devices: imx708: Add a new IMX708 helper class

This class provides a convenient helper function set enable/disable
sensor HDR mode without relying on external tools. Usage example:

-----
from picamera2.devices.imx708 import IMX708
from picamera2 import Picamera2

camera_num = 0
c = IMX708(camera_num)
c.set_hdr_mode(True)
picam2 = Picamera2(camera_num)
-----

Note that after calling IMX708.set_hdr_mode(), you must re-initialise
the Picamera2 instance.

A change to the CameraManager class is also needed to allow it to be
reset as it caches sensor modes internally in libcamera.

Signed-off-by: Naushir Patuck <[email protected]>

picamera2/devices/imx708/__init__.py

@@ -0,0 +1 @@
+from .imx708 import IMX708

picamera2/devices/imx708/imx708.py

@@ -0,0 +1,54 @@
+import fcntl
+import libcamera
+import os
+
+from picamera2 import Picamera2
+from v4l2 import *
+
+HDR_CTRL_ID = 0x009a0915
+
+
+class IMX708:
+    def __init__(self, camera_num: int):
+        self.device_fd = None
+
+        camera_id = None
+        for c in Picamera2.global_camera_info():
+            if c['Num'] == camera_num:
+                camera_id = c['Id']
+
+        if camera_id is None:
+            raise RuntimeError('IMX708: Requested camera number {camera_num} cound not be found')
+
+        for i in range(16):
+            test_dir = f'/sys/class/video4linux/v4l-subdev{i}/device'
+            module_dir = f'{test_dir}/driver/module'
+            id_dir = f'{test_dir}/of_node'
+            if os.path.exists(module_dir) and os.path.islink(module_dir) and 'imx708' in os.readlink(module_dir):
+                if os.path.islink(id_dir) and camera_id in os.readlink(id_dir):
+                    self.device_fd = open(f'/dev/v4l-subdev{i}', 'rb+', buffering=0)
+                    break
+
+        if self.device_fd is None:
+            raise RuntimeError('IMX708: Requested camera device node not found')
+
+    def __del__(self):
+        if self.device_fd:
+            self.device_fd.close()
+
+    def set_hdr_mode(self, enable: bool):
+        """
+        Set the HDR mode (True/False) on the IMX708 device. Note that after changing the HDR mode, you must re-initialise
+        the Picamera2 object to cache the updated sensor modes.
+        """
+        ctrl = v4l2_control()
+        ctrl.id = HDR_CTRL_ID
+        ctrl.value = int(enable)
+
+        try:
+            fcntl.ioctl(self.device_fd, VIDIOC_S_CTRL, ctrl)
+        except OSError as err:
+            print(f'IMX708: Unable to set HDR control in the device node: {err}')
+
+        # Re-initialise the camera manager as it (also) caches sensor modes.
+        Picamera2._cm.reset()

picamera2/picamera2.py

@@ -69,6 +69,11 @@ def cms(self):
             self._cms = libcamera.CameraManager.singleton()
         return self._cms
 
+    def reset(self):
+        with self._lock:
+            self._cms = None
+            self._cms = libcamera.CameraManager.singleton()
+
     def add(self, index, camera):
         with self._lock:
             self.cameras[index] = camera

setup.py

@@ -30,7 +30,8 @@
         "Programming Language :: Python :: 3.9",
         "Topic :: Multimedia :: Graphics :: Capture :: Digital Camera",
     ],
-    packages=['picamera2', 'picamera2.encoders', 'picamera2.outputs', 'picamera2.previews', 'picamera2.allocators'],
+    packages=['picamera2', 'picamera2.devices.imx708', 'picamera2.encoders', 'picamera2.outputs', 'picamera2.previews',
+              'picamera2.allocators'],
     python_requires='>=3.9',
     licence='BSD 2-Clause License',
     install_requires=['numpy', 'PiDNG', 'piexif', 'pillow', 'simplejpeg', 'v4l2-python3', 'python-prctl', 'av'],