GSoC PRU: AM35xx Clock driver

Nils Hölscher nilhoel1 at
Wed Jul 24 13:06:41 UTC 2019

Hi again,

I just decompiled my device tree and checked.
The probe code of the prcm driver is as follows:
static int
am335x_prcm_probe(device_t dev)

    if (!ofw_bus_status_okay(dev)){
        return (ENXIO);

    if (ofw_bus_is_compatible(dev, "ti,am3-prcm")) {
        device_set_desc(dev, "AM335x Power and Clock Management");
        printk("PROBE SUCESSFULL\n");
    printk("ofw_bus incompatible\n");
    return (ENXIO);
So it seems the prcm part in the device tree has to be compatible to
The thing is the decompiled device tree states just that:
prcm at 0 {
                        compatible = "ti,am3-prcm\0simple-bus";
                        reg = <0x00 0x2000>;
                        #address-cells = <0x01>;
                        #size-cells = <0x01>;
                        ranges = <0x00 0x00 0x2000>;
                        phandle = <0x5a>;
Any ideas would help, cause I am currently not able to understand this
Also without this driver even the dev_usb_bbb driver shouldn't work.
However it attaches because it doesn't check for the clocks error code.


On Wed, 24 Jul 2019 at 14:43, Nils Hölscher <nilhoel1 at> wrote:

> Hi,
> I just found out that the prcm driver fails to probe on the simplebus and
> therefore cannot apply itself.
> Seems like I am back to checking dtb.
> Best,
> Nils
> On Tue, 23 Jul 2019 at 14:26, Nils Hölscher <nilhoel1 at> wrote:
>> Hi,
>> After debugging with printk, didn't get the module loading working as
>> suggested by Sebastian.
>> I just found out that my PRU driver can't be attached, cause the AM35xx
>> clock driver isn't loaded.
>> The driver can be found her:
>> Can anyone tell me how to load this driver and obisouly before I
>> initialize my BSD modules?
>> FYI: The code line that fails is this one, cause the driver hasn't been
>> initialized.
>> Thanks,
>> Nils
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