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

   1 /*
   2  * Copyright (C) 2013 NVIDIA Corporation
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that copyright
   7  * notice and this permission notice appear in supporting documentation, and
   8  * that the name of the copyright holders not be used in advertising or
   9  * publicity pertaining to distribution of the software without specific,
  10  * written prior permission.  The copyright holders make no representations
  11  * about the suitability of this software for any purpose.  It is provided "as
  12  * is" without express or implied warranty.
  13  *
  14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  20  * OF THIS SOFTWARE.
  21  */
  22
  23 #include <linux/errno.h>
  24 #include <linux/kernel.h>
  25
  26 #include "mipi-phy.h"
  27
  28 /*
  29  * Default D-PHY timings based on MIPI D-PHY specification. Derived from
  30  * the valid ranges specified in Section 5.9 of the D-PHY specification
  31  * with minor adjustments.
  32  */
  33 int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing,
  34                                  unsigned long period)
  35 {
  36         timing->clkmiss = 0;
  37         timing->clkpost = 70 + 52 * period;
  38         timing->clkpre = 8;
  39         timing->clkprepare = 65;
  40         timing->clksettle = 95;
  41         timing->clktermen = 0;
  42         timing->clktrail = 80;
  43         timing->clkzero = 260;
  44         timing->dtermen = 0;
  45         timing->eot = 0;
  46         timing->hsexit = 120;
  47         timing->hsprepare = 65 + 5 * period;
  48         timing->hszero = 145 + 5 * period;
  49         timing->hssettle = 85 + 6 * period;
  50         timing->hsskip = 40;
  51         timing->hstrail = max(8 * period, 60 + 4 * period);
  52         timing->init = 100000;
  53         timing->lpx = 60;
  54         timing->taget = 5 * timing->lpx;
  55         timing->tago = 4 * timing->lpx;
  56         timing->tasure = 2 * timing->lpx;
  57         timing->wakeup = 1000000;
  58
  59         return 0;
  60 }
  61
  62 /*
  63  * Validate D-PHY timing according to MIPI Alliance Specification for D-PHY,
  64  * Section 5.9 "Global Operation Timing Parameters".
  65  */
  66 int mipi_dphy_timing_validate(struct mipi_dphy_timing *timing,
  67                               unsigned long period)
  68 {
  69         if (timing->clkmiss > 60)
  70                 return -EINVAL;
  71
  72         if (timing->clkpost < (60 + 52 * period))
  73                 return -EINVAL;
  74
  75         if (timing->clkpre < 8)
  76                 return -EINVAL;
  77
  78         if (timing->clkprepare < 38 || timing->clkprepare > 95)
  79                 return -EINVAL;
  80
  81         if (timing->clksettle < 95 || timing->clksettle > 300)
  82                 return -EINVAL;
  83
  84         if (timing->clktermen > 38)
  85                 return -EINVAL;
  86
  87         if (timing->clktrail < 60)
  88                 return -EINVAL;
  89
  90         if (timing->clkprepare + timing->clkzero < 300)
  91                 return -EINVAL;
  92
  93         if (timing->dtermen > 35 + 4 * period)
  94                 return -EINVAL;
  95
  96         if (timing->eot > 105 + 12 * period)
  97                 return -EINVAL;
  98
  99         if (timing->hsexit < 100)
 100                 return -EINVAL;
 101
 102         if (timing->hsprepare < 40 + 4 * period ||
 103             timing->hsprepare > 85 + 6 * period)
 104                 return -EINVAL;
 105
 106         if (timing->hsprepare + timing->hszero < 145 + 10 * period)
 107                 return -EINVAL;
 108
 109         if ((timing->hssettle < 85 + 6 * period) ||
 110             (timing->hssettle > 145 + 10 * period))
 111                 return -EINVAL;
 112
 113         if (timing->hsskip < 40 || timing->hsskip > 55 + 4 * period)
 114                 return -EINVAL;
 115
 116         if (timing->hstrail < max(8 * period, 60 + 4 * period))
 117                 return -EINVAL;
 118
 119         if (timing->init < 100000)
 120                 return -EINVAL;
 121
 122         if (timing->lpx < 50)
 123                 return -EINVAL;
 124
 125         if (timing->taget != 5 * timing->lpx)
 126                 return -EINVAL;
 127
 128         if (timing->tago != 4 * timing->lpx)
 129                 return -EINVAL;
 130
 131         if (timing->tasure < timing->lpx || timing->tasure > 2 * timing->lpx)
 132                 return -EINVAL;
 133
 134         if (timing->wakeup < 1000000)
 135                 return -EINVAL;
 136
 137         return 0;
 138 }