==========================================================================
  Interface for registering and calling firmware-specific operations for ARM
  ==========================================================================

  Written by Tomasz Figa <t.figa@samsung.com>
  
  Some boards are running with secure firmware running in TrustZone secure
  world, which changes the way some things have to be initialized. This makes
  a need to provide an interface for such platforms to specify available firmware
  operations and call them when needed.

  Firmware operations can be specified by filling in a struct firmware_ops
  with appropriate callbacks and then registering it with register_firmware_ops()

  function::

  
  	void register_firmware_ops(const struct firmware_ops *ops)

  The ops pointer must be non-NULL. More information about struct firmware_ops
  and its members can be found in arch/arm/include/asm/firmware.h header.

  
  There is a default, empty set of operations provided, so there is no need to
  set anything if platform does not require firmware operations.

  To call a firmware operation, a helper macro is provided::

  
  	#define call_firmware_op(op, ...)				\
  		((firmware_ops->op) ? firmware_ops->op(__VA_ARGS__) : (-ENOSYS))
  
  the macro checks if the operation is provided and calls it or otherwise returns
  -ENOSYS to signal that given operation is not available (for example, to allow
  fallback to legacy operation).

  Example of registering firmware operations::

  
  	/* board file */
  
  	static int platformX_do_idle(void)
  	{
  		/* tell platformX firmware to enter idle */
  		return 0;
  	}
  
  	static int platformX_cpu_boot(int i)
  	{
  		/* tell platformX firmware to boot CPU i */
  		return 0;
  	}
  
  	static const struct firmware_ops platformX_firmware_ops = {
  		.do_idle        = exynos_do_idle,
  		.cpu_boot       = exynos_cpu_boot,
  		/* other operations not available on platformX */
  	};
  
  	/* init_early callback of machine descriptor */
  	static void __init board_init_early(void)
  	{
  		register_firmware_ops(&platformX_firmware_ops);
  	}

  Example of using a firmware operation::

  
  	/* some platform code, e.g. SMP initialization */

  	__raw_writel(__pa_symbol(exynos4_secondary_startup),

  		CPU1_BOOT_REG);
  
  	/* Call Exynos specific smc call */
  	if (call_firmware_op(cpu_boot, cpu) == -ENOSYS)
  		cpu_boot_legacy(...); /* Try legacy way */
  
  	gic_raise_softirq(cpumask_of(cpu), 1);