eLinux.org - Changes related to "BeagleBone" [en]

Capemgr

2013-05-20T16:38:29Z

Capemgr page. Take from Capebus which I made a minute ago, but was told was the wrong name.

New page

[[Category: Linux]]
[[Category: BeagleBoard]]
[[Category: BeagleBone]]
[[Category: Kernel]]

This page contains information on Capemgr, an in-kernel mechanism for dynamically loading [[Device_Trees|Device Tree]] fragments from userspace.

<br>

= About =

Capemgr was created out of a need for boards like the [[BeagleBone|BeagleBone]] to be able to detect installed expansion boards at boot time and allocate appropriate resources (load drivers, allocate GPIO, reserve bus addresses, etc) on kernels which use Device Tree. Traditionally, a Device Tree was a static file (or set of files) which described a machine (often an Embedded SoC and the board it's installed on). This of course is not able to support dynamically changing hardware, such as the BeagleBone and its add-on capes.

Further, it is one of the goals of the BeagleBone to allow 3rd parties to create their own capes and to allow users to install and use these capes without re-compiling the kernel.

A key feature of Capemgr is the ability to load Device Tree fragments as overlays to the existing Device Tree at runtime. On the BeagleBone, each cape has a Device Tree fragment which describes it.

= Implementation =

Capemgr is completely implemented in the kernel. There is no userspace component. Since the BeagleBone uses a kernel which is ahead of mainline, the Capemgr implementation is currently located in the BeagleBone kernel patch set at https://github.com/beagleboard/kernel/tree/3.8 .

In the BeagleBone kernel, cape Device Tree fragments are located in <code>firmware/capes</code>. Each cape is represented by a single DTS (Device Tree Source) fragment file. At kernel build time, these fragments are compiled by the Device Tree Compiler into dtbo files (Device Tree Blob Object). At install time, these dtbo objects are copied to <code>/lib/firmware</code>.

Each BeagleBone capes has an EEPROM on SPI bus 0 which contains information about the cape. The format of the data in the EEPROM is described in the System Reference Manual (SRM) [http://circuitco.com/support/index.php Available from CircuitCo]. The Board Name EEPROM field is used by Capemgr to determine which cape fragment to load. There are two ways this board name can be used. The first method is that the Board Name can be mapped in the BeagleBone's main Device Tree Source file (<code>arch/arm/boot/dts/am335x-bone-common.dtsi</code>) to a filename using a structure like the following:

/* mrf24j40 cape */
cape@10 {
part-number = "BB-BONE-MRF24J40";
version@00A0 {
version = "00A0";
dtbo = "cape-bone-mrf24j40-00A0.dtbo";
};
};

The above DT snippet maps the device named BB-BONE-MRF24J40 version 00A0 to the file <code>/lib/firmware/cape-bone-mrf24j40-00A0.dtbo</code>

Alternatively, if there is no mapping the the main DTS file, the Capemgr loader will attempt to load a filename which matches the Board Name and Version fields in the EEPROM. For example, for a board named BB-BONE-LCD7-01 with version 00A2, the Capemgr loader will try to load <code>/lib/firmware/BB-BONE-LCD7-01-00A2.dtbo</code> . This way capes can be added to a system without modifying the BeagleBone's main Device Tree (<code>arch/arm/boot/dts/am335x-bone-common.dtsi</code>).

== Loading a Fragment at Runtime ==

Capemgr provides a sysfs interface to load Device Tree fragments at runtime. <code>/sys/devices/bone_capemgr*/</code>contains information and controls for the Capemgr system. To manually load a DTBO fragment, one can run:

echo BB-BONE-MRF24J40 >/sys/devices/bone_capemgr.7/slots

The above command will cause Capemgr to act as though a device with a Board Name of BB-BONE-MRF24J40 was detected. It will then check if there is a mapping in <code>arch/arm/boot/dts/am335x-bone-common.dtsi</code> and load the appropriate dtbo file from <code>/lib/firmware</code>. If not, it will attempt to load <code>/lib/firmware/BB-BONE-MRF24J40-00A0.dtbo</code> as described in the above section.

One can also specify a version number on the command line:

echo BB-BONE-MRF24J40:00A1 >/sys/devices/bone_capemgr.7/slots

This will attempt to load revision 00A1, first using the mapping in <code>arch/arm/boot/dts/am335x-bone-common.dtsi</code>, and then trying to load <code>/lib/firmware/BB-BONE-MRF24J40-00A1.dtbo</code>.

== Compiling a DTS Fragment Outside the kernel build ==

On a BeagleBone, with the default Angstrom image, use the <code>dtc</code> compiler located at <code>/usr/bin/dtc</code> to compile Device Tree sources into DTBO Device Tree objects without modifying any kernel source. The resulting dtbo can be manually copied into <code>/lib/firmware</code>.

BeagleBoardUbuntu

2013-05-20T15:27:33Z

wording...

BeagleBoardDebian

2013-05-20T15:26:53Z

‎Debian Wheezy snapshot: debian-7.0.0-console-armhf-2013-05-18

BeagleBoardUbuntu

2013-05-20T15:25:05Z

‎Quantal 12.10 armhf: ubuntu-12.10-console-armhf-2013-05-18

@@ Line 104: / Line 104: @@
 Services Active:
   Note: Depending on your internal network these may work out the box
-  Apache, Port 80: http://arm/ (Bone: or via usb) http://192.168.7.2
+  Apache, Port 80: http://arm/ (Bone: via usb) http://192.168.7.2
-  SSH, Port 22: ssh ubuntu@arm (Bone: or via usb) ubuntu@192.168.7.2
+  SSH, Port 22: ssh ubuntu@arm (Bone: via usb) ubuntu@192.168.7.2
-  shellinabox, Port 4200: https://arm:4200/ (Bone: or via usb) https://192.168.7.2:4200
+  shellinabox, Port 4200: https://arm:4200/ (Bone: via usb) https://192.168.7.2:4200
   Getty, Serial Port

@@ Line 73: / Line 73: @@
 Image Updated:
 *2013-04-26
 ** Beagle/Panda/Panda ES: v3.7.10-x10 kernel
@@ Line 80: / Line 84: @@
 ** Beagle/Panda/Panda ES: v3.7.10-x10 kernel
 ** Bone: v3.2.33-psp26 kernel (--uboot bone_dtb = v3.8.4-bone9)
 Services Active:
   Note: Depending on your internal network these may work out the box
-  Apache, Port 80: http://arm/
+  Apache, Port 80: http://arm/ (Bone: via usb) http://192.168.7.2
-  SSH, Port 22: ssh ubuntu@arm
+  SSH, Port 22: ssh ubuntu@arm (Bone: via usb) ubuntu@192.168.7.2
   Getty, Serial Port
 Get prebuilt image:
-  wget http://rcn-ee.net/deb/rootfs/wheezy/debian-wheezy-console-armhf-2013-04-26.tar.xz
+  wget http://rcn-ee.net/deb/rootfs/wheezy/debian-7.0.0-console-armhf-2013-05-18.tar.xz
 Verify Image with:
-  md5sum debian-wheezy-console-armhf-2013-04-26.tar.xz
+  md5sum debian-7.0.0-console-armhf-2013-05-18.tar.xz
-a1c4ff53f3b2a42419ee1c7c1f47e40  debian-wheezy-console-armhf-2013-04-26.tar.xz
+  dfe308e3e534d8adef75db5308174cf6  debian-7.0.0-console-armhf-2013-05-18.tar.xz
 Unpack Image:
-  tar xJf debian-wheezy-console-armhf-2013-04-26.tar.xz
+  tar xJf debian-7.0.0-console-armhf-2013-05-18.tar.xz
-  cd debian-wheezy-console-armhf-2013-04-26
+  cd debian-7.0.0-console-armhf-2013-05-18
 Install Image:

@@ Line 90: / Line 90: @@
 === Raring 13.04 armhf ===
 Image Updated:
 *2013-04-26
 ** Beagle/Panda/Panda ES: v3.7.10-x10 kernel
@@ Line 97: / Line 101: @@
 ** Beagle/Panda/Panda ES: v3.7.10-x10 kernel
 ** Bone: v3.2.33-psp26 kernel (--uboot bone_dtb = v3.8.4-bone9)
 Services Active:
   Note: Depending on your internal network these may work out the box
-  Apache, Port 80: http://arm/
+  Apache, Port 80: http://arm/ (Bone: or via usb) http://192.168.7.2
-  SSH, Port 22: ssh ubuntu@arm
+  SSH, Port 22: ssh ubuntu@arm (Bone: or via usb) ubuntu@192.168.7.2
   Getty, Serial Port
@@ Line 111: / Line 113: @@
 Get prebuilt image:
-  wget http://rcn-ee.net/deb/rootfs/raring/ubuntu-13.04-console-armhf-2013-04-26.tar.xz
+  wget http://rcn-ee.net/deb/rootfs/raring/ubuntu-13.04-console-armhf-2013-05-18.tar.xz
   mirrors (will take some time to update):
-  wget http://ynezz.ibawizard.net/beagleboard/raring/ubuntu-13.04-console-armhf-2013-04-26.tar.xz
+  wget http://ynezz.ibawizard.net/beagleboard/raring/ubuntu-13.04-console-armhf-2013-05-18.tar.xz
 Verify image with:
-  md5sum ubuntu-13.04-console-armhf-2013-04-26.tar.xz
+  md5sum ubuntu-13.04-console-armhf-2013-05-18.tar.xz
-  e54b8693cb92b40d694e5885e4a1b86c  ubuntu-13.04-console-armhf-2013-04-26.tar.xz
+c791b69ee4c6ddfd1ce4c9049ecf23e  ubuntu-13.04-console-armhf-2013-05-18.tar.xz
 Unpack image:
-  tar xJf ubuntu-13.04-console-armhf-2013-04-26.tar.xz
+  tar xJf ubuntu-13.04-console-armhf-2013-05-18.tar.xz
-  cd ubuntu-13.04-console-armhf-2013-04-26
+  cd ubuntu-13.04-console-armhf-2013-05-18
 If you don't know the location of your SD card:
@@ Line 202: / Line 204: @@
   git clone git://github.com/RobertCNelson/omap-image-builder.git
   cd omap-image-builder
-  git checkout v2013.04 -b v2013.04
+  git checkout v2013.05 -b v2013.05
   touch release
   ./build_image.sh
@@ Line 209: / Line 211: @@
 Image Updated:
 *2013-04-26
 ** Beagle/Panda/Panda ES: v3.7.10-x10 kernel
@@ Line 216: / Line 222: @@
 ** Beagle/Panda/Panda ES: v3.7.10-x10 kernel
 ** Bone: v3.2.33-psp26 kernel (--uboot bone_dtb = v3.8.4-bone9)
 Get prebuilt image:
-  wget http://rcn-ee.net/deb/rootfs/quantal/ubuntu-12.10-console-armhf-2013-04-26.tar.xz
+  wget http://rcn-ee.net/deb/rootfs/quantal/ubuntu-12.10-console-armhf-2013-05-18.tar.xz
 Verify image with:
-  md5sum ubuntu-12.10-console-armhf-2013-04-26.tar.xz
+  md5sum ubuntu-12.10-console-armhf-2013-05-18.tar.xz
-  b7cd2f94c0dbc75f8d6897e559d52c0a  ubuntu-12.10-console-armhf-2013-04-26.tar.xz
+  feb3e41208dba6ec1593ac0b910cff3d  ubuntu-12.10-console-armhf-2013-05-18.tar.xz
 Unpack image:
-  tar xJf ubuntu-12.10-console-armhf-2013-04-26.tar.xz
+  tar xJf ubuntu-12.10-console-armhf-2013-05-18.tar.xz
-  cd ubuntu-12.10-console-armhf-2013-04-26
+  cd ubuntu-12.10-console-armhf-2013-05-18
 Then follow directions show above with the other images...