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
  16  * the valid ranges specified in Section 5.9 of the D-PHY specification
  17  * with minor adjustments.
  18  */
  19 int 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         timing->hstrail = max(8 * period, 60 + 4 * period);
  38         timing->init = 100000;
  39         timing->lpx = 60;
  40         timing->taget = 5 * timing->lpx;
  41         timing->tago = 4 * timing->lpx;
  42         timing->tasure = 2 * timing->lpx;
  43         timing->wakeup = 1000000;
  44
  45         return 0;
  46 }
  47
  48 /*
  49  * Validate D-PHY timing according to MIPI Alliance Specification for D-PHY,
  50  * Section 5.9 "Global Operation Timing Parameters".
  51  */
  52 int mipi_dphy_timing_validate(struct mipi_dphy_timing *timing,
  53                               unsigned long period)
  54 {
  55         if (timing->clkmiss > 60)
  56                 return -EINVAL;
  57
  58         if (timing->clkpost < (60 + 52 * period))
  59                 return -EINVAL;
  60
  61         if (timing->clkpre < 8)
  62                 return -EINVAL;
  63
  64         if (timing->clkprepare < 38 || timing->clkprepare > 95)
  65                 return -EINVAL;
  66
  67         if (timing->clksettle < 95 || timing->clksettle > 300)
  68                 return -EINVAL;
  69
  70         if (timing->clktermen > 38)
  71                 return -EINVAL;
  72
  73         if (timing->clktrail < 60)
  74                 return -EINVAL;
  75
  76         if (timing->clkprepare + timing->clkzero < 300)
  77                 return -EINVAL;
  78
  79         if (timing->dtermen > 35 + 4 * period)
  80                 return -EINVAL;
  81
  82         if (timing->eot > 105 + 12 * period)
  83                 return -EINVAL;
  84
  85         if (timing->hsexit < 100)
  86                 return -EINVAL;
  87
  88         if (timing->hsprepare < 40 + 4 * period ||
  89             timing->hsprepare > 85 + 6 * period)
  90                 return -EINVAL;
  91
  92         if (timing->hsprepare + timing->hszero < 145 + 10 * period)
  93                 return -EINVAL;
  94
  95         if ((timing->hssettle < 85 + 6 * period) ||
  96             (timing->hssettle > 145 + 10 * period))
  97                 return -EINVAL;
  98
  99         if (timing->hsskip < 40 || timing->hsskip > 55 + 4 * period)
 100                 return -EINVAL;
 101
 102         if (timing->hstrail < max(8 * period, 60 + 4 * period))
 103                 return -EINVAL;
 104
 105         if (timing->init < 100000)
 106                 return -EINVAL;
 107
 108         if (timing->lpx < 50)
 109                 return -EINVAL;
 110
 111         if (timing->taget != 5 * timing->lpx)
 112                 return -EINVAL;
 113
 114         if (timing->tago != 4 * timing->lpx)
 115                 return -EINVAL;
 116
 117         if (timing->tasure < timing->lpx || timing->tasure > 2 * timing->lpx)
 118                 return -EINVAL;
 119
 120         if (timing->wakeup < 1000000)
 121                 return -EINVAL;
 122
 123         return 0;
 124 }