dts: jedec,spi-nor: add support for deep-power-down specification

Provide information required to allow the driver to put the flash chip
into a deep power down mode.  This can reduce standby current by as
much as 90%.

Signed-off-by: Peter A. Bigot <[email protected]>

Author: pabigot

boards/arm/nrf52840_pca10056/nrf52840_pca10056.dts

@@ -199,6 +199,9 @@ arduino_i2c: &i2c0 {
 		jedec-id = [c2 28 17];
 		size = <67108864>;
 		has-be32k;
+		has-dpd;
+		t-enter-dpd = <10000>;
+		dpd-wakeup-sequence = <30000 20 45000>;
 		wp-gpios = <&gpio0 22 0>;
 		hold-gpios = <&gpio0 23 0>;
 	};

boards/arm/particle_argon/dts/mesh_feather.dtsi

@@ -142,6 +142,9 @@
 		hold-gpios = <&gpio0 23 0>;
 		size = <0x2000000>;
 		has-be32k;
+		has-dpd;
+		t-enter-dpd = <10000>;
+		t-exit-dpd = <100000>;
 		jedec-id = [c2 20 16];
 	};
 };

boards/arm/particle_boron/dts/mesh_feather.dtsi

@@ -142,6 +142,9 @@
 		hold-gpios = <&gpio0 23 0>;
 		size = <0x2000000>;
 		has-be32k;
+		has-dpd;
+		t-enter-dpd = <10000>;
+		t-exit-dpd = <100000>;
 		jedec-id = [c2 20 16];
 	};
 };

boards/arm/particle_xenon/dts/mesh_feather.dtsi

@@ -142,6 +142,9 @@
 		hold-gpios = <&gpio0 23 0>;
 		size = <0x2000000>;
 		has-be32k;
+		has-dpd;
+		t-enter-dpd = <10000>;
+		t-exit-dpd = <100000>;
 		jedec-id = [c2 20 16];
 	};
 };

dts/bindings/mtd/jedec,spi-nor.yaml

@@ -32,6 +32,60 @@ properties:
       property to indicate that the BPR must be unlocked before write
       operations can proceed.
 
+  has-dpd:
+    type: boolean
+    required: false
+    description: |
+      Indicates the device supports the DPD (0xB9) command.
+
+      Use this property to indicate the flash chip supports the Deep
+      Power-Down mode that is entered by command 0xB9 to reduce power
+      consumption below normal standby levels.  Use of this property
+      implies that the RDPD (0xAB) Release from Deep Power Down command
+      is also supported.  (On some chips this command functions as Read
+      Electronic Signature; see t-enter-dpd).
+
+  dpd-wakeup-sequence:
+    type: array
+    required: false
+    description: |
+      Specifies wakeup durations for devices without RDPD.
+
+      Some devices (Macronix MX25R in particular) wake from deep power
+      down by a timed sequence of CSn toggles rather than the RDPD
+      command.  This property specifies three durations measured in
+      nanoseconds, in this order:
+      (1) tDPDD (Delay Time for Release from Deep Power-Down Mode)
+      (2) tCDRP (CSn Toggling Time before Release from Deep Power-Down Mode)
+      (3) tRDP (Recovery Time for Release from Deep Power-Down Mode)
+
+      Absence of this property indicates that the RDPD command should be
+      used to wake the chip from Deep Power-Down mode.
+
+  t-enter-dpd:
+    type: int
+    required: false
+    description: |
+      Duration required to complete the DPD command.
+
+      This provides the duration, in nanoseconds, that CSn must be
+      remain deasserted after issuing DPD before the chip will enter
+      deep power down.
+
+      If not provided the driver does not enforce a delay.
+
+  t-exit-dpd:
+    type: int
+    required: false
+    description: |
+      Duration required to complete the RDPD command.
+
+      This provides the duration, in nanoseconds, that CSn must be
+      remain deasserted after issuing RDPD before the chip will exit
+      deep power down and be ready to receive additional commands.
+
+      If not provided the driver does not enforce a delay.
+
   size:
     type: int
     required: true