dt-bindings: phy: Document Samsung UFS PHY bindings

This patch documents Samsung UFS PHY device tree bindings
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Link: https://lore.kernel.org/r/20200716192217.35740-1-alim.akhtar@samsung.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/samsung,ufs-phy.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/samsung,ufs-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Samsung SoC series UFS PHY Device Tree Bindings
+
+maintainers:
+  - Alim Akhtar <alim.akhtar@samsung.com>
+
+properties:
+  "#phy-cells":
+    const: 0
+
+  compatible:
+    enum:
+      - samsung,exynos7-ufs-phy
+
+  reg:
+    maxItems: 1
+
+  reg-names:
+    items:
+      - const: phy-pma
+
+  clocks:
+    items:
+      - description: PLL reference clock
+      - description: symbol clock for input symbol ( rx0-ch0 symbol clock)
+      - description: symbol clock for input symbol ( rx1-ch1 symbol clock)
+      - description: symbol clock for output symbol ( tx0 symbol clock)
+
+  clock-names:
+    items:
+      - const: ref_clk
+      - const: rx1_symbol_clk
+      - const: rx0_symbol_clk
+      - const: tx0_symbol_clk
+
+  samsung,pmu-syscon:
+    $ref: '/schemas/types.yaml#/definitions/phandle'
+    description: phandle for PMU system controller interface, used to
+                 control pmu registers bits for ufs m-phy
+
+required:
+  - "#phy-cells"
+  - compatible
+  - reg
+  - reg-names
+  - clocks
+  - clock-names
+  - samsung,pmu-syscon
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/exynos7-clk.h>
+
+    ufs_phy: ufs-phy@15571800 {
+        compatible = "samsung,exynos7-ufs-phy";
+        reg = <0x15571800 0x240>;
+        reg-names = "phy-pma";
+        samsung,pmu-syscon = <&pmu_system_controller>;
+        #phy-cells = <0>;
+        clocks = <&clock_fsys1 SCLK_COMBO_PHY_EMBEDDED_26M>,
+                 <&clock_fsys1 PHYCLK_UFS20_RX1_SYMBOL_USER>,
+                 <&clock_fsys1 PHYCLK_UFS20_RX0_SYMBOL_USER>,
+                 <&clock_fsys1 PHYCLK_UFS20_TX0_SYMBOL_USER>;
+        clock-names = "ref_clk", "rx1_symbol_clk",
+                      "rx0_symbol_clk", "tx0_symbol_clk";
+
+    };
+...