clock updates

[MyungJoo Ham]

Hello,

On Thu, Jun 24, 2010 at 8:24 AM, Ben Dooks <ben-linux at fluff.org> wrote:
> I've been looking into updating the current samsung socs to use
> clkdev to lookup clocks. Currently we have a few issues that we
> could do with sorting before running the conversion to clkdev.
>
> Firstly, the s5pc100 has some clocks that could be merged into
> common s5p, and a few which don't seem to match the others in
> the s5p series.
>
> The i2s clocks which we should look at mergining are:
>
> i2s_cdclk<0..2>
> pcm_cdclk<0..l>
>
> also, clocks that have may need changing:
>
> rotator      => rot
> keyif        => keypad
>
> this isn't an complete list, still working on the changes.
>
> The big changes with respect to drivers is that we will now be using
> clk_get(dev, NULL) to get the clock names, and any bus clocks such
> as the sdhci bus clock will be updated.
>
> The intention with both the SDHCI and the SPI is to change the clock
> lookups to reflect the mux positions, so the sdhci clocks on the
> s3c64xx would be changed to use the following lookups:
>
> hsmmc   => mux0
> mmc_bus => mux2
> 48m     => mux3
>
> This would avoid passing the clock names through the platform data, if
> the boards or the arch needs to avoid a clock, an array of clock enable
> or disable bits. Any unimplemented clocks will return NULL to ensure
> that they can be distinguished from a clock that isn't available.
>
> The changes would be to remove the .name field from all the s3c struct clk,
> and replace it with a pointer to a lookup (so that if the clock does not
> need a name then it doesn't need a lookup).

I also like the idea using clk_get based on the name of struct device
and getting rid of name field from clk.

However, what about devices and clocks with the same name and
different id numbers (i.e., platform_device.id)? Are you going to add
.id lookup to clkdev's clk_find? There are multiple clocks with the
same name and different id number.


>
> There are also a number of clocks that probably don't need a name as they
> are part of the clock heirarchy, it would be useful to have a call that
> returns all possible parents of a given clock.
>
> I'll post the script whcih runs the changes once i've finished the last
> few details to show what happens.
>
> With resepect to the clkdev clk_get() function, we may need to do a couple of
> updates (ie, override it for ourselves) due to the following two problems:
>
> 1) The s3c/s5p devices change name depending on the soc they are attached
>   to, which means we may need to cut the s3cxxxx- part of the device name
>   off before running the lookup
>
> 2) Some of the lookups are done early for the serial driver, which means
>   that the platform devices's name has not been setup, so something needs
>   to be done about this.
>
> --
> Ben
>
>
>
>
>
>
>
>
>
>
> --
> Ben
>
> Q:      What's a light-year?
> A:      One-third less calories than a regular year.
>
>
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>


Cheers!

-- 
MyungJoo Ham (함명주), Ph.D.
Mobile Software Platform Lab,
Digital Media and Communications (DMC) Business
Samsung Electronics
cell: 82-10-6714-2858