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edd20e95bc
In order to use i2c from a cold boot, the i2c peripheral must be taken out of reset. We request a shared reset controller each time a bus driver is loaded, as the reset is shared between the 14 i2c buses. On remove the reset is asserted, which only touches the hardware once the last i2c bus is removed. The reset is required as the I2C buses will not work without releasing the reset. Previously the driver only worked with out of tree hacks that released this reset before the driver was loaded. Update the device tree bindings to reflect this. Signed-off-by: Joel Stanley <joel@jms.id.au> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
52 lines
1.4 KiB
Plaintext
52 lines
1.4 KiB
Plaintext
Device tree configuration for the I2C busses on the AST24XX and AST25XX SoCs.
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Required Properties:
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- #address-cells : should be 1
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- #size-cells : should be 0
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- reg : address offset and range of bus
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- compatible : should be "aspeed,ast2400-i2c-bus"
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or "aspeed,ast2500-i2c-bus"
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- clocks : root clock of bus, should reference the APB
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clock in the second cell
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- resets : phandle to reset controller with the reset number in
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the second cell
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- interrupts : interrupt number
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- interrupt-parent : interrupt controller for bus, should reference a
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aspeed,ast2400-i2c-ic or aspeed,ast2500-i2c-ic
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interrupt controller
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Optional Properties:
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- bus-frequency : frequency of the bus clock in Hz defaults to 100 kHz when not
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specified
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- multi-master : states that there is another master active on this bus.
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Example:
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i2c {
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compatible = "simple-bus";
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#address-cells = <1>;
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#size-cells = <1>;
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ranges = <0 0x1e78a000 0x1000>;
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i2c_ic: interrupt-controller@0 {
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#interrupt-cells = <1>;
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compatible = "aspeed,ast2400-i2c-ic";
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reg = <0x0 0x40>;
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interrupts = <12>;
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interrupt-controller;
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};
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i2c0: i2c-bus@40 {
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#address-cells = <1>;
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#size-cells = <0>;
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#interrupt-cells = <1>;
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reg = <0x40 0x40>;
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compatible = "aspeed,ast2400-i2c-bus";
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clocks = <&syscon ASPEED_CLK_APB>;
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resets = <&syscon ASPEED_RESET_I2C>;
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bus-frequency = <100000>;
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interrupts = <0>;
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interrupt-parent = <&i2c_ic>;
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};
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};
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