[ARM PATCH] 1712/1: pxa2xx_udc (1/5) add INIT_MACHINE

Patch from David Brownell

This adds a mechanism for a per-machine initcall, one that's
guaranteed to run only to initialize a kernel running on that
specific hardware.  It's not strictly necessary, but it does
eliminate the need for certain boilerplate in machine-specific
support, to ensure it's only running on the right hardware:

      /* in arch/arm/mach-xxx/MYMACHINE.c */
      ...
      static int __init init_MYMACHINE(void)
      {
           if (!mach_is_MYMACHINE())       // often forgotten!!
                return -EINVAL;
           ... declare and customize platform devices
           ...
           return 0;
      }
      arch_initcall(init_MYMACHINE);

An init_MYMACHINE() call still exists, but it'd be declared
as part of the machine definition.

arch/arm/kernel/setup.c

@@ -654,6 +654,17 @@ static struct init_tags {
 	{ 0, ATAG_NONE }
 };
 
+static void (*init_machine)(void) __initdata;
+
+static int __init customize_machine(void)
+{
+	/* customizes platform devices, or adds new ones */
+	if (init_machine)
+		init_machine();
+	return 0;
+}
+arch_initcall(customize_machine);
+
 void __init setup_arch(char **cmdline_p)
 {
 	struct tag *tags = (struct tag *)&init_tags;
@@ -704,6 +715,7 @@ void __init setup_arch(char **cmdline_p)
 	 * Set up various architecture-specific pointers
 	 */
 	init_arch_irq = mdesc->init_irq;
+	init_machine = mdesc->init_machine;
 
 #ifdef CONFIG_VT
 #if defined(CONFIG_VGA_CONSOLE)

include/asm-arm/mach/arch.h

@@ -12,7 +12,7 @@
  * The size of struct machine_desc
  *   (for assembler code)
  */
-#define SIZEOF_MACHINE_DESC	48
+#define SIZEOF_MACHINE_DESC	52
 
 #ifndef __ASSEMBLY__
 
@@ -45,6 +45,7 @@ struct machine_desc {
 					 struct meminfo *);
 	void			(*map_io)(void);/* IO mapping function	*/
 	void			(*init_irq)(void);
+	void			(*init_machine)(void);
 };
 
 /*
@@ -86,6 +87,9 @@ const struct machine_desc __mach_desc_##_type	\
 #define INITIRQ(_func)				\
 	.init_irq	= _func,
 
+#define INIT_MACHINE(_func)			\
+	.init_machine	= _func,
+
 #define MACHINE_END				\
 };