media: atmel: atmel-isc-base: expose white balance as v4l2 controls

This exposes the white balance configuration of the ISC as v4l2 controls
into userspace.
There are 8 controls available:
4 gain controls, sliders, for each of the BAYER components: R, B, GR, GB.
These gains are multipliers for each component, in format unsigned 0:4:9
with a default value of 512 (1.0 multiplier).
4 offset controls, sliders, for each of the BAYER components: R, B, GR, GB.
These offsets are added/substracted from each component, in format signed
1:12:0 with a default value of 0 (+/- 0)

To expose this to userspace, added 8 custom controls, in an auto cluster.

To summarize the functionality:
The auto cluster switch is the auto white balance control, and it works
like this:
AWB == 1: autowhitebalance is on, the do_white_balance button is inactive,
the gains/offsets are inactive, but volatile and readable.
Thus, the results of the whitebalance algorithm are available to userspace
to read at any time.
AWB == 0: autowhitebalance is off, cluster is in manual mode, user can
configure the gain/offsets directly. More than that, if the
do_white_balance button is pressed, the driver will perform
one-time-adjustment, (preferably with color checker card) and the userspace
can read again the new values.

With this feature, the userspace can save the coefficients and reinstall
them for example after reboot or reprobing the driver.

[hverkuil: fix checkpatch warning]
[hverkuil: minor spacing adjustments in the functionality description]
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/atmel/atmel-isc.h

@@ -213,7 +213,6 @@ struct isc_device {
 	struct fmt_config	try_config;
 
 	struct isc_ctrls	ctrls;
-	struct v4l2_ctrl	*do_wb_ctrl;
 	struct work_struct	awb_work;
 
 	struct mutex		lock; /* serialize access to file operations */
@@ -223,6 +222,28 @@ struct isc_device {
 
 	struct isc_subdev_entity	*current_subdev;
 	struct list_head		subdev_entities;
+
+	struct {
+#define ISC_CTRL_DO_WB 1
+#define ISC_CTRL_R_GAIN 2
+#define ISC_CTRL_B_GAIN 3
+#define ISC_CTRL_GR_GAIN 4
+#define ISC_CTRL_GB_GAIN 5
+#define ISC_CTRL_R_OFF 6
+#define ISC_CTRL_B_OFF 7
+#define ISC_CTRL_GR_OFF 8
+#define ISC_CTRL_GB_OFF 9
+		struct v4l2_ctrl	*awb_ctrl;
+		struct v4l2_ctrl	*do_wb_ctrl;
+		struct v4l2_ctrl	*r_gain_ctrl;
+		struct v4l2_ctrl	*b_gain_ctrl;
+		struct v4l2_ctrl	*gr_gain_ctrl;
+		struct v4l2_ctrl	*gb_gain_ctrl;
+		struct v4l2_ctrl	*r_off_ctrl;
+		struct v4l2_ctrl	*b_off_ctrl;
+		struct v4l2_ctrl	*gr_off_ctrl;
+		struct v4l2_ctrl	*gb_off_ctrl;
+	};
 };
 
 #define GAMMA_MAX	2

include/linux/atmel-isc-media.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2019 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Eugen Hristev <eugen.hristev@microchip.com>
+ */
+
+#ifndef __LINUX_ATMEL_ISC_MEDIA_H__
+#define __LINUX_ATMEL_ISC_MEDIA_H__
+
+/*
+ * There are 8 controls available:
+ * 4 gain controls, sliders, for each of the BAYER components: R, B, GR, GB.
+ * These gains are multipliers for each component, in format unsigned 0:4:9 with
+ * a default value of 512 (1.0 multiplier).
+ * 4 offset controls, sliders, for each of the BAYER components: R, B, GR, GB.
+ * These offsets are added/substracted from each component, in format signed
+ * 1:12:0 with a default value of 0 (+/- 0)
+ *
+ * To expose this to userspace, added 8 custom controls, in an auto cluster.
+ *
+ * To summarize the functionality:
+ * The auto cluster switch is the auto white balance control, and it works
+ * like this:
+ * AWB == 1: autowhitebalance is on, the do_white_balance button is inactive,
+ * the gains/offsets are inactive, but volatile and readable.
+ * Thus, the results of the whitebalance algorithm are available to userspace to
+ * read at any time.
+ * AWB == 0: autowhitebalance is off, cluster is in manual mode, user can
+ * configure the gain/offsets directly.
+ * More than that, if the do_white_balance button is
+ * pressed, the driver will perform one-time-adjustment, (preferably with color
+ * checker card) and the userspace can read again the new values.
+ *
+ * With this feature, the userspace can save the coefficients and reinstall them
+ * for example after reboot or reprobing the driver.
+ */
+
+enum atmel_isc_ctrl_id {
+	/* Red component gain control */
+	ISC_CID_R_GAIN = (V4L2_CID_USER_ATMEL_ISC_BASE + 0),
+	/* Blue component gain control */
+	ISC_CID_B_GAIN,
+	/* Green Red component gain control */
+	ISC_CID_GR_GAIN,
+	/* Green Blue gain control */
+	ISC_CID_GB_GAIN,
+	/* Red component offset control */
+	ISC_CID_R_OFFSET,
+	/* Blue component offset control */
+	ISC_CID_B_OFFSET,
+	/* Green Red component offset control */
+	ISC_CID_GR_OFFSET,
+	/* Green Blue component offset control */
+	ISC_CID_GB_OFFSET,
+};
+
+#endif

include/uapi/linux/v4l2-controls.h

@@ -192,6 +192,12 @@ enum v4l2_colorfx {
  * We reserve 16 controls for this driver. */
 #define V4L2_CID_USER_IMX_BASE			(V4L2_CID_USER_BASE + 0x10b0)
 
+/*
+ * The base for the atmel isc driver controls.
+ * We reserve 32 controls for this driver.
+ */
+#define V4L2_CID_USER_ATMEL_ISC_BASE		(V4L2_CID_USER_BASE + 0x10c0)
+
 /* MPEG-class control IDs */
 /* The MPEG controls are applicable to all codec controls
  * and the 'MPEG' part of the define is historical */