summaryrefslogtreecommitdiff
path: root/Documentation
diff options
context:
space:
mode:
authorRichard Cochran <richardcochran@gmail.com>2011-04-22 12:03:54 +0200
committerJohn Stultz <john.stultz@linaro.org>2011-05-23 13:10:14 -0700
commitc78275f366c687b5b3ead3d99fc96d1f02d38a8e (patch)
tree279a8cccfc56fd347b4864c3f400935f18244a5f /Documentation
parentd94ba80ebbea17f036cecb104398fbcd788aa742 (diff)
ptp: Added a clock that uses the eTSEC found on the MPC85xx.
The eTSEC includes a PTP clock with quite a few features. This patch adds support for the basic clock adjustment functions, plus two external time stamps, one alarm, and the PPS callback. Signed-off-by: Richard Cochran <richard.cochran@omicron.at> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: John Stultz <john.stultz@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/net/fsl-tsec-phy.txt54
1 files changed, 54 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/net/fsl-tsec-phy.txt b/Documentation/devicetree/bindings/net/fsl-tsec-phy.txt
index edb7ae19e868..2c6be0377f55 100644
--- a/Documentation/devicetree/bindings/net/fsl-tsec-phy.txt
+++ b/Documentation/devicetree/bindings/net/fsl-tsec-phy.txt
@@ -74,3 +74,57 @@ Example:
interrupt-parent = <&mpic>;
phy-handle = <&phy0>
};
+
+* Gianfar PTP clock nodes
+
+General Properties:
+
+ - compatible Should be "fsl,etsec-ptp"
+ - reg Offset and length of the register set for the device
+ - interrupts There should be at least two interrupts. Some devices
+ have as many as four PTP related interrupts.
+
+Clock Properties:
+
+ - fsl,tclk-period Timer reference clock period in nanoseconds.
+ - fsl,tmr-prsc Prescaler, divides the output clock.
+ - fsl,tmr-add Frequency compensation value.
+ - fsl,tmr-fiper1 Fixed interval period pulse generator.
+ - fsl,tmr-fiper2 Fixed interval period pulse generator.
+ - fsl,max-adj Maximum frequency adjustment in parts per billion.
+
+ These properties set the operational parameters for the PTP
+ clock. You must choose these carefully for the clock to work right.
+ Here is how to figure good values:
+
+ TimerOsc = system clock MHz
+ tclk_period = desired clock period nanoseconds
+ NominalFreq = 1000 / tclk_period MHz
+ FreqDivRatio = TimerOsc / NominalFreq (must be greater that 1.0)
+ tmr_add = ceil(2^32 / FreqDivRatio)
+ OutputClock = NominalFreq / tmr_prsc MHz
+ PulseWidth = 1 / OutputClock microseconds
+ FiperFreq1 = desired frequency in Hz
+ FiperDiv1 = 1000000 * OutputClock / FiperFreq1
+ tmr_fiper1 = tmr_prsc * tclk_period * FiperDiv1 - tclk_period
+ max_adj = 1000000000 * (FreqDivRatio - 1.0) - 1
+
+ The calculation for tmr_fiper2 is the same as for tmr_fiper1. The
+ driver expects that tmr_fiper1 will be correctly set to produce a 1
+ Pulse Per Second (PPS) signal, since this will be offered to the PPS
+ subsystem to synchronize the Linux clock.
+
+Example:
+
+ ptp_clock@24E00 {
+ compatible = "fsl,etsec-ptp";
+ reg = <0x24E00 0xB0>;
+ interrupts = <12 0x8 13 0x8>;
+ interrupt-parent = < &ipic >;
+ fsl,tclk-period = <10>;
+ fsl,tmr-prsc = <100>;
+ fsl,tmr-add = <0x999999A4>;
+ fsl,tmr-fiper1 = <0x3B9AC9F6>;
+ fsl,tmr-fiper2 = <0x00018696>;
+ fsl,max-adj = <659999998>;
+ };