Hi, Rob > On Mon, Jul 1, 2019 at 3:47 AM <Anson.Huang@xxxxxxx> wrote: > > > > From: Anson Huang <Anson.Huang@xxxxxxx> > > 'dt-bindings: timer: ...' for the subject. OK, I made a mistake. > > > > > Systems which use platform driver model for clock driver require the > > clock frequency to be supplied via device tree when system counter > > driver is enabled. > > This is a DT binding. What's a platform driver? It is just trying to explain why we need to introduce this "clock-frequency" property, nothing about the binding and platform driver. > > > > > This is necessary as in the platform driver model the of_clk > > operations do not work correctly because system counter driver is > > initialized in early phase of system boot up, and clock driver using > > platform driver model is NOT ready at that time, it will cause system > > counter driver initialization failed. > > > > Add clock-frequency property to the device tree bindings of the NXP > > system counter, so the driver can tell timer-of driver to get clock > > frequency from DT directly instead of doing of_clk operations via clk > > APIs. > > While you've now given a good explanation why you need this, it all sounds > like linux specific issues and a DT change should not be necessary. > > Presumably, 'clocks' points to a fixed-clock node, right? Just parse the 'clocks' > phandle and fetch the frequency from that node if you need to get the > frequency 'early'. Sound like a better solution, I will try that, since the system counter's clock is from osc_24m and divided by 3, since different platforms may have different divider, so maybe I can create a fixed-clock node in DT, then system counter driver can parse the clock and fetch the frequency from that node, will redo a V5 patch. > > > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx> > > --- > > No change. > > --- > > .../devicetree/bindings/timer/nxp,sysctr-timer.txt | 15 +++++++++------ > > 1 file changed, 9 insertions(+), 6 deletions(-) > > > > diff --git > > a/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt > > b/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt > > index d576599..7088a0e 100644 > > --- a/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt > > +++ b/Documentation/devicetree/bindings/timer/nxp,sysctr-timer.txt > > @@ -11,15 +11,18 @@ Required properties: > > - reg : Specifies the base physical address and size of the comapre > > frame and the counter control, read & compare. > > - interrupts : should be the first compare frames' interrupt > > -- clocks : Specifies the counter clock. > > -- clock-names: Specifies the clock's name of this module > > +- clocks : Specifies the counter clock, mutually exclusive with clock- > frequency. > > +- clock-names : Specifies the clock's name of this module, mutually > exclusive with > > + clock-frequency. > > +- clock-frequency : Specifies system counter clock frequency, mutually > exclusive with > > + clocks/clock-names. > > It doesn't really work to say one or the other is needed unless you make the > OS support both cases. The OS already support both cases now with this patch series. Thanks, Anson
