New interface makes more explicit the split between the device driver
API and the public API.

CDL
---

cdl_option CYGBLD_LEGACY_FLASH_DEVICE. 
	Include a device named 'flash' which interfaces with V1 flash
	devices.

cdl_interface CYGHWR_IO_FLASH_DEVICE_V2.
	A device driver should implement this if it implements the V2
	flash device driver interface.

cdl_??? CYGSEM_IO_FLASH_LEGACY_COMPAT.
	Provide legacy public flash API.

Public Flash Interface
----------------------

L: Has legacy support #define.

cyg_flash_init (was: flash_init) L
	Init the flash subsystem. Used to call flash_query and do full
	device setup. This bit is now in cyg_flash_open. This function
	just egisters the workspace etc.

cyg_flash_open (NEW)
	Opens a particular flash device. Calls the ->query function.

cyg_flash_read (NEW)
	What it says on the tin. Calls ->read.

cyg_flash_erase (was: flash_erase) L
	calls ->erase_block

cyg_flash_program (was: flash_program) L
	calls ->program_block

cyg_flash_dev_query (was: flash_dev_query) L
	Arranges to call ->query_hwr. Use to call flash_query and
	was used by flash_hwr_init. Now it is used by ->query. 
	Should be private/part of driver API?

cyg_flash_lock (was: flash_lock) L
	Locks a region of flash. calls ->lock

cyg_flash_unlock (was: flash_unlock) L
	Unlocks a region of flash. calls ->unlock

cyg_flash_verify_addr (was: flash_verify_addr) L
	Checks if an address lies inside the flash.
	Possible to deprecate?

cyg_flash_get_limit (was: flash_get_limits) :
        Returns the size of the flash device. used to return start and
	end points. Could possibly be renames to get_size?

cyg_flash_get_block_info (was: flash_get_block_info) :
	Returns information about block structure of flash.
	(doesn't need to call down to driver, yet)

cyg_flash_code_overlaps (was: flash_code_overlaps) L
	Determines if a range of code overlaps flash. Calls
	f_i->code_overlaps.

cyg_flash_errmsg (was: flash_errmsg) L
	Returns string version of a flash error

cyg_flash_hwr_map_error (was: flash_hwr_map_error) L
	Calls ->map_error. 
	Should be made private/part of driver API?
			
Internal Flash Driver Interface
-------------------------------

1-2: Has a different prototype for a V1 device to a V2 device.
M: Is copied to RAM for execution (and therefore has a _length
counterpart which should be filled in)


Function Pointers

->query (in devtab) (was: flash_hwr_init)
	Calls cyg_flash_dev_query which calls through to ->query_hwr.
	(possibly rename to ->open?)

->read (was: memcpy etc...) 1-2

->query_hwr (was: flash_query) 1-2 M
	Perform QRY command. (possibly rename to ->query if above renamed)
	
->code_overlaps (was: flash_code_overlaps) 1-2

->lock (was: flash_lock_block) 1-2 M

->unlock (was: flash_unlock_block) 1-2 M

->erase_block (was: flash_erase_block) 1-2 M

->program_buf (was: flash_program_buf) 1-2 M

->map_error (was: flash_hwr_map_error)