The CPTS driver is capable of configuring GENFy (Periodic Signal Generator Function) present in the CPTS module, to generate periodic output signals with a custom time period. In order to generate a PPS signal on the GENFy output, the device-tree property "ti,pps" has to be used. The "ti,pps" property is used to declare the mapping between the CPTS HWx_TS_PUSH (Hardware Timestamp trigger) input and the GENFy output that is configured to generate a PPS signal. The mapping is of the form: <x-1 y> where the value x corresponds to HWx_TS_PUSH input (1-based indexing) and the value y corresponds to GENFy (0-based indexing). To verify that the signal is a PPS signal, the GENFy output signal is fed into the CPTS HWx_TS_PUSH input, which generates a timestamp event on the rising edge of the GENFy signal. The GENFy output signal can be routed to the HWx_TS_PUSH input by using the Time Sync Router. This is done by mentioning the mapping between the GENFy output and the HWx_TS_PUSH input within the "timesync_router" device-tree node. The Input Sources to the Time Sync Router are documented at: [1] The Output Destinations of the Time Sync Router are documented at: [2] The PPS signal can be verified using testptp and ppstest tools as follows: # ./testptp -d /dev/ptp0 -P 1 pps for system time request okay # ./ppstest /dev/pps0 trying PPS source "/dev/pps0" found PPS source "/dev/pps0" ok, found 1 source(s), now start fetching data... source 0 - assert 48.000000013, sequence: 8 - clear 0.000000000, sequence: 0 source 0 - assert 49.000000013, sequence: 9 - clear 0.000000000, sequence: 0 source 0 - assert 50.000000013, sequence: 10 - clear 0.000000000, sequence: 0 Add an example in the device-tree, enabling PPS generation on GENF1. The HW3_TS_PUSH Timestamp trigger input is used to verify the PPS signal. [1] Link: https://software-dl.ti.com/tisci/esd/latest/5_soc_doc/am62x/interrupt_cfg.html#timesync-event-router0-interrupt-router-input-sources [2] Link: https://software-dl.ti.com/tisci/esd/latest/5_soc_doc/am62x/interrupt_cfg.html#timesync-event-router0-interrupt-router-output-destinations Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx> --- arch/arm64/boot/dts/ti/k3-am625-sk.dts | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/arch/arm64/boot/dts/ti/k3-am625-sk.dts b/arch/arm64/boot/dts/ti/k3-am625-sk.dts index 4f179b146cab..962a922cc94b 100644 --- a/arch/arm64/boot/dts/ti/k3-am625-sk.dts +++ b/arch/arm64/boot/dts/ti/k3-am625-sk.dts @@ -366,6 +366,10 @@ &cpsw3g { pinctrl-names = "default"; pinctrl-0 = <&main_rgmii1_pins_default &main_rgmii2_pins_default>; + + cpts@3d000 { + ti,pps = <2 1>; + }; }; &cpsw_port1 { @@ -464,3 +468,19 @@ partition@3fc0000 { }; }; }; + +#define TS_OFFSET(pa, val) (0x4+(pa)*4) (0x10000 | val) + +×ync_router { + status = "okay"; + pinctrl-names = "default"; + pinctrl-0 = <&cpsw_cpts>; + + /* Example of the timesync routing */ + cpsw_cpts: cpsw-cpts { + pinctrl-single,pins = < + /* pps [cpsw cpts genf1] in17 -> out12 [cpsw cpts hw3_push] */ + TS_OFFSET(12, 17) + >; + }; +}; -- 2.25.1
