[PATCH 02/11] soc/fsl: Introduce DPAA BMan device management driver
horia.geanta at freescale.com
Thu Jul 23 02:15:20 AEST 2015
On 7/10/2015 9:50 PM, scottwood at freescale.com (Scott Wood) wrote:
> On Fri, 2015-07-10 at 13:29 -0500, Pledge Roy-R01356 wrote:
>>> return in_be32((void *)bm + offset);
>>>> [...]/drivers/soc/fsl/qbman/bman.c: In function â€˜__bm_outâ€™:
>>>> [...]/drivers/soc/fsl/qbman/bman.c:172:2: error: implicit declaration
>>>> of function â€˜out_be32â€™ [-Werror=implicit-function-declaration]
>>>> out_be32((void *)bm + offset, val);
>>> These PPCisms will need to be fixed. LS1043A is an ARM chip with DPAA
>> LS1043 (ARM, Little Endian) support is still work in progress. The patches
>> for that are being tested now but are based on the SDK version of the
>> driver and will need to be massaged in order to get them applied here. Our
>> plan of record is to add upstream support for this at a later time.
> If you're already reworking this for upstream acceptance, why not fix the
> more obvious PPCisms now?
Other drivers are facing similar problems wrt. I/O accessors.
How should the problem be solved?
For caam driver (drivers/crypto/caam) we have the following combinations:
ARCH CORE CAAM SoC, options
PPC BIG BIG P4080 etc.
PPC BIG LITTLE N/A
PPC LITTLE BIG P4080 + CONFIG_CPU_LITTLE_ENDIAN
PPC LITTLE LITTLE N/A
ARM LITTLE LITTLE LS1021A, LS2085A etc.
ARM LITTLE BIG LS1043A
ARM BIG LITTLE LS1021A + CONFIG_CPU_BIG_ENDIAN
ARM BIG BIG LS1043A + CONFIG_CPU_BIG_ENDIAN
Not all need to be supported, but for e.g. we are being requested to run
on ARM in BE mode.
Existing MMIO accessors have one of the following drawbacks:
-readl/writel: on ARM do swapping (cpu <--> le), while on PPC are
bus-specific (for PCI)
-have weak semantics (no barriers / sequence points etc.), like __raw_*
Thus, it looks like drivers have to define their own MMIO accessors,
taking into account:
-core endianness (which is independent of arch)
-already-defined MMIO accessors availability, depending on arch
-semantics will have to match
Unfortunately, the code will look terrible. In each driver.
P.S. Sorry if the To/Cc list is screwed up, I've taken the message from
More information about the Linuxppc-dev