doc: unbind man-page

Provide a man-page for the unbind command.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

doc/usage/cmd/unbind.rst

@@ -0,0 +1,95 @@
+.. SPDX-License-Identifier: GPL-2.0+:
+
+unbind command
+==============
+
+Synopsis
+--------
+
+::
+
+    unbind <node path>
+    unbind <class> <index>
+    unbind <class> <index> <driver>
+
+Description
+-----------
+
+The unbind command is used to unbind a device from a driver. This makes the
+device unavailable in U-Boot.
+
+node path
+    path of the device's device-tree node
+
+class
+    device class name
+
+index
+    index of the device in the device class
+
+driver
+    device driver name
+
+Example
+-------
+
+Given a system with a real time clock device with device path */pl031@9010000*
+and using driver rtc-pl031 unbinding and binding of the device is demonstrated
+using the three alternative unbind syntaxes.
+
+.. code-block::
+
+    => dm tree
+     Class     Index  Probed  Driver                Name
+    -----------------------------------------------------------
+     root          0  [ + ]   root_driver           root_driver
+    ...
+     rtc           0  [   ]   rtc-pl031             |-- pl031@9010000
+    ...
+    => fdt addr $fdtcontroladdr
+    Working FDT set to 7ed7fdb0
+    => fdt print
+    / {
+            interrupt-parent = <0x00008003>;
+            model = "linux,dummy-virt";
+            #size-cells = <0x00000002>;
+            #address-cells = <0x00000002>;
+            compatible = "linux,dummy-virt";
+    ...
+            pl031@9010000 {
+                    clock-names = "apb_pclk";
+                    clocks = <0x00008000>;
+                    interrupts = <0x00000000 0x00000002 0x00000004>;
+                    reg = <0x00000000 0x09010000 0x00000000 0x00001000>;
+                    compatible = "arm,pl031", "arm,primecell";
+            };
+    ...
+    }
+    => unbind /pl031@9010000
+    => dm tree
+     Class     Index  Probed  Driver                Name
+    -----------------------------------------------------------
+     root          0  [ + ]   root_driver           root_driver
+    ...
+    => unbind /pl031@9010000
+    Cannot find a device with path /pl031@9010000
+    => bind /pl031@9010000 rtc-pl031
+    => dm tree
+     Class     Index  Probed  Driver                Name
+    -----------------------------------------------------------
+     root          0  [ + ]   root_driver           root_driver
+    ...
+     rtc           0  [   ]   rtc-pl031             |-- pl031@9010000
+    => unbind rtc 0
+    => bind /pl031@9010000 rtc-pl031
+    => unbind rtc 0 rtc-pl031
+
+Configuration
+-------------
+
+The unbind command is only available if CONFIG_CMD_BIND=y.
+
+Return code
+-----------
+
+The return code $? is 0 (true) on success and 1 (false) on failure.

doc/usage/index.rst

@@ -97,6 +97,7 @@ Shell commands
    cmd/trace
    cmd/true
    cmd/ums
+   cmd/unbind
    cmd/ut
    cmd/wdt
    cmd/wget