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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 22:06:58 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 22:06:58 +0100 |
commit | 7ef58b32f571bffb7763c6252ad7527562081f34 (patch) | |
tree | 6d1493304ec7a47e4d9e3e84dc9f6e53547dff91 /Documentation/devicetree/bindings/chosen.txt | |
parent | Merge tag 'fbdev-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tomba... (diff) | |
parent | of: Delete unnecessary check before calling "of_node_put()" (diff) | |
download | linux-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.txt | 46 |
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. |