1Generic device tree bindings for I2C busses 2=========================================== 3 4This document describes generic bindings which can be used to describe I2C 5busses in a device tree. 6 7Required properties 8------------------- 9 10- #address-cells - should be <1>. Read more about addresses below. 11- #size-cells - should be <0>. 12- compatible - name of I2C bus controller following generic names 13 recommended practice. 14 15For other required properties e.g. to describe register sets, 16clocks, etc. check the binding documentation of the specific driver. 17 18The cells properties above define that an address of children of an I2C bus 19are described by a single value. This is usually a 7 bit address. However, 20flags can be attached to the address. I2C_TEN_BIT_ADDRESS is used to mark a 10 21bit address. It is needed to avoid the ambiguity between e.g. a 7 bit address 22of 0x50 and a 10 bit address of 0x050 which, in theory, can be on the same bus. 23Another flag is I2C_OWN_SLAVE_ADDRESS to mark addresses on which we listen to 24be devices ourselves. 25 26Optional properties 27------------------- 28 29These properties may not be supported by all drivers. However, if a driver 30wants to support one of the below features, it should adapt the bindings below. 31 32- clock-frequency - frequency of bus clock in Hz. 33- wakeup-source - device can be used as a wakeup source. 34 35- interrupts - interrupts used by the device. 36- interrupt-names - "irq" and "wakeup" names are recognized by I2C core, 37 other names are left to individual drivers. 38 39Binding may contain optional "interrupts" property, describing interrupts 40used by the device. I2C core will assign "irq" interrupt (or the very first 41interrupt if not using interrupt names) as primary interrupt for the slave. 42 43Also, if device is marked as a wakeup source, I2C core will set up "wakeup" 44interrupt for the device. If "wakeup" interrupt name is not present in the 45binding, then primary interrupt will be used as wakeup interrupt. 46