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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 21:06:58 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 21:06:58 (GMT) |
commit | 7ef58b32f571bffb7763c6252ad7527562081f34 (patch) | |
tree | 6d1493304ec7a47e4d9e3e84dc9f6e53547dff91 /Documentation/devicetree | |
parent | 413fd0e3fbf52873f2310eb75bfa6c7b72847277 (diff) | |
parent | c46ca3c8310b61d253a39ff1375ea97912794cd1 (diff) | |
download | linux-7ef58b32f571bffb7763c6252ad7527562081f34.tar.xz |
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')
-rw-r--r-- | Documentation/devicetree/bindings/chosen.txt | 46 | ||||
-rw-r--r-- | Documentation/devicetree/bindings/serial/pl011.txt | 28 | ||||
-rw-r--r-- | Documentation/devicetree/bindings/unittest.txt | 14 | ||||
-rw-r--r-- | Documentation/devicetree/of_selftest.txt | 20 | ||||
-rw-r--r-- | Documentation/devicetree/overlay-notes.txt | 133 | ||||
-rw-r--r-- | Documentation/devicetree/todo.txt | 1 |
6 files changed, 221 insertions, 21 deletions
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt new file mode 100644 index 0000000..ed838f4 --- /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. diff --git a/Documentation/devicetree/bindings/serial/pl011.txt b/Documentation/devicetree/bindings/serial/pl011.txt index 5d2e840..52464918 100644 --- a/Documentation/devicetree/bindings/serial/pl011.txt +++ b/Documentation/devicetree/bindings/serial/pl011.txt @@ -6,12 +6,34 @@ Required properties: - interrupts: exactly one interrupt specifier Optional properties: -- pinctrl: When present, must have one state named "sleep" - and one state named "default" -- clocks: When present, must refer to exactly one clock named +- pinctrl: When present, must have one state named "default", + and may contain a second name named "sleep". The former + state sets up pins for ordinary operation whereas + the latter state will put the associated pins to sleep + when the UART is unused +- clocks: When present, the first clock listed must correspond to + the clock named UARTCLK on the IP block, i.e. the clock + to the external serial line, whereas the second clock + must correspond to the PCLK clocking the internal logic + of the block. Just listing one clock (the first one) is + deprecated. +- clocks-names: When present, the first clock listed must be named + "uartclk" and the second clock listed must be named "apb_pclk" - dmas: When present, may have one or two dma channels. The first one must be named "rx", the second one must be named "tx". See also bindings/arm/primecell.txt + +Example: + +uart@80120000 { + compatible = "arm,pl011", "arm,primecell"; + reg = <0x80120000 0x1000>; + interrupts = <0 11 IRQ_TYPE_LEVEL_HIGH>; + dmas = <&dma 13 0 0x2>, <&dma 13 0 0x0>; + dma-names = "rx", "tx"; + clocks = <&foo_clk>, <&bar_clk>; + clock-names = "uartclk", "apb_pclk"; +}; diff --git a/Documentation/devicetree/bindings/unittest.txt b/Documentation/devicetree/bindings/unittest.txt new file mode 100644 index 0000000..0f92a22 --- /dev/null +++ b/Documentation/devicetree/bindings/unittest.txt @@ -0,0 +1,14 @@ +* OF selftest platform device + +** selftest + +Required properties: +- compatible: must be "selftest" + +All other properties are optional. + +Example: + selftest { + compatible = "selftest"; + status = "okay"; + }; diff --git a/Documentation/devicetree/of_selftest.txt b/Documentation/devicetree/of_selftest.txt index 1e3d5c9..57a808b 100644 --- a/Documentation/devicetree/of_selftest.txt +++ b/Documentation/devicetree/of_selftest.txt @@ -63,7 +63,6 @@ struct device_node { struct device_node *parent; struct device_node *child; struct device_node *sibling; - struct device_node *allnext; /* next in list of all nodes */ ... }; @@ -99,12 +98,6 @@ child11 -> sibling12 -> sibling13 -> sibling14 -> null Figure 1: Generic structure of un-flattened device tree -*allnext: it is used to link all the nodes of DT into a list. So, for the - above tree the list would be as follows: - -root->child1->child11->sibling12->sibling13->child131->sibling14->sibling2-> -child21->sibling22->sibling23->sibling3->child31->sibling32->sibling4->null - Before executing OF selftest, it is required to attach the test data to machine's device tree (if present). So, when selftest_data_add() is called, at first it reads the flattened device tree data linked into the kernel image @@ -131,11 +124,6 @@ root ('/') test-child01 null null null -allnext list: - -root->testcase-data->test-child0->test-child01->test-sibling1->test-sibling2 -->test-sibling3->null - Figure 2: Example test data tree to be attached to live tree. According to the scenario above, the live tree is already present so it isn't @@ -204,8 +192,6 @@ detached and then moving up the parent nodes are removed, and eventually the whole tree). selftest_data_remove() calls detach_node_and_children() that uses of_detach_node() to detach the nodes from the live device tree. -To detach a node, of_detach_node() first updates all_next linked list, by -attaching the previous node's allnext to current node's allnext pointer. And -then, it either updates the child pointer of given node's parent to its -sibling or attaches the previous sibling to the given node's sibling, as -appropriate. That is it :) +To detach a node, of_detach_node() either updates the child pointer of given +node's parent to its sibling or attaches the previous sibling to the given +node's sibling, as appropriate. That is it :) diff --git a/Documentation/devicetree/overlay-notes.txt b/Documentation/devicetree/overlay-notes.txt new file mode 100644 index 0000000..30ae758 --- /dev/null +++ b/Documentation/devicetree/overlay-notes.txt @@ -0,0 +1,133 @@ +Device Tree Overlay Notes +------------------------- + +This document describes the implementation of the in-kernel +device tree overlay functionality residing in drivers/of/overlay.c and is a +companion document to Documentation/devicetree/dt-object-internal.txt[1] & +Documentation/devicetree/dynamic-resolution-notes.txt[2] + +How overlays work +----------------- + +A Device Tree's overlay purpose is to modify the kernel's live tree, and +have the modification affecting the state of the the kernel in a way that +is reflecting the changes. +Since the kernel mainly deals with devices, any new device node that result +in an active device should have it created while if the device node is either +disabled or removed all together, the affected device should be deregistered. + +Lets take an example where we have a foo board with the following base tree +which is taken from [1]. + +---- foo.dts ----------------------------------------------------------------- + /* FOO platform */ + / { + compatible = "corp,foo"; + + /* shared resources */ + res: res { + }; + + /* On chip peripherals */ + ocp: ocp { + /* peripherals that are always instantiated */ + peripheral1 { ... }; + } + }; +---- foo.dts ----------------------------------------------------------------- + +The overlay bar.dts, when loaded (and resolved as described in [2]) should + +---- bar.dts ----------------------------------------------------------------- +/plugin/; /* allow undefined label references and record them */ +/ { + .... /* various properties for loader use; i.e. part id etc. */ + fragment@0 { + target = <&ocp>; + __overlay__ { + /* bar peripheral */ + bar { + compatible = "corp,bar"; + ... /* various properties and child nodes */ + } + }; + }; +}; +---- bar.dts ----------------------------------------------------------------- + +result in foo+bar.dts + +---- foo+bar.dts ------------------------------------------------------------- + /* FOO platform + bar peripheral */ + / { + compatible = "corp,foo"; + + /* shared resources */ + res: res { + }; + + /* On chip peripherals */ + ocp: ocp { + /* peripherals that are always instantiated */ + peripheral1 { ... }; + + /* bar peripheral */ + bar { + compatible = "corp,bar"; + ... /* various properties and child nodes */ + } + } + }; +---- foo+bar.dts ------------------------------------------------------------- + +As a result of the the overlay, a new device node (bar) has been created +so a bar platform device will be registered and if a matching device driver +is loaded the device will be created as expected. + +Overlay in-kernel API +-------------------------------- + +The API is quite easy to use. + +1. Call of_overlay_create() to create and apply an overlay. The return value +is a cookie identifying this overlay. + +2. Call of_overlay_destroy() to remove and cleanup the overlay previously +created via the call to of_overlay_create(). Removal of an overlay that +is stacked by another will not be permitted. + +Finally, if you need to remove all overlays in one-go, just call +of_overlay_destroy_all() which will remove every single one in the correct +order. + +Overlay DTS Format +------------------ + +The DTS of an overlay should have the following format: + +{ + /* ignored properties by the overlay */ + + fragment@0 { /* first child node */ + + target=<phandle>; /* phandle target of the overlay */ + or + target-path="/path"; /* target path of the overlay */ + + __overlay__ { + property-a; /* add property-a to the target */ + node-a { /* add to an existing, or create a node-a */ + ... + }; + }; + } + fragment@1 { /* second child node */ + ... + }; + /* more fragments follow */ +} + +Using the non-phandle based target method allows one to use a base DT which does +not contain a __symbols__ node, i.e. it was not compiled with the -@ option. +The __symbols__ node is only required for the target=<phandle> method, since it +contains the information required to map from a phandle to a tree location. diff --git a/Documentation/devicetree/todo.txt b/Documentation/devicetree/todo.txt index c3cf065..b5139d1 100644 --- a/Documentation/devicetree/todo.txt +++ b/Documentation/devicetree/todo.txt @@ -2,7 +2,6 @@ Todo list for devicetree: === General structure === - Switch from custom lists to (h)list_head for nodes and properties structure -- Remove of_allnodes list and iterate using list of child nodes alone === CONFIG_OF_DYNAMIC === - Switch to RCU for tree updates and get rid of global spinlock |