dt-bindings: input: Add document bindings for DA7280

Add device tree binding information for DA7280 haptic driver.
Example bindings for DA7280 are added.

Signed-off-by: Roy Im <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>.
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/dlg,da7280.txt

···
+Dialog Semiconductor DA7280 Haptics bindings
+
+Required properties:
+- compatible: Should be "dlg,da7280".
+- reg: Specifies the I2C slave address.
+
+- interrupt-parent : Specifies the phandle of the interrupt controller to
+  which the IRQs from DA7280 are delivered to.
+
+- dlg,actuator-type: Set Actuator type. it should be one of:
+  "LRA" - Linear Resonance Actuator type.
+  "ERM-bar" - Bar type Eccentric Rotating Mass.
+  "ERM-coin" - Coin type Eccentric Rotating Mass.
+
+- dlg,const-op-mode: Haptic operation mode for FF_CONSTANT.
+  Possible values:
+	1 - Direct register override(DRO) mode triggered by i2c(default),
+	2 - PWM data source mode controlled by PWM duty,
+- dlg,periodic-op-mode: Haptic operation mode for FF_PERIODIC.
+  Possible values:
+	1 - Register triggered waveform memory(RTWM) mode, the pattern
+	    assigned to the PS_SEQ_ID played as much times as PS_SEQ_LOOP,
+	2 - Edge triggered waveform memory(ETWM) mode, external GPI(N)
+	    control are required to enable/disable and it needs to keep
+	    device enabled by sending magnitude (X > 0),
+	    the pattern is assigned to the GPI(N)_SEQUENCE_ID below.
+	The default value is 1 for both of the operation modes.
+	For more details, please see the datasheet.
+
+- dlg,nom-microvolt: Nominal actuator voltage rating.
+  Valid values: 0 - 6000000.
+- dlg,abs-max-microvolt: Absolute actuator maximum voltage rating.
+  Valid values: 0 - 6000000.
+- dlg,imax-microamp: Actuator max current rating.
+  Valid values: 0 - 252000.
+  Default: 130000.
+- dlg,impd-micro-ohms: the impedance of the actuator in micro ohms.
+  Valid values: 0 - 1500000000.
+
+Optional properties:
+- pwms : phandle to the physical PWM(Pulse Width Modulation) device.
+  PWM properties should be named "pwms". And number of cell is different
+  for each pwm device.
+  (See Documentation/devicetree/bindings/pwm/pwm.txt
+   for further information relating to pwm properties)
+
+- dlg,ps-seq-id: the PS_SEQ_ID(pattern ID in waveform memory inside chip)
+  to play back when RTWM-MODE is enabled.
+  Valid range: 0 - 15.
+- dlg,ps-seq-loop: the PS_SEQ_LOOP, Number of times the pre-stored sequence
+  pointed to by PS_SEQ_ID or GPI(N)_SEQUENCE_ID is repeated.
+  Valid range: 0 - 15.
+- dlg,gpiN-seq-id: the GPI(N)_SEQUENCE_ID, pattern to play
+  when gpi0 is triggered, 'N' must be 0 - 2.
+  Valid range: 0 - 15.
+- dlg,gpiN-mode: the pattern mode which can select either
+  "Single-pattern" or "Multi-pattern", 'N' must be 0 - 2.
+- dlg,gpiN-polarity: gpiN polarity which can be chosen among
+  "Rising-edge", "Falling-edge" and "Both-edge",
+  'N' must be 0 - 2
+  Haptic will work by this edge option in case of ETWM mode.
+
+- dlg,resonant-freq-hz: use in case of LRA.
+  the frequency range: 50 - 300.
+  Default: 205.
+
+- dlg,bemf-sens-enable: Enable for internal loop computations.
+- dlg,freq-track-enable: Enable for resonant frequency tracking.
+- dlg,acc-enable: Enable for active acceleration.
+- dlg,rapid-stop-enable: Enable for rapid stop.
+- dlg,amp-pid-enable: Enable for the amplitude PID.
+- dlg,mem-array: Customized waveform memory(patterns) data downloaded to
+  the device during initialization. This is an array of 100 values(u8).
+
+For further information, see device datasheet.
+
+======
+
+Example:
+
+	haptics: da7280-haptics@4a {
+		compatible = "dlg,da7280";
+		reg = <0x4a>;
+		interrupt-parent = <&gpio6>;
+		interrupts = <11 IRQ_TYPE_LEVEL_LOW>;
+		dlg,actuator-type = "LRA";
+		dlg,dlg,const-op-mode = <1>;
+		dlg,dlg,periodic-op-mode = <1>;
+		dlg,nom-microvolt = <2000000>;
+		dlg,abs-max-microvolt = <2000000>;
+		dlg,imax-microamp = <170000>;
+		dlg,resonant-freq-hz = <180>;
+		dlg,impd-micro-ohms = <10500000>;
+		dlg,freq-track-enable;
+		dlg,rapid-stop-enable;
+		dlg,mem-array = <
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		  0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
+		>;
+	};