[PATCH v3] dt-bindings: misc: add binding for Xilinx AXI-Stream FIFO

[Aditya Chari <adi25charis@gmail.com>]

The axis-fifo driver's compatible strings were undocumented, flagged
by checkpatch.pl as UNDOCUMENTED_DT_STRING. Add a YAML devicetree
binding document for drivers/staging/axis-fifo, converted from and
replacing the existing free-form text binding (axis-fifo.txt), which
this patch removes.

Constrain xlnx,tx-fifo-depth to a minimum of 4, since the driver
subtracts 4 from this value in its transmit bounds check and a
smaller value would underflow that check.

Signed-off-by: Aditya Chari <adi25charis@gmail.com>
---

Changes since v2:
- Added $ref: /schemas/types.yaml#/definitions/string to the three
  AXI-Stream protocol enum properties (xlnx,axi-str-rxd-protocol,
  xlnx,axi-str-txd-protocol, xlnx,axi-str-txc-protocol) for explicit
  type consistency with the rest of the schema.
- Added minimum: 4 to xlnx,tx-fifo-depth, since the driver subtracts
  4 from this value in its transmit bounds check
  (axis_fifo_write()) and a smaller configured value would underflow
  that unsigned check, bypassing the oversized-packet guard.

Changes since v1:
- Fixed xlnx,rx/tx-fifo-depth: depth is in 32-bit words, not bytes,
  matching the driver's overflow check in axis_fifo_write() and the
  wording of the original text binding.
- Restored the full set of hardware-generated properties (interrupt-
  names, AXI-Stream protocol/width properties, has-axis-t* feature
  flags, fifo threshold properties, etc.) so that additionalProperties:
  false does not reject valid device trees generated for real hardware.
- Removed the now-superseded axis-fifo.txt text binding.


 .../bindings/misc/xlnx,axi-fifo-mm-s.yaml     | 227 ++++++++++++++++++
 drivers/staging/axis-fifo/axis-fifo.txt       |  96 --------
 2 files changed, 227 insertions(+), 96 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
 delete mode 100644 drivers/staging/axis-fifo/axis-fifo.txt

diff --git a/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml b/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
new file mode 100644
index 000000000..53bf52524
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/xlnx,axi-fifo-mm-s.yaml
@@ -0,0 +1,227 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/misc/xlnx,axi-fifo-mm-s.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xilinx AXI-Stream FIFO (axis-fifo)
+
+maintainers:
+  - Jacob Feder <jacobsfeder@gmail.com>
+
+description:
+  The AXI-Stream FIFO (AXIS-FIFO) IP core provides a memory-mapped AXI4-Lite
+  interface for sending and receiving data over an AXI4-Stream interface
+  using FIFO buffers. Currently supports only store-forward mode with a
+  32-bit AXI4-Lite interface; cut-through mode and full AXI4 are not
+  supported. See Xilinx PG080 for IP details.
+
+properties:
+  compatible:
+    enum:
+      - xlnx,axi-fifo-mm-s-4.1
+      - xlnx,axi-fifo-mm-s-4.2
+      - xlnx,axi-fifo-mm-s-4.3
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  interrupt-names:
+    items:
+      - const: interrupt
+
+  xlnx,axi-str-rxd-tdata-width:
+    description:
+      Width in bits of the AXI4-Stream receive data interface. Only a
+      width of 32 is currently supported by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 32
+
+  xlnx,axi-str-txd-tdata-width:
+    description:
+      Width in bits of the AXI4-Stream transmit data interface. Only a
+      width of 32 is currently supported by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 32
+
+  xlnx,axi-str-txc-tdata-width:
+    description:
+      Width in bits of the AXI4-Stream transmit control interface.
+      Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,axi-str-rxd-protocol:
+    description: AXI-Stream receive data protocol. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [ XIL_AXI_STREAM_ETH_DATA ]
+
+  xlnx,axi-str-txd-protocol:
+    description: AXI-Stream transmit data protocol. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [ XIL_AXI_STREAM_ETH_DATA ]
+
+  xlnx,axi-str-txc-protocol:
+    description: AXI-Stream transmit control protocol. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [ XIL_AXI_STREAM_ETH_CTRL ]
+
+  xlnx,axis-tdest-width:
+    description: AXI-Stream TDEST width. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,axis-tid-width:
+    description: AXI-Stream TID width. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,axis-tuser-width:
+    description: AXI-Stream TUSER width. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,data-interface-type:
+    description: Data interface type. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,has-axis-tdest:
+    description:
+      Whether the AXI-Stream interface has TDEST. This feature is not
+      supported by the driver and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,has-axis-tid:
+    description:
+      Whether the AXI-Stream interface has TID. This feature is not
+      supported by the driver and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,has-axis-tkeep:
+    description:
+      Whether the AXI-Stream interface has TKEEP. This feature is not
+      supported by the driver and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,has-axis-tstrb:
+    description:
+      Whether the AXI-Stream interface has TSTRB. This feature is not
+      supported by the driver and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,has-axis-tuser:
+    description:
+      Whether the AXI-Stream interface has TUSER. This feature is not
+      supported by the driver and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,rx-fifo-depth:
+    description:
+      Depth in 32-bit words of the receive FIFO, as configured in the
+      IP core.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,rx-fifo-pe-threshold:
+    description: RX programmable empty interrupt threshold. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,rx-fifo-pf-threshold:
+    description: RX programmable full interrupt threshold. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,s-axi-id-width:
+    description: AXI4-Lite ID width. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,s-axi4-data-width:
+    description: AXI4-Lite data width. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,select-xpm:
+    description: Whether XPM macros are used. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,tx-fifo-depth:
+    description:
+      Depth in 32-bit words of the transmit FIFO, as configured in the
+      IP core. Must be at least 4; the driver subtracts 4 from this
+      value when bounds-checking transmit writes, and a smaller value
+      underflows that check.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 4
+
+  xlnx,tx-fifo-pe-threshold:
+    description: TX programmable empty interrupt threshold. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,tx-fifo-pf-threshold:
+    description: TX programmable full interrupt threshold. Ignored by the driver.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  xlnx,use-rx-cut-through:
+    description:
+      Whether RX cut-through mode is used. Not supported by the driver
+      and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,use-rx-data:
+    description:
+      Indicates whether the receive data path is present, as configured
+      in the IP core. A value of 1 enables the receive path, 0 disables it.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [ 0, 1 ]
+
+  xlnx,use-tx-ctrl:
+    description:
+      Whether the transmit control interface is used. Not supported by
+      the driver and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,use-tx-cut-through:
+    description:
+      Whether TX cut-through mode is used. Not supported by the driver
+      and must be 0.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    const: 0
+
+  xlnx,use-tx-data:
+    description:
+      Indicates whether the transmit data path is present, as configured
+      in the IP core. A value of 1 enables the transmit path, 0 disables it.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [ 0, 1 ]
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - xlnx,axi-str-rxd-tdata-width
+  - xlnx,axi-str-txd-tdata-width
+  - xlnx,rx-fifo-depth
+  - xlnx,tx-fifo-depth
+  - xlnx,use-rx-data
+  - xlnx,use-tx-data
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    axi_fifo_mm_s_0: axi-fifo-mm-s@40000000 {
+        compatible = "xlnx,axi-fifo-mm-s-4.1";
+        reg = <0x40000000 0x10000>;
+        interrupts = <0 29 IRQ_TYPE_LEVEL_HIGH>;
+        xlnx,axi-str-rxd-tdata-width = <32>;
+        xlnx,axi-str-txd-tdata-width = <32>;
+        xlnx,rx-fifo-depth = <512>;
+        xlnx,tx-fifo-depth = <32768>;
+        xlnx,use-rx-data = <1>;
+        xlnx,use-tx-data = <1>;
+    };
diff --git a/drivers/staging/axis-fifo/axis-fifo.txt b/drivers/staging/axis-fifo/axis-fifo.txt
deleted file mode 100644
index 413b81a53..000000000
--- a/drivers/staging/axis-fifo/axis-fifo.txt
+++ /dev/null
@@ -1,96 +0,0 @@
-Xilinx AXI-Stream FIFO v4.1 IP core
-
-This IP core has read and write AXI-Stream FIFOs, the contents of which can
-be accessed from the AXI4 memory-mapped interface. This is useful for
-transferring data from a processor into the FPGA fabric. The driver creates
-a character device that can be read/written to with standard
-open/read/write/close.
-
-See Xilinx PG080 document for IP details.
-
-Currently supports only store-forward mode with a 32-bit
-AXI4-Lite interface. DOES NOT support:
-	- cut-through mode
-	- AXI4 (non-lite)
-
-Required properties:
-- compatible: Should be one of:
-    "xlnx,axi-fifo-mm-s-4.1"
-    "xlnx,axi-fifo-mm-s-4.2"
-    "xlnx,axi-fifo-mm-s-4.3"
-- interrupt-names: Should be "interrupt"
-- interrupt-parent: Should be <&intc>
-- interrupts: Should contain interrupts lines.
-- reg: Should contain registers location and length.
-- xlnx,axi-str-rxd-protocol: Should be "XIL_AXI_STREAM_ETH_DATA"
-- xlnx,axi-str-rxd-tdata-width: Should be <0x20>
-- xlnx,axi-str-txc-protocol: Should be "XIL_AXI_STREAM_ETH_CTRL"
-- xlnx,axi-str-txc-tdata-width: Should be <0x20>
-- xlnx,axi-str-txd-protocol: Should be "XIL_AXI_STREAM_ETH_DATA"
-- xlnx,axi-str-txd-tdata-width: Should be <0x20>
-- xlnx,axis-tdest-width: AXI-Stream TDEST width (ignored by the driver)
-- xlnx,axis-tid-width: AXI-Stream TID width (ignored by the driver)
-- xlnx,axis-tuser-width: AXI-Stream TUSER width (ignored by the driver)
-- xlnx,data-interface-type: Should be <0x0> (ignored by the driver)
-- xlnx,has-axis-tdest: Should be <0x0> (this feature isn't supported)
-- xlnx,has-axis-tid: Should be <0x0> (this feature isn't supported)
-- xlnx,has-axis-tkeep: Should be <0x0> (this feature isn't supported)
-- xlnx,has-axis-tstrb: Should be <0x0> (this feature isn't supported)
-- xlnx,has-axis-tuser: Should be <0x0> (this feature isn't supported)
-- xlnx,rx-fifo-depth: Depth of RX FIFO in words
-- xlnx,rx-fifo-pe-threshold: RX programmable empty interrupt threshold
-	(ignored by the driver)
-- xlnx,rx-fifo-pf-threshold: RX programmable full interrupt threshold
-	(ignored by the driver)
-- xlnx,s-axi-id-width: Should be <0x4> (ignored by the driver)
-- xlnx,s-axi4-data-width: Should be <0x20> (ignored by the driver)
-- xlnx,select-xpm: Should be <0x0> (ignored by the driver)
-- xlnx,tx-fifo-depth: Depth of TX FIFO in words
-- xlnx,tx-fifo-pe-threshold: TX programmable empty interrupt threshold
-	(ignored by the driver)
-- xlnx,tx-fifo-pf-threshold: TX programmable full interrupt threshold
-	(ignored by the driver)
-- xlnx,use-rx-cut-through: Should be <0x0> (this feature isn't supported)
-- xlnx,use-rx-data: <0x1> if RX FIFO is enabled, <0x0> otherwise
-- xlnx,use-tx-ctrl: Should be <0x0> (this feature isn't supported)
-- xlnx,use-tx-cut-through: Should be <0x0> (this feature isn't supported)
-- xlnx,use-tx-data: <0x1> if TX FIFO is enabled, <0x0> otherwise
-
-Example:
-
-axi_fifo_mm_s_0: axi_fifo_mm_s@43c00000 {
-	compatible = "xlnx,axi-fifo-mm-s-4.1";
-	interrupt-names = "interrupt";
-	interrupt-parent = <&intc>;
-	interrupts = <0 29 4>;
-	reg = <0x43c00000 0x10000>;
-	xlnx,axi-str-rxd-protocol = "XIL_AXI_STREAM_ETH_DATA";
-	xlnx,axi-str-rxd-tdata-width = <0x20>;
-	xlnx,axi-str-txc-protocol = "XIL_AXI_STREAM_ETH_CTRL";
-	xlnx,axi-str-txc-tdata-width = <0x20>;
-	xlnx,axi-str-txd-protocol = "XIL_AXI_STREAM_ETH_DATA";
-	xlnx,axi-str-txd-tdata-width = <0x20>;
-	xlnx,axis-tdest-width = <0x4>;
-	xlnx,axis-tid-width = <0x4>;
-	xlnx,axis-tuser-width = <0x4>;
-	xlnx,data-interface-type = <0x0>;
-	xlnx,has-axis-tdest = <0x0>;
-	xlnx,has-axis-tid = <0x0>;
-	xlnx,has-axis-tkeep = <0x0>;
-	xlnx,has-axis-tstrb = <0x0>;
-	xlnx,has-axis-tuser = <0x0>;
-	xlnx,rx-fifo-depth = <0x200>;
-	xlnx,rx-fifo-pe-threshold = <0x2>;
-	xlnx,rx-fifo-pf-threshold = <0x1fb>;
-	xlnx,s-axi-id-width = <0x4>;
-	xlnx,s-axi4-data-width = <0x20>;
-	xlnx,select-xpm = <0x0>;
-	xlnx,tx-fifo-depth = <0x8000>;
-	xlnx,tx-fifo-pe-threshold = <0x200>;
-	xlnx,tx-fifo-pf-threshold = <0x7ffb>;
-	xlnx,use-rx-cut-through = <0x0>;
-	xlnx,use-rx-data = <0x0>;
-	xlnx,use-tx-ctrl = <0x0>;
-	xlnx,use-tx-cut-through = <0x0>;
-	xlnx,use-tx-data = <0x1>;
-};
-- 
2.53.0