linux-kernel - [PATCH 02/16] dt-bindings: spi: Add bcmbca-hsspi controller support

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Date:   Fri,  6 Jan 2023 12:07:54 -0800
From:   William Zhang <william.zhang@...adcom.com>
To:     Linux SPI List <linux-spi@...r.kernel.org>,
        Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>
Cc:     anand.gore@...adcom.com, tomer.yacoby@...adcom.com,
        dan.beygelman@...adcom.com, joel.peshkin@...adcom.com,
        f.fainelli@...il.com, jonas.gorski@...il.com,
        kursad.oney@...adcom.com, dregan@...l.com,
        William Zhang <william.zhang@...adcom.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 02/16] dt-bindings: spi: Add bcmbca-hsspi controller support

The new Broadcom Broadband BCMBCA SoCs includes a updated HSSPI
controller. Add a new compatible string and required fields for the new
driver.  Also add myself and Kursad as the maintainers.

Signed-off-by: William Zhang <william.zhang@...adcom.com>
---

 .../bindings/spi/brcm,bcm63xx-hsspi.yaml      | 84 +++++++++++++++++--
 1 file changed, 78 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/brcm,bcm63xx-hsspi.yaml b/Documentation/devicetree/bindings/spi/brcm,bcm63xx-hsspi.yaml
index 45f1417b1213..56e69d4a1faf 100644
--- a/Documentation/devicetree/bindings/spi/brcm,bcm63xx-hsspi.yaml
+++ b/Documentation/devicetree/bindings/spi/brcm,bcm63xx-hsspi.yaml
@@ -4,22 +4,51 @@
 $id: http://devicetree.org/schemas/spi/brcm,bcm63xx-hsspi.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: Broadcom BCM6328 High Speed SPI controller
+title: Broadcom Broadband SoC High Speed SPI controller
 
 maintainers:
+
+  - William Zhang <william.zhang@...adcom.com>
+  - Kursad Oney <kursad.oney@...adcom.com>
   - Jonas Gorski <jonas.gorski@...il.com>
 
+description: |
+  Broadcom Broadband SoC supports High Speed SPI master controller since the
+  early MIPS based chips such as BCM6328 and BCM63268.  This controller was
+  carried over to recent ARM based chips, such as BCM63138, BCM4908 and BCM6858.
+
+  It has a limitation that can not keep the chip select line active between
+  the SPI transfers within the same SPI message. This can terminate the
+  transaction to some SPI devices prematurely. The issue can be worked around by
+  either the controller's prepend mode or using the dummy chip select
+  workaround. This controller uses the compatible string brcm,bcm6328-hsspi.
+
+  The newer SoCs such as BCM6756, BCM4912 and BCM6855 include an updated SPI
+  controller that add the capability to allow the driver to control chip select
+  explicitly. This solves the issue in the old controller. This new controller
+  uses the compatible string brcm,bcmbca-hsspi.
+
 properties:
   compatible:
-    const: brcm,bcm6328-hsspi
+    enum:
+      - brcm,bcm6328-hsspi
+      - brcm,bcmbca-hsspi
 
   reg:
-    maxItems: 1
+    items:
+      - description: main registers
+      - description: miscellaneous control registers
+    minItems: 1
+
+  reg-names:
+    items:
+      - const: hsspi
+      - const: spim-ctrl
 
   clocks:
     items:
-      - description: spi master reference clock
-      - description: spi master pll clock
+      - description: SPI master reference clock
+      - description: SPI master pll clock
 
   clock-names:
     items:
@@ -29,12 +58,43 @@ properties:
   interrupts:
     maxItems: 1
 
+  brcm,use-cs-workaround:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: |
+      Enable dummy chip select workaround for SPI transfers that can not be
+      supported by the default controller's prepend mode, i.e. delay or cs
+      change needed between SPI transfers.
+
 required:
   - compatible
   - reg
   - clocks
   - clock-names
-  - interrupts
+
+allOf:
+  - $ref: "spi-controller.yaml#"
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - brcm,bcm6328-hsspi
+    then:
+      properties:
+        reg:
+          minItems: 1
+          maxItems: 1
+    else:
+      properties:
+        reg:
+          minItems: 2
+          maxItems: 2
+        reg-names:
+          minItems: 2
+          maxItems: 2
+        brcm,use-cs-workaround: false
+      required:
+        - reg-names
 
 unevaluatedProperties: false
 
@@ -50,3 +110,15 @@ examples:
         #address-cells = <1>;
         #size-cells = <0>;
     };
+  - |
+    spi@...01000 {
+        compatible = "brcm,bcmbca-hsspi";
+        reg = <0xff801000 0x1000>,
+              <0xff802610 0x4>;
+        reg-names = "hsspi", "spim-ctrl";
+        clocks = <&hsspi>, <&hsspi_pll>;
+        clock-names = "hsspi", "pll";
+        num-cs = <8>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+    };
-- 
2.37.3