1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2013 NVIDIA Corporation 4 */ 5 6 #include <linux/errno.h> 7 #include <linux/kernel.h> 8 9 #include "mipi-phy.h" 10 11 /* 12 * Default D-PHY timings based on MIPI D-PHY specification. Derived from the 13 * valid ranges specified in Section 6.9, Table 14, Page 40 of the D-PHY 14 * specification (v1.2) with minor adjustments. 15 */ 16 int mipi_dphy_timing_get_default(struct mipi_dphy_timing *timing, 17 unsigned long period) 18 { 19 timing->clkmiss = 0; 20 timing->clkpost = 70 + 52 * period; 21 timing->clkpre = 8; 22 timing->clkprepare = 65; 23 timing->clksettle = 95; 24 timing->clktermen = 0; 25 timing->clktrail = 80; 26 timing->clkzero = 260; 27 timing->dtermen = 0; 28 timing->eot = 0; 29 timing->hsexit = 120; 30 timing->hsprepare = 65 + 5 * period; 31 timing->hszero = 145 + 5 * period; 32 timing->hssettle = 85 + 6 * period; 33 timing->hsskip = 40; 34 35 /* 36 * The MIPI D-PHY specification (Section 6.9, v1.2, Table 14, Page 40) 37 * contains this formula as: 38 * 39 * T_HS-TRAIL = max(n * 8 * period, 60 + n * 4 * period) 40 * 41 * where n = 1 for forward-direction HS mode and n = 4 for reverse- 42 * direction HS mode. There's only one setting and this function does 43 * not parameterize on anything other that period, so this code will 44 * assumes that reverse-direction HS mode is supported and uses n = 4. 45 */ 46 timing->hstrail = max(4 * 8 * period, 60 + 4 * 4 * period); 47 48 timing->init = 100000; 49 timing->lpx = 60; 50 timing->taget = 5 * timing->lpx; 51 timing->tago = 4 * timing->lpx; 52 timing->tasure = 2 * timing->lpx; 53 timing->wakeup = 1000000; 54 55 return 0; 56 } 57 58 /* 59 * Validate D-PHY timing according to MIPI D-PHY specification (v1.2, Section 60 * Section 6.9 "Global Operation Timing Parameters"). 61 */ 62 int mipi_dphy_timing_validate(struct mipi_dphy_timing *timing, 63 unsigned long period) 64 { 65 if (timing->clkmiss > 60) 66 return -EINVAL; 67 68 if (timing->clkpost < (60 + 52 * period)) 69 return -EINVAL; 70 71 if (timing->clkpre < 8) 72 return -EINVAL; 73 74 if (timing->clkprepare < 38 || timing->clkprepare > 95) 75 return -EINVAL; 76 77 if (timing->clksettle < 95 || timing->clksettle > 300) 78 return -EINVAL; 79 80 if (timing->clktermen > 38) 81 return -EINVAL; 82 83 if (timing->clktrail < 60) 84 return -EINVAL; 85 86 if (timing->clkprepare + timing->clkzero < 300) 87 return -EINVAL; 88 89 if (timing->dtermen > 35 + 4 * period) 90 return -EINVAL; 91 92 if (timing->eot > 105 + 12 * period) 93 return -EINVAL; 94 95 if (timing->hsexit < 100) 96 return -EINVAL; 97 98 if (timing->hsprepare < 40 + 4 * period || 99 timing->hsprepare > 85 + 6 * period) 100 return -EINVAL; 101 102 if (timing->hsprepare + timing->hszero < 145 + 10 * period) 103 return -EINVAL; 104 105 if ((timing->hssettle < 85 + 6 * period) || 106 (timing->hssettle > 145 + 10 * period)) 107 return -EINVAL; 108 109 if (timing->hsskip < 40 || timing->hsskip > 55 + 4 * period) 110 return -EINVAL; 111 112 if (timing->hstrail < max(8 * period, 60 + 4 * period)) 113 return -EINVAL; 114 115 if (timing->init < 100000) 116 return -EINVAL; 117 118 if (timing->lpx < 50) 119 return -EINVAL; 120 121 if (timing->taget != 5 * timing->lpx) 122 return -EINVAL; 123 124 if (timing->tago != 4 * timing->lpx) 125 return -EINVAL; 126 127 if (timing->tasure < timing->lpx || timing->tasure > 2 * timing->lpx) 128 return -EINVAL; 129 130 if (timing->wakeup < 1000000) 131 return -EINVAL; 132 133 return 0; 134 } 135