mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-25 12:33:41 +00:00
425c08faa8
In some cases, the best config cannot be used because the VCO would be out-of-spec. In these cases, we may need to try a worse combination of r/od in order to find the best representable config. This also adds a few test cases to catch this and other (possible) unlikely errors. Signed-off-by: Sean Anderson <seanga2@gmail.com> Reviewed-by: Simon Glass <sjg@chromium.org>
94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
// 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 <kendryte/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 = abs((error - BIT(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);
|