mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-27 13:33:40 +00:00
c16e69f702
Add the DTS documentation for the Micrel KSZ90x1 binding. The original document was from: [commit 4b405efbe12de28b26289282b431323d73992381 from the Linux kernel] This takes the original document and adds a clarification on how the skew values are represented in the code. 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 Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com> Acked-by: Joe Hershberger <joe.hershberger@ni.com>
165 lines
4.9 KiB
Text
165 lines
4.9 KiB
Text
Micrel KSZ9021/KSZ9031 Gigabit Ethernet PHY
|
|
|
|
Some boards require special tuning values, particularly when it comes to
|
|
clock delays. You can specify clock delay values by adding
|
|
micrel-specific properties 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 1800, and it is incremented by 120ps
|
|
steps.
|
|
|
|
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 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:
|
|
|
|
- rxc-skew-ps : Skew control of RX clock pad
|
|
- txc-skew-ps : Skew control of TX clock pad
|
|
|
|
Maximum value of 900:
|
|
|
|
- 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
|
|
|
|
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 {
|
|
status = "okay";
|
|
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.
|