Re: Question about Talitos Linux driver for MPC885

[leroy christophe <christophe.leroy@c-s.fr>]

Dear Kim,

Thank you for you quick answer.
I didn't have much time to look at it until this week unfortunatly.

I have some more questions/observations below

Le 26/09/2012 02:47, Kim Phillips a écrit :
> On Tue, 25 Sep 2012 10:45:17 +0200
> leroy christophe <christophe.leroy@c-s.fr> wrote:
>
>> I'm trying to use the Talitos crypto driver with the MPC885
>> microcontroller. For the time being, it doesn't work.
> yes, they're not exactly compatible...
>
>> The kernel startup blocks at the test of the DES function.
>>
>> I have added the following definition in the DTS file:
>>
>>           crypto@20000 {
>>               compatible = "fsl,sec2.0";
> interesting, its called "SEC Lite" and its version register does
> indeed say 2.  I see it has a single channel FIFO instead of a ring,
> that the SEC v1.x (MPC185) used, so you probably don't have to
> rewrite talitos_submit.
Good news, it was also my understanding.
>
>>               reg = <0x20000 0x8000>;
>>               interrupts = <1 1>;
> I couldn't find the IRQ line in the MPC855RM - if there's no IRQ
> line, then that's a problem.
Neither do I on the drawing, however in Table 52-1, there are 3 bits in 
the CPTR register for defining the interrupt level of the SEC lite, just 
like you do for the CPM and for the FEC.
So I believe this should be ok ?
>
>>               interrupt-parent = <&PIC>;
>>               fsl,num-channels = <1>;
>>               fsl,channel-fifo-len = <24>;
>>               fsl,exec-units-mask = <0x4c>;
>>               fsl,descriptor-types-mask = <0x301f>;
> the descriptor type enumeration isn't uniform across into the mpc8xx
> SEC version, e.g., the SEC Lite doesn't support the ipsec_esp
> descriptor type, represented in mpc8xxx SEC versions as the second
> bit, so this descriptor-types-mask setting should be fixed to at
> least omit that since the driver checks for, and uses it if
> available.
>
>> Is there anything wrong in what I did ? Or is there something else I
>> should do ?
> might want to go through the defines in talitos.h, e.g,
> TALITOS_MCR_SWR is 0x1 on mpc8xxx vs. 0x10000000 on
> mpc8xx (I suppose CONFIG_PPC_8xx can be used as the ifdef, btw).
I'm surprised about this, I didn't check the talitos.h file, but had 
checked the Reference Manual of the MPC 8272.
I rechecked yesterday and the SWR bit is at the same place as on the 
MPC885 which is different from what is defined in talitos.h
>
> Descriptor header and pointer formats, along with field locations,
> sizes, and enumerations may also be different.
>
> It also appears the SEC Lite doesn't support scatter-gather tables,
> which will make performance hurt for fragmented (large) packet sizes.
Does it mean something has to be modified if the SW ?
>
> Kim
>
Thanks,
Christophe