dt-bindings: ufs: add common platform bindings

Add bindings for common parts (platform) of Universal Flash Storage
(UFS) Host Controllers in dtschema format.

Include also the bindings directory in the UFS maintainers entry.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220306111125.116455-2-krzysztof.kozlowski@canonical.com

Documentation/devicetree/bindings/ufs/ufs-common.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ufs/ufs-common.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common properties for Universal Flash Storage (UFS) Host Controllers
+
+maintainers:
+  - Alim Akhtar <alim.akhtar@samsung.com>
+  - Avri Altman <avri.altman@wdc.com>
+
+properties:
+  clocks: true
+
+  clock-names: true
+
+  freq-table-hz:
+    items:
+      items:
+        - description: Minimum frequency for given clock in Hz
+        - description: Maximum frequency for given clock in Hz
+    description: |
+      Array of <min max> operating frequencies in Hz stored in the same order
+      as the clocks property. If this property is not defined or a value in the
+      array is "0" then it is assumed that the frequency is set by the parent
+      clock or a fixed rate clock source.
+
+  interrupts:
+    maxItems: 1
+
+  lanes-per-direction:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 2]
+    default: 2
+    description:
+      Number of lanes available per direction.  Note that it is assume same
+      number of lanes is used both directions at once.
+
+  vdd-hba-supply:
+    description:
+      Phandle to UFS host controller supply regulator node.
+
+  vcc-supply:
+    description:
+      Phandle to VCC supply regulator node.
+
+  vccq-supply:
+    description:
+      Phandle to VCCQ supply regulator node.
+
+  vccq2-supply:
+    description:
+      Phandle to VCCQ2 supply regulator node.
+
+  vcc-supply-1p8:
+    type: boolean
+    description:
+      For embedded UFS devices, valid VCC range is 1.7-1.95V or 2.7-3.6V. This
+      boolean property when set, specifies to use low voltage range of
+      1.7-1.95V. Note for external UFS cards this property is invalid and valid
+      VCC range is always 2.7-3.6V.
+
+  vcc-max-microamp:
+    description:
+      Specifies max. load that can be drawn from VCC supply.
+
+  vccq-max-microamp:
+    description:
+      Specifies max. load that can be drawn from VCCQ supply.
+
+  vccq2-max-microamp:
+    description:
+      Specifies max. load that can be drawn from VCCQ2 supply.
+
+dependencies:
+  freq-table-hz: [ 'clocks' ]
+
+required:
+  - interrupts
+
+additionalProperties: true

MAINTAINERS

@@ -19773,6 +19773,7 @@ R:	Alim Akhtar <alim.akhtar@samsung.com>
 R:	Avri Altman <avri.altman@wdc.com>
 L:	linux-scsi@vger.kernel.org
 S:	Supported
+F:	Documentation/devicetree/bindings/ufs/
 F:	Documentation/scsi/ufs.rst
 F:	drivers/scsi/ufs/