diff options
Diffstat (limited to 'Documentation/devicetree/bindings/net/micrel-ksz90x1.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/net/micrel-ksz90x1.txt | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt b/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt new file mode 100644 index 000000000..df9e844dd --- /dev/null +++ b/Documentation/devicetree/bindings/net/micrel-ksz90x1.txt @@ -0,0 +1,227 @@ +Micrel KSZ9021/KSZ9031/KSZ9131 Gigabit Ethernet PHY + +Some boards require special tuning values, particularly when it comes +to clock delays. You can specify clock delay values in the PHY OF +device node. Deprecated, but still supported, these properties can +also be added to an Ethernet OF device node. + +Note that these settings are applied after any phy-specific fixup from +phy_fixup_list (see phy_init_hw() from drivers/net/phy/phy_device.c), +and therefore may overwrite them. + +KSZ9021: + + All skew control options are specified in picoseconds. The minimum + value is 0, the maximum value is 3000, and it can be specified in 200ps + steps, *but* these values are in not fact what you get because this chip's + skew values actually increase in 120ps steps, starting from -840ps. The + incorrect values came from an error in the original KSZ9021 datasheet + before it was corrected in revision 1.2 (Feb 2014), but it is too late to + change the driver now because of the many existing device trees that have + been created using values that go up in increments of 200. + + The following table shows the actual skew delay you will get for each of the + possible devicetree values, and the number that will be programmed into the + corresponding pad skew register: + + Device Tree Value Delay Pad Skew Register Value + ----------------------------------------------------- + 0 -840ps 0000 + 200 -720ps 0001 + 400 -600ps 0010 + 600 -480ps 0011 + 800 -360ps 0100 + 1000 -240ps 0101 + 1200 -120ps 0110 + 1400 0ps 0111 + 1600 120ps 1000 + 1800 240ps 1001 + 2000 360ps 1010 + 2200 480ps 1011 + 2400 600ps 1100 + 2600 720ps 1101 + 2800 840ps 1110 + 3000 960ps 1111 + + Optional properties: + + - rxc-skew-ps : Skew control of RXC pad + - rxdv-skew-ps : Skew control of RX CTL pad + - txc-skew-ps : Skew control of TXC pad + - txen-skew-ps : Skew control of TX CTL pad + - rxd0-skew-ps : Skew control of RX data 0 pad + - rxd1-skew-ps : Skew control of RX data 1 pad + - rxd2-skew-ps : Skew control of RX data 2 pad + - rxd3-skew-ps : Skew control of RX data 3 pad + - txd0-skew-ps : Skew control of TX data 0 pad + - txd1-skew-ps : Skew control of TX data 1 pad + - txd2-skew-ps : Skew control of TX data 2 pad + - txd3-skew-ps : Skew control of TX data 3 pad + +KSZ9031: + + All skew control options are specified in picoseconds. The minimum + value is 0, and the maximum is property-dependent. The increment + step is 60ps. The default value is the neutral setting, so setting + rxc-skew-ps=<0> actually results in -900 picoseconds adjustment. + + The KSZ9031 hardware supports a range of skew values from negative to + positive, where the specific range is property dependent. All values + specified in the devicetree are offset by the minimum value so they + can be represented as positive integers in the devicetree since it's + difficult to represent a negative number in the devictree. + + The following 5-bit values table apply to rxc-skew-ps and txc-skew-ps. + + Pad Skew Value Delay (ps) Devicetree Value + ------------------------------------------------------ + 0_0000 -900ps 0 + 0_0001 -840ps 60 + 0_0010 -780ps 120 + 0_0011 -720ps 180 + 0_0100 -660ps 240 + 0_0101 -600ps 300 + 0_0110 -540ps 360 + 0_0111 -480ps 420 + 0_1000 -420ps 480 + 0_1001 -360ps 540 + 0_1010 -300ps 600 + 0_1011 -240ps 660 + 0_1100 -180ps 720 + 0_1101 -120ps 780 + 0_1110 -60ps 840 + 0_1111 0ps 900 + 1_0000 60ps 960 + 1_0001 120ps 1020 + 1_0010 180ps 1080 + 1_0011 240ps 1140 + 1_0100 300ps 1200 + 1_0101 360ps 1260 + 1_0110 420ps 1320 + 1_0111 480ps 1380 + 1_1000 540ps 1440 + 1_1001 600ps 1500 + 1_1010 660ps 1560 + 1_1011 720ps 1620 + 1_1100 780ps 1680 + 1_1101 840ps 1740 + 1_1110 900ps 1800 + 1_1111 960ps 1860 + + The following 4-bit values table apply to the txdX-skew-ps, rxdX-skew-ps + data pads, and the rxdv-skew-ps, txen-skew-ps control pads. + + Pad Skew Value Delay (ps) Devicetree Value + ------------------------------------------------------ + 0000 -420ps 0 + 0001 -360ps 60 + 0010 -300ps 120 + 0011 -240ps 180 + 0100 -180ps 240 + 0101 -120ps 300 + 0110 -60ps 360 + 0111 0ps 420 + 1000 60ps 480 + 1001 120ps 540 + 1010 180ps 600 + 1011 240ps 660 + 1100 300ps 720 + 1101 360ps 780 + 1110 420ps 840 + 1111 480ps 900 + + Optional properties: + + Maximum value of 1860, default value 900: + + - rxc-skew-ps : Skew control of RX clock pad + - txc-skew-ps : Skew control of TX clock pad + + Maximum value of 900, default value 420: + + - rxdv-skew-ps : Skew control of RX CTL pad + - txen-skew-ps : Skew control of TX CTL pad + - rxd0-skew-ps : Skew control of RX data 0 pad + - rxd1-skew-ps : Skew control of RX data 1 pad + - rxd2-skew-ps : Skew control of RX data 2 pad + - rxd3-skew-ps : Skew control of RX data 3 pad + - txd0-skew-ps : Skew control of TX data 0 pad + - txd1-skew-ps : Skew control of TX data 1 pad + - txd2-skew-ps : Skew control of TX data 2 pad + - txd3-skew-ps : Skew control of TX data 3 pad + + - micrel,force-master: + Boolean, force phy to master mode. Only set this option if the phy + reference clock provided at CLK125_NDO pin is used as MAC reference + clock because the clock jitter in slave mode is to high (errata#2). + Attention: The link partner must be configurable as slave otherwise + no link will be established. + +KSZ9131: + + All skew control options are specified in picoseconds. The increment + step is 100ps. Unlike KSZ9031, the values represent picoseccond delays. + A negative value can be assigned as rxc-skew-psec = <(-100)>;. + + Optional properties: + + Range of the value -700 to 2400, default value 0: + + - rxc-skew-psec : Skew control of RX clock pad + - txc-skew-psec : Skew control of TX clock pad + + Range of the value -700 to 800, default value 0: + + - rxdv-skew-psec : Skew control of RX CTL pad + - txen-skew-psec : Skew control of TX CTL pad + - rxd0-skew-psec : Skew control of RX data 0 pad + - rxd1-skew-psec : Skew control of RX data 1 pad + - rxd2-skew-psec : Skew control of RX data 2 pad + - rxd3-skew-psec : Skew control of RX data 3 pad + - txd0-skew-psec : Skew control of TX data 0 pad + - txd1-skew-psec : Skew control of TX data 1 pad + - txd2-skew-psec : Skew control of TX data 2 pad + - txd3-skew-psec : Skew control of TX data 3 pad + +Examples: + + /* Attach to an Ethernet device with autodetected PHY */ + &enet { + rxc-skew-ps = <1800>; + rxdv-skew-ps = <0>; + txc-skew-ps = <1800>; + txen-skew-ps = <0>; + status = "okay"; + }; + + /* Attach to an explicitly-specified PHY */ + mdio { + phy0: ethernet-phy@0 { + rxc-skew-ps = <1800>; + rxdv-skew-ps = <0>; + txc-skew-ps = <1800>; + txen-skew-ps = <0>; + reg = <0>; + }; + }; + ethernet@70000 { + phy = <&phy0>; + phy-mode = "rgmii-id"; + }; + +References + + Micrel ksz9021rl/rn Data Sheet, Revision 1.2. Dated 2/13/2014. + http://www.micrel.com/_PDF/Ethernet/datasheets/ksz9021rl-rn_ds.pdf + + Micrel ksz9031rnx Data Sheet, Revision 2.1. Dated 11/20/2014. + http://www.micrel.com/_PDF/Ethernet/datasheets/KSZ9031RNX.pdf + +Notes: + + Note that a previous version of the Micrel ksz9021rl/rn Data Sheet + was missing extended register 106 (transmit data pad skews), and + incorrectly specified the ps per step as 200ps/step instead of + 120ps/step. The latest update to this document reflects the latest + revision of the Micrel specification even though usage in the kernel + still reflects that incorrect document. |