linux/drivers/media/v4l2-core/v4l2-common.c

/*
 *	Video for Linux Two
 *
 *	A generic video device interface for the LINUX operating system
 *	using a set of device structures/vectors for low level operations.
 *
 *	This file replaces the videodev.c file that comes with the
 *	regular kernel distribution.
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 * Author:	Bill Dirks <bill@thedirks.org>
 *		based on code by Alan Cox, <alan@cymru.net>
 *
 */

/*
 * Video capture interface for Linux
 *
 *	A generic video device interface for the LINUX operating system
 *	using a set of device structures/vectors for low level operations.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Author:	Alan Cox, <alan@lxorguk.ukuu.org.uk>
 *
 * Fixes:
 */

/*
 * Video4linux 1/2 integration by Justin Schoeman
 * <justin@suntiger.ee.up.ac.za>
 * 2.4 PROCFS support ported from 2.4 kernels by
 *  Iñaki García Etxebarria <garetxe@euskalnet.net>
 * Makefile fix by "W. Michael Petullo" <mike@flyn.org>
 * 2.4 devfs support ported from 2.4 kernels by
 *  Dan Merillat <dan@merillat.org>
 * Added Gerd Knorrs v4l1 enhancements (Justin Schoeman)
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#if defined(CONFIG_SPI)
#include <linux/spi/spi.h>
#endif
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/div64.h>
#include <media/v4l2-common.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ctrls.h>

#include <linux/videodev2.h>

MODULE_AUTHOR("Bill Dirks, Justin Schoeman, Gerd Knorr");
MODULE_DESCRIPTION("misc helper functions for v4l2 device drivers");
MODULE_LICENSE("GPL");

/*
 *
 *	V 4 L 2   D R I V E R   H E L P E R   A P I
 *
 */

/*
 *  Video Standard Operations (contributed by Michael Schimek)
 */

/* Helper functions for control handling			     */

/* Check for correctness of the ctrl's value based on the data from
   struct v4l2_queryctrl and the available menu items. Note that
   menu_items may be NULL, in that case it is ignored. */
int v4l2_ctrl_check(struct v4l2_ext_control *ctrl, struct v4l2_queryctrl *qctrl,
		const char * const *menu_items)
{
	if (qctrl->flags & V4L2_CTRL_FLAG_DISABLED)
		return -EINVAL;
	if (qctrl->flags & V4L2_CTRL_FLAG_GRABBED)
		return -EBUSY;
	if (qctrl->type == V4L2_CTRL_TYPE_STRING)
		return 0;
	if (qctrl->type == V4L2_CTRL_TYPE_BUTTON ||
	    qctrl->type == V4L2_CTRL_TYPE_INTEGER64 ||
	    qctrl->type == V4L2_CTRL_TYPE_CTRL_CLASS)
		return 0;
	if (ctrl->value < qctrl->minimum || ctrl->value > qctrl->maximum)
		return -ERANGE;
	if (qctrl->type == V4L2_CTRL_TYPE_MENU && menu_items != NULL) {
		if (menu_items[ctrl->value] == NULL ||
		    menu_items[ctrl->value][0] == '\0')
			return -EINVAL;
	}
	if (qctrl->type == V4L2_CTRL_TYPE_BITMASK &&
			(ctrl->value & ~qctrl->maximum))
		return -ERANGE;
	return 0;
}
EXPORT_SYMBOL(v4l2_ctrl_check);

/* Fill in a struct v4l2_queryctrl */
int v4l2_ctrl_query_fill(struct v4l2_queryctrl *qctrl, s32 min, s32 max, s32 step, s32 def)
{
	const char *name;

	v4l2_ctrl_fill(qctrl->id, &name, &qctrl->type,
		       &min, &max, &step, &def, &qctrl->flags);

	if (name == NULL)
		return -EINVAL;

	qctrl->minimum = min;
	qctrl->maximum = max;
	qctrl->step = step;
	qctrl->default_value = def;
	qctrl->reserved[0] = qctrl->reserved[1] = 0;
	strlcpy(qctrl->name, name, sizeof(qctrl->name));
	return 0;
}
EXPORT_SYMBOL(v4l2_ctrl_query_fill);

/* Fill in a struct v4l2_querymenu based on the struct v4l2_queryctrl and
   the menu. The qctrl pointer may be NULL, in which case it is ignored.
   If menu_items is NULL, then the menu items are retrieved using
   v4l2_ctrl_get_menu. */
int v4l2_ctrl_query_menu(struct v4l2_querymenu *qmenu, struct v4l2_queryctrl *qctrl,
	       const char * const *menu_items)
{
	int i;

	qmenu->reserved = 0;
	if (menu_items == NULL)
		menu_items = v4l2_ctrl_get_menu(qmenu->id);
	if (menu_items == NULL ||
	    (qctrl && (qmenu->index < qctrl->minimum || qmenu->index > qctrl->maximum)))
		return -EINVAL;
	for (i = 0; i < qmenu->index && menu_items[i]; i++) ;
	if (menu_items[i] == NULL || menu_items[i][0] == '\0')
		return -EINVAL;
	strlcpy(qmenu->name, menu_items[qmenu->index], sizeof(qmenu->name));
	return 0;
}
EXPORT_SYMBOL(v4l2_ctrl_query_menu);

/* Fill in a struct v4l2_querymenu based on the specified array of valid
   menu items (terminated by V4L2_CTRL_MENU_IDS_END).
   Use this if there are 'holes' in the list of valid menu items. */
int v4l2_ctrl_query_menu_valid_items(struct v4l2_querymenu *qmenu, const u32 *ids)
{
	const char * const *menu_items = v4l2_ctrl_get_menu(qmenu->id);

	qmenu->reserved = 0;
	if (menu_items == NULL || ids == NULL)
		return -EINVAL;
	while (*ids != V4L2_CTRL_MENU_IDS_END) {
		if (*ids++ == qmenu->index) {
			strlcpy(qmenu->name, menu_items[qmenu->index],
					sizeof(qmenu->name));
			return 0;
		}
	}
	return -EINVAL;
}
EXPORT_SYMBOL(v4l2_ctrl_query_menu_valid_items);

/* ctrl_classes points to an array of u32 pointers, the last element is
   a NULL pointer. Each u32 array is a 0-terminated array of control IDs.
   Each array must be sorted low to high and belong to the same control
   class. The array of u32 pointers must also be sorted, from low class IDs
   to high class IDs.

   This function returns the first ID that follows after the given ID.
   When no more controls are available 0 is returned. */
u32 v4l2_ctrl_next(const u32 * const * ctrl_classes, u32 id)
{
	u32 ctrl_class = V4L2_CTRL_ID2CLASS(id);
	const u32 *pctrl;

	if (ctrl_classes == NULL)
		return 0;

	/* if no query is desired, then check if the ID is part of ctrl_classes */
	if ((id & V4L2_CTRL_FLAG_NEXT_CTRL) == 0) {
		/* find class */
		while (*ctrl_classes && V4L2_CTRL_ID2CLASS(**ctrl_classes) != ctrl_class)
			ctrl_classes++;
		if (*ctrl_classes == NULL)
			return 0;
		pctrl = *ctrl_classes;
		/* find control ID */
		while (*pctrl && *pctrl != id) pctrl++;
		return *pctrl ? id : 0;
	}
	id &= V4L2_CTRL_ID_MASK;
	id++;	/* select next control */
	/* find first class that matches (or is greater than) the class of
	   the ID */
	while (*ctrl_classes && V4L2_CTRL_ID2CLASS(**ctrl_classes) < ctrl_class)
		ctrl_classes++;
	/* no more classes */
	if (*ctrl_classes == NULL)
		return 0;
	pctrl = *ctrl_classes;
	/* find first ctrl within the class that is >= ID */
	while (*pctrl && *pctrl < id) pctrl++;
	if (*pctrl)
		return *pctrl;
	/* we are at the end of the controls of the current class. */
	/* continue with next class if available */
	ctrl_classes++;
	if (*ctrl_classes == NULL)
		return 0;
	return **ctrl_classes;
}
EXPORT_SYMBOL(v4l2_ctrl_next);

/* I2C Helper functions */

#if IS_ENABLED(CONFIG_I2C)

void v4l2_i2c_subdev_init(struct v4l2_subdev *sd, struct i2c_client *client,
		const struct v4l2_subdev_ops *ops)
{
	v4l2_subdev_init(sd, ops);
	sd->flags |= V4L2_SUBDEV_FL_IS_I2C;
	/* the owner is the same as the i2c_client's driver owner */
	sd->owner = client->driver->driver.owner;
	/* i2c_client and v4l2_subdev point to one another */
	v4l2_set_subdevdata(sd, client);
	i2c_set_clientdata(client, sd);
	/* initialize name */
	snprintf(sd->name, sizeof(sd->name), "%s %d-%04x",
		client->driver->driver.name, i2c_adapter_id(client->adapter),
		client->addr);
}
EXPORT_SYMBOL_GPL(v4l2_i2c_subdev_init);

/* Load an i2c sub-device. */
struct v4l2_subdev *v4l2_i2c_new_subdev_board(struct v4l2_device *v4l2_dev,
		struct i2c_adapter *adapter, struct i2c_board_info *info,
		const unsigned short *probe_addrs)
{
	struct v4l2_subdev *sd = NULL;
	struct i2c_client *client;

	BUG_ON(!v4l2_dev);

	request_module(I2C_MODULE_PREFIX "%s", info->type);

	/* Create the i2c client */
	if (info->addr == 0 && probe_addrs)
		client = i2c_new_probed_device(adapter, info, probe_addrs,
					       NULL);
	else
		client = i2c_new_device(adapter, info);

	/* Note: by loading the module first we are certain that c->driver
	   will be set if the driver was found. If the module was not loaded
	   first, then the i2c core tries to delay-load the module for us,
	   and then c->driver is still NULL until the module is finally
	   loaded. This delay-load mechanism doesn't work if other drivers
	   want to use the i2c device, so explicitly loading the module
	   is the best alternative. */
	if (client == NULL || client->driver == NULL)
		goto error;

	/* Lock the module so we can safely get the v4l2_subdev pointer */
	if (!try_module_get(client->driver->driver.owner))
		goto error;
	sd = i2c_get_clientdata(client);

	/* Register with the v4l2_device which increases the module's
	   use count as well. */
	if (v4l2_device_register_subdev(v4l2_dev, sd))
		sd = NULL;
	/* Decrease the module use count to match the first try_module_get. */
	module_put(client->driver->driver.owner);

error:
	/* If we have a client but no subdev, then something went wrong and
	   we must unregister the client. */
	if (client && sd == NULL)
		i2c_unregister_device(client);
	return sd;
}
EXPORT_SYMBOL_GPL(v4l2_i2c_new_subdev_board);

struct v4l2_subdev *v4l2_i2c_new_subdev(struct v4l2_device *v4l2_dev,
		struct i2c_adapter *adapter, const char *client_type,
		u8 addr, const unsigned short *probe_addrs)
{
	struct i2c_board_info info;

	/* Setup the i2c board info with the device type and
	   the device address. */
	memset(&info, 0, sizeof(info));
	strlcpy(info.type, client_type, sizeof(info.type));
	info.addr = addr;

	return v4l2_i2c_new_subdev_board(v4l2_dev, adapter, &info, probe_addrs);
}
EXPORT_SYMBOL_GPL(v4l2_i2c_new_subdev);

/* Return i2c client address of v4l2_subdev. */
unsigned short v4l2_i2c_subdev_addr(struct v4l2_subdev *sd)
{
	struct i2c_client *client = v4l2_get_subdevdata(sd);

	return client ? client->addr : I2C_CLIENT_END;
}
EXPORT_SYMBOL_GPL(v4l2_i2c_subdev_addr);

/* Return a list of I2C tuner addresses to probe. Use only if the tuner
   addresses are unknown. */
const unsigned short *v4l2_i2c_tuner_addrs(enum v4l2_i2c_tuner_type type)
{
	static const unsigned short radio_addrs[] = {
#if IS_ENABLED(CONFIG_MEDIA_TUNER_TEA5761)
		0x10,
#endif
		0x60,
		I2C_CLIENT_END
	};
	static const unsigned short demod_addrs[] = {
		0x42, 0x43, 0x4a, 0x4b,
		I2C_CLIENT_END
	};
	static const unsigned short tv_addrs[] = {
		0x42, 0x43, 0x4a, 0x4b,		/* tda8290 */
		0x60, 0x61, 0x62, 0x63, 0x64,
		I2C_CLIENT_END
	};

	switch (type) {
	case ADDRS_RADIO:
		return radio_addrs;
	case ADDRS_DEMOD:
		return demod_addrs;
	case ADDRS_TV:
		return tv_addrs;
	case ADDRS_TV_WITH_DEMOD:
		return tv_addrs + 4;
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(v4l2_i2c_tuner_addrs);

#endif /* defined(CONFIG_I2C) */

#if defined(CONFIG_SPI)

/* Load an spi sub-device. */

void v4l2_spi_subdev_init(struct v4l2_subdev *sd, struct spi_device *spi,
		const struct v4l2_subdev_ops *ops)
{
	v4l2_subdev_init(sd, ops);
	sd->flags |= V4L2_SUBDEV_FL_IS_SPI;
	/* the owner is the same as the spi_device's driver owner */
	sd->owner = spi->dev.driver->owner;
	/* spi_device and v4l2_subdev point to one another */
	v4l2_set_subdevdata(sd, spi);
	spi_set_drvdata(spi, sd);
	/* initialize name */
	strlcpy(sd->name, spi->dev.driver->name, sizeof(sd->name));
}
EXPORT_SYMBOL_GPL(v4l2_spi_subdev_init);

struct v4l2_subdev *v4l2_spi_new_subdev(struct v4l2_device *v4l2_dev,
		struct spi_master *master, struct spi_board_info *info)
{
	struct v4l2_subdev *sd = NULL;
	struct spi_device *spi = NULL;

	BUG_ON(!v4l2_dev);

	if (info->modalias[0])
		request_module(info->modalias);

	spi = spi_new_device(master, info);

	if (spi == NULL || spi->dev.driver == NULL)
		goto error;

	if (!try_module_get(spi->dev.driver->owner))
		goto error;

	sd = spi_get_drvdata(spi);

	/* Register with the v4l2_device which increases the module's
	   use count as well. */
	if (v4l2_device_register_subdev(v4l2_dev, sd))
		sd = NULL;

	/* Decrease the module use count to match the first try_module_get. */
	module_put(spi->dev.driver->owner);

error:
	/* If we have a client but no subdev, then something went wrong and
	   we must unregister the client. */
	if (spi && sd == NULL)
		spi_unregister_device(spi);

	return sd;
}
EXPORT_SYMBOL_GPL(v4l2_spi_new_subdev);

#endif /* defined(CONFIG_SPI) */

/* Clamp x to be between min and max, aligned to a multiple of 2^align.  min
 * and max don't have to be aligned, but there must be at least one valid
 * value.  E.g., min=17,max=31,align=4 is not allowed as there are no multiples
 * of 16 between 17 and 31.  */
static unsigned int clamp_align(unsigned int x, unsigned int min,
				unsigned int max, unsigned int align)
{
	/* Bits that must be zero to be aligned */
	unsigned int mask = ~((1 << align) - 1);

	/* Round to nearest aligned value */
	if (align)
		x = (x + (1 << (align - 1))) & mask;

	/* Clamp to aligned value of min and max */
	if (x < min)
		x = (min + ~mask) & mask;
	else if (x > max)
		x = max & mask;

	return x;
}

/* Bound an image to have a width between wmin and wmax, and height between
 * hmin and hmax, inclusive.  Additionally, the width will be a multiple of
 * 2^walign, the height will be a multiple of 2^halign, and the overall size
 * (width*height) will be a multiple of 2^salign.  The image may be shrunk
 * or enlarged to fit the alignment constraints.
 *
 * The width or height maximum must not be smaller than the corresponding
 * minimum.  The alignments must not be so high there are no possible image
 * sizes within the allowed bounds.  wmin and hmin must be at least 1
 * (don't use 0).  If you don't care about a certain alignment, specify 0,
 * as 2^0 is 1 and one byte alignment is equivalent to no alignment.  If
 * you only want to adjust downward, specify a maximum that's the same as
 * the initial value.
 */
void v4l_bound_align_image(u32 *w, unsigned int wmin, unsigned int wmax,
			   unsigned int walign,
			   u32 *h, unsigned int hmin, unsigned int hmax,
			   unsigned int halign, unsigned int salign)
{
	*w = clamp_align(*w, wmin, wmax, walign);
	*h = clamp_align(*h, hmin, hmax, halign);

	/* Usually we don't need to align the size and are done now. */
	if (!salign)
		return;

	/* How much alignment do we have? */
	walign = __ffs(*w);
	halign = __ffs(*h);
	/* Enough to satisfy the image alignment? */
	if (walign + halign < salign) {
		/* Max walign where there is still a valid width */
		unsigned int wmaxa = __fls(wmax ^ (wmin - 1));
		/* Max halign where there is still a valid height */
		unsigned int hmaxa = __fls(hmax ^ (hmin - 1));

		/* up the smaller alignment until we have enough */
		do {
			if (halign >= hmaxa ||
			    (walign <= halign && walign < wmaxa)) {
				*w = clamp_align(*w, wmin, wmax, walign + 1);
				walign = __ffs(*w);
			} else {
				*h = clamp_align(*h, hmin, hmax, halign + 1);
				halign = __ffs(*h);
			}
		} while (halign + walign < salign);
	}
}
EXPORT_SYMBOL_GPL(v4l_bound_align_image);

/**
 * v4l_match_dv_timings - check if two timings match
 * @t1 - compare this v4l2_dv_timings struct...
 * @t2 - with this struct.
 * @pclock_delta - the allowed pixelclock deviation.
 *
 * Compare t1 with t2 with a given margin of error for the pixelclock.
 */
bool v4l_match_dv_timings(const struct v4l2_dv_timings *t1,
			  const struct v4l2_dv_timings *t2,
			  unsigned pclock_delta)
{
	if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
		return false;
	if (t1->bt.width == t2->bt.width &&
	    t1->bt.height == t2->bt.height &&
	    t1->bt.interlaced == t2->bt.interlaced &&
	    t1->bt.polarities == t2->bt.polarities &&
	    t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
	    t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
	    t1->bt.hfrontporch == t2->bt.hfrontporch &&
	    t1->bt.vfrontporch == t2->bt.vfrontporch &&
	    t1->bt.vsync == t2->bt.vsync &&
	    t1->bt.vbackporch == t2->bt.vbackporch &&
	    (!t1->bt.interlaced ||
		(t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
		 t1->bt.il_vsync == t2->bt.il_vsync &&
		 t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
		return true;
	return false;
}
EXPORT_SYMBOL_GPL(v4l_match_dv_timings);

/*
 * CVT defines
 * Based on Coordinated Video Timings Standard
 * version 1.1 September 10, 2003
 */

#define CVT_PXL_CLK_GRAN	250000	/* pixel clock granularity */

/* Normal blanking */
#define CVT_MIN_V_BPORCH	7	/* lines */
#define CVT_MIN_V_PORCH_RND	3	/* lines */
#define CVT_MIN_VSYNC_BP	550	/* min time of vsync + back porch (us) */

/* Normal blanking for CVT uses GTF to calculate horizontal blanking */
#define CVT_CELL_GRAN		8	/* character cell granularity */
#define CVT_M			600	/* blanking formula gradient */
#define CVT_C			40	/* blanking formula offset */
#define CVT_K			128	/* blanking formula scaling factor */
#define CVT_J			20	/* blanking formula scaling factor */
#define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
#define CVT_M_PRIME (CVT_K * CVT_M / 256)

/* Reduced Blanking */
#define CVT_RB_MIN_V_BPORCH    7       /* lines  */
#define CVT_RB_V_FPORCH        3       /* lines  */
#define CVT_RB_MIN_V_BLANK   460     /* us     */
#define CVT_RB_H_SYNC         32       /* pixels */
#define CVT_RB_H_BPORCH       80       /* pixels */
#define CVT_RB_H_BLANK       160       /* pixels */

/** v4l2_detect_cvt - detect if the given timings follow the CVT standard
 * @frame_height - the total height of the frame (including blanking) in lines.
 * @hfreq - the horizontal frequency in Hz.
 * @vsync - the height of the vertical sync in lines.
 * @polarities - the horizontal and vertical polarities (same as struct
 *		v4l2_bt_timings polarities).
 * @fmt - the resulting timings.
 *
 * This function will attempt to detect if the given values correspond to a
 * valid CVT format. If so, then it will return true, and fmt will be filled
 * in with the found CVT timings.
 */
bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
		u32 polarities, struct v4l2_dv_timings *fmt)
{
	int  v_fp, v_bp, h_fp, h_bp, hsync;
	int  frame_width, image_height, image_width;
	bool reduced_blanking;
	unsigned pix_clk;

	if (vsync < 4 || vsync > 7)
		return false;

	if (polarities == V4L2_DV_VSYNC_POS_POL)
		reduced_blanking = false;
	else if (polarities == V4L2_DV_HSYNC_POS_POL)
		reduced_blanking = true;
	else
		return false;

	/* Vertical */
	if (reduced_blanking) {
		v_fp = CVT_RB_V_FPORCH;
		v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 999999) / 1000000;
		v_bp -= vsync + v_fp;

		if (v_bp < CVT_RB_MIN_V_BPORCH)
			v_bp = CVT_RB_MIN_V_BPORCH;
	} else {
		v_fp = CVT_MIN_V_PORCH_RND;
		v_bp = (CVT_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;

		if (v_bp < CVT_MIN_V_BPORCH)
			v_bp = CVT_MIN_V_BPORCH;
	}
	image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;

	/* Aspect ratio based on vsync */
	switch (vsync) {
	case 4:
		image_width = (image_height * 4) / 3;
		break;
	case 5:
		image_width = (image_height * 16) / 9;
		break;
	case 6:
		image_width = (image_height * 16) / 10;
		break;
	case 7:
		/* special case */
		if (image_height == 1024)
			image_width = (image_height * 5) / 4;
		else if (image_height == 768)
			image_width = (image_height * 15) / 9;
		else
			return false;
		break;
	default:
		return false;
	}

	image_width = image_width & ~7;

	/* Horizontal */
	if (reduced_blanking) {
		pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
		pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;

		h_bp = CVT_RB_H_BPORCH;
		hsync = CVT_RB_H_SYNC;
		h_fp = CVT_RB_H_BLANK - h_bp - hsync;

		frame_width = image_width + CVT_RB_H_BLANK;
	} else {
		int h_blank;
		unsigned ideal_duty_cycle = CVT_C_PRIME - (CVT_M_PRIME * 1000) / hfreq;

		h_blank = (image_width * ideal_duty_cycle + (100 - ideal_duty_cycle) / 2) /
						(100 - ideal_duty_cycle);
		h_blank = h_blank - h_blank % (2 * CVT_CELL_GRAN);

		if (h_blank * 100 / image_width < 20) {
			h_blank = image_width / 5;
			h_blank = (h_blank + 0x7) & ~0x7;
		}

		pix_clk = (image_width + h_blank) * hfreq;
		pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;

		h_bp = h_blank / 2;
		frame_width = image_width + h_blank;

		hsync = (frame_width * 8 + 50) / 100;
		hsync = hsync - hsync % CVT_CELL_GRAN;
		h_fp = h_blank - hsync - h_bp;
	}

	fmt->bt.polarities = polarities;
	fmt->bt.width = image_width;
	fmt->bt.height = image_height;
	fmt->bt.hfrontporch = h_fp;
	fmt->bt.vfrontporch = v_fp;
	fmt->bt.hsync = hsync;
	fmt->bt.vsync = vsync;
	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
	fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
	fmt->bt.pixelclock = pix_clk;
	fmt->bt.standards = V4L2_DV_BT_STD_CVT;
	if (reduced_blanking)
		fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
	return true;
}
EXPORT_SYMBOL_GPL(v4l2_detect_cvt);

/*
 * GTF defines
 * Based on Generalized Timing Formula Standard
 * Version 1.1 September 2, 1999
 */

#define GTF_PXL_CLK_GRAN	250000	/* pixel clock granularity */

#define GTF_MIN_VSYNC_BP	550	/* min time of vsync + back porch (us) */
#define GTF_V_FP		1	/* vertical front porch (lines) */
#define GTF_CELL_GRAN		8	/* character cell granularity */

/* Default */
#define GTF_D_M			600	/* blanking formula gradient */
#define GTF_D_C			40	/* blanking formula offset */
#define GTF_D_K			128	/* blanking formula scaling factor */
#define GTF_D_J			20	/* blanking formula scaling factor */
#define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
#define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)

/* Secondary */
#define GTF_S_M			3600	/* blanking formula gradient */
#define GTF_S_C			40	/* blanking formula offset */
#define GTF_S_K			128	/* blanking formula scaling factor */
#define GTF_S_J			35	/* blanking formula scaling factor */
#define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
#define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)

/** v4l2_detect_gtf - detect if the given timings follow the GTF standard
 * @frame_height - the total height of the frame (including blanking) in lines.
 * @hfreq - the horizontal frequency in Hz.
 * @vsync - the height of the vertical sync in lines.
 * @polarities - the horizontal and vertical polarities (same as struct
 *		v4l2_bt_timings polarities).
 * @aspect - preferred aspect ratio. GTF has no method of determining the
 *		aspect ratio in order to derive the image width from the
 *		image height, so it has to be passed explicitly. Usually
 *		the native screen aspect ratio is used for this. If it
 *		is not filled in correctly, then 16:9 will be assumed.
 * @fmt - the resulting timings.
 *
 * This function will attempt to detect if the given values correspond to a
 * valid GTF format. If so, then it will return true, and fmt will be filled
 * in with the found GTF timings.
 */
bool v4l2_detect_gtf(unsigned frame_height,
		unsigned hfreq,
		unsigned vsync,
		u32 polarities,
		struct v4l2_fract aspect,
		struct v4l2_dv_timings *fmt)
{
	int pix_clk;
	int  v_fp, v_bp, h_fp, hsync;
	int frame_width, image_height, image_width;
	bool default_gtf;
	int h_blank;

	if (vsync != 3)
		return false;

	if (polarities == V4L2_DV_VSYNC_POS_POL)
		default_gtf = true;
	else if (polarities == V4L2_DV_HSYNC_POS_POL)
		default_gtf = false;
	else
		return false;

	/* Vertical */
	v_fp = GTF_V_FP;
	v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;
	image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;

	if (aspect.numerator == 0 || aspect.denominator == 0) {
		aspect.numerator = 16;
		aspect.denominator = 9;
	}
	image_width = ((image_height * aspect.numerator) / aspect.denominator);

	/* Horizontal */
	if (default_gtf)
		h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
					(image_width * GTF_D_M_PRIME * 1000) +
			(hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
			(hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
	else
		h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
					(image_width * GTF_S_M_PRIME * 1000) +
			(hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
			(hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);

	h_blank = h_blank - h_blank % (2 * GTF_CELL_GRAN);
	frame_width = image_width + h_blank;

	pix_clk = (image_width + h_blank) * hfreq;
	pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;

	hsync = (frame_width * 8 + 50) / 100;
	hsync = hsync - hsync % GTF_CELL_GRAN;

	h_fp = h_blank / 2 - hsync;

	fmt->bt.polarities = polarities;
	fmt->bt.width = image_width;
	fmt->bt.height = image_height;
	fmt->bt.hfrontporch = h_fp;
	fmt->bt.vfrontporch = v_fp;
	fmt->bt.hsync = hsync;
	fmt->bt.vsync = vsync;
	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
	fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
	fmt->bt.pixelclock = pix_clk;
	fmt->bt.standards = V4L2_DV_BT_STD_GTF;
	if (!default_gtf)
		fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
	return true;
}
EXPORT_SYMBOL_GPL(v4l2_detect_gtf);

/** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
 *	0x15 and 0x16 from the EDID.
 * @hor_landscape - byte 0x15 from the EDID.
 * @vert_portrait - byte 0x16 from the EDID.
 *
 * Determines the aspect ratio from the EDID.
 * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
 * "Horizontal and Vertical Screen Size or Aspect Ratio"
 */
struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
{
	struct v4l2_fract aspect = { 16, 9 };
	u32 tmp;
	u8 ratio;

	/* Nothing filled in, fallback to 16:9 */
	if (!hor_landscape && !vert_portrait)
		return aspect;
	/* Both filled in, so they are interpreted as the screen size in cm */
	if (hor_landscape && vert_portrait) {
		aspect.numerator = hor_landscape;
		aspect.denominator = vert_portrait;
		return aspect;
	}
	/* Only one is filled in, so interpret them as a ratio:
	   (val + 99) / 100 */
	ratio = hor_landscape | vert_portrait;
	/* Change some rounded values into the exact aspect ratio */
	if (ratio == 79) {
		aspect.numerator = 16;
		aspect.denominator = 9;
	} else if (ratio == 34) {
		aspect.numerator = 4;
		aspect.numerator = 3;
	} else if (ratio == 68) {
		aspect.numerator = 15;
		aspect.numerator = 9;
	} else {
		aspect.numerator = hor_landscape + 99;
		aspect.denominator = 100;
	}
	if (hor_landscape)
		return aspect;
	/* The aspect ratio is for portrait, so swap numerator and denominator */
	tmp = aspect.denominator;
	aspect.denominator = aspect.numerator;
	aspect.numerator = tmp;
	return aspect;
}
EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);

const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(
		const struct v4l2_discrete_probe *probe,
		s32 width, s32 height)
{
	int i;
	u32 error, min_error = UINT_MAX;
	const struct v4l2_frmsize_discrete *size, *best = NULL;

	if (!probe)
		return best;

	for (i = 0, size = probe->sizes; i < probe->num_sizes; i++, size++) {
		error = abs(size->width - width) + abs(size->height - height);
		if (error < min_error) {
			min_error = error;
			best = size;
		}
		if (!error)
			break;
	}

	return best;
}
EXPORT_SYMBOL_GPL(v4l2_find_nearest_format);

void v4l2_get_timestamp(struct timeval *tv)
{
	struct timespec ts;

	ktime_get_ts(&ts);
	tv->tv_sec = ts.tv_sec;
	tv->tv_usec = ts.tv_nsec / NSEC_PER_USEC;
}
EXPORT_SYMBOL_GPL(v4l2_get_timestamp);