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authorLinus Torvalds <torvalds@linux-foundation.org>2015-09-09 01:16:26 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-09 01:16:26 +0200
commitacceba598eda9817bc187f3a683a2d2ee7e7fbc7 (patch)
tree761b3950789d5eee179b75ecdafafc988ee42a46 /Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
parentMerge tag 'rtc-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/abellon... (diff)
parenti2c: mux: reg Change ioread endianness for readback (diff)
downloadlinux-acceba598eda9817bc187f3a683a2d2ee7e7fbc7.tar.xz
linux-acceba598eda9817bc187f3a683a2d2ee7e7fbc7.zip
Merge branch 'i2c/for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c updates from Wolfram Sang: "Features: - new drivers: Renesas EMEV2, register based MUX, NXP LPC2xxx - core: scans DT and assigns wakeup interrupts. no driver changes needed. - core: some refcouting issues fixed and better API for that - core: new helper function for best effort block read emulation - slave framework: proper DT bindings and userspace instantiation - some bigger work for xiic, pxa, omap drivers .. and quite a number of smaller driver fixes, cleanups, improvements" * 'i2c/for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (65 commits) i2c: mux: reg Change ioread endianness for readback i2c: mux: reg: fix compilation warnings i2c: mux: reg: simplify register size checking i2c: muxes: fix leaked i2c adapter device node references i2c: allow specifying separate wakeup interrupt in device tree of/irq: export of_get_irq_byname() i2c: xgene-slimpro: dma_mapping_error() doesn't return an error code i2c: Replace I2C_CROS_EC_TUNNEL dependency eeprom: at24: use i2c_smbus_read_i2c_block_data_or_emulated i2c: core: Add support for best effort block read emulation i2c: lpc2k: add driver i2c: mux: Add register-based mux i2c-mux-reg i2c: dt: describe generic bindings i2c: slave: print warning if slave flag not set i2c: support 10 bit and slave addresses in sysfs 'new_device' i2c: take address space into account when checking for used addresses i2c: apply DT flags when probing i2c: make address check indpendent from client struct i2c: rename address check functions i2c: apply address offset for slaves, too ...
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+Register-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses a single register
+to route the I2C signals.
+
+Required properties:
+- compatible: i2c-mux-reg
+- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
+ port is connected to.
+* Standard I2C mux properties. See mux.txt in this directory.
+* I2C child bus nodes. See mux.txt in this directory.
+
+Optional properties:
+- reg: this pair of <offset size> specifies the register to control the mux.
+ The <offset size> depends on its parent node. It can be any memory-mapped
+ address. The size must be either 1, 2, or 4 bytes. If reg is omitted, the
+ resource of this device will be used.
+- little-endian: The existence indicates the register is in little endian.
+- big-endian: The existence indicates the register is in big endian.
+ If both little-endian and big-endian are omitted, the endianness of the
+ CPU will be used.
+- write-only: The existence indicates the register is write-only.
+- idle-state: value to set the muxer to when idle. When no value is
+ given, it defaults to the last value used.
+
+Whenever an access is made to a device on a child bus, the value set
+in the revelant node's reg property will be output to the register.
+
+If an idle state is defined, using the idle-state (optional) property,
+whenever an access is not being made to a device on a child bus, the
+register will be set according to the idle value.
+
+If an idle state is not defined, the most recently used value will be
+left programmed into the register.
+
+Example of a mux on PCIe card, the host is a powerpc SoC (big endian):
+
+ i2c-mux {
+ /* the <offset size> depends on the address translation
+ * of the parent device. If omitted, device resource
+ * will be used instead. The size is to determine
+ * whether iowrite32, iowrite16, or iowrite8 will be used.
+ */
+ reg = <0x6028 0x4>;
+ little-endian; /* little endian register on PCIe */
+ compatible = "i2c-mux-reg";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ i2c-parent = <&i2c1>;
+ i2c@0 {
+ reg = <0>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ si5338: clock-generator@70 {
+ compatible = "silabs,si5338";
+ reg = <0x70>;
+ /* other stuff */
+ };
+ };
+
+ i2c@1 {
+ /* data is written using iowrite32 */
+ reg = <1>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ si5338: clock-generator@70 {
+ compatible = "silabs,si5338";
+ reg = <0x70>;
+ /* other stuff */
+ };
+ };
+ };