// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013 NVIDIA Corporation
 */

#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 6.9, Table 14, Page 40 of the D-PHY
 * specification (v1.2) 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;

        /*
         * The MIPI D-PHY specification (Section 6.9, v1.2, Table 14, Page 40)
         * contains this formula as:
         *
         *     T_HS-TRAIL = max(n * 8 * period, 60 + n * 4 * period)
         *
         * where n = 1 for forward-direction HS mode and n = 4 for reverse-
         * direction HS mode. There's only one setting and this function does
         * not parameterize on anything other that period, so this code will
         * assumes that reverse-direction HS mode is supported and uses n = 4.
         */
        timing->hstrail = max(4 * 8 * period, 60 + 4 * 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 D-PHY specification (v1.2, Section
 * Section 6.9 "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;
}