mirror of
https://github.com/torvalds/linux.git
synced 2024-11-25 21:51:40 +00:00
2790e2a33a
In light of the recent discovery that the fractional divisor approximation does not utilize the full available range for clocks that are flagged CLK_FRAC_DIVIDER_ZERO_BASED [1], implement tests for the edge cases of this clock type. Signed-off-by: Frank Oltmanns <frank@oltmanns.dev> Link: https://lore.kernel.org/lkml/20230529133433.56215-1-frank@oltmanns.dev [1] Link: https://lore.kernel.org/r/20230617131041.18313-3-frank@oltmanns.dev [sboyd@kernel.org: Rename suite and tests slightly, drop unused includes, store parent rate to compare instead of repeating equation] Signed-off-by: Stephen Boyd <sboyd@kernel.org>
148 lines
4.2 KiB
C
148 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Kunit test for clock fractional divider
|
|
*/
|
|
#include <linux/clk-provider.h>
|
|
#include <kunit/test.h>
|
|
|
|
#include "clk-fractional-divider.h"
|
|
|
|
/*
|
|
* Test the maximum denominator case for fd clock without flags.
|
|
*
|
|
* Expect the highest possible denominator to be used in order to get as close as possible to the
|
|
* requested rate.
|
|
*/
|
|
static void clk_fd_test_approximation_max_denominator(struct kunit *test)
|
|
{
|
|
struct clk_fractional_divider *fd;
|
|
unsigned long rate, parent_rate, parent_rate_before, m, n, max_n;
|
|
|
|
fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
|
|
KUNIT_ASSERT_NOT_NULL(test, fd);
|
|
|
|
fd->mwidth = 3;
|
|
fd->nwidth = 3;
|
|
max_n = 7;
|
|
|
|
rate = 240000000;
|
|
parent_rate = (max_n + 1) * rate; /* so that it exceeds the maximum divisor */
|
|
parent_rate_before = parent_rate;
|
|
|
|
clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
|
|
KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
|
|
|
|
KUNIT_EXPECT_EQ(test, m, 1);
|
|
KUNIT_EXPECT_EQ(test, n, max_n);
|
|
}
|
|
|
|
/*
|
|
* Test the maximum numerator case for fd clock without flags.
|
|
*
|
|
* Expect the highest possible numerator to be used in order to get as close as possible to the
|
|
* requested rate.
|
|
*/
|
|
static void clk_fd_test_approximation_max_numerator(struct kunit *test)
|
|
{
|
|
struct clk_fractional_divider *fd;
|
|
unsigned long rate, parent_rate, parent_rate_before, m, n, max_m;
|
|
|
|
fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
|
|
KUNIT_ASSERT_NOT_NULL(test, fd);
|
|
|
|
fd->mwidth = 3;
|
|
max_m = 7;
|
|
fd->nwidth = 3;
|
|
|
|
rate = 240000000;
|
|
parent_rate = rate / (max_m + 1); /* so that it exceeds the maximum numerator */
|
|
parent_rate_before = parent_rate;
|
|
|
|
clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
|
|
KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
|
|
|
|
KUNIT_EXPECT_EQ(test, m, max_m);
|
|
KUNIT_EXPECT_EQ(test, n, 1);
|
|
}
|
|
|
|
/*
|
|
* Test the maximum denominator case for zero based fd clock.
|
|
*
|
|
* Expect the highest possible denominator to be used in order to get as close as possible to the
|
|
* requested rate.
|
|
*/
|
|
static void clk_fd_test_approximation_max_denominator_zero_based(struct kunit *test)
|
|
{
|
|
struct clk_fractional_divider *fd;
|
|
unsigned long rate, parent_rate, parent_rate_before, m, n, max_n;
|
|
|
|
fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
|
|
KUNIT_ASSERT_NOT_NULL(test, fd);
|
|
|
|
fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED;
|
|
fd->mwidth = 3;
|
|
fd->nwidth = 3;
|
|
max_n = 8;
|
|
|
|
rate = 240000000;
|
|
parent_rate = (max_n + 1) * rate; /* so that it exceeds the maximum divisor */
|
|
parent_rate_before = parent_rate;
|
|
|
|
clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
|
|
KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
|
|
|
|
KUNIT_EXPECT_EQ(test, m, 1);
|
|
KUNIT_EXPECT_EQ(test, n, max_n);
|
|
}
|
|
|
|
/*
|
|
* Test the maximum numerator case for zero based fd clock.
|
|
*
|
|
* Expect the highest possible numerator to be used in order to get as close as possible to the
|
|
* requested rate.
|
|
*/
|
|
static void clk_fd_test_approximation_max_numerator_zero_based(struct kunit *test)
|
|
{
|
|
struct clk_fractional_divider *fd;
|
|
unsigned long rate, parent_rate, parent_rate_before, m, n, max_m;
|
|
|
|
fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
|
|
KUNIT_ASSERT_NOT_NULL(test, fd);
|
|
|
|
fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED;
|
|
fd->mwidth = 3;
|
|
max_m = 8;
|
|
fd->nwidth = 3;
|
|
|
|
rate = 240000000;
|
|
parent_rate = rate / (max_m + 1); /* so that it exceeds the maximum numerator */
|
|
parent_rate_before = parent_rate;
|
|
|
|
clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
|
|
KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
|
|
|
|
KUNIT_EXPECT_EQ(test, m, max_m);
|
|
KUNIT_EXPECT_EQ(test, n, 1);
|
|
}
|
|
|
|
static struct kunit_case clk_fd_approximation_test_cases[] = {
|
|
KUNIT_CASE(clk_fd_test_approximation_max_denominator),
|
|
KUNIT_CASE(clk_fd_test_approximation_max_numerator),
|
|
KUNIT_CASE(clk_fd_test_approximation_max_denominator_zero_based),
|
|
KUNIT_CASE(clk_fd_test_approximation_max_numerator_zero_based),
|
|
{}
|
|
};
|
|
|
|
/*
|
|
* Test suite for clk_fractional_divider_general_approximation().
|
|
*/
|
|
static struct kunit_suite clk_fd_approximation_suite = {
|
|
.name = "clk-fd-approximation",
|
|
.test_cases = clk_fd_approximation_test_cases,
|
|
};
|
|
|
|
kunit_test_suites(
|
|
&clk_fd_approximation_suite
|
|
);
|
|
MODULE_LICENSE("GPL");
|