78 lines
2.2 KiB
Plaintext
78 lines
2.2 KiB
Plaintext
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Intersil ISL12057 I2C RTC/Alarm chip
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ISL12057 is a trivial I2C device (it has simple device tree bindings,
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consisting of a compatible field, an address and possibly an interrupt
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line).
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Nonetheless, it also supports an option boolean property
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("wakeup-source") to handle the specific use-case found
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on at least three in-tree users of the chip (NETGEAR ReadyNAS 102, 104
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and 2120 ARM-based NAS); On those devices, the IRQ#2 pin of the chip
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(associated with the alarm supported by the driver) is not connected
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to the SoC but to a PMIC. It allows the device to be powered up when
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RTC alarm rings. In order to mark the device has a wakeup source and
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get access to the 'wakealarm' sysfs entry, this specific property can
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be set when the IRQ#2 pin of the chip is not connected to the SoC but
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can wake up the device.
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Required properties supported by the device:
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- "compatible": must be "isil,isl12057"
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- "reg": I2C bus address of the device
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Optional properties:
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- "wakeup-source": mark the chip as a wakeup source, independently of
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the availability of an IRQ line connected to the SoC.
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- "interrupt-parent", "interrupts": for passing the interrupt line
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of the SoC connected to IRQ#2 of the RTC chip.
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Example isl12057 node without IRQ#2 pin connected (no alarm support):
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isl12057: isl12057@68 {
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compatible = "isil,isl12057";
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reg = <0x68>;
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};
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Example isl12057 node with IRQ#2 pin connected to main SoC via MPP6 (note
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that the pinctrl-related properties below are given for completeness and
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may not be required or may be different depending on your system or
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SoC, and the main function of the MPP used as IRQ line, i.e.
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"interrupt-parent" and "interrupts" are usually sufficient):
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pinctrl {
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...
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rtc_alarm_pin: rtc_alarm_pin {
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marvell,pins = "mpp6";
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marvell,function = "gpio";
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};
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...
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};
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...
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isl12057: isl12057@68 {
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compatible = "isil,isl12057";
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reg = <0x68>;
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pinctrl-0 = <&rtc_alarm_pin>;
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pinctrl-names = "default";
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interrupt-parent = <&gpio0>;
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interrupts = <6 IRQ_TYPE_EDGE_FALLING>;
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};
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Example isl12057 node without IRQ#2 pin connected to the SoC but to a
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PMIC, allowing the device to be started based on configured alarm:
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isl12057: isl12057@68 {
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compatible = "isil,isl12057";
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reg = <0x68>;
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wakeup-source;
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};
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