[lkml]   [2012]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] ARM: OMAP: AM33XX: CAN: d_can: Add support for Bosch D_CAN controller
On 04/03/2012 04:29 PM, AnilKumar, Chimata wrote:
>>>> Please explain why this CAN controller cannot be handled by the existing
>>>> C_CAN driver, eventually with some extensions. The register layout seems
>>>> almost identical, at least.
>>>> Wolfgang.
>>> These are the some of the pointers I can say, why I had gone for separate
>>> file instead of existing driver:
>>> * In case of D_CAN driver we can see all the registers are 32bit length
>>> but in case of C_CAN registers are in 16bit length.
>> How many bits in these 32 bit registers are used?
> In some cases (D_CAN_TXRQ, D_CAN_INTPND, D_CAN_MSGVAL) I have used all the
> bits, in some cases used few bits.
> Roughly I can say that its (higher 16bits) % of usages is similar as compare
> to 16bits
> While checking the status of TXRequest registers and INT pending register,
> which is a hot code path, we have to put if checks for register access.

The c_can already has a c_can_read_reg32() function. It's for example
used in the rx_poll function. You can make it a function pointer (i.e.
pric->read_reg32()) for easy abstraction.

>>> * Some of the registers, bit masks are different, so we have to add
>>> checks on every API for differentiating the kind of device
>> Which registers are this? Can you give us an example?
> I am pointing out some of the resisters
> * Single registers in case of D_CAN but multiple register in case of C_CAN
> So masks will change MASK, ARB, INTPND
> * D_CAN_IFCMD is the combination of COMM request and COMM mask registers

Maybe you can use the read_reg32 function on both c_can and d_can.

regards, Marc

Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | |

[unhandled content-type:application/pgp-signature]
 \ /
  Last update: 2012-04-03 17:37    [W:0.061 / U:1.268 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site