linux-kernel - [PATCH V3 2/6] dt-bindings: timestamp: Add Tegra234 support

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Message-ID: <20230310190634.5053-3-dipenp@nvidia.com>
Date:   Fri, 10 Mar 2023 11:06:30 -0800
From:   Dipen Patel <dipenp@...dia.com>
To:     <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <linux-kernel@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>, <linus.walleij@...aro.org>,
        <devicetree@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <robh+dt@...nel.org>, <timestamp@...ts.linux.dev>,
        <krzysztof.kozlowski+dt@...aro.org>, <brgl@...ev.pl>,
        <corbet@....net>, <gregkh@...uxfoundation.org>
CC:     Dipen Patel <dipenp@...dia.com>
Subject: [PATCH V3 2/6] dt-bindings: timestamp: Add Tegra234 support

Added timestamp provider support for the Tegra234 in devicetree
bindings. In addition, it addresses review comments from the
previous review round as follows:
- Removes nvidia,slices property. This was not necessary as it
is a constant value and can be hardcoded inside the driver code.
- Adds nvidia,gpio-controller property. This simplifies how GTE driver
retrieves GPIO controller instance, see below explanation.

Without this property code would look like:
if (of_device_is_compatible(dev->of_node, "nvidia,tegra194-gte-aon"))
	hte_dev->c = gpiochip_find("tegra194-gpio-aon",
				   tegra_get_gpiochip_from_name);
else if (of_device_is_compatible(dev->of_node, "nvidia,tegra234-gte-aon"))
	hte_dev->c = gpiochip_find("tegra234-gpio-aon",
				   tegra_get_gpiochip_from_name);
else
	return -ENODEV;

This means for every future addition of the compatible string, if else
condition statements have to be expanded.

With the property:
gpio_ctrl = of_parse_phandle(dev->of_node, "nvidia,gpio-controller", 0);
....
hte_dev->c = gpiochip_find(gpio_ctrl, tegra_get_gpiochip_from_of_node);

We haven't technically started making use of these bindings, so
backwards-compatibility shouldn't be an issue yet.

Signed-off-by: Dipen Patel <dipenp@...dia.com>
---
v2:
- Removed nvidia,slices property
- Added nvidia,gpio-controller based on review comments from Thierry,
  this will help simplify the  hte provider driver.

v3:
- Explained changes in detail in commit message
- Added allOf section per review comment

 .../timestamp/nvidia,tegra194-hte.yaml        | 31 ++++++++++++-------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml
index c31e207d1652..eb904ac2f331 100644
--- a/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml
+++ b/Documentation/devicetree/bindings/timestamp/nvidia,tegra194-hte.yaml
@@ -4,7 +4,7 @@
 $id: http://devicetree.org/schemas/timestamp/nvidia,tegra194-hte.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: Tegra194 on chip generic hardware timestamping engine (HTE)
+title: Tegra on chip generic hardware timestamping engine (HTE) provider
 
 maintainers:
   - Dipen Patel <dipenp@...dia.com>
@@ -23,6 +23,8 @@ properties:
     enum:
       - nvidia,tegra194-gte-aon
       - nvidia,tegra194-gte-lic
+      - nvidia,tegra234-gte-aon
+      - nvidia,tegra234-gte-lic
 
   reg:
     maxItems: 1
@@ -38,14 +40,11 @@ properties:
     minimum: 1
     maximum: 256
 
-  nvidia,slices:
-    $ref: /schemas/types.yaml#/definitions/uint32
+  nvidia,gpio-controller:
+    $ref: /schemas/types.yaml#/definitions/phandle
     description:
-      HTE lines are arranged in 32 bit slice where each bit represents different
-      line/signal that it can enable/configure for the timestamp. It is u32
-      property and depends on the HTE instance in the chip. The value 3 is for
-      GPIO GTE and 11 for IRQ GTE.
-    enum: [3, 11]
+      The phandle to AON gpio controller instance. This is required to handle
+      namespace conversion between GPIO and GTE.
 
   '#timestamp-cells':
     description:
@@ -59,9 +58,20 @@ required:
   - compatible
   - reg
   - interrupts
-  - nvidia,slices
   - "#timestamp-cells"
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - nvidia,tegra194-gte-aon
+              - nvidia,tegra234-gte-aon
+    then:
+      required:
+        - nvidia,gpio-controller
+
 additionalProperties: false
 
 examples:
@@ -71,7 +81,7 @@ examples:
               reg = <0xc1e0000 0x10000>;
               interrupts = <0 13 0x4>;
               nvidia,int-threshold = <1>;
-              nvidia,slices = <3>;
+              nvidia,gpio-controller = <&gpio_aon>;
               #timestamp-cells = <1>;
     };
 
@@ -81,7 +91,6 @@ examples:
               reg = <0x3aa0000 0x10000>;
               interrupts = <0 11 0x4>;
               nvidia,int-threshold = <1>;
-              nvidia,slices = <11>;
               #timestamp-cells = <1>;
     };
 
-- 
2.17.1