Commit graph

146 commits

Author SHA1 Message Date
Michael Kurz
b1a8de7e07 ARM: DTS: stm32: add stm32f746-disco device tree files
This patch adds the DTS source files needed for stm32f746-disco board
The files are based on the stm32f429/469 files from current linux
kernel.

Source for "arch/arm/dts/armv7-m.dtsi": Linux: "arch/arm/boot/dts/armv7-m.dtsi"

Signed-off-by: Michael Kurz <michi.kurz@gmail.com>
Acked-by: Vikas MANOCHA <vikas.manocha@st.com>
2017-01-28 14:04:42 -05:00
Vignesh R
bd2e9714c8 regulator: fixed: Add support to handle enable-active-high DT property
Add support to handle enable-active-high DT property. This property is
used to drive the gpio controlling fixed regulator as active high when
claiming gpio line.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Acked-by: Simon Glass <sjg@chromium.org>
2016-12-27 08:22:57 -05:00
Konstantin Porotchkin
f99386c5b1 arm64: mvebu: Add pin control nodes to A8K family DTS files
Add pin control nodes to APN806, CP-master, CP-slave and
Armada-7040 and Armada-8040 boards DTS files

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Omri Itach <omrii@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>
2016-12-12 09:04:52 +01:00
Konstantin Porotchkin
656e6cc86b arm64: mvebu: pinctrl: Add pin control driver for A8K family
Add a DM port of Marvell pin control driver.
The A8K SoC family contains several silicone dies interconnected
in a single package. Every die is normally equipped with its own
pin controller unit.
There are 2 pin controllers in A70x0 SoC and 3 in A80x0 SoC.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Omri Itach <omrii@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>
2016-12-12 09:04:52 +01:00
Fabian Vogt
165316e38f serial: pl01x: expose skip_init platdata option in DT
To be able to represent the skip-init platdata element with OF_CONTROL,
it needs to be read from the device tree as well and put into the platform data.

Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-11-28 20:09:47 -05:00
Fabian Vogt
9f755f5d09 serial: bcm283x_mu: add device tree support
This patch adds device tree support for the bcm283x mini-uart driver.

Signed-off-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-11-28 20:09:46 -05:00
Fabian Vogt
4faf5f93c6 gpio: bcm2835: add device tree support
This patch adds device tree support for the bcm2835 GPIO driver.

Signed-off-by: Fabian Vogt <fvogt@suse.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-11-28 20:09:45 -05:00
Jagan Teki
6645fd2c18 sf: Rename sf_params.c to spi_flash_ids.c
Now the flash params table as renamed to spi_flash_ids structure,
so rename the sf_params.c to spi_flash_ids.c and remove the legacy.

Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: York Sun <york.sun@nxp.com>
Cc: Vignesh R <vigneshr@ti.com>
Cc: Mugunthan V N <mugunthanvnm@ti.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Tested-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
2016-11-18 13:04:54 +05:30
Stephen Warren
afb970f78a dt: net: add DWC EQoS binding
The Synopsys DWC EQoS is a configurable Ethernet MAC/DMA IP block which
supports multiple options for bus type, clocking and reset structure, and
feature list.

This patch imports the binding from the Linux kernel, including my V3
patch to extend the binding to cover the Tegra186, which is applied for
next-20160912. So far, my changes have been acked by Lars Persson, the
original author of the binding.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
2016-11-07 11:28:15 -06:00
Stefan Agner
c571d6828d power: pmic: add Ricoh RN5T567 PMIC support
Add device model enabled PMIC driver for Ricoh RN5T567 PMIC used
on Colibri iMX7.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-10-07 12:26:15 +02:00
Stefan Agner
a99546ab62 dm: imx: serial: support device tree
Support instatiation through device tree. Also parse the fsl,dte-mode
property to determine whether DTE mode shall be used.

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-10-07 12:26:14 +02:00
John Keeping
7302fbb31d regulator: fixed: obey startup delay
When enabling a fixed regulator, it may take some time to rise to the
correct voltage.  If we do not delay here then subsequent operations
will fail.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-09-06 13:18:21 -04:00
Wenyou Yang
256a3f2466 atmel: Bring in at91 pio4 device tree file and bindings
Bring in required device tree file and bindings from Linux.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Andreas Bießmann <andreas@biessmann.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-08-15 22:58:04 +02:00
Songjun Wu
e3b7599be7 i2c: atmel: DT binding for i2c driver
DT binding documentation for atmel i2c driver.

Signed-off-by: Songjun Wu <songjun.wu@atmel.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Acked-by: Heiko Schocher <hs@denx.de>
2016-08-15 22:12:00 +02:00
Vignesh R
5746b0df9c gpio: Add driver for TI PCF8575 I2C GPIO expander
TI's PCF8575 is a 16-bit I2C GPIO expander.The device features a
16-bit quasi-bidirectional I/O ports. Each quasi-bidirectional I/O can
be used as an input or output without the use of a data-direction
control signal. The I/Os should be high before being used as inputs.
Read the device documentation for more details[1].

This driver is based on pcf857x driver available in Linux v4.7 kernel.
It supports basic reading and writing of gpio pins.

[1] http://www.ti.com/lit/ds/symlink/pcf8575.pdf

Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mugunthan V N <mugunthanvnm@ti.com>
2016-08-08 13:32:53 -04:00
Stephen Warren
6e7a11e64e dt-bindings: add Tegra186 BPMP I2C binding
In Tegra186, the BPMP (Boot and Power Management Processor) owns certain
HW devices, such as the I2C controller for the power management I2C bus.
Software running on other CPUs must perform IPC to the BPMP in order to
execute transactions on that I2C bus. This binding describes an I2C bus
that is accessed in such a fashion.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
2016-08-04 13:36:59 -07:00
Stephen Warren
390ae57c76 dt-bindings: allow child nodes inside the Tegra BPMP
The BPMP implements some services which must be represented by separate
nodes. For example, it can provide access to certain I2C controllers, and
the I2C bindings represent each I2C controller as a device tree node.
Update the binding to describe how the BPMP supports this.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>
2016-08-04 13:36:59 -07:00
Stephen Warren
7b9cb49405 ARM: tegra: add BPMP DT bindings
The Tegra BPMP (Boot and Power Management Processor) is a separate
auxiliary CPU embedded into Tegra to perform power management work, and
controls related features such as clocks, resets, power domains, PMIC I2C
bus, etc. These bindings dictate how to represent the BPMP in device tree.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
2016-08-04 13:36:58 -07:00
Stephen Warren
729c2db7a9 ARM: tegra: adapt to latest HSP DT binding
The DT binding for the Tegra186 HSP module apparently wasn't quite final
when I posted initial U-Boot support for it. Add the final DT binding doc
and adapt all code and DT files to match it.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
2016-08-04 13:36:58 -07:00
Yoshinori Sato
747431b9d5 serial_sh: Add standrad SCI (w/o FIFO) support
Add support for standard type SCI (without FIFO) port.

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
2016-07-09 05:51:57 +09:00
Yoshinori Sato
359787cfe4 serial_sh: Device Tree support
Add Device Tree bindings.

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
2016-07-09 05:51:57 +09:00
Stephen Warren
89c1e2da78 Add a reset driver framework/uclass
A reset controller is a hardware module that controls reset signals that
affect other hardware modules or chips.

This patch defines a standard API that connects reset clients (i.e. the
drivers for devices affected by reset signals) to drivers for reset
controllers/providers. Initially, DT is the only supported method for
connecting the two.

The DT binding specification (reset.txt) was taken from Linux kernel
v4.5's Documentation/devicetree/bindings/reset/reset.txt.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
2016-06-19 17:05:55 -06:00
Bin Meng
2600ba6de0 x86: Update x86-pinctrl driver device-tree-bindings doc
This updates the device-tree-bindings doc for x86-pinctrl driver:

 - clarify "gpio-offset" is required only when "mode-gpio" is set
 - correct property name "pull-strength"
 - use tab instead of space at several places

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-06-12 12:19:35 +08:00
Stephen Warren
074a1fdd27 gpio: add Tegra186 GPIO driver
Tegra186's GPIO controller register layout is significantly different from
previous chips, so add a new driver for it. In fact, there are two
different GPIO controllers in Tegra186 that share a similar register
layout, but very different port mapping. This driver covers both.

The DT binding is already present in the Linux kernel (in linux-next via
the Tegra tree so far).

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org> # v1
Signed-off-by: Tom Warren <twarren@nvidia.com>
2016-05-31 09:54:24 -07:00
Stephen Warren
6238935d01 Add a mailbox driver framework/uclass
A mailbox is a hardware mechanism for transferring small message and/or
notifications between the CPU on which U-Boot runs and some other device
such as an auxilliary CPU running firmware or a hardware module.

This patch defines a standard API that connects mailbox clients to mailbox
providers (drivers). Initially, DT is the only supported method for
connecting the two.

The DT binding specification (mailbox.txt) was taken from Linux kernel
v4.5's Documentation/devicetree/bindings/mailbox/mailbox.txt.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
2016-05-26 20:48:31 -06:00
Tom Rini
2ee490a024 Merge branch 'master' of git://git.denx.de/u-boot-net
Signed-off-by: Tom Rini <trini@konsulko.com>

Conflicts:
	drivers/net/zynq_gem.c
2016-05-24 11:59:02 -04:00
Dan Murphy
c7ba7bdc9d net: phy: dp83867: Add device tree bindings and documentation
Add the device tree bindings and the accompanying documentation
for the TI DP83867 Giga bit ethernet phy driver.

The original document was from:
    [commit 2a10154abcb75ad0d7b6bfea6210ac743ec60897 from the Linux kernel]

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Reviewed-by: Mugunthan V N <mugunthanvnm@ti.com>
Tested-by: Mugunthan V N <mugunthanvnm@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
2016-05-24 11:42:04 -05:00
Tom Rini
6d54868eeb Merge branch 'master' of git://git.denx.de/u-boot-x86 2016-05-23 18:32:47 -04:00
Bin Meng
d4e61f505b x86: irq: Enable SCI on IRQ9
By default SCI is disabled after power on. ACTL is the register to
enable SCI and route it to PIC/APIC. To support both ACPI in PIC
mode and APIC mode, configure SCI to use IRQ9.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
2016-05-23 15:18:00 +08:00
Wills Wang
b85dc46072 drivers: spi: add spi support for QCA/Atheros ath79 SOCs
This patch add a compatible spi driver for ath79 series SOC.

Signed-off-by: Wills Wang <wills.wang@live.com>
Reviewed-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
2016-05-21 01:25:50 +02:00
Wills Wang
60b49761e9 drivers: serial: add serial driver for ar933x SOC
This patch add support for ar933x serial.

Signed-off-by: Wills Wang <wills.wang@live.com>
Reviewed-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-05-21 01:25:50 +02:00
Moritz Fischer
17573c2791 i2c: Describe Cadence I2C devicetree bindings
Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
2016-04-13 18:29:07 +02:00
York Sun
3c1d218a1d armv8: LS2080A: Consolidate LS2080A and LS2085A
LS2080A is the primary SoC, and LS2085A is a personality with AIOP
and DPAA DDR. The RDB and QDS boards support both personality. By
detecting the SVR at runtime, a single image per board can support
both SoCs. It gives users flexibility to swtich SoC without the need
to reprogram the board.

Signed-off-by: York Sun <york.sun@nxp.com>
CC: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
2016-04-06 10:26:46 -07:00
Mateusz Kulikowski
120800df72 gpio: Add support for Qualcomm PM8916 gpios
This driver supports GPIOs present on PM8916 PMIC.
There are 2 device drivers inside:
- GPIO driver (4 "generic" GPIOs)
- Keypad driver that presents itself as GPIO with 2 inputs (power and reset)

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:13 -04:00
Mateusz Kulikowski
c2f74c8f53 pmic: Add support for Qualcomm PM8916 PMIC
This PMIC is connected on SPMI bus so needs SPMI support enabled.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:13 -04:00
Mateusz Kulikowski
5b47271c18 drivers: spmi: Add support for Qualcomm SPMI bus driver
Support SPMI arbiter on Qualcomm Snapdragon devices.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:12 -04:00
Mateusz Kulikowski
d33776e43d spmi: Add sandbox test driver
This patch adds emulated spmi bus controller with part of
pm8916 pmic on it to sandbox and tests validating SPMI uclass.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:12 -04:00
Mateusz Kulikowski
5a8221181e ehci: Add support for Qualcomm EHCI
This driver is able to reconfigure OTG controller into HOST mode.
Board can add board-specific initialization as board_prepare_usb().
It requires USB_ULPI_VIEWPORT enabled in board configuration.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Acked-by: Marek Vasut <marex@denx.de>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:11 -04:00
Mateusz Kulikowski
9d11d12a16 mmc: Add support for Qualcomm SDHCI controller
Add support for SD/eMMC controller present on some Qualcomm Snapdragon
devices. This controller implements SDHCI 2.0 interface but requires
vendor-specific initialization.
Driver works in PIO mode as ADMA is not supported by U-Boot (yet).

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:08 -04:00
Mateusz Kulikowski
81a87e1894 gpio: Add support for Qualcomm gpio controller
Add support for gpio controllers on Qualcomm Snapdragon devices.
This devices are usually called Top Level Mode Multiplexing in
Qualcomm documentation.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:07 -04:00
Mateusz Kulikowski
142a20c367 serial: Add support for Qualcomm serial port
This driver works in "new" Data Mover UART mode, so
will be compatible with modern Qualcomm chips only.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
2016-04-01 17:18:07 -04:00
Vagrant Cascadian
a6f70a3d14 Fix spelling of "transferred".
Signed-off-by: Vagrant Cascadian <vagrant@debian.org>
Acked-by: Marek Vasut <marex@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
2016-03-22 12:16:16 -04:00
Simon Glass
b24f5c4f27 x86: broadwell: Add a pinctrl driver
GPIO pins need to be set up on start-up. Add a driver to provide this,
configured from the device tree.

The binding is slightly different from the existing ICH6 binding, since that
is quite verbose. The new binding should be just as extensible.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Bin Meng <bmeng.cn@gmail.com>
2016-03-17 10:27:26 +08:00
Simon Glass
c13dcb3dc7 x86: dts: Update the pinctrl binding a little
Make a few minor updates to make the meaning clearer.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2016-03-17 10:27:25 +08:00
Simon Glass
7ac99be6e2 x86: Add an ICH6 pin configuration driver
Add a driver which sets up the pin configuration on x86 devices with an ICH6
(or later) Platform Controller Hub.

The driver is not in the pinctrl uclass due to some oddities of the way x86
devices work:

- The GPIO controller is not present in I/O space until it is set up
- This is done by writing a register in the PCH
- The PCH has a driver which itself uses PCI, another driver
- The pinctrl uclass requires that a pinctrl device be available before any
other device can be probed

It would be possible to work around the limitations by:
- Hard-coding the GPIO address rather than reading it from the PCH
- Using special x86 PCI access to set the GPIO address in the PCH

However it is not clear that this is better, since the pin configuration
driver does not actually provide normal pin configuration services - it
simply sets up all the pins statically when probed. While this remains the
case, it seems better to use a syscon uclass instead. This can be probed
whenever it is needed, without any limitations.

Also add an 'invert' property to support inverting the input.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2016-03-17 10:27:25 +08:00
Jacob Chen
c87c30e3ba doc: dt-bindings: Describe rockchip LVDS interface
I didn't have a common board to enable LVDS.
So add this dcocument to help others who want to enable LVDS in their board.

Signed-off-by: Jacob Chen <jacob-chen@iotwrt.com>
Acked-by: Simon Glass <sjg@chromium.org>
2016-03-14 22:24:44 +01:00
Paul Thacker
9e160ee823 drivers: serial: add driver for Microchip PIC32 UART controller.
This adds PIC32 UART controller support based on driver model.

Signed-off-by: Paul Thacker <paul.thacker@microchip.com>
Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-02-01 22:14:00 +01:00
Purna Chandra Mandal
a0e7908326 drivers: clk: Add clock driver for Microchip PIC32 Microcontroller.
PIC32 clock module consists of multiple oscillators, PLLs, mutiplexers
and dividers capable of supplying clock to various controllers
on or off-chip.

Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
2016-02-01 22:14:00 +01:00
Tom Rini
82d72a1b99 Merge branch 'master' of git://git.denx.de/u-boot-net 2016-01-28 18:42:10 -05:00
Dinh Nguyen
c16e69f702 net: phy: micrel: add documentation for Micrel KSZ90x1 binding
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>
2016-01-28 13:20:29 -06:00