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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
*/
#include <common.h>
/* For DIV_ROUND_DOWN_ULL, defined in linux/kernel.h */
#include <div64.h>
#include <dm/test.h>
#include <k210/pll.h>
#include <test/ut.h>
static int dm_test_k210_pll_calc_config(u32 rate, u32 rate_in,
struct k210_pll_config *best)
{
u64 f, r, od, max_r, inv_ratio;
s64 error, best_error;
best_error = S64_MAX;
error = best_error;
max_r = min(16ULL, DIV_ROUND_DOWN_ULL(rate_in, 13300000));
inv_ratio = DIV_ROUND_CLOSEST_ULL((u64)rate_in << 32, rate);
/* Brute force it */
for (r = 1; r <= max_r; r++) {
for (f = 1; f <= 64; f++) {
for (od = 1; od <= 16; od++) {
u64 vco = DIV_ROUND_CLOSEST_ULL(rate_in * f, r);
if (vco > 1750000000 || vco < 340000000)
continue;
error = DIV_ROUND_CLOSEST_ULL(f * inv_ratio,
r * od);
/* The lower 16 bits are spurious */
error = abs64((error - BIT_ULL(32))) >> 16;
if (error < best_error) {
best->r = r;
best->f = f;
best->od = od;
best_error = error;
}
}
}
}
if (best_error == S64_MAX)
return -EINVAL;
return 0;
}
static int dm_test_k210_pll_compare(struct k210_pll_config *ours,
struct k210_pll_config *theirs)
{
return (u32)ours->f * theirs->r * theirs->od !=
(u32)theirs->f * ours->r * ours->od;
}
static int dm_test_k210_pll(struct unit_test_state *uts)
{
struct k210_pll_config ours, theirs;
/* General range checks */
ut_asserteq(-EINVAL, k210_pll_calc_config(0, 26000000, &theirs));
ut_asserteq(-EINVAL, k210_pll_calc_config(390000000, 0, &theirs));
ut_asserteq(-EINVAL, k210_pll_calc_config(2000000000, 26000000,
&theirs));
ut_asserteq(-EINVAL, k210_pll_calc_config(390000000, 2000000000,
&theirs));
ut_asserteq(-EINVAL, k210_pll_calc_config(1500000000, 20000000,
&theirs));
ut_asserteq(-EINVAL, k210_pll_calc_config(1750000000, 13300000,
&theirs));
/* Verify we get the same output with brute-force */
#define compare(rate, rate_in) do { \
ut_assertok(dm_test_k210_pll_calc_config(rate, rate_in, &ours)); \
ut_assertok(k210_pll_calc_config(rate, rate_in, &theirs)); \
ut_assertok(dm_test_k210_pll_compare(&ours, &theirs)); \
} while (0)
compare(390000000, 26000000);
compare(26000000, 390000000);
compare(400000000, 26000000);
compare(27000000, 26000000);
compare(26000000, 27000000);
compare(13300000 * 64, 13300000);
compare(21250000, 21250000 * 70);
compare(21250000, 1750000000);
compare(1750000000, 1750000000);
return 0;
}
DM_TEST(dm_test_k210_pll, 0);
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