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authorLinus Torvalds <torvalds@linux-foundation.org>2016-05-13 09:40:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-13 09:40:32 -0700
commitc42b8fe941e361bb05de23a11c04d5a4adc61cc8 (patch)
tree37cf872fceb1760532b5c24f7aefed0e9a850a72 /Documentation
parent90fa7c7fa38730f918c950ecf05120f223718b89 (diff)
parent2a2cd5219023ea2e485c3e37486c24177a6da55a (diff)
downloadleg-kernel-c42b8fe941e361bb05de23a11c04d5a4adc61cc8.tar.gz
Merge tag 'regmap-fix-v4.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap
Pull regmap fixes from Mark Brown: "This is rather too late so it'd be completely understandable if you don't want to pull it at this point, I had thought I'd sent this earlier but it seems I didn't. Everything has been in -next for some time now. The main set of fixes here are mopping up some more issues with MMIO, fixing handling of endianness configuration in DT (which just wasn't working at all) and cases where the register and value endianness are different. There is also a fix for bulk register reads on SPMI" * tag 'regmap-fix-v4.6-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap: regmap: spmi: Fix regmap_spmi_ext_read in multi-byte case regmap: mmio: Explicitly say little endian is the defualt in the bus config regmap: mmio: Parse endianness definitions from DT regmap: Fix implicit inclusion of device.h regmap: mmio: Fix value endianness selection regmap: fix documentation to match code
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/regmap/regmap.txt59
1 files changed, 19 insertions, 40 deletions
diff --git a/Documentation/devicetree/bindings/regmap/regmap.txt b/Documentation/devicetree/bindings/regmap/regmap.txt
index e98a9652ccc8..0127be360fe8 100644
--- a/Documentation/devicetree/bindings/regmap/regmap.txt
+++ b/Documentation/devicetree/bindings/regmap/regmap.txt
@@ -1,50 +1,29 @@
-Device-Tree binding for regmap
-
-The endianness mode of CPU & Device scenarios:
-Index Device Endianness properties
----------------------------------------------------
-1 BE 'big-endian'
-2 LE 'little-endian'
-3 Native 'native-endian'
-
-For one device driver, which will run in different scenarios above
-on different SoCs using the devicetree, we need one way to simplify
-this.
+Devicetree binding for regmap
Optional properties:
-- {big,little,native}-endian: these are boolean properties, if absent
- then the implementation will choose a default based on the device
- being controlled. These properties are for register values and all
- the buffers only. Native endian means that the CPU and device have
- the same endianness.
-Examples:
-Scenario 1 : CPU in LE mode & device in LE mode.
-dev: dev@40031000 {
- compatible = "name";
- reg = <0x40031000 0x1000>;
- ...
-};
+ little-endian,
+ big-endian,
+ native-endian: See common-properties.txt for a definition
-Scenario 2 : CPU in LE mode & device in BE mode.
-dev: dev@40031000 {
- compatible = "name";
- reg = <0x40031000 0x1000>;
- ...
- big-endian;
-};
+Note:
+Regmap defaults to little-endian register access on MMIO based
+devices, this is by far the most common setting. On CPU
+architectures that typically run big-endian operating systems
+(e.g. PowerPC), registers can be defined as big-endian and must
+be marked that way in the devicetree.
-Scenario 3 : CPU in BE mode & device in BE mode.
-dev: dev@40031000 {
- compatible = "name";
- reg = <0x40031000 0x1000>;
- ...
-};
+On SoCs that can be operated in both big-endian and little-endian
+modes, with a single hardware switch controlling both the endianess
+of the CPU and a byteswap for MMIO registers (e.g. many Broadcom MIPS
+chips), "native-endian" is used to allow using the same device tree
+blob in both cases.
-Scenario 4 : CPU in BE mode & device in LE mode.
+Examples:
+Scenario 1 : a register set in big-endian mode.
dev: dev@40031000 {
- compatible = "name";
+ compatible = "syscon";
reg = <0x40031000 0x1000>;
+ big-endian;
...
- little-endian;
};