drivers/gpu/drm/drm_color_mgmt.c - third_party/kernel - Git at Google

 /*
  * Copyright (c) 2016 Intel Corporation
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that copyright
  * notice and this permission notice appear in supporting documentation, and
  * that the name of the copyright holders not be used in advertising or
  * publicity pertaining to distribution of the software without specific,
  * written prior permission.  The copyright holders make no representations
  * about the suitability of this software for any purpose.  It is provided "as
  * is" without express or implied warranty.
  *
  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  * OF THIS SOFTWARE.
  */

 #include <linux/uaccess.h>

 #include <drm/drm_color_mgmt.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_print.h>

 #include "drm_crtc_internal.h"

 /**
  * DOC: overview
  *
  * Color management or color space adjustments is supported through a set of 5
  * properties on the &drm_crtc object. They are set up by calling
  * drm_crtc_enable_color_mgmt().
  *
  * "DEGAMMA_LUT”:
  *	Blob property to set the degamma lookup table (LUT) mapping pixel data
  *	from the framebuffer before it is given to the transformation matrix.
  *	The data is interpreted as an array of &struct drm_color_lut elements.
  *	Hardware might choose not to use the full precision of the LUT elements
  *	nor use all the elements of the LUT (for example the hardware might
  *	choose to interpolate between LUT[0] and LUT[4]).
  *
  *	Setting this to NULL (blob property value set to 0) means a
  *	linear/pass-thru gamma table should be used. This is generally the
  *	driver boot-up state too. Drivers can access this blob through
  *	&drm_crtc_state.degamma_lut.
  *
  * “DEGAMMA_LUT_SIZE”:
  *	Unsinged range property to give the size of the lookup table to be set
  *	on the DEGAMMA_LUT property (the size depends on the underlying
  *	hardware). If drivers support multiple LUT sizes then they should
  *	publish the largest size, and sub-sample smaller sized LUTs (e.g. for
  *	split-gamma modes) appropriately.
  *
  * “CTM”:
  *	Blob property to set the current transformation matrix (CTM) apply to
  *	pixel data after the lookup through the degamma LUT and before the
  *	lookup through the gamma LUT. The data is interpreted as a struct
  *	&drm_color_ctm.
  *
  *	Setting this to NULL (blob property value set to 0) means a
  *	unit/pass-thru matrix should be used. This is generally the driver
  *	boot-up state too. Drivers can access the blob for the color conversion
  *	matrix through &drm_crtc_state.ctm.
  *
  * “GAMMA_LUT”:
  *	Blob property to set the gamma lookup table (LUT) mapping pixel data
  *	after the transformation matrix to data sent to the connector. The
  *	data is interpreted as an array of &struct drm_color_lut elements.
  *	Hardware might choose not to use the full precision of the LUT elements
  *	nor use all the elements of the LUT (for example the hardware might
  *	choose to interpolate between LUT[0] and LUT[4]).
  *
  *	Setting this to NULL (blob property value set to 0) means a
  *	linear/pass-thru gamma table should be used. This is generally the
  *	driver boot-up state too. Drivers can access this blob through
  *	&drm_crtc_state.gamma_lut.
  *
  * “GAMMA_LUT_SIZE”:
  *	Unsigned range property to give the size of the lookup table to be set
  *	on the GAMMA_LUT property (the size depends on the underlying hardware).
  *	If drivers support multiple LUT sizes then they should publish the
  *	largest size, and sub-sample smaller sized LUTs (e.g. for split-gamma
  *	modes) appropriately.
  *
  * There is also support for a legacy gamma table, which is set up by calling
  * drm_mode_crtc_set_gamma_size(). Drivers which support both should use
  * drm_atomic_helper_legacy_gamma_set() to alias the legacy gamma ramp with the
  * "GAMMA_LUT" property above.
  *
  * Support for different non RGB color encodings is controlled through
  * &drm_plane specific COLOR_ENCODING and COLOR_RANGE properties. They
  * are set up by calling drm_plane_create_color_properties().
  *
  * "COLOR_ENCODING"
  * 	Optional plane enum property to support different non RGB
  * 	color encodings. The driver can provide a subset of standard
  * 	enum values supported by the DRM plane.
  *
  * "COLOR_RANGE"
  * 	Optional plane enum property to support different non RGB
  * 	color parameter ranges. The driver can provide a subset of
  * 	standard enum values supported by the DRM plane.
  */

 /**
  * drm_color_lut_extract - clamp and round LUT entries
  * @user_input: input value
  * @bit_precision: number of bits the hw LUT supports
  *
  * Extract a degamma/gamma LUT value provided by user (in the form of
  * &drm_color_lut entries) and round it to the precision supported by the
  * hardware.
  */
 uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision)
 {
 	uint32_t val = user_input;
 	uint32_t max = 0xffff >> (16 - bit_precision);

 	/* Round only if we're not using full precision. */
 	if (bit_precision < 16) {
 		val += 1UL << (16 - bit_precision - 1);
 		val >>= 16 - bit_precision;
 	}

 	return clamp_val(val, 0, max);
 }
 EXPORT_SYMBOL(drm_color_lut_extract);

 /**
  * drm_crtc_enable_color_mgmt - enable color management properties
  * @crtc: DRM CRTC
  * @degamma_lut_size: the size of the degamma lut (before CSC)
  * @has_ctm: whether to attach ctm_property for CSC matrix
  * @gamma_lut_size: the size of the gamma lut (after CSC)
  *
  * This function lets the driver enable the color correction
  * properties on a CRTC. This includes 3 degamma, csc and gamma
  * properties that userspace can set and 2 size properties to inform
  * the userspace of the lut sizes. Each of the properties are
  * optional. The gamma and degamma properties are only attached if
  * their size is not 0 and ctm_property is only attached if has_ctm is
  * true.
  *
  * Drivers should use drm_atomic_helper_legacy_gamma_set() to implement the
  * legacy &drm_crtc_funcs.gamma_set callback.
  */
 void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
 				uint degamma_lut_size,
 				bool has_ctm,
 				uint gamma_lut_size)
 {
 	struct drm_device *dev = crtc->dev;
 	struct drm_mode_config *config = &dev->mode_config;

 	if (degamma_lut_size) {
 		drm_object_attach_property(&crtc->base,
 					   config->degamma_lut_property, 0);
 		drm_object_attach_property(&crtc->base,
 					   config->degamma_lut_size_property,
 					   degamma_lut_size);
 	}

 	if (has_ctm)
 		drm_object_attach_property(&crtc->base,
 					   config->ctm_property, 0);

 	if (gamma_lut_size) {
 		drm_object_attach_property(&crtc->base,
 					   config->gamma_lut_property, 0);
 		drm_object_attach_property(&crtc->base,
 					   config->gamma_lut_size_property,
 					   gamma_lut_size);
 	}
 }
 EXPORT_SYMBOL(drm_crtc_enable_color_mgmt);

 /**
  * drm_mode_crtc_set_gamma_size - set the gamma table size
  * @crtc: CRTC to set the gamma table size for
  * @gamma_size: size of the gamma table
  *
  * Drivers which support gamma tables should set this to the supported gamma
  * table size when initializing the CRTC. Currently the drm core only supports a
  * fixed gamma table size.
  *
  * Returns:
  * Zero on success, negative errno on failure.
  */
 int drm_mode_crtc_set_gamma_size(struct drm_crtc *crtc,
 				 int gamma_size)
 {
 	uint16_t *r_base, *g_base, *b_base;
 	int i;

 	crtc->gamma_size = gamma_size;

 	crtc->gamma_store = kcalloc(gamma_size, sizeof(uint16_t) * 3,
 				    GFP_KERNEL);
 	if (!crtc->gamma_store) {
 		crtc->gamma_size = 0;
 		return -ENOMEM;
 	}

 	r_base = crtc->gamma_store;
 	g_base = r_base + gamma_size;
 	b_base = g_base + gamma_size;
 	for (i = 0; i < gamma_size; i++) {
 		r_base[i] = i << 8;
 		g_base[i] = i << 8;
 		b_base[i] = i << 8;
 	}


 	return 0;
 }
 EXPORT_SYMBOL(drm_mode_crtc_set_gamma_size);

 /**
  * drm_mode_gamma_set_ioctl - set the gamma table
  * @dev: DRM device
  * @data: ioctl data
  * @file_priv: DRM file info
  *
  * Set the gamma table of a CRTC to the one passed in by the user. Userspace can
  * inquire the required gamma table size through drm_mode_gamma_get_ioctl.
  *
  * Called by the user via ioctl.
  *
  * Returns:
  * Zero on success, negative errno on failure.
  */
 int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 			     void *data, struct drm_file *file_priv)
 {
 	struct drm_mode_crtc_lut *crtc_lut = data;
 	struct drm_crtc *crtc;
 	void *r_base, *g_base, *b_base;
 	int size;
 	struct drm_modeset_acquire_ctx ctx;
 	int ret = 0;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return -EOPNOTSUPP;

 	crtc = drm_crtc_find(dev, file_priv, crtc_lut->crtc_id);
 	if (!crtc)
 		return -ENOENT;

 	if (crtc->funcs->gamma_set == NULL)
 		return -ENOSYS;

 	/* memcpy into gamma store */
 	if (crtc_lut->gamma_size != crtc->gamma_size)
 		return -EINVAL;

 	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);

 	size = crtc_lut->gamma_size * (sizeof(uint16_t));
 	r_base = crtc->gamma_store;
 	if (copy_from_user(r_base, (void __user *)(unsigned long)crtc_lut->red, size)) {
 		ret = -EFAULT;
 		goto out;
 	}

 	g_base = r_base + size;
 	if (copy_from_user(g_base, (void __user *)(unsigned long)crtc_lut->green, size)) {
 		ret = -EFAULT;
 		goto out;
 	}

 	b_base = g_base + size;
 	if (copy_from_user(b_base, (void __user *)(unsigned long)crtc_lut->blue, size)) {
 		ret = -EFAULT;
 		goto out;
 	}

 	ret = crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
 				     crtc->gamma_size, &ctx);

 out:
 	DRM_MODESET_LOCK_ALL_END(ctx, ret);
 	return ret;

 }

 /**
  * drm_mode_gamma_get_ioctl - get the gamma table
  * @dev: DRM device
  * @data: ioctl data
  * @file_priv: DRM file info
  *
  * Copy the current gamma table into the storage provided. This also provides
  * the gamma table size the driver expects, which can be used to size the
  * allocated storage.
  *
  * Called by the user via ioctl.
  *
  * Returns:
  * Zero on success, negative errno on failure.
  */
 int drm_mode_gamma_get_ioctl(struct drm_device *dev,
 			     void *data, struct drm_file *file_priv)
 {
 	struct drm_mode_crtc_lut *crtc_lut = data;
 	struct drm_crtc *crtc;
 	void *r_base, *g_base, *b_base;
 	int size;
 	int ret = 0;

 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return -EOPNOTSUPP;

 	crtc = drm_crtc_find(dev, file_priv, crtc_lut->crtc_id);
 	if (!crtc)
 		return -ENOENT;

 	/* memcpy into gamma store */
 	if (crtc_lut->gamma_size != crtc->gamma_size)
 		return -EINVAL;

 	drm_modeset_lock(&crtc->mutex, NULL);
 	size = crtc_lut->gamma_size * (sizeof(uint16_t));
 	r_base = crtc->gamma_store;
 	if (copy_to_user((void __user *)(unsigned long)crtc_lut->red, r_base, size)) {
 		ret = -EFAULT;
 		goto out;
 	}

 	g_base = r_base + size;
 	if (copy_to_user((void __user *)(unsigned long)crtc_lut->green, g_base, size)) {
 		ret = -EFAULT;
 		goto out;
 	}

 	b_base = g_base + size;
 	if (copy_to_user((void __user *)(unsigned long)crtc_lut->blue, b_base, size)) {
 		ret = -EFAULT;
 		goto out;
 	}
 out:
 	drm_modeset_unlock(&crtc->mutex);
 	return ret;
 }

 static const char * const color_encoding_name[] = {
 	[DRM_COLOR_YCBCR_BT601] = "ITU-R BT.601 YCbCr",
 	[DRM_COLOR_YCBCR_BT709] = "ITU-R BT.709 YCbCr",
 	[DRM_COLOR_YCBCR_BT2020] = "ITU-R BT.2020 YCbCr",
 };

 static const char * const color_range_name[] = {
 	[DRM_COLOR_YCBCR_FULL_RANGE] = "YCbCr full range",
 	[DRM_COLOR_YCBCR_LIMITED_RANGE] = "YCbCr limited range",
 };

 /**
  * drm_get_color_encoding_name - return a string for color encoding
  * @encoding: color encoding to compute name of
  *
  * In contrast to the other drm_get_*_name functions this one here returns a
  * const pointer and hence is threadsafe.
  */
 const char *drm_get_color_encoding_name(enum drm_color_encoding encoding)
 {
 	if (WARN_ON(encoding >= ARRAY_SIZE(color_encoding_name)))
 		return "unknown";

 	return color_encoding_name[encoding];
 }

 /**
  * drm_get_color_range_name - return a string for color range
  * @range: color range to compute name of
  *
  * In contrast to the other drm_get_*_name functions this one here returns a
  * const pointer and hence is threadsafe.
  */
 const char *drm_get_color_range_name(enum drm_color_range range)
 {
 	if (WARN_ON(range >= ARRAY_SIZE(color_range_name)))
 		return "unknown";

 	return color_range_name[range];
 }

 /**
  * drm_plane_create_color_properties - color encoding related plane properties
  * @plane: plane object
  * @supported_encodings: bitfield indicating supported color encodings
  * @supported_ranges: bitfileld indicating supported color ranges
  * @default_encoding: default color encoding
  * @default_range: default color range
  *
  * Create and attach plane specific COLOR_ENCODING and COLOR_RANGE
  * properties to @plane. The supported encodings and ranges should
  * be provided in supported_encodings and supported_ranges bitmasks.
  * Each bit set in the bitmask indicates that its number as enum
  * value is supported.
  */
 int drm_plane_create_color_properties(struct drm_plane *plane,
 				      u32 supported_encodings,
 				      u32 supported_ranges,
 				      enum drm_color_encoding default_encoding,
 				      enum drm_color_range default_range)
 {
 	struct drm_device *dev = plane->dev;
 	struct drm_property *prop;
 	struct drm_prop_enum_list enum_list[max_t(int, DRM_COLOR_ENCODING_MAX,
 						       DRM_COLOR_RANGE_MAX)];
 	int i, len;

 	if (WARN_ON(supported_encodings == 0 ||
 		    (supported_encodings & -BIT(DRM_COLOR_ENCODING_MAX)) != 0 ||
 		    (supported_encodings & BIT(default_encoding)) == 0))
 		return -EINVAL;

 	if (WARN_ON(supported_ranges == 0 ||
 		    (supported_ranges & -BIT(DRM_COLOR_RANGE_MAX)) != 0 ||
 		    (supported_ranges & BIT(default_range)) == 0))
 		return -EINVAL;

 	len = 0;
 	for (i = 0; i < DRM_COLOR_ENCODING_MAX; i++) {
 		if ((supported_encodings & BIT(i)) == 0)
 			continue;

 		enum_list[len].type = i;
 		enum_list[len].name = color_encoding_name[i];
 		len++;
 	}

 	prop = drm_property_create_enum(dev, 0, "COLOR_ENCODING",
 					enum_list, len);
 	if (!prop)
 		return -ENOMEM;
 	plane->color_encoding_property = prop;
 	drm_object_attach_property(&plane->base, prop, default_encoding);
 	if (plane->state)
 		plane->state->color_encoding = default_encoding;

 	len = 0;
 	for (i = 0; i < DRM_COLOR_RANGE_MAX; i++) {
 		if ((supported_ranges & BIT(i)) == 0)
 			continue;

 		enum_list[len].type = i;
 		enum_list[len].name = color_range_name[i];
 		len++;
 	}

 	prop = drm_property_create_enum(dev, 0,	"COLOR_RANGE",
 					enum_list, len);
 	if (!prop)
 		return -ENOMEM;
 	plane->color_range_property = prop;
 	drm_object_attach_property(&plane->base, prop, default_range);
 	if (plane->state)
 		plane->state->color_range = default_range;

 	return 0;
 }
 EXPORT_SYMBOL(drm_plane_create_color_properties);

 /**
  * drm_color_lut_check - check validity of lookup table
  * @lut: property blob containing LUT to check
  * @tests: bitmask of tests to run
  *
  * Helper to check whether a userspace-provided lookup table is valid and
  * satisfies hardware requirements.  Drivers pass a bitmask indicating which of
  * the tests in &drm_color_lut_tests should be performed.
  *
  * Returns 0 on success, -EINVAL on failure.
  */
 int drm_color_lut_check(const struct drm_property_blob *lut, u32 tests)
 {
 	const struct drm_color_lut *entry;
 	int i;

 	if (!lut || !tests)
 		return 0;

 	entry = lut->data;
 	for (i = 0; i < drm_color_lut_size(lut); i++) {
 		if (tests & DRM_COLOR_LUT_EQUAL_CHANNELS) {
 			if (entry[i].red != entry[i].blue ||
 			    entry[i].red != entry[i].green) {
 				DRM_DEBUG_KMS("All LUT entries must have equal r/g/b\n");
 				return -EINVAL;
 			}
 		}

 		if (i > 0 && tests & DRM_COLOR_LUT_NON_DECREASING) {
 			if (entry[i].red < entry[i - 1].red ||
 			    entry[i].green < entry[i - 1].green ||
 			    entry[i].blue < entry[i - 1].blue) {
 				DRM_DEBUG_KMS("LUT entries must never decrease.\n");
 				return -EINVAL;
 			}
 		}
 	}

 	return 0;
 }
 EXPORT_SYMBOL(drm_color_lut_check);
	/*
	* Copyright (c) 2016 Intel Corporation
	*
	* Permission to use, copy, modify, distribute, and sell this software and its
	* documentation for any purpose is hereby granted without fee, provided that
	* the above copyright notice appear in all copies and that both that copyright
	* notice and this permission notice appear in supporting documentation, and
	* that the name of the copyright holders not be used in advertising or
	* publicity pertaining to distribution of the software without specific,
	* written prior permission. The copyright holders make no representations
	* about the suitability of this software for any purpose. It is provided "as
	* is" without express or implied warranty.
	*
	* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
	* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
	* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
	* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
	* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
	* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	* OF THIS SOFTWARE.
	*/

	#include <linux/uaccess.h>

	#include <drm/drm_color_mgmt.h>
	#include <drm/drm_crtc.h>
	#include <drm/drm_device.h>
	#include <drm/drm_drv.h>
	#include <drm/drm_print.h>

	#include "drm_crtc_internal.h"

	/**
	* DOC: overview
	*
	* Color management or color space adjustments is supported through a set of 5
	* properties on the &drm_crtc object. They are set up by calling
	* drm_crtc_enable_color_mgmt().
	*
	* "DEGAMMA_LUT”:
	* Blob property to set the degamma lookup table (LUT) mapping pixel data
	* from the framebuffer before it is given to the transformation matrix.
	* The data is interpreted as an array of &struct drm_color_lut elements.
	* Hardware might choose not to use the full precision of the LUT elements
	* nor use all the elements of the LUT (for example the hardware might
	* choose to interpolate between LUT[0] and LUT[4]).
	*
	* Setting this to NULL (blob property value set to 0) means a
	* linear/pass-thru gamma table should be used. This is generally the
	* driver boot-up state too. Drivers can access this blob through
	* &drm_crtc_state.degamma_lut.
	*
	* “DEGAMMA_LUT_SIZE”:
	* Unsinged range property to give the size of the lookup table to be set
	* on the DEGAMMA_LUT property (the size depends on the underlying
	* hardware). If drivers support multiple LUT sizes then they should
	* publish the largest size, and sub-sample smaller sized LUTs (e.g. for
	* split-gamma modes) appropriately.
	*
	* “CTM”:
	* Blob property to set the current transformation matrix (CTM) apply to
	* pixel data after the lookup through the degamma LUT and before the
	* lookup through the gamma LUT. The data is interpreted as a struct
	* &drm_color_ctm.
	*
	* Setting this to NULL (blob property value set to 0) means a
	* unit/pass-thru matrix should be used. This is generally the driver
	* boot-up state too. Drivers can access the blob for the color conversion
	* matrix through &drm_crtc_state.ctm.
	*
	* “GAMMA_LUT”:
	* Blob property to set the gamma lookup table (LUT) mapping pixel data
	* after the transformation matrix to data sent to the connector. The
	* data is interpreted as an array of &struct drm_color_lut elements.
	* Hardware might choose not to use the full precision of the LUT elements
	* nor use all the elements of the LUT (for example the hardware might
	* choose to interpolate between LUT[0] and LUT[4]).
	*
	* Setting this to NULL (blob property value set to 0) means a
	* linear/pass-thru gamma table should be used. This is generally the
	* driver boot-up state too. Drivers can access this blob through
	* &drm_crtc_state.gamma_lut.
	*
	* “GAMMA_LUT_SIZE”:
	* Unsigned range property to give the size of the lookup table to be set
	* on the GAMMA_LUT property (the size depends on the underlying hardware).
	* If drivers support multiple LUT sizes then they should publish the
	* largest size, and sub-sample smaller sized LUTs (e.g. for split-gamma
	* modes) appropriately.
	*
	* There is also support for a legacy gamma table, which is set up by calling
	* drm_mode_crtc_set_gamma_size(). Drivers which support both should use
	* drm_atomic_helper_legacy_gamma_set() to alias the legacy gamma ramp with the
	* "GAMMA_LUT" property above.
	*
	* Support for different non RGB color encodings is controlled through
	* &drm_plane specific COLOR_ENCODING and COLOR_RANGE properties. They
	* are set up by calling drm_plane_create_color_properties().
	*
	* "COLOR_ENCODING"
	* Optional plane enum property to support different non RGB
	* color encodings. The driver can provide a subset of standard
	* enum values supported by the DRM plane.
	*
	* "COLOR_RANGE"
	* Optional plane enum property to support different non RGB
	* color parameter ranges. The driver can provide a subset of
	* standard enum values supported by the DRM plane.
	*/

	/**
	* drm_color_lut_extract - clamp and round LUT entries
	* @user_input: input value
	* @bit_precision: number of bits the hw LUT supports
	*
	* Extract a degamma/gamma LUT value provided by user (in the form of
	* &drm_color_lut entries) and round it to the precision supported by the
	* hardware.
	*/
	uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision)
	{
	uint32_t val = user_input;
	uint32_t max = 0xffff >> (16 - bit_precision);

	/* Round only if we're not using full precision. */
	if (bit_precision < 16) {
	val += 1UL << (16 - bit_precision - 1);
	val >>= 16 - bit_precision;
	}

	return clamp_val(val, 0, max);
	}
	EXPORT_SYMBOL(drm_color_lut_extract);

	/**
	* drm_crtc_enable_color_mgmt - enable color management properties
	* @crtc: DRM CRTC
	* @degamma_lut_size: the size of the degamma lut (before CSC)
	* @has_ctm: whether to attach ctm_property for CSC matrix
	* @gamma_lut_size: the size of the gamma lut (after CSC)
	*
	* This function lets the driver enable the color correction
	* properties on a CRTC. This includes 3 degamma, csc and gamma
	* properties that userspace can set and 2 size properties to inform
	* the userspace of the lut sizes. Each of the properties are
	* optional. The gamma and degamma properties are only attached if
	* their size is not 0 and ctm_property is only attached if has_ctm is
	* true.
	*
	* Drivers should use drm_atomic_helper_legacy_gamma_set() to implement the
	* legacy &drm_crtc_funcs.gamma_set callback.
	*/
	void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
	uint degamma_lut_size,
	bool has_ctm,
	uint gamma_lut_size)
	{
	struct drm_device *dev = crtc->dev;
	struct drm_mode_config *config = &dev->mode_config;

	if (degamma_lut_size) {
	drm_object_attach_property(&crtc->base,
	config->degamma_lut_property, 0);
	drm_object_attach_property(&crtc->base,
	config->degamma_lut_size_property,
	degamma_lut_size);
	}

	if (has_ctm)
	drm_object_attach_property(&crtc->base,
	config->ctm_property, 0);

	if (gamma_lut_size) {
	drm_object_attach_property(&crtc->base,
	config->gamma_lut_property, 0);
	drm_object_attach_property(&crtc->base,
	config->gamma_lut_size_property,
	gamma_lut_size);
	}
	}
	EXPORT_SYMBOL(drm_crtc_enable_color_mgmt);

	/**
	* drm_mode_crtc_set_gamma_size - set the gamma table size
	* @crtc: CRTC to set the gamma table size for
	* @gamma_size: size of the gamma table
	*
	* Drivers which support gamma tables should set this to the supported gamma
	* table size when initializing the CRTC. Currently the drm core only supports a
	* fixed gamma table size.
	*
	* Returns:
	* Zero on success, negative errno on failure.
	*/
	int drm_mode_crtc_set_gamma_size(struct drm_crtc *crtc,
	int gamma_size)
	{
	uint16_t r_base, g_base, *b_base;
	int i;

	crtc->gamma_size = gamma_size;

	crtc->gamma_store = kcalloc(gamma_size, sizeof(uint16_t) * 3,
	GFP_KERNEL);
	if (!crtc->gamma_store) {
	crtc->gamma_size = 0;
	return -ENOMEM;
	}

	r_base = crtc->gamma_store;
	g_base = r_base + gamma_size;
	b_base = g_base + gamma_size;
	for (i = 0; i < gamma_size; i++) {
	r_base[i] = i << 8;
	g_base[i] = i << 8;
	b_base[i] = i << 8;
	}


	return 0;
	}
	EXPORT_SYMBOL(drm_mode_crtc_set_gamma_size);

	/**
	* drm_mode_gamma_set_ioctl - set the gamma table
	* @dev: DRM device
	* @data: ioctl data
	* @file_priv: DRM file info
	*
	* Set the gamma table of a CRTC to the one passed in by the user. Userspace can
	* inquire the required gamma table size through drm_mode_gamma_get_ioctl.
	*
	* Called by the user via ioctl.
	*
	* Returns:
	* Zero on success, negative errno on failure.
	*/
	int drm_mode_gamma_set_ioctl(struct drm_device *dev,
	void data, struct drm_file file_priv)
	{
	struct drm_mode_crtc_lut *crtc_lut = data;
	struct drm_crtc *crtc;
	void r_base, g_base, *b_base;
	int size;
	struct drm_modeset_acquire_ctx ctx;
	int ret = 0;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	return -EOPNOTSUPP;

	crtc = drm_crtc_find(dev, file_priv, crtc_lut->crtc_id);
	if (!crtc)
	return -ENOENT;

	if (crtc->funcs->gamma_set == NULL)
	return -ENOSYS;

	/* memcpy into gamma store */
	if (crtc_lut->gamma_size != crtc->gamma_size)
	return -EINVAL;

	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);

	size = crtc_lut->gamma_size * (sizeof(uint16_t));
	r_base = crtc->gamma_store;
	if (copy_from_user(r_base, (void __user *)(unsigned long)crtc_lut->red, size)) {
	ret = -EFAULT;
	goto out;
	}

	g_base = r_base + size;
	if (copy_from_user(g_base, (void __user *)(unsigned long)crtc_lut->green, size)) {
	ret = -EFAULT;
	goto out;
	}

	b_base = g_base + size;
	if (copy_from_user(b_base, (void __user *)(unsigned long)crtc_lut->blue, size)) {
	ret = -EFAULT;
	goto out;
	}

	ret = crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
	crtc->gamma_size, &ctx);

	out:
	DRM_MODESET_LOCK_ALL_END(ctx, ret);
	return ret;

	}

	/**
	* drm_mode_gamma_get_ioctl - get the gamma table
	* @dev: DRM device
	* @data: ioctl data
	* @file_priv: DRM file info
	*
	* Copy the current gamma table into the storage provided. This also provides
	* the gamma table size the driver expects, which can be used to size the
	* allocated storage.
	*
	* Called by the user via ioctl.
	*
	* Returns:
	* Zero on success, negative errno on failure.
	*/
	int drm_mode_gamma_get_ioctl(struct drm_device *dev,
	void data, struct drm_file file_priv)
	{
	struct drm_mode_crtc_lut *crtc_lut = data;
	struct drm_crtc *crtc;
	void r_base, g_base, *b_base;
	int size;
	int ret = 0;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
	return -EOPNOTSUPP;

	crtc = drm_crtc_find(dev, file_priv, crtc_lut->crtc_id);
	if (!crtc)
	return -ENOENT;

	/* memcpy into gamma store */
	if (crtc_lut->gamma_size != crtc->gamma_size)
	return -EINVAL;

	drm_modeset_lock(&crtc->mutex, NULL);
	size = crtc_lut->gamma_size * (sizeof(uint16_t));
	r_base = crtc->gamma_store;
	if (copy_to_user((void __user *)(unsigned long)crtc_lut->red, r_base, size)) {
	ret = -EFAULT;
	goto out;
	}

	g_base = r_base + size;
	if (copy_to_user((void __user *)(unsigned long)crtc_lut->green, g_base, size)) {
	ret = -EFAULT;
	goto out;
	}

	b_base = g_base + size;
	if (copy_to_user((void __user *)(unsigned long)crtc_lut->blue, b_base, size)) {
	ret = -EFAULT;
	goto out;
	}
	out:
	drm_modeset_unlock(&crtc->mutex);
	return ret;
	}

	static const char * const color_encoding_name[] = {
	[DRM_COLOR_YCBCR_BT601] = "ITU-R BT.601 YCbCr",
	[DRM_COLOR_YCBCR_BT709] = "ITU-R BT.709 YCbCr",
	[DRM_COLOR_YCBCR_BT2020] = "ITU-R BT.2020 YCbCr",
	};

	static const char * const color_range_name[] = {
	[DRM_COLOR_YCBCR_FULL_RANGE] = "YCbCr full range",
	[DRM_COLOR_YCBCR_LIMITED_RANGE] = "YCbCr limited range",
	};

	/**
	* drm_get_color_encoding_name - return a string for color encoding
	* @encoding: color encoding to compute name of
	*
	* In contrast to the other drm_get_*_name functions this one here returns a
	* const pointer and hence is threadsafe.
	*/
	const char *drm_get_color_encoding_name(enum drm_color_encoding encoding)
	{
	if (WARN_ON(encoding >= ARRAY_SIZE(color_encoding_name)))
	return "unknown";

	return color_encoding_name[encoding];
	}

	/**
	* drm_get_color_range_name - return a string for color range
	* @range: color range to compute name of
	*
	* In contrast to the other drm_get_*_name functions this one here returns a
	* const pointer and hence is threadsafe.
	*/
	const char *drm_get_color_range_name(enum drm_color_range range)
	{
	if (WARN_ON(range >= ARRAY_SIZE(color_range_name)))
	return "unknown";

	return color_range_name[range];
	}

	/**
	* drm_plane_create_color_properties - color encoding related plane properties
	* @plane: plane object
	* @supported_encodings: bitfield indicating supported color encodings
	* @supported_ranges: bitfileld indicating supported color ranges
	* @default_encoding: default color encoding
	* @default_range: default color range
	*
	* Create and attach plane specific COLOR_ENCODING and COLOR_RANGE
	* properties to @plane. The supported encodings and ranges should
	* be provided in supported_encodings and supported_ranges bitmasks.
	* Each bit set in the bitmask indicates that its number as enum
	* value is supported.
	*/
	int drm_plane_create_color_properties(struct drm_plane *plane,
	u32 supported_encodings,
	u32 supported_ranges,
	enum drm_color_encoding default_encoding,
	enum drm_color_range default_range)
	{
	struct drm_device *dev = plane->dev;
	struct drm_property *prop;
	struct drm_prop_enum_list enum_list[max_t(int, DRM_COLOR_ENCODING_MAX,
	DRM_COLOR_RANGE_MAX)];
	int i, len;

	if (WARN_ON(supported_encodings == 0 \|\|
	(supported_encodings & -BIT(DRM_COLOR_ENCODING_MAX)) != 0 \|\|
	(supported_encodings & BIT(default_encoding)) == 0))
	return -EINVAL;

	if (WARN_ON(supported_ranges == 0 \|\|
	(supported_ranges & -BIT(DRM_COLOR_RANGE_MAX)) != 0 \|\|
	(supported_ranges & BIT(default_range)) == 0))
	return -EINVAL;

	len = 0;
	for (i = 0; i < DRM_COLOR_ENCODING_MAX; i++) {
	if ((supported_encodings & BIT(i)) == 0)
	continue;

	enum_list[len].type = i;
	enum_list[len].name = color_encoding_name[i];
	len++;
	}

	prop = drm_property_create_enum(dev, 0, "COLOR_ENCODING",
	enum_list, len);
	if (!prop)
	return -ENOMEM;
	plane->color_encoding_property = prop;
	drm_object_attach_property(&plane->base, prop, default_encoding);
	if (plane->state)
	plane->state->color_encoding = default_encoding;

	len = 0;
	for (i = 0; i < DRM_COLOR_RANGE_MAX; i++) {
	if ((supported_ranges & BIT(i)) == 0)
	continue;

	enum_list[len].type = i;
	enum_list[len].name = color_range_name[i];
	len++;
	}

	prop = drm_property_create_enum(dev, 0, "COLOR_RANGE",
	enum_list, len);
	if (!prop)
	return -ENOMEM;
	plane->color_range_property = prop;
	drm_object_attach_property(&plane->base, prop, default_range);
	if (plane->state)
	plane->state->color_range = default_range;

	return 0;
	}
	EXPORT_SYMBOL(drm_plane_create_color_properties);

	/**
	* drm_color_lut_check - check validity of lookup table
	* @lut: property blob containing LUT to check
	* @tests: bitmask of tests to run
	*
	* Helper to check whether a userspace-provided lookup table is valid and
	* satisfies hardware requirements. Drivers pass a bitmask indicating which of
	* the tests in &drm_color_lut_tests should be performed.
	*
	* Returns 0 on success, -EINVAL on failure.
	*/
	int drm_color_lut_check(const struct drm_property_blob *lut, u32 tests)
	{
	const struct drm_color_lut *entry;
	int i;

	if (!lut \|\| !tests)
	return 0;

	entry = lut->data;
	for (i = 0; i < drm_color_lut_size(lut); i++) {
	if (tests & DRM_COLOR_LUT_EQUAL_CHANNELS) {
	if (entry[i].red != entry[i].blue \|\|
	entry[i].red != entry[i].green) {
	DRM_DEBUG_KMS("All LUT entries must have equal r/g/b\n");
	return -EINVAL;
	}
	}

	if (i > 0 && tests & DRM_COLOR_LUT_NON_DECREASING) {
	if (entry[i].red < entry[i - 1].red \|\|
	entry[i].green < entry[i - 1].green \|\|
	entry[i].blue < entry[i - 1].blue) {
	DRM_DEBUG_KMS("LUT entries must never decrease.\n");
	return -EINVAL;
	}
	}
	}

	return 0;
	}
	EXPORT_SYMBOL(drm_color_lut_check);