On Tue, Jan 10, 2017 at 07:44:01AM -0800, Tony Lindgren wrote:
> * Tony Lindgren <tony@xxxxxxxxxxx> [170109 15:43]:
> > Texas Instruments omap variant SoCs starting with omap4 have a clkctrl
> > clock controller instance for each interconnect target module. The clkctrl
> > controls functional and interface clocks for the module.
> >
> > The clkctrl clocks are currently handled by arch/arm/mach-omap2 hwmod code.
> > With this binding and a related clock device driver we can start moving the
> > clkctrl clock handling to live in drivers/clk/ti.
> >
> > For hardware reference, see omap4430 TRM "Table 3-1312. L4PER_CM2 Registers
> > Mapping Summary" for example. It show one instance of a clkctrl clock
> > controller with multiple clkctrl registers.
> >
> > Note that this binding allows keeping the clockdomain related parts out of
> > drivers/clock. The CLKCTCTRL and DYNAMICDEP registers can be handled by
> > using a separate driver in drivers/soc/ti and genpd. If the clockdomain
> > driver needs to know it's clocks, we can just set the the clkctrl device
> > instances to be children of the related clockdomain device.
> >
> > On omap4 CM_L3INIT_USB_HOST_HS_CLKCTRL on omap5 has eight OPTFCLKEN bits.
> > So we need to shift the clock index to avoid index conflict for the clock
> > consumer binding with the next clkctrl offset on omap4.
> >
> > Cc: Paul Walmsley <paul@xxxxxxxxx>
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> > ---
> >
> > So here's what I was able to come up for the clkctr binding based on
> > all we've discussed so far. Can you guys please take a look and see
> > if it looks OK to you before we do the device driver?
> >
> > Also, does anybody have better suggestions for addressing the optional
> > clocks in each clkctrl register?
>
> The other option that might be worth considering is to make use of the
> #clock-cells property. Then the index of any optional clock could be passed
> in the second cell.
>
> The third cell could be used to set the modulemode for the clock (software
> controlled or hardware controlled) instead of using a custom property
> at the clock controllel level.
I guess I prefer this way. Or you could do a mixture of both proposals
with 2 cells. The first being the clock id and the 2nd flags.
What's the max optional clocks in theory? B picked from the current
worst case seems a bit worrying. Why not 16? Upper half is offset, lower
half is index.
> In that case clock consume usage would look like the following using
> #clock-cells = <3>:
>
> #define OMAP4_CLKCTRL_OFFSET 0x20
> #define MODULEMODE_HWCTRL 1
> #define MODULEMODE_SWCTRL 2
Can you make one of these 0 instead or is both being set valid?
>
> #define OMAP_CLKCTRL_INDEX(offset) ((offset) - OMAP4_CLKCTRL_OFFSET)
>
> #define OMAP4_GPTIMER10_CLKTRL OMAP_CLKCTRL_INDEX(0x28)
> #define OMAP4_GPTIMER11_CLKTRL OMAP_CLKCTRL_INDEX(0x30)
> #define OMAP4_GPTIMER2_CLKTRL OMAP_CLKCTRL_INDEX(0x38)
> ...
> #define OMAP4_GPIO2_CLKCTRL OMAP_CLKCTRL_INDEX(0x60)
> ...
>
> &gpio2 {
> clocks = <&cm_l4per_clkctrl OMAP4_GPIO2_CLKCTRL 0 MODULEMODE_HWCTRL
> &cm_l4per_clkctrl OMAP4_GPIO2_CLKCTRL_DBCLK 1 0>;
Drop the _DBCLK here, right?
Rob
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