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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (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>
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+Device tree configuration for i2c-ocores
+
+Required properties:
+- compatible : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
+- reg : bus address start and address range size of device
+- interrupts : interrupt number
+- clocks : handle to the controller clock; see the note below.
+ Mutually exclusive with opencores,ip-clock-frequency
+- opencores,ip-clock-frequency: frequency of the controller clock in Hz;
+ see the note below. Mutually exclusive with clocks
+- #address-cells : should be <1>
+- #size-cells : should be <0>
+
+Optional properties:
+- clock-frequency : frequency of bus clock in Hz; see the note below.
+ Defaults to 100 KHz when the property is not specified
+- reg-shift : device register offsets are shifted by this value
+- reg-io-width : io register width in bytes (1, 2 or 4)
+- regstep : deprecated, use reg-shift above
+
+Note
+clock-frequency property is meant to control the bus frequency for i2c bus
+drivers, but it was incorrectly used to specify i2c controller input clock
+frequency. So the following rules are set to fix this situation:
+- if clock-frequency is present and neither opencores,ip-clock-frequency nor
+ clocks are, then clock-frequency specifies i2c controller clock frequency.
+ This is to keep backwards compatibility with setups using old DTB. i2c bus
+ frequency is fixed at 100 KHz.
+- if clocks is present it specifies i2c controller clock. clock-frequency
+ property specifies i2c bus frequency.
+- if opencores,ip-clock-frequency is present it specifies i2c controller
+ clock frequency. clock-frequency property specifies i2c bus frequency.
+
+Examples:
+
+ i2c0: ocores@a0000000 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ compatible = "opencores,i2c-ocores";
+ reg = <0xa0000000 0x8>;
+ interrupts = <10>;
+ opencores,ip-clock-frequency = <20000000>;
+
+ reg-shift = <0>; /* 8 bit registers */
+ reg-io-width = <1>; /* 8 bit read/write */
+
+ dummy@60 {
+ compatible = "dummy";
+ reg = <0x60>;
+ };
+ };
+or
+ i2c0: ocores@a0000000 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ compatible = "opencores,i2c-ocores";
+ reg = <0xa0000000 0x8>;
+ interrupts = <10>;
+ clocks = <&osc>;
+ clock-frequency = <400000>; /* i2c bus frequency 400 KHz */
+
+ reg-shift = <0>; /* 8 bit registers */
+ reg-io-width = <1>; /* 8 bit read/write */
+
+ dummy@60 {
+ compatible = "dummy";
+ reg = <0x60>;
+ };
+ };