linux_kernel/drivers/gpu/drm/tegra/mipi-phy.c

/*
 * Copyright (C) 2013 NVIDIA 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/errno.h>
#include <linux/kernel.h>

#include "mipi-phy.h"

/*
 * Default D-PHY timings based on MIPI D-PHY specification. Derived from
 * the valid ranges specified in Section 5.9 of the D-PHY specification
 * with minor adjustments.
 */
int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing,
				 unsigned long period)
{
	timing->clkmiss = 0;
	timing->clkpost = 70 + 52 * period;
	timing->clkpre = 8;
	timing->clkprepare = 65;
	timing->clksettle = 95;
	timing->clktermen = 0;
	timing->clktrail = 80;
	timing->clkzero = 260;
	timing->dtermen = 0;
	timing->eot = 0;
	timing->hsexit = 120;
	timing->hsprepare = 65 + 5 * period;
	timing->hszero = 145 + 5 * period;
	timing->hssettle = 85 + 6 * period;
	timing->hsskip = 40;
	timing->hstrail = max(8 * period, 60 + 4 * period);
	timing->init = 100000;
	timing->lpx = 60;
	timing->taget = 5 * timing->lpx;
	timing->tago = 4 * timing->lpx;
	timing->tasure = 2 * timing->lpx;
	timing->wakeup = 1000000;

	return 0;
}

/*
 * Validate D-PHY timing according to MIPI Alliance Specification for D-PHY,
 * Section 5.9 "Global Operation Timing Parameters".
 */
int mipi_dphy_timing_validate(struct mipi_dphy_timing *timing,
			      unsigned long period)
{
	if (timing->clkmiss > 60)
		return -EINVAL;

	if (timing->clkpost < (60 + 52 * period))
		return -EINVAL;

	if (timing->clkpre < 8)
		return -EINVAL;

	if (timing->clkprepare < 38 || timing->clkprepare > 95)
		return -EINVAL;

	if (timing->clksettle < 95 || timing->clksettle > 300)
		return -EINVAL;

	if (timing->clktermen > 38)
		return -EINVAL;

	if (timing->clktrail < 60)
		return -EINVAL;

	if (timing->clkprepare + timing->clkzero < 300)
		return -EINVAL;

	if (timing->dtermen > 35 + 4 * period)
		return -EINVAL;

	if (timing->eot > 105 + 12 * period)
		return -EINVAL;

	if (timing->hsexit < 100)
		return -EINVAL;

	if (timing->hsprepare < 40 + 4 * period ||
	    timing->hsprepare > 85 + 6 * period)
		return -EINVAL;

	if (timing->hsprepare + timing->hszero < 145 + 10 * period)
		return -EINVAL;

	if ((timing->hssettle < 85 + 6 * period) ||
	    (timing->hssettle > 145 + 10 * period))
		return -EINVAL;

	if (timing->hsskip < 40 || timing->hsskip > 55 + 4 * period)
		return -EINVAL;

	if (timing->hstrail < max(8 * period, 60 + 4 * period))
		return -EINVAL;

	if (timing->init < 100000)
		return -EINVAL;

	if (timing->lpx < 50)
		return -EINVAL;

	if (timing->taget != 5 * timing->lpx)
		return -EINVAL;

	if (timing->tago != 4 * timing->lpx)
		return -EINVAL;

	if (timing->tasure < timing->lpx || timing->tasure > 2 * timing->lpx)
		return -EINVAL;

	if (timing->wakeup < 1000000)
		return -EINVAL;

	return 0;
}