drivers/phy/phy-core-mipi-dphy.c

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (C) 2013 NVIDIA Corporation
   4  * Copyright (C) 2018 Cadence Design Systems Inc.
   5  */
   6
   7 #include <linux/errno.h>
   8 #include <linux/export.h>
   9 #include <linux/kernel.h>
  10 #include <linux/time64.h>
  11
  12 #include <linux/phy/phy.h>
  13 #include <linux/phy/phy-mipi-dphy.h>
  14
  15 #define PSEC_PER_SEC    1000000000000LL
  16
  17 /*
  18  * Minimum D-PHY timings based on MIPI D-PHY specification. Derived
  19  * from the valid ranges specified in Section 6.9, Table 14, Page 41
  20  * of the D-PHY specification (v2.1).
  21  */
  22 int phy_mipi_dphy_get_default_config(unsigned long pixel_clock,
  23                                      unsigned int bpp,
  24                                      unsigned int lanes,
  25                                      struct phy_configure_opts_mipi_dphy *cfg)
  26 {
  27         unsigned long long hs_clk_rate;
  28         unsigned long long ui;
  29
  30         if (!cfg)
  31                 return -EINVAL;
  32
  33         hs_clk_rate = pixel_clock * bpp;
  34         do_div(hs_clk_rate, lanes);
  35
  36         ui = ALIGN(PSEC_PER_SEC, hs_clk_rate);
  37         do_div(ui, hs_clk_rate);
  38
  39         cfg->clk_miss = 0;
  40         cfg->clk_post = 60000 + 52 * ui;
  41         cfg->clk_pre = 8000;
  42         cfg->clk_prepare = 38000;
  43         cfg->clk_settle = 95000;
  44         cfg->clk_term_en = 0;
  45         cfg->clk_trail = 60000;
  46         cfg->clk_zero = 262000;
  47         cfg->d_term_en = 0;
  48         cfg->eot = 0;
  49         cfg->hs_exit = 100000;
  50         cfg->hs_prepare = 40000 + 4 * ui;
  51         cfg->hs_zero = 105000 + 6 * ui;
  52         cfg->hs_settle = 85000 + 6 * ui;
  53         cfg->hs_skip = 40000;
  54
  55         /*
  56          * The MIPI D-PHY specification (Section 6.9, v1.2, Table 14, Page 40)
  57          * contains this formula as:
  58          *
  59          *     T_HS-TRAIL = max(n * 8 * ui, 60 + n * 4 * ui)
  60          *
  61          * where n = 1 for forward-direction HS mode and n = 4 for reverse-
  62          * direction HS mode. There's only one setting and this function does
  63          * not parameterize on anything other that ui, so this code will
  64          * assumes that reverse-direction HS mode is supported and uses n = 4.
  65          */
  66         cfg->hs_trail = max(4 * 8 * ui, 60000 + 4 * 4 * ui);
  67
  68         cfg->init = 100000000;
  69         cfg->lpx = 60000;
  70         cfg->ta_get = 5 * cfg->lpx;
  71         cfg->ta_go = 4 * cfg->lpx;
  72         cfg->ta_sure = 2 * cfg->lpx;
  73         cfg->wakeup = 1000000000;
  74
  75         cfg->hs_clk_rate = hs_clk_rate;
  76         cfg->lanes = lanes;
  77
  78         return 0;
  79 }
  80 EXPORT_SYMBOL(phy_mipi_dphy_get_default_config);
  81
  82 /*
  83  * Validate D-PHY configuration according to MIPI D-PHY specification
  84  * (v1.2, Section Section 6.9 "Global Operation Timing Parameters").
  85  */
  86 int phy_mipi_dphy_config_validate(struct phy_configure_opts_mipi_dphy *cfg)
  87 {
  88         unsigned long long ui;
  89
  90         if (!cfg)
  91                 return -EINVAL;
  92
  93         ui = ALIGN(PSEC_PER_SEC, cfg->hs_clk_rate);
  94         do_div(ui, cfg->hs_clk_rate);
  95
  96         if (cfg->clk_miss > 60000)
  97                 return -EINVAL;
  98
  99         if (cfg->clk_post < (60000 + 52 * ui))
 100                 return -EINVAL;
 101
 102         if (cfg->clk_pre < 8000)
 103                 return -EINVAL;
 104
 105         if (cfg->clk_prepare < 38000 || cfg->clk_prepare > 95000)
 106                 return -EINVAL;
 107
 108         if (cfg->clk_settle < 95000 || cfg->clk_settle > 300000)
 109                 return -EINVAL;
 110
 111         if (cfg->clk_term_en > 38000)
 112                 return -EINVAL;
 113
 114         if (cfg->clk_trail < 60000)
 115                 return -EINVAL;
 116
 117         if ((cfg->clk_prepare + cfg->clk_zero) < 300000)
 118                 return -EINVAL;
 119
 120         if (cfg->d_term_en > (35000 + 4 * ui))
 121                 return -EINVAL;
 122
 123         if (cfg->eot > (105000 + 12 * ui))
 124                 return -EINVAL;
 125
 126         if (cfg->hs_exit < 100000)
 127                 return -EINVAL;
 128
 129         if (cfg->hs_prepare < (40000 + 4 * ui) ||
 130             cfg->hs_prepare > (85000 + 6 * ui))
 131                 return -EINVAL;
 132
 133         if ((cfg->hs_prepare + cfg->hs_zero) < (145000 + 10 * ui))
 134                 return -EINVAL;
 135
 136         if ((cfg->hs_settle < (85000 + 6 * ui)) ||
 137             (cfg->hs_settle > (145000 + 10 * ui)))
 138                 return -EINVAL;
 139
 140         if (cfg->hs_skip < 40000 || cfg->hs_skip > (55000 + 4 * ui))
 141                 return -EINVAL;
 142
 143         if (cfg->hs_trail < max(8 * ui, 60000 + 4 * ui))
 144                 return -EINVAL;
 145
 146         if (cfg->init < 100000000)
 147                 return -EINVAL;
 148
 149         if (cfg->lpx < 50000)
 150                 return -EINVAL;
 151
 152         if (cfg->ta_get != (5 * cfg->lpx))
 153                 return -EINVAL;
 154
 155         if (cfg->ta_go != (4 * cfg->lpx))
 156                 return -EINVAL;
 157
 158         if (cfg->ta_sure < cfg->lpx || cfg->ta_sure > (2 * cfg->lpx))
 159                 return -EINVAL;
 160
 161         if (cfg->wakeup < 1000000000)
 162                 return -EINVAL;
 163
 164         return 0;
 165 }
 166 EXPORT_SYMBOL(phy_mipi_dphy_config_validate);