summaryrefslogtreecommitdiffstats
path: root/Documentation/devicetree/bindings/chosen.txt
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-11 22:06:58 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-11 22:06:58 +0100
commit7ef58b32f571bffb7763c6252ad7527562081f34 (patch)
tree6d1493304ec7a47e4d9e3e84dc9f6e53547dff91 /Documentation/devicetree/bindings/chosen.txt
parentMerge tag 'fbdev-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tomba... (diff)
parentof: Delete unnecessary check before calling "of_node_put()" (diff)
downloadlinux-7ef58b32f571bffb7763c6252ad7527562081f34.tar.xz
linux-7ef58b32f571bffb7763c6252ad7527562081f34.zip
Merge tag 'devicetree-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux
Pull devicetree changes from Grant Likely: "Lots of activity in the devicetree code for v3.18. Most of it is related to getting all of the overlay support code in place, but there are other important things in there. Highlights: - OF_RECONFIG notifiers for SPI, I2C and Platform devices. Those subsystems can now respond to live changes to the device tree. - CONFIG_OF_OVERLAY method for applying live changes to the device tree - Removal of the of_allnodes list. This used to be used to iterate over all the nodes in the device tree, but it is unnecessary because the same thing can be done by iterating over the list of child pointers. Getting rid of of_allnodes saves some memory and avoids the possibility of of_allnodes being sorted differently from the child lists. - Support for retrieving original DTB blob via sysfs. Needed by kexec. - More unittests - Documentation and minor bug fixes" * tag 'devicetree-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux: (42 commits) of: Delete unnecessary check before calling "of_node_put()" of: Drop ->next pointer from struct device_node spi: Check for spi_of_notifier when CONFIG_OF_DYNAMIC=y of: support passing console options with stdout-path of: add optional options parameter to of_find_node_by_path() of: Add bindings for chosen node, stdout-path of: Remove unneeded and incorrect MODULE_DEVICE_TABLE ARM: dt: fix up PL011 device tree bindings of: base, fix of_property_read_string_helper kernel-doc of: remove select of non-existant OF_DEVICE config symbol spi/of: Add OF notifier handler spi/of: Create new device registration method and accessors i2c/of: Add OF_RECONFIG notifier handler i2c/of: Factor out Devicetree registration code of/overlay: Add overlay unittests of/overlay: Introduce DT overlay support of/reconfig: Add OF_DYNAMIC notifier for platform_bus_type of/reconfig: Always use the same structure for notifiers of/reconfig: Add debug output for OF_RECONFIG notifiers of/reconfig: Add empty stubs for the of_reconfig methods ...
Diffstat (limited to 'Documentation/devicetree/bindings/chosen.txt')
-rw-r--r--Documentation/devicetree/bindings/chosen.txt46
1 files changed, 46 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
new file mode 100644
index 000000000000..ed838f453f7a
--- /dev/null
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -0,0 +1,46 @@
+The chosen node
+---------------
+
+The chosen node does not represent a real device, but serves as a place
+for passing data between firmware and the operating system, like boot
+arguments. Data in the chosen node does not represent the hardware.
+
+
+stdout-path property
+--------------------
+
+Device trees may specify the device to be used for boot console output
+with a stdout-path property under /chosen, as described in ePAPR, e.g.
+
+/ {
+ chosen {
+ stdout-path = "/serial@f00:115200";
+ };
+
+ serial@f00 {
+ compatible = "vendor,some-uart";
+ reg = <0xf00 0x10>;
+ };
+};
+
+If the character ":" is present in the value, this terminates the path.
+The meaning of any characters following the ":" is device-specific, and
+must be specified in the relevant binding documentation.
+
+For UART devices, the preferred binding is a string in the form:
+
+ <baud>{<parity>{<bits>{<flow>}}}
+
+where
+
+ baud - baud rate in decimal
+ parity - 'n' (none), 'o', (odd) or 'e' (even)
+ bits - number of data bits
+ flow - 'r' (rts)
+
+For example: 115200n8r
+
+Implementation note: Linux will look for the property "linux,stdout-path" or
+on PowerPC "stdout" if "stdout-path" is not found. However, the
+"linux,stdout-path" and "stdout" properties are deprecated. New platforms
+should only use the "stdout-path" property.