On Tue, 6 May 2014 05:11:23 -0500 Gupta Ruchika-R66431 <ruchika.gupta@xxxxxxxxxxxxx> wrote: > > From: Kim Phillips [mailto:kim.phillips@xxxxxxxxxxxxx] > > Sent: Friday, May 02, 2014 2:15 AM > > > > On Tue, 29 Apr 2014 15:34:37 +0530 > > Ruchika Gupta <ruchika.gupta@xxxxxxxxxxxxx> wrote: > > > > > Few read only registers like CHAVID, CTPR etc were wrongly defined as > > > 64 bit registers. This functioned properly on the powerpc platforms. > > > However ARM SoC's wouldn't function correctly if these registers are > > > defined as 64 bit. > > > > why wouldn't they function correctly? > > The SEC IP guide states these registers as 2 32 bit registers. So register definition in I'm looking at LS2100A's SEC reference manual, it clearly has the CHAVID defined as one, single 64-bit register. What are you looking at? > crypto code should also have them defined as 32 bit registers. Defining them as 64 bit in this case would be incorrect. > > Endianness of the CAAM IP varies with core's endiannes. In ARM SoC's , CAAM block is also little endian. So in case the 2 - 32 bit registers are treated as a 64 bit register, the result would be word swapped as compared to powerpc platforms. As a result, the reads won't return the right result. > > For eg. > For the 2 32 bit registers CHAVID_MS(at address 0x0) and CHAVID_LS(address 0x4) , if core reads them as 64 bit word, > > In powerpc (big endian) platform - > CHAVID_MS would be available in most significant portion of the 64 bit word. > CHAVID_LS would be the in least significant portion. > This is as expected. > > In ARM (little endian) platform, 64 bit read would result in - > CHAVID_MS in Least significant portion of the word and > CHAVID_LS in the most significant location. > This result is word swapped and the value read wouldn't be correct. hmm, have you looked at using the DWT "Double Word Transpose" bit in the MCFGR? Kim -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
