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2023-12-11 1f93a7dfd1f8d5ff7a5c53246c7534fe2332d6f4

 kernel/Documentation/devicetree/bindings/i2c/i2c.txt
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 ===========================================
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 This document describes generic bindings which can be used to describe I2C
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-busses in a device tree.
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+busses and their child devices in a device tree.
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-Required properties
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--------------------
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+Required properties (per bus)
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+-----------------------------
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 - #address-cells  - should be <1>. Read more about addresses below.
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 - #size-cells     - should be <0>.
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-- compatible      - name of I2C bus controller following generic names
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-		    recommended practice.
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+- compatible      - name of I2C bus controller
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 For other required properties e.g. to describe register sets,
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 clocks, etc. check the binding documentation of the specific driver.
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 The cells properties above define that an address of children of an I2C bus
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-are described by a single value. This is usually a 7 bit address. However,
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-flags can be attached to the address. I2C_TEN_BIT_ADDRESS is used to mark a 10
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-bit address. It is needed to avoid the ambiguity between e.g. a 7 bit address
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-of 0x50 and a 10 bit address of 0x050 which, in theory, can be on the same bus.
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-Another flag is I2C_OWN_SLAVE_ADDRESS to mark addresses on which we listen to
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-be devices ourselves.
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+are described by a single value.
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-Optional properties
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--------------------
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+Optional properties (per bus)
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+-----------------------------
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 These properties may not be supported by all drivers. However, if a driver
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-wants to support one of the below features, it should adapt the bindings below.
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+wants to support one of the below features, it should adapt these bindings.
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 - clock-frequency
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 	frequency of bus clock in Hz.
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 	Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
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 	specification.
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+- i2c-analog-filter
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+	Enable analog filter for i2c lines.
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+
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+- i2c-digital-filter
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+	Enable digital filter for i2c lines.
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+
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+- i2c-digital-filter-width-ns
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+	Width of spikes which can be filtered by digital filter
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+	(i2c-digital-filter). This width is specified in nanoseconds.
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+
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+- i2c-analog-filter-cutoff-frequency
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+	Frequency that the analog filter (i2c-analog-filter) uses to distinguish
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+	which signal to filter. Signal with higher frequency than specified will
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+	be filtered out. Only lower frequency will pass (this is applicable to
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+	a low-pass analog filter). Typical value should be above the normal
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+	i2c bus clock frequency (clock-frequency).
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+	Specified in Hz.
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+
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+- multi-master
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+	states that there is another master active on this bus. The OS can use
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+	this information to adapt power management to keep the arbitration awake
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+	all the time, for example. Can not be combined with 'single-master'.
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+
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+- pinctrl
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+	add extra pinctrl to configure SCL/SDA pins to GPIO function for bus
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+	recovery, call it "gpio" or "recovery" (deprecated) state
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+
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+- scl-gpios
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+	specify the gpio related to SCL pin. Used for GPIO bus recovery.
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+
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+- sda-gpios
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+	specify the gpio related to SDA pin. Optional for GPIO bus recovery.
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+
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+- single-master
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+	states that there is no other master active on this bus. The OS can use
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+	this information to detect a stalled bus more reliably, for example.
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+	Can not be combined with 'multi-master'.
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+
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+- smbus
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+	states that additional SMBus restrictions and features apply to this bus.
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+	Examples of features are SMBusHostNotify and SMBusAlert. Examples of
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+	restrictions are more reserved addresses and timeout definitions.
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+
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+Required properties (per child device)
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+--------------------------------------
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+
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+- compatible
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+	name of I2C slave device
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+
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+- reg
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+	One or many I2C slave addresses. These are usually a 7 bit addresses.
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+	However, flags can be attached to an address. I2C_TEN_BIT_ADDRESS is
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+	used to mark a 10 bit address. It is needed to avoid the ambiguity
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+	between e.g. a 7 bit address of 0x50 and a 10 bit address of 0x050
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+	which, in theory, can be on the same bus.
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+	Another flag is I2C_OWN_SLAVE_ADDRESS to mark addresses on which we
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+	listen to be devices ourselves.
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+
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+Optional properties (per child device)
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+--------------------------------------
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+
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+These properties may not be supported by all drivers. However, if a driver
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+wants to support one of the below features, it should adapt these bindings.
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+
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+- host-notify
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+	device uses SMBus host notify protocol instead of interrupt line.
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+
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 - interrupts
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 	interrupts used by the device.
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 	"irq", "wakeup" and "smbus_alert" names are recognized by I2C core,
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 	other names are	left to individual drivers.
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-- host-notify
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-	device uses SMBus host notify protocol instead of interrupt line.
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-
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-- multi-master
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-	states that there is another master active on this bus. The OS can use
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-	this information to adapt power management to keep the arbitration awake
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-	all the time, for example.
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-
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-- wakeup-source
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-	device can be used as a wakeup source.
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-
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-- reg
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-	I2C slave addresses
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-
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 - reg-names
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 	Names of map programmable addresses.
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 	It can contain any map needing another address than default one.
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+
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+- wakeup-source
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+	device can be used as a wakeup source.
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 Binding may contain optional "interrupts" property, describing interrupts
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 used by the device. I2C core will assign "irq" interrupt (or the very first
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 interrupt if not using interrupt names) as primary interrupt for the slave.
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-Alternatively, devices supporting SMbus Host Notify, and connected to
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+Alternatively, devices supporting SMBus Host Notify, and connected to
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 adapters that support this feature, may use "host-notify" property. I2C
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 core will create a virtual interrupt for Host Notify and assign it as
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 primary interrupt for the slave.