Am Montag, den 11.01.2016, 22:29 +0800 schrieb Wills Wang:
On 01/11/2016 06:55 PM, Purna Chandra Mandal wrote:
On 01/09/2016 10:02 PM, Daniel Schwierzeck wrote:
This patch series updates all MIPS asm header files containing I/O code as well as processor, register and assembly definitions. The source of the update are the MIPS asm header files of linux -4.4.
The main goal is to get a complete set of I/O accessors on MIPS and to support platform-specific address spaces and mappings. Also a working ioremap() implementation will be added, which supports platform-specific callbacks. Furthermore support for bit manipulating I/O accessors (clrbits_X, setbits_X, clrsetbits_X) will be added.
The patch series is also available on git://git.denx.de/u-boot -mips.git in branch mips_io_v1 and based on next branch.
@Wills I changed map_physmem() and used the new and working ioremap() function. Thus you can discard your patch.
@Wills, Purna You can use now ioremap() directly in your drivers. You can also use the new bit manipulating I/O accessors as requested by Marek. Please rebase and test your patch series against this series, thanks.
Thanks Daniel. Rebased my PIC32 patches on 'mips_io_v1' branch and tested functionality to work fine. Also updated drivers to use ioremap() (instead of pic32_ioremap()) and clrsetbits_le() wherever applicable.
Should we use these macros with the explicitly endianess in driver? if chip can select big-endian and little-endian by hardware pin, i think driver may not work properly, what's your idea?
that depends on the SoC and the peripheral.
Peripherals usually have a fixed endianess and the bus between CPU and peripheral converts the CPU endianess to peripheral one in hardware. In that case a driver should never swap. You could use the __raw_readX/__raw_writeX variants. Or you could implement this explicitely with readX/writeX resp. readX_be/writeX_be and make this configurable at compile time or runtime.
For an example you could look at kernel commit 37786c7fee40771d13901de129af7e084ed48b55.
If the bus does not convert the endianess, a driver must explicitely use I/O accessors according to the peripheral endianess.