Hi Javier, 2014-02-06 Javier Martinez Canillas <martinez.javier@gmail.com>:

Hello Matthias,

On Wed, Feb 5, 2014 at 6:02 PM, Matthias Brugger <matthias.bgg@gmail.com> wrote:

...

Hi,

I'm stuck with dts problem. Whenever I try to find a clock for my device, the of_get_clk returns an error "Kernel panic - not syncing: Can't get timer clock"

My DTS looks like this (reduced to relevant parts for easier reading):

Could you give more details about your platform?

I would take a look to Documentation/devicetree/bindings/clock/<your platform>-clock.txt to be sure that you are using the bindings correctly.

This is part of some effort to port Linux to a new SoC, so no documentation up to now... Anyway I found the error. I forgot to add my SoC to arch/arm/Makefile so that my SoC specific init funtion weren't called. So my device tree wasn't populated and therefore the clock had no properties.

...

#include <dt-bindings/interrupt-controller/irq.h> #include <dt-bindings/interrupt-controller/arm-gic.h> #include "skeleton.dtsi"

/ {

[...]

soc { #address-cells = <1>; #size-cells = <1>; compatible = "simple-bus"; ranges;

gic: interrupt-controller@10212000 { compatible = "arm,cortex-a9-gic"; interrupt-controller; #interrupt-cells = <3>; reg = <0x10211000 0x1000>, <0x10212000 0x1000>; };

osc: oscillator { compatible = "fixed-clock"; #clock-cells = <1>;

Looking at Documentation/devicetree/bindings/clock/fixed-clock.txt it says:

#clock-cells : from common clock binding; shall be set to 0

Yes, you are right.

while your are setting your clock-cells to 1.

...

clock-frequency = <15000000>; clock-output-names = "osc"; };

timer: timer-mysoc { compatible = "mysoc,mysoc-timer"; reg = <0x10008000 0x30>; interrupts = <GIC_SPI 113 IRQ_TYPE_EDGE_RISING>; clocks = <&osc 0>; clock-names = "system15m"; }; };

Documentation/devicetree/bindings/clock/clock-bindings.txt also says:

==Clock consumers==

Required properties: clocks: List of phandle and clock specifier pairs, one pair for each clock input to the device. Note: if the clock provider specifies '0' for #clock-cells, then only the phandle portion of the pair will appear.

So my educated guess is that you should use #clock-cells = <0>; your your clock provider device node and clocks = <&osc> on your clock consumer device node.

Thats true.

By looking at DTS and DTSI that uses the fixed-clock binding I see that all platforms don't have their clocks providers device nodes under soc {} but on a separate clocks {} node. I didn't find on the clock-bindings.txt DT bindings documentation that this is a requirement so probably that is not issue in your case but still something to keep in mind.

The code I posted is nearly similar to the example in Documentation/devicetree/bindings/clock/clock-bindings.txt. Anyway it seems that of_clk_get searches for the "#clock-cells" cells in the list "clocks". I suppose that the "clocks" list is populated by the node present under clocks {}. Thanks a lot for your hints. Matthias

...

};

my /drivers/clocksource/mysoc-timer.c looks like this (reduced to relevant parts for easier reading):

[...]

static void __init mysoc_timer_init(struct device_node *node) { unsigned long rate = 0; struct clk *clk; int ret, irq; u32 val;

gpt_base = of_iomap(node, 0); if (!gpt_base) panic("Can't map registers");

irq = irq_of_parse_and_map(node, 0); if (irq <= 0) panic("Can't parse IRQ");

clk = of_clk_get(node, 0); if (IS_ERR(clk)) panic("Can't get timer clock"); clk_prepare_enable(clk);

rate = clk_get_rate(clk);

} CLOCKSOURCE_OF_DECLARE(mtk_mt6589, "mysoc,mysoc-timer", mysoc_timer_init);

What I'm missing? I seems as if the clock "osc" is not found in the device tree. Any idea why. Building the DTB works without errors, but I suppose that doesn't mean too much anyway.

Cheers, Matthias

-- motzblog.wordpress.com

Hope it helps,

Javier

-- motzblog.wordpress.com