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 */ 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 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 */ 65 int 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