Documentation/core-api/dma-isa-lpc.rst

12 ------------------------
16 	#include <linux/dma-mapping.h>
20 bus addresses (see Documentation/core-api/dma-api.rst for details).
23 this is not present on all platforms make sure you construct your
24 Kconfig to be dependent on ISA_DMA_API (not ISA) so that nobody tries
25 to build your driver on unsupported platforms.
28 -----------------
30 The ISA DMA controller has some very strict requirements on which
37 The DMA-able address space is the lowest 16 MB of _physical_ memory.
39 or 128 KiB depending on which channel you use).
45 allocate the memory during boot-up it's a good idea to also pass
52 -------------------
66 --------
69 8-bit transfers and the upper four are for 16-bit transfers.
72 channel 4 is used to give DMA access for the second controller (0-3).
73 This means that of the four 16-bits channels only three are usable.)
80 The ability to use 16-bit or 8-bit transfers is _not_ up to you as a
81 driver author but depends on what the hardware supports. Check your
85 -------------
96 controller that is used for the non-atomic operations. As long as you
98 reset this once.
104 Set the address from where the transfer should start (this needs to
105 be 16-bit aligned for 16-bit transfers) and how many bytes to
145 Suspend/resume
146 --------------
150 are lost when the system suspends so if your driver relies on the DMA
152 registers upon resume.