Commit d9a9c617 authored May 01, 2016 by William Breathitt Gray Committed by Greg Kroah-Hartman May 02, 2016

isa: Implement the max_num_isa_dev macro

max_num_isa_dev is a macro to determine the maximum possible number of
ISA devices which may be registered in the I/O port address space given
the address extent of the ISA devices.

The highest base address possible for an ISA device is 0x3FF; this
results in 1024 possible base addresses. Dividing the number of possible
base addresses by the address extent taken by each device results in the
maximum number of devices on a system.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 339e6e31

include/linux/isa.h

+11 −0

Original line number	Diff line number	Diff line
		@@ -57,4 +57,15 @@ static void __exit __isa_driver##_exit(void) \
		} \
		module_exit(__isa_driver##_exit);

		/**
		* max_num_isa_dev() - Maximum possible number registered of an ISA device
		* @__ida_dev_ext: ISA device address extent
		*
		* The highest base address possible for an ISA device is 0x3FF; this results in
		* 1024 possible base addresses. Dividing the number of possible base addresses
		* by the address extent taken by each device results in the maximum number of
		* devices on a system.
		*/
		#define max_num_isa_dev(__isa_dev_ext) (1024 / __isa_dev_ext)

		#endif /* __LINUX_ISA_H */