[PATCH v6 1/5] media: v4l2-core: Make the v4l2-core code enable/disable the privacy LED if present

[Hans de Goede <hdegoede@redhat.com>]

Make v4l2_async_register_subdev_sensor() try to get a privacy LED
associated with the sensor and extend the call_s_stream() wrapper to
enable/disable the privacy LED if found.

This makes the core handle privacy LED control, rather then having to
duplicate this code in all the sensor drivers.

Suggested-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v6:
- Add v4l2_subdev_privacy_led_get()/_put() helpers
- At least the _put helper is necessary for cleanup on errors later on in
  v4l2_async_register_subdev_sensor()
- This puts all the LED related coded into a single file (v4l2-subdev.c)
  removing the need to build the async + fwnode code into videodev.ko,
  so that patch is dropped
- Move the (non-error-exit) cleanup from v4l2_subdev_cleanup() to
   v4l2_async_unregister_subdev()

Changes in v4 (requested by Laurent Pinchart):
- Move the led_get() call to v4l2_async_register_subdev_sensor() and
  make errors other then -ENOENT fail the register() call.
- Move the led_disable_sysfs() call to be done at led_get() time, instead
  of only disabling the sysfs interface when the sensor is streaming.
---
 drivers/media/v4l2-core/v4l2-async.c       |  4 ++
 drivers/media/v4l2-core/v4l2-fwnode.c      |  7 ++++
 drivers/media/v4l2-core/v4l2-subdev-priv.h | 14 +++++++
 drivers/media/v4l2-core/v4l2-subdev.c      | 44 ++++++++++++++++++++++
 include/media/v4l2-subdev.h                |  3 ++
 5 files changed, 72 insertions(+)
 create mode 100644 drivers/media/v4l2-core/v4l2-subdev-priv.h

diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index 2f1b718a9189..d7e9ffc7aa23 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -24,6 +24,8 @@
 #include <media/v4l2-fwnode.h>
 #include <media/v4l2-subdev.h>
 
+#include "v4l2-subdev-priv.h"
+
 static int v4l2_async_nf_call_bound(struct v4l2_async_notifier *n,
 				    struct v4l2_subdev *subdev,
 				    struct v4l2_async_subdev *asd)
@@ -822,6 +824,8 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
 	if (!sd->async_list.next)
 		return;
 
+	v4l2_subdev_put_privacy_led(sd);
+
 	mutex_lock(&list_lock);
 
 	__v4l2_async_nf_unregister(sd->subdev_notifier);
diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
index 3d9533c1b202..049c2f2001ea 100644
--- a/drivers/media/v4l2-core/v4l2-fwnode.c
+++ b/drivers/media/v4l2-core/v4l2-fwnode.c
@@ -28,6 +28,8 @@
 #include <media/v4l2-fwnode.h>
 #include <media/v4l2-subdev.h>
 
+#include "v4l2-subdev-priv.h"
+
 static const struct v4l2_fwnode_bus_conv {
 	enum v4l2_fwnode_bus_type fwnode_bus_type;
 	enum v4l2_mbus_type mbus_type;
@@ -1302,6 +1304,10 @@ int v4l2_async_register_subdev_sensor(struct v4l2_subdev *sd)
 
 	v4l2_async_nf_init(notifier);
 
+	ret = v4l2_subdev_get_privacy_led(sd);
+	if (ret < 0)
+		goto out_cleanup;
+
 	ret = v4l2_async_nf_parse_fwnode_sensor(sd->dev, notifier);
 	if (ret < 0)
 		goto out_cleanup;
@@ -1322,6 +1328,7 @@ int v4l2_async_register_subdev_sensor(struct v4l2_subdev *sd)
 	v4l2_async_nf_unregister(notifier);
 
 out_cleanup:
+	v4l2_subdev_put_privacy_led(sd);
 	v4l2_async_nf_cleanup(notifier);
 	kfree(notifier);
 
diff --git a/drivers/media/v4l2-core/v4l2-subdev-priv.h b/drivers/media/v4l2-core/v4l2-subdev-priv.h
new file mode 100644
index 000000000000..52391d6d8ab7
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-subdev-priv.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * V4L2 sub-device pivate header.
+ *
+ * Copyright (C) 2023 Hans de Goede <hdegoede@redhat.com>
+ */
+
+#ifndef _V4L2_SUBDEV_PRIV_H_
+#define _V4L2_SUBDEV_PRIV_H_
+
+int v4l2_subdev_get_privacy_led(struct v4l2_subdev *sd);
+void v4l2_subdev_put_privacy_led(struct v4l2_subdev *sd);
+
+#endif
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 4988a25bd8f4..9fd183628285 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/ioctl.h>
+#include <linux/leds.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -23,6 +24,8 @@
 #include <media/v4l2-fh.h>
 #include <media/v4l2-event.h>
 
+#include "v4l2-subdev-priv.h"
+
 #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
 static int subdev_fh_init(struct v4l2_subdev_fh *fh, struct v4l2_subdev *sd)
 {
@@ -322,6 +325,14 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
 {
 	int ret;
 
+#if IS_REACHABLE(CONFIG_LEDS_CLASS)
+	if (!IS_ERR_OR_NULL(sd->privacy_led)) {
+		if (enable)
+			led_set_brightness(sd->privacy_led, sd->privacy_led->max_brightness);
+		else
+			led_set_brightness(sd->privacy_led, 0);
+	}
+#endif
 	ret = sd->ops->video->s_stream(sd, enable);
 
 	if (!enable && ret < 0) {
@@ -1090,6 +1101,7 @@ void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)
 	sd->grp_id = 0;
 	sd->dev_priv = NULL;
 	sd->host_priv = NULL;
+	sd->privacy_led = NULL;
 #if defined(CONFIG_MEDIA_CONTROLLER)
 	sd->entity.name = sd->name;
 	sd->entity.obj_type = MEDIA_ENTITY_TYPE_V4L2_SUBDEV;
@@ -1105,3 +1117,35 @@ void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
 	v4l2_subdev_notify(sd, V4L2_DEVICE_NOTIFY_EVENT, (void *)ev);
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_notify_event);
+
+int v4l2_subdev_get_privacy_led(struct v4l2_subdev *sd)
+{
+#if IS_REACHABLE(CONFIG_LEDS_CLASS)
+	sd->privacy_led = led_get(sd->dev, "privacy-led");
+	if (IS_ERR(sd->privacy_led) && PTR_ERR(sd->privacy_led) != -ENOENT)
+		return dev_err_probe(sd->dev, PTR_ERR(sd->privacy_led), "getting privacy LED\n");
+
+	if (!IS_ERR_OR_NULL(sd->privacy_led)) {
+		mutex_lock(&sd->privacy_led->led_access);
+		led_sysfs_disable(sd->privacy_led);
+		led_trigger_remove(sd->privacy_led);
+		led_set_brightness(sd->privacy_led, 0);
+		mutex_unlock(&sd->privacy_led->led_access);
+	}
+#endif
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_get_privacy_led);
+
+void v4l2_subdev_put_privacy_led(struct v4l2_subdev *sd)
+{
+#if IS_REACHABLE(CONFIG_LEDS_CLASS)
+	if (!IS_ERR_OR_NULL(sd->privacy_led)) {
+		mutex_lock(&sd->privacy_led->led_access);
+		led_sysfs_enable(sd->privacy_led);
+		mutex_unlock(&sd->privacy_led->led_access);
+		led_put(sd->privacy_led);
+	}
+#endif
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_put_privacy_led);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index b15fa9930f30..0547313f98cc 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -38,6 +38,7 @@ struct v4l2_subdev;
 struct v4l2_subdev_fh;
 struct tuner_setup;
 struct v4l2_mbus_frame_desc;
+struct led_classdev;
 
 /**
  * struct v4l2_decode_vbi_line - used to decode_vbi_line
@@ -982,6 +983,8 @@ struct v4l2_subdev {
 	 * appropriate functions.
 	 */
 
+	struct led_classdev *privacy_led;
+
 	/*
 	 * TODO: active_state should most likely be changed from a pointer to an
 	 * embedded field. For the time being it's kept as a pointer to more
-- 
2.39.1