Add a bunch more documentation.
Signed-off-by: Richard Cochran <richardcochran@gmail.com>master
Richard Cochran
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README.org
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README.org
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@ -30,6 +30,140 @@
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- Modular design allowing painless addition of new transports and
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clock servos.
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* System Requirements
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In order to run this software, you need to run a recent Linux kernel
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version 3.0 or newer, and the kernel header files must available at
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compile time.
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In addition, you will also need to have either:
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1. A supported Ethernet MAC device.
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2. A supported PHY device paired with a MAC that allows time
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stamping in the PHY (indicated by PHY=Y in the table below).
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** Linux Kernel Support
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In order to support PTP, the operating system needs to provide two
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services: network packet time stamping and clock control. In 2009,
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Patrick Ohly added a new socket option called SO_TIMESTAMPING for
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packet time stamping, especially for PTP. This work appeared in
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Linux version 2.6.30.
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In July of 2011, the PTP Hardware Clock (PHC) subsystem was merged
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into Linux version 3.0. The PHC code provides a driver framework and
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the user space API for clock control.
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** Driver Support Matrix
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The table below shows the Linux drivers that support the new
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API. The meaning of the column abbreviations is as follows.
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- SOTS: SO_TIMESTAMPING support. This comes in three flavors.
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1. RAW: Supports time stamping using the PHC time values.
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2. SW: Supports software time stamping using the system time.
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3. SYS: Supports time stamping using PHC time values scaled to
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the system time. This is a legacy mode and its use in new
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drivers is discouraged.
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- PHC: PTP Hardware Clock support. These drivers will offer a
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character device that allows direct control of the hardware
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clock.
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- PHY: Supports time stamping in the PHY. This indicates an
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Ethernet MAC driver supporting SO_TIMESTAMPING and PHC in the
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PHY. If you have or build a computer that combines this MAC with
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a PTP capable PHY, then it will work with the Linux PHC
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subsystem.
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- VER: Linux kernel version when the PTP API support was added.
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*** Hardware Timestamping
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|------------+-------------------------+------+-----+-----+---------|
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| Driver | Hardware | SOTS | PHC | PHY | VER |
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|------------+-------------------------+------+-----+-----+---------|
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| bfin_mac | Analog Blackfin | SYS | N | NA | pre 3.0 |
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| igb | Intel 82576, 82580 | SYS | N | NA | pre 3.0 |
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| dp83640 | Nat Semi PHYTER | RAW | Y | NA | 3.0 |
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| gianfar | Freescale eTSEC PowerPC | RAW | Y | NA | 3.0 |
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| ptp_ixp46x | Intel IXP465 | RAW | Y | NA | 3.0 |
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|------------+-------------------------+------+-----+-----+---------|
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*** Software Timestamping
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|--------------+--------------------------+------+-----+-----+-----|
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| Driver | Hardware | SOTS | PHC | PHY | VER |
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|--------------+--------------------------+------+-----+-----+-----|
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| davinci_emac | TI DaVinci, Sitara | SW | N | Y | 3.1 |
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| dnet | Dave Ethernet MAC | SW | N | Y | 3.1 |
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| emaclite | Xilinx Ethernet Lite | SW | N | Y | 3.1 |
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| ethoc | OpenCores 10/100 MAC | SW | N | Y | 3.1 |
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| fec | Freescale Coldfire | SW | N | Y | 3.1 |
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| fec_mpc52xx | Freescale MPC5200 | SW | N | Y | 3.1 |
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| fs_enet | Freescale MPC512x | SW | N | Y | 3.1 |
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| ixp4xx_eth | Intel IXP4xx | SW | N | Y | 3.0 |
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| lib8390 | Asix AX88796 | SW | N | Y | 3.1 |
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| lib8390 | Various 8390 based HW | SW | N | N | 3.1 |
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| ll_temac | Xilinx LL TEMAC | SW | N | Y | 3.1 |
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| macb | Atmel AT32, AT91 | SW | N | Y | 3.1 |
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| mv643xx_eth | Marvell Discovery, Orion | SW | N | Y | 3.1 |
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| pxa168_eth | Marvell pxa168 | SW | N | Y | 3.1 |
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| r6040 | RDC Ethernet MAC | SW | N | Y | 3.1 |
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| smsc911x | SMSC LAN911x, LAN921x | SW | N | Y | 3.1 |
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| smsc9420 | SMSC LAN9420 PCI | SW | N | Y | 3.1 |
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| stmmac | STM Synopsys IP Core | SW | N | Y | 3.1 |
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| tg3 | Broadcom Tigon3 PCI | SW | N | Y | 3.1 |
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| ucc_geth | Freescale QE Gigabit | SW | N | Y | 3.1 |
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|--------------+--------------------------+------+-----+-----+-----|
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* Installation
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** Linux kernel
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There are many ways of getting a precompiled Linux kernel or
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compiling your own, so this section is only meant as an example. It
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is important to have the kernel headers available when compiling
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the Linux PTP stack.
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#+BEGIN_EXAMPLE
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export ARCH=x86
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export CROSS_COMPILE=
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export KBUILD_OUTPUT=/home/richard/kernel/ptp_debian
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mkdir -p $KBUILD_OUTPUT
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cp /boot/config-2.6.38-bpo.2-686 $KBUILD_OUTPUT/.config
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make oldnoconfig
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make menuconfig
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time make -j4
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make headers_install
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#+END_EXAMPLE
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Here is a table of kernel configuration options needed for PTP
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support. In addtion to these, you should enable the specific
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Ethernet MAC and PHY drivers for your hardware.
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|---------------------------------+-----------------------------|
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| Option | Description |
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|---------------------------------+-----------------------------|
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| CONFIG_EXPERIMENTAL | Required |
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| CONFIG_PPS | Required |
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| CONFIG_NETWORK_PHY_TIMESTAMPING | Timestamping in PHY devices |
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| PTP_1588_CLOCK | PTP clock support |
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|---------------------------------+-----------------------------|
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** PTP stack
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1. Just type 'make'
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2. If you compiled your own kernel (and the headers are not
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installed into the system path), then you should set the
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KBUILD_OUTPUT environment variable as in the example, above.
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3. There is no install target. You can run the program in place or
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copy it into the system path, like /usr/local/bin.
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* Getting Involved
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The software development is hosted at Source Forge.
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@ -41,7 +175,26 @@
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Please report any bugs or other issues with the software to the
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linuxptp-users mailing list.
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https://lists.sourceforge.net/lists/listinfo/linuxptp-users
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** Development
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If you would like to get involved in improving the software, please
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join the linuxptp-devel mailing list.
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https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
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* Other PTP Applications
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As of yet there are no other open source applications making use of
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the new Linux APIs for PTP. However, patches are available for the
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*ptpd* program adapting it to the new calls. These patches do not
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really turn the *ptpd* into a perfect solution for hardware time
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stamping under Linux. Instead, they merely illustrate how the newer
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APIs work.
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You can get the patches over at github. There are two branches,
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*phc1* and *phc2*, for PTP versions 1 and 2, respectively.
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- git://github.com/richardcochran/ptpd-phc.git
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- https://github.com/richardcochran/ptpd-phc
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