media: Add registration helpers for V4L2 flash sub-devices

This patch adds helper functions for registering/unregistering
LED Flash class devices as V4L2 sub-devices. The functions should
be called from the LED subsystem device driver. In case the
support for V4L2 Flash sub-devices is disabled in the kernel
config the functions' empty versions will be used.
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/media/v4l2-core/Kconfig

@@ -44,6 +44,17 @@ config V4L2_MEM2MEM_DEV
         tristate
         depends on VIDEOBUF2_CORE
 
+# Used by LED subsystem flash drivers
+config V4L2_FLASH_LED_CLASS
+	tristate "V4L2 flash API for LED flash class devices"
+	depends on VIDEO_V4L2_SUBDEV_API
+	depends on LEDS_CLASS_FLASH
+	---help---
+	  Say Y here to enable V4L2 flash API support for LED flash
+	  class drivers.
+
+	  When in doubt, say N.
+
 # Used by drivers that need Videobuf modules
 config VIDEOBUF_GEN
 	tristate

drivers/media/v4l2-core/Makefile

@@ -22,6 +22,8 @@ obj-$(CONFIG_VIDEO_TUNER) += tuner.o
 
 obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
 
+obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o
+
 obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
 obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o
 obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o

include/media/v4l2-flash-led-class.h

+/*
+ * V4L2 flash LED sub-device registration helpers.
+ *
+ *	Copyright (C) 2015 Samsung Electronics Co., Ltd
+ *	Author: Jacek Anaszewski <j.anaszewski@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _V4L2_FLASH_H
+#define _V4L2_FLASH_H
+
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-subdev.h>
+
+struct led_classdev_flash;
+struct led_classdev;
+struct v4l2_flash;
+enum led_brightness;
+
+/*
+ * struct v4l2_flash_ctrl_data - flash control initialization data, filled
+ *				basing on the features declared by the LED flash
+ *				class driver in the v4l2_flash_config
+ * @config:	initialization data for a control
+ * @cid:	contains v4l2 flash control id if the config
+ *		field was initialized, 0 otherwise
+ */
+struct v4l2_flash_ctrl_data {
+	struct v4l2_ctrl_config config;
+	u32 cid;
+};
+
+struct v4l2_flash_ops {
+	/* setup strobing the flash by hardware pin state assertion */
+	int (*external_strobe_set)(struct v4l2_flash *v4l2_flash,
+					bool enable);
+	/* convert intensity to brightness in a device specific manner */
+	enum led_brightness (*intensity_to_led_brightness)
+		(struct v4l2_flash *v4l2_flash, s32 intensity);
+	/* convert brightness to intensity in a device specific manner */
+	s32 (*led_brightness_to_intensity)
+		(struct v4l2_flash *v4l2_flash, enum led_brightness);
+};
+
+/**
+ * struct v4l2_flash_config - V4L2 Flash sub-device initialization data
+ * @dev_name:			the name of the media entity,
+				unique in the system
+ * @torch_intensity:		constraints for the LED in torch mode
+ * @indicator_intensity:	constraints for the indicator LED
+ * @flash_faults:		bitmask of flash faults that the LED flash class
+				device can report; corresponding LED_FAULT* bit
+				definitions are available in the header file
+				<linux/led-class-flash.h>
+ * @has_external_strobe:	external strobe capability
+ */
+struct v4l2_flash_config {
+	char dev_name[32];
+	struct led_flash_setting torch_intensity;
+	struct led_flash_setting indicator_intensity;
+	u32 flash_faults;
+	unsigned int has_external_strobe:1;
+};
+
+/**
+ * struct v4l2_flash - Flash sub-device context
+ * @fled_cdev:		LED flash class device controlled by this sub-device
+ * @iled_cdev:		LED class device representing indicator LED associated
+ *			with the LED flash class device
+ * @ops:		V4L2 specific flash ops
+ * @sd:			V4L2 sub-device
+ * @hdl:		flash controls handler
+ * @ctrls:		array of pointers to controls, whose values define
+ *			the sub-device state
+ */
+struct v4l2_flash {
+	struct led_classdev_flash *fled_cdev;
+	struct led_classdev_flash *iled_cdev;
+	const struct v4l2_flash_ops *ops;
+
+	struct v4l2_subdev sd;
+	struct v4l2_ctrl_handler hdl;
+	struct v4l2_ctrl **ctrls;
+};
+
+static inline struct v4l2_flash *v4l2_subdev_to_v4l2_flash(
+							struct v4l2_subdev *sd)
+{
+	return container_of(sd, struct v4l2_flash, sd);
+}
+
+static inline struct v4l2_flash *v4l2_ctrl_to_v4l2_flash(struct v4l2_ctrl *c)
+{
+	return container_of(c->handler, struct v4l2_flash, hdl);
+}
+
+#if IS_ENABLED(CONFIG_V4L2_FLASH_LED_CLASS)
+/**
+ * v4l2_flash_init - initialize V4L2 flash led sub-device
+ * @dev:	flash device, e.g. an I2C device
+ * @of_node:	of_node of the LED, may be NULL if the same as device's
+ * @fled_cdev:	LED flash class device to wrap
+ * @iled_cdev:	LED flash class device representing indicator LED associated
+ *		with fled_cdev, may be NULL
+ * @flash_ops:	V4L2 Flash device ops
+ * @config:	initialization data for V4L2 Flash sub-device
+ *
+ * Create V4L2 Flash sub-device wrapping given LED subsystem device.
+ *
+ * Returns: A valid pointer, or, when an error occurs, the return
+ * value is encoded using ERR_PTR(). Use IS_ERR() to check and
+ * PTR_ERR() to obtain the numeric return value.
+ */
+struct v4l2_flash *v4l2_flash_init(
+	struct device *dev, struct device_node *of_node,
+	struct led_classdev_flash *fled_cdev,
+	struct led_classdev_flash *iled_cdev,
+	const struct v4l2_flash_ops *ops,
+	struct v4l2_flash_config *config);
+
+/**
+ * v4l2_flash_release - release V4L2 Flash sub-device
+ * @flash: the V4L2 Flash sub-device to release
+ *
+ * Release V4L2 Flash sub-device.
+ */
+void v4l2_flash_release(struct v4l2_flash *v4l2_flash);
+
+#else
+static inline struct v4l2_flash *v4l2_flash_init(
+	struct device *dev, struct device_node *of_node,
+	struct led_classdev_flash *fled_cdev,
+	struct led_classdev_flash *iled_cdev,
+	const struct v4l2_flash_ops *ops,
+	struct v4l2_flash_config *config)
+{
+	return NULL;
+}
+
+static inline void v4l2_flash_release(struct v4l2_flash *v4l2_flash)
+{
+}
+#endif /* CONFIG_V4L2_FLASH_LED_CLASS */
+
+#endif /* _V4L2_FLASH_H */