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Message-ID: <20160929143411.GE16583@xsjsorenbubuntu>
Date: Thu, 29 Sep 2016 07:34:11 -0700
From: Sören Brinkmann <soren.brinkmann@...inx.com>
To: Muhammad Abdul WAHAB <muhammadabdul.wahab@...elec.fr>
CC: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Russell King <linux@...linux.org.uk>,
Michal Simek <michal.simek@...inx.com>,
<linux-arm-kernel@...ts.infradead.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Adding Support for Coresight Components on Zynq 7000.
Hi Muhammad,
On Thu, 2016-09-29 at 12:26:13 +0200, Muhammad Abdul WAHAB wrote:
> The Coresight components are present on the Zynq SoC but the corresponding
> device tree entries are missing. This patch adds device tree entries for
> coresight components while explaining how it was done in order to allow
> porting towards other boards easily.
>
> By adding the entries for Coresight components in the device tree: if no
> files are created in sysfile system, you need to contact the board designer
> to sort out the problem. On some boards, Coresight components are not
> powered on boot.
>
> Signed-off-by: Muhammad Abdul Wahab <muhammadabdul.wahab@...tralesupelec.fr>
> ---
> The documentation file was very helpful
> (Documentation/devicetree/bindings/arm/coresight.txt). However, few details
> can be added to make it more clear for beginners.
>
> Things to modify in device tree when changing the board are mainly:
>
> - address
> - `clocks` field
> - some references in other entries may be missing (e.g. for `CPU` field in
> ETM/PTM component, references need to be created)
>
> Furthermore, the `reg` field should be adapted according to
> `#address-cells` and `#size-cells`. It may appear obvious, not for
> beginners.
>
> ## Testing
>
> The trace sink components need to be enabled by accessing through sysfile
> system.
>
> echo 1 > /sys/bus/coresight/devices/@...r.etb/enable\_sink
>
> Then enable the CS source component:
>
> echo 1 > /sys/bus/coresight/devices/@...r.ptm/enable\_source
>
> By default, CS Source components are configured to trace the kernel.
>
> Then the trace can be read by dumping ETB.
>
> dd if=/dev/@...r.etb of=trace_kernel.bin
>
> The trace can be visualized by:
>
> hexdump -C trace_kernel.bin
>
> Or stored using:
>
> hexdump -C trace_kernel.bin > trace_kernel.txt
>
> The trace need to be decoded to be readable. All these above steps can now
> be performed with Perf Library which was not available at the time I was
> playing with DT entries.
I'm curious, did you test that with external debug tools. I have the
feeling the kernel using the debug HW could interfere with JTAG
debuggers, external trace tools, etc.
>
> --- linux-4.7/arch/arm/boot/dts/zynq-7000.dtsi.orig 2016-07-24
> 21:23:50.000000000 +0200
> +++ linux-4.7/arch/arm/boot/dts/zynq-7000.dtsi 2016-09-28
> 19:13:52.651881000 +0200
> @@ -363,5 +363,159 @@
> reg = <0xf8005000 0x1000>;
> timeout-sec = <10>;
> };
> +
> + etb@...01000 {
> + compatible = "arm,coresight-etb10", "arm,primecell";
> + reg = <0xf8801000 0x1000>;
> + coresight-default-sink;
> + clocks = <&clkc 47>;
> + clock-names = "apb_pclk";
> +
> + port {
> +
> + endpoint@0 {
> + slave-mode;
> + remote-endpoint = <0x8>;
Use labels please.
> + linux,phandle = <0xd>;
> + phandle = <0xd>;
Do these phandle properties need to be here?
> + };
> + };
> + };
> +
> + tpiu@...03000 {
> + compatible = "arm,coresight-tpiu", "arm,primecell";
> + reg = <0xf8803000 0x1000>;
> + clocks = <&clkc 47>, <&clkc 16>;
I'm not sure this is correct for every setup. Sorry, that I don't recall
all the details, I haven't used tracing in a long time. But I guess this
clock is configurable as you're referring an fclk here. The other thing
that makes me a little suspicious is, that nothing in here uses the
'dbg_trc' clock that the clock controller provides.
> + clock-names = "apb_pclk", "fclk1";
Those names (at least fclk1) is not a good name for tpiu to identify
it's input. fclk1 is a zynq-specific clock, and as mentioned above, it
seems likely that this could easily become a different one. The
clock-names are meant to identify an input from the consumer's
perspective. The correct names should be documented in the DT binding.
> + clock-frequency=<0xee6b280>;
I cannot find this property in the binding.
> +
> + port {
> +
> + endpoint@0 {
> + slave-mode;
> + remote-endpoint = <0x9>;
> + linux,phandle = <0xe>;
> + phandle = <0xe>;
> + };
> + };
> + };
> +
> + funnel@...04000 {
> + compatible = "arm,coresight-funnel", "arm,primecell";
> + reg = <0xf8804000 0x1000>;
> + clocks = <&clkc 47>;
> + clock-names = "apb_pclk";
> +
> + ports {
> + #address-cells = <0x1>;
> + #size-cells = <0x0>;
> +
> + port@0 {
> + reg = <0x0>;
> +
> + endpoint {
> + remote-endpoint = <0xa>;
> + linux,phandle = <0xf>;
> + phandle = <0xf>;
> + };
> + };
> +
> + port@1 {
> + reg = <0x0>;
> +
> + endpoint {
> + slave-mode;
> + remote-endpoint = <0xb>;
> + linux,phandle = <0x11>;
> + phandle = <0x11>;
> + };
> + };
> +
> + port@2 {
> + reg = <0x1>;
> +
> + endpoint {
> + slave-mode;
> + remote-endpoint = <0xc>;
> + linux,phandle = <0x13>;
> + phandle = <0x13>;
> + };
> + };
> + };
> + };
> +
> + replicator {
> + compatible = "arm,coresight-replicator";
> +
> + ports {
> + #address-cells = <0x1>;
> + #size-cells = <0x0>;
> +
> + port@0 {
> + reg = <0x0>;
> +
> + endpoint {
> + remote-endpoint = <0xd>;
> + linux,phandle = <0x8>;
> + phandle = <0x8>;
> + };
> + };
> +
> + port@1 {
> + reg = <0x1>;
> +
> + endpoint {
> + remote-endpoint = <0xe>;
> + linux,phandle = <0x9>;
> + phandle = <0x9>;
> + };
> + };
> +
> + port@2 {
> + reg = <0x0>;
> +
> + endpoint {
> + slave-mode;
> + remote-endpoint = <0xf>;
> + linux,phandle = <0xa>;
> + phandle = <0xa>;
> + };
> + };
> + };
> + };
> +
> + ptm0@...9C000 {
> + compatible = "arm,coresight-etm3x", "arm,primecell";
> + reg = <0xf889c000 0x1000>;
> + cpu = <0x10>;
> + clocks = <&clkc 47>;
> + clock-names = "apb_pclk";
> +
> + port {
> +
> + endpoint {
> + remote-endpoint = <0x11>;
> + linux,phandle = <0xb>;
> + phandle = <0xb>;
> + };
> + };
> + };
> +
> + ptm1@...9D000 {
> + compatible = "arm,coresight-etm3x", "arm,primecell";
> + reg = <0xf889d000 0x1000>;
> + cpu = <0x12>;
> + clocks = <&clkc 47>;
> + clock-names = "apb_pclk";
> +
> + port {
> +
> + endpoint {
> + remote-endpoint = <0x13>;
> + linux,phandle = <0xc>;
> + phandle = <0xc>;
> + };
> + };
> + };
> };
> };
I think nodes were ordered alphabetically in our DTs.
Sören
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