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 } 139