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author | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 12:17:53 -0700 |
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committer | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 15:44:42 -0700 |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/devicetree/bindings/common-properties.txt | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/devicetree/bindings/common-properties.txt')
-rw-r--r-- | kernel/Documentation/devicetree/bindings/common-properties.txt | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/kernel/Documentation/devicetree/bindings/common-properties.txt b/kernel/Documentation/devicetree/bindings/common-properties.txt new file mode 100644 index 000000000..3193979b1 --- /dev/null +++ b/kernel/Documentation/devicetree/bindings/common-properties.txt @@ -0,0 +1,60 @@ +Common properties + +The ePAPR specification does not define any properties related to hardware +byteswapping, but endianness issues show up frequently in porting Linux to +different machine types. This document attempts to provide a consistent +way of handling byteswapping across drivers. + +Optional properties: + - big-endian: Boolean; force big endian register accesses + unconditionally (e.g. ioread32be/iowrite32be). Use this if you + know the peripheral always needs to be accessed in BE mode. + - little-endian: Boolean; force little endian register accesses + unconditionally (e.g. readl/writel). Use this if you know the + peripheral always needs to be accessed in LE mode. + - native-endian: Boolean; always use register accesses matched to the + endianness of the kernel binary (e.g. LE vmlinux -> readl/writel, + BE vmlinux -> ioread32be/iowrite32be). In this case no byteswaps + will ever be performed. Use this if the hardware "self-adjusts" + register endianness based on the CPU's configured endianness. + +If a binding supports these properties, then the binding should also +specify the default behavior if none of these properties are present. +In such cases, little-endian is the preferred default, but it is not +a requirement. The of_device_is_big_endian() and of_fdt_is_big_endian() +helper functions do assume that little-endian is the default, because +most existing (PCI-based) drivers implicitly default to LE by using +readl/writel for MMIO accesses. + +Examples: +Scenario 1 : CPU in LE mode & device in LE mode. +dev: dev@40031000 { + compatible = "name"; + reg = <0x40031000 0x1000>; + ... + native-endian; +}; + +Scenario 2 : CPU in LE mode & device in BE mode. +dev: dev@40031000 { + compatible = "name"; + reg = <0x40031000 0x1000>; + ... + big-endian; +}; + +Scenario 3 : CPU in BE mode & device in BE mode. +dev: dev@40031000 { + compatible = "name"; + reg = <0x40031000 0x1000>; + ... + native-endian; +}; + +Scenario 4 : CPU in BE mode & device in LE mode. +dev: dev@40031000 { + compatible = "name"; + reg = <0x40031000 0x1000>; + ... + little-endian; +}; |