LXR linux/drivers/gpu/drm/tegra/mipi-phy.c

   1/*
   2 * Copyright (C) 2013 NVIDIA Corporation
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#include <linux/errno.h>
  10#include <linux/kernel.h>
  11
  12#include "mipi-phy.h"
  13
  14/*
  15 * Default D-PHY timings based on MIPI D-PHY specification. Derived from the
  16 * valid ranges specified in Section 6.9, Table 14, Page 40 of the D-PHY
  17 * specification (v1.2) with minor adjustments.
  18 */
  19int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing,
  20                                 unsigned long period)
  21{
  22        timing->clkmiss = 0;
  23        timing->clkpost = 70 + 52 * period;
  24        timing->clkpre = 8;
  25        timing->clkprepare = 65;
  26        timing->clksettle = 95;
  27        timing->clktermen = 0;
  28        timing->clktrail = 80;
  29        timing->clkzero = 260;
  30        timing->dtermen = 0;
  31        timing->eot = 0;
  32        timing->hsexit = 120;
  33        timing->hsprepare = 65 + 5 * period;
  34        timing->hszero = 145 + 5 * period;
  35        timing->hssettle = 85 + 6 * period;
  36        timing->hsskip = 40;
  37
  38        /*
  39         * The MIPI D-PHY specification (Section 6.9, v1.2, Table 14, Page 40)
  40         * contains this formula as:
  41         *
  42         *     T_HS-TRAIL = max(n * 8 * period, 60 + n * 4 * period)
  43         *
  44         * where n = 1 for forward-direction HS mode and n = 4 for reverse-
  45         * direction HS mode. There's only one setting and this function does
  46         * not parameterize on anything other that period, so this code will
  47         * assumes that reverse-direction HS mode is supported and uses n = 4.
  48         */
  49        timing->hstrail = max(4 * 8 * period, 60 + 4 * 4 * period);
  50
  51        timing->init = 100000;
  52        timing->lpx = 60;
  53        timing->taget = 5 * timing->lpx;
  54        timing->tago = 4 * timing->lpx;
  55        timing->tasure = 2 * timing->lpx;
  56        timing->wakeup = 1000000;
  57
  58        return 0;
  59}
  60
  61/*
  62 * Validate D-PHY timing according to MIPI D-PHY specification (v1.2, Section
  63 * Section 6.9 "Global Operation Timing Parameters").
  64 */
  65int mipi_dphy_timing_validate(struct mipi_dphy_timing *timing,
  66                              unsigned long period)
  67{
  68        if (timing->clkmiss > 60)
  69                return -EINVAL;
  70
  71        if (timing->clkpost < (60 + 52 * period))
  72                return -EINVAL;
  73
  74        if (timing->clkpre < 8)
  75                return -EINVAL;
  76
  77        if (timing->clkprepare < 38 || timing->clkprepare > 95)
  78                return -EINVAL;
  79
  80        if (timing->clksettle < 95 || timing->clksettle > 300)
  81                return -EINVAL;
  82
  83        if (timing->clktermen > 38)
  84                return -EINVAL;
  85
  86        if (timing->clktrail < 60)
  87                return -EINVAL;
  88
  89        if (timing->clkprepare + timing->clkzero < 300)
  90                return -EINVAL;
  91
  92        if (timing->dtermen > 35 + 4 * period)
  93                return -EINVAL;
  94
  95        if (timing->eot > 105 + 12 * period)
  96                return -EINVAL;
  97
  98        if (timing->hsexit < 100)
  99                return -EINVAL;
 100
 101        if (timing->hsprepare < 40 + 4 * period ||
 102            timing->hsprepare > 85 + 6 * period)
 103                return -EINVAL;
 104
 105        if (timing->hsprepare + timing->hszero < 145 + 10 * period)
 106                return -EINVAL;
 107
 108        if ((timing->hssettle < 85 + 6 * period) ||
 109            (timing->hssettle > 145 + 10 * period))
 110                return -EINVAL;
 111
 112        if (timing->hsskip < 40 || timing->hsskip > 55 + 4 * period)
 113                return -EINVAL;
 114
 115        if (timing->hstrail < max(8 * period, 60 + 4 * period))
 116                return -EINVAL;
 117
 118        if (timing->init < 100000)
 119                return -EINVAL;
 120
 121        if (timing->lpx < 50)
 122                return -EINVAL;
 123
 124        if (timing->taget != 5 * timing->lpx)
 125                return -EINVAL;
 126
 127        if (timing->tago != 4 * timing->lpx)
 128                return -EINVAL;
 129
 130        if (timing->tasure < timing->lpx || timing->tasure > 2 * timing->lpx)
 131                return -EINVAL;
 132
 133        if (timing->wakeup < 1000000)
 134                return -EINVAL;
 135
 136        return 0;
 137}
 138