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authorLinus Torvalds <torvalds@linux-foundation.org>2015-11-10 11:58:25 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-10 11:58:25 -0800
commitd55fc37856244c929965c190c8e9dcb49e2c07aa (patch)
treeccb348340a6f0aac546b06487ea6a1d1d35490f6 /Documentation/acpi/i2c-muxes.txt
parent42d4ebb42a17754d2e8344dc1aa486119671d0eb (diff)
parent75ecc64ef5a1f310fc80f732ad8cfb7e1bdc59d5 (diff)
Merge branch 'i2c/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c updates from Wolfram Sang: - New drivers: UniPhier (with and without FIFO) - some drivers got some bigger rework: ismt, designware, img-scb (rcar had to be reverted because issues were showing up just lately) - ACPI: reworked the device scanning and added support for muxes ... and quite a lot of driver bugfixes and cleanups this time. All files touched outside of the i2c realm have proper acks. * 'i2c/for-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (70 commits) i2c: rcar: Revert the latest refactoring series i2c: pnx: remove superfluous assignment MAINTAINERS: i2c: drop i2c-pnx maintainer MAINTAINERS: i2c: mark also subdirectories as maintained i2c: cadence: enable driver for ARM64 i2c: i801: Document Intel DNV and Broxton i2c: at91: manage unexpected RXRDY flag when starting a transfer i2c: pnx: Use setup_timer instead of open coding it i2c: add ACPI support for I2C mux ports acpi: add acpi_preset_companion() stub i2c: pxa: Add support for pxa910/988 & new configuration features i2c: au1550: Convert to devm_kzalloc and devm_ioremap_resource i2c-dev: Fix I2C_SLAVE ioctl comment i2c-dev: Fix typo in ioctl name reference i2c: sirf: tune the divider to make i2c bus freq more accurate i2c: imx: Use -ENXIO as error in the NACK case i2c: i801: Add support for Intel Broxton i2c: i801: Add support for Intel DNV i2c: mediatek: add i2c resume support i2c: imx: implement bus recovery ...
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+ACPI I2C Muxes
+--------------
+
+Describing an I2C device hierarchy that includes I2C muxes requires an ACPI
+Device () scope per mux channel.
+
+Consider this topology:
+
++------+ +------+
+| SMB1 |-->| MUX0 |--CH00--> i2c client A (0x50)
+| | | 0x70 |--CH01--> i2c client B (0x50)
++------+ +------+
+
+which corresponds to the following ASL:
+
+Device (SMB1)
+{
+ Name (_HID, ...)
+ Device (MUX0)
+ {
+ Name (_HID, ...)
+ Name (_CRS, ResourceTemplate () {
+ I2cSerialBus (0x70, ControllerInitiated, I2C_SPEED,
+ AddressingMode7Bit, "^SMB1", 0x00,
+ ResourceConsumer,,)
+ }
+
+ Device (CH00)
+ {
+ Name (_ADR, 0)
+
+ Device (CLIA)
+ {
+ Name (_HID, ...)
+ Name (_CRS, ResourceTemplate () {
+ I2cSerialBus (0x50, ControllerInitiated, I2C_SPEED,
+ AddressingMode7Bit, "^CH00", 0x00,
+ ResourceConsumer,,)
+ }
+ }
+ }
+
+ Device (CH01)
+ {
+ Name (_ADR, 1)
+
+ Device (CLIB)
+ {
+ Name (_HID, ...)
+ Name (_CRS, ResourceTemplate () {
+ I2cSerialBus (0x50, ControllerInitiated, I2C_SPEED,
+ AddressingMode7Bit, "^CH01", 0x00,
+ ResourceConsumer,,)
+ }
+ }
+ }
+ }
+}