Re: [RFC 5/5] [powerpc] Implement a p1010rdb clock source.

On Mon, Aug 08, 2011 at 02:07:32PM +0200, Marc Kleine-Budde wrote:

On 08/08/2011 01:31 PM, Robin Holt wrote:

quoted

On Mon, Aug 08, 2011 at 10:37:58AM +0200, Wolfgang Grandegger wrote:

quoted

On 08/06/2011 04:34 PM, Robin Holt wrote:

quoted

flexcan driver needs the clk_get, clk_get_rate, etc functions
to work.  This patch provides the minimum functionality.

This needs some more general thoughts... apart from the question where
the code should go.

Like for the MSCAN on the MPC5200, the user should be *able* to select
an appropriate clock source and divider via DTS node properties.
Currently it seems, that the DTS properties must match some
pre-configured values, most likely set by the boot loader. Please
correct me if I'm wrong. For me this is generic and should go into the
Flexcan driver. From there, a platform specific function, e.g.
flexcan_set_clock() might be called.

OK.  Dug a bit more.  The p1010 built-in clocksource seems to be the
periphereal clock frequency which is system bus frequency divided
by 2.  The clock source can not be changed, but the clock divider can
by freezing the interface and setting the CTRL register.  This appears

Which bit(s) in the CTRL register is/are this?

PRESDIV bits 24-31.  Documented on the P1010 reference manual section 21.3.3.2.

Robin