On Monday 28 of October 2013 14:43:35 Sören Brinkmann wrote: > On Mon, Oct 28, 2013 at 10:13:28PM +0100, Tomasz Figa wrote: > > Hi Soren, > > > > On Thursday 10 of October 2013 10:10:17 Soren Brinkmann wrote: > > > In some use cases Zynq's FPGA clocks are used as static clock > > > generators for IP in the FPGA part of the SOC for which no Linux > > > driver > > > exists and would control those clocks. To avoid automatic > > > gating of these clocks in such cases a new property - fclk-enable - > > > is > > > added to the clock controller's DT description to accomodate such > > > use > > > cases. It's value is a bitmask, where a set bit results in enabling > > > the corresponding FCLK through the clkc. > > > > > > FPGA clocks are handled following the rules below: > > > > > > If an FCLK is not enabled by bootloaders, that FCLK will be disabled > > > in > > > Linux. Drivers can enable and control it through the CCF as usual. > > > > > > If an FCLK is enabled by bootloaders AND the corresponding bit in > > > the > > > 'fclk-enable' DT property is set, that FCLK will be enabled by the > > > clkc, resulting in an off by one reference count for that clock. > > > Ensuring it will always be running. > > > > > > Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx> > > > --- > > > > > > v2: > > > - change default value for fclk-enable to '0' > > > > > > --- > > > > > > Documentation/devicetree/bindings/clock/zynq-7000.txt | 4 ++++ > > > drivers/clk/zynq/clkc.c | 18 > > > > > > +++++++++++++++--- 2 files changed, 19 insertions(+), 3 deletions(-) > > > > > > diff --git a/Documentation/devicetree/bindings/clock/zynq-7000.txt > > > b/Documentation/devicetree/bindings/clock/zynq-7000.txt index > > > d99af878f5d7..11fdd146ec83 100644 > > > --- a/Documentation/devicetree/bindings/clock/zynq-7000.txt > > > +++ b/Documentation/devicetree/bindings/clock/zynq-7000.txt > > > > > > @@ -22,6 +22,10 @@ Required properties: > > > Optional properties: > > > - clocks : as described in the clock bindings > > > - clock-names : as described in the clock bindings > > > > > > + - fclk-enable : Bit mask to enable FCLKs in cases no proper CCF > > > > Since it's a vendor specific property, it should include vendor > > prefix. > > The whole driver is vendor specific. Should there really be another > prefix for that property? Yes. If a property is introduced just for use by this particular driver then it must be prepended by a vendor prefix. That's a general rule. > > Also CCF is a Linux-specific implementation detail, which DT bindings > > should not be involved into. If you really need to implement this > > using > > this way, then at least property description should say something like > > this: > > > > xlnx,fclk-enable : Bit mask of bits of fclk enable register that must > > be statically enabled at boot-up time. > > Fair enough. I'll change the description > > > However, I wonder why you can't simply define an FPGA block using a > > single node, which would be a consumer to all the fclk clocks you > > need to enable and then make a driver for it that would simply enable > > all clocks specified in clocks property. > > Well, then we'd have a dummy driver that wouldn't fit into any subsystem > and wouldn't do anything but enabling clocks. Seems much easier to > handle it in this driver. Especially, since I hope that this is just a > workaround and that the majority of use cases involves drivers for > their soft-IP that simply uses the CCF. Hmm, I'm not really convinced, but well, let's say that I'm fine with your proposed solution, unless someone else complains. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
