/src/u-boot/test/dm/k210_pll.c
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1 | | // SPDX-License-Identifier: GPL-2.0 |
2 | | /* |
3 | | * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com> |
4 | | */ |
5 | | |
6 | | /* For DIV_ROUND_DOWN_ULL, defined in linux/kernel.h */ |
7 | | #include <div64.h> |
8 | | #include <dm/test.h> |
9 | | #include <k210/pll.h> |
10 | | #include <test/ut.h> |
11 | | |
12 | | static int dm_test_k210_pll_calc_config(u32 rate, u32 rate_in, |
13 | | struct k210_pll_config *best) |
14 | 0 | { |
15 | 0 | u64 f, r, od, max_r, inv_ratio; |
16 | 0 | s64 error, best_error; |
17 | |
|
18 | 0 | best_error = S64_MAX; |
19 | 0 | error = best_error; |
20 | 0 | max_r = min(16ULL, DIV_ROUND_DOWN_ULL(rate_in, 13300000)); |
21 | 0 | inv_ratio = DIV_ROUND_CLOSEST_ULL((u64)rate_in << 32, rate); |
22 | | |
23 | | /* Brute force it */ |
24 | 0 | for (r = 1; r <= max_r; r++) { |
25 | 0 | for (f = 1; f <= 64; f++) { |
26 | 0 | for (od = 1; od <= 16; od++) { |
27 | 0 | u64 vco = DIV_ROUND_CLOSEST_ULL(rate_in * f, r); |
28 | |
|
29 | 0 | if (vco > 1750000000 || vco < 340000000) |
30 | 0 | continue; |
31 | | |
32 | 0 | error = DIV_ROUND_CLOSEST_ULL(f * inv_ratio, |
33 | 0 | r * od); |
34 | | /* The lower 16 bits are spurious */ |
35 | 0 | error = abs64((error - BIT_ULL(32))) >> 16; |
36 | 0 | if (error < best_error) { |
37 | 0 | best->r = r; |
38 | 0 | best->f = f; |
39 | 0 | best->od = od; |
40 | 0 | best_error = error; |
41 | 0 | } |
42 | 0 | } |
43 | 0 | } |
44 | 0 | } |
45 | |
|
46 | 0 | if (best_error == S64_MAX) |
47 | 0 | return -EINVAL; |
48 | 0 | return 0; |
49 | 0 | } |
50 | | |
51 | | static int dm_test_k210_pll_compare(struct k210_pll_config *ours, |
52 | | struct k210_pll_config *theirs) |
53 | 0 | { |
54 | 0 | return (u32)ours->f * theirs->r * theirs->od != |
55 | 0 | (u32)theirs->f * ours->r * ours->od; |
56 | 0 | } |
57 | | |
58 | | static int dm_test_k210_pll(struct unit_test_state *uts) |
59 | 0 | { |
60 | 0 | struct k210_pll_config ours, theirs; |
61 | | |
62 | | /* General range checks */ |
63 | 0 | ut_asserteq(-EINVAL, k210_pll_calc_config(0, 26000000, &theirs)); |
64 | 0 | ut_asserteq(-EINVAL, k210_pll_calc_config(390000000, 0, &theirs)); |
65 | 0 | ut_asserteq(-EINVAL, k210_pll_calc_config(2000000000, 26000000, |
66 | 0 | &theirs)); |
67 | 0 | ut_asserteq(-EINVAL, k210_pll_calc_config(390000000, 2000000000, |
68 | 0 | &theirs)); |
69 | 0 | ut_asserteq(-EINVAL, k210_pll_calc_config(1500000000, 20000000, |
70 | 0 | &theirs)); |
71 | 0 | ut_asserteq(-EINVAL, k210_pll_calc_config(1750000000, 13300000, |
72 | 0 | &theirs)); |
73 | | |
74 | | /* Verify we get the same output with brute-force */ |
75 | 0 | #define compare(rate, rate_in) do { \ |
76 | 0 | ut_assertok(dm_test_k210_pll_calc_config(rate, rate_in, &ours)); \ |
77 | 0 | ut_assertok(k210_pll_calc_config(rate, rate_in, &theirs)); \ |
78 | 0 | ut_assertok(dm_test_k210_pll_compare(&ours, &theirs)); \ |
79 | 0 | } while (0) |
80 | |
|
81 | 0 | compare(390000000, 26000000); |
82 | 0 | compare(26000000, 390000000); |
83 | 0 | compare(400000000, 26000000); |
84 | 0 | compare(27000000, 26000000); |
85 | 0 | compare(26000000, 27000000); |
86 | 0 | compare(13300000 * 64, 13300000); |
87 | 0 | compare(21250000, 21250000 * 70); |
88 | 0 | compare(21250000, 1750000000); |
89 | 0 | compare(1750000000, 1750000000); |
90 | |
|
91 | 0 | return 0; |
92 | 0 | } |
93 | | DM_TEST(dm_test_k210_pll, 0); |