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 | |