC, break_point_trap);
 #endif
 
+	/* Save off the BIOS VBR, if there is one */
+	sh_bios_vbr_init();
+
 	/* Setup VBR for boot cpu */
 	per_cpu_trap_init();
 }