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authorMark Brown <broonie@kernel.org>2020-06-01 14:01:44 +0200
committerMark Brown <broonie@kernel.org>2020-06-01 14:01:44 +0200
commit5fb565b69dabd5a256fc116702331b54a4621dc9 (patch)
tree55c3cd9ba11101f9c2e3b6789d0b4d87f91e0732 /lib
parentMerge remote-tracking branch 'regulator/for-5.7' into regulator-linus (diff)
parentregulator: max8998: max8998_set_current_limit() can be static (diff)
downloadlinux-5fb565b69dabd5a256fc116702331b54a4621dc9.tar.xz
linux-5fb565b69dabd5a256fc116702331b54a4621dc9.zip
Merge remote-tracking branch 'regulator/for-5.8' into regulator-linus
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig3
-rw-r--r--lib/Kconfig.debug12
-rw-r--r--lib/Makefile2
-rw-r--r--lib/linear_ranges.c245
-rw-r--r--lib/test_linear_ranges.c228
5 files changed, 490 insertions, 0 deletions
diff --git a/lib/Kconfig b/lib/Kconfig
index 5d53f9609c25..8ec05335426c 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -19,6 +19,9 @@ config RAID6_PQ_BENCHMARK
Benchmark all available RAID6 PQ functions on init and choose the
fastest one.
+config LINEAR_RANGES
+ tristate
+
config PACKING
bool "Generic bitfield packing and unpacking"
default n
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 21d9c5f6e7ec..f3322a620674 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2092,6 +2092,18 @@ config LIST_KUNIT_TEST
If unsure, say N.
+config LINEAR_RANGES_TEST
+ tristate "KUnit test for linear_ranges"
+ depends on KUNIT
+ select LINEAR_RANGES
+ help
+ This builds the linear_ranges unit test, which runs on boot.
+ Tests the linear_ranges logic correctness.
+ For more information on KUnit and unit tests in general please refer
+ to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+ If unsure, say N.
+
config TEST_UDELAY
tristate "udelay test driver"
help
diff --git a/lib/Makefile b/lib/Makefile
index 685aee60de1d..cd548bfa8df9 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -125,6 +125,7 @@ obj-$(CONFIG_DEBUG_LIST) += list_debug.o
obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o
obj-$(CONFIG_BITREVERSE) += bitrev.o
+obj-$(CONFIG_LINEAR_RANGES) += linear_ranges.o
obj-$(CONFIG_PACKING) += packing.o
obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o
obj-$(CONFIG_CRC16) += crc16.o
@@ -309,3 +310,4 @@ obj-$(CONFIG_OBJAGG) += objagg.o
# KUnit tests
obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
+obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
diff --git a/lib/linear_ranges.c b/lib/linear_ranges.c
new file mode 100644
index 000000000000..9495ef3572b7
--- /dev/null
+++ b/lib/linear_ranges.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * helpers to map values in a linear range to range index
+ *
+ * Original idea borrowed from regulator framework
+ *
+ * It might be useful if we could support also inversely proportional ranges?
+ * Copyright 2020 ROHM Semiconductors
+ */
+
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/linear_range.h>
+#include <linux/module.h>
+
+/**
+ * linear_range_values_in_range - return the amount of values in a range
+ * @r: pointer to linear range where values are counted
+ *
+ * Compute the amount of values in range pointed by @r. Note, values can
+ * be all equal - range with selectors 0,...,2 with step 0 still contains
+ * 3 values even though they are all equal.
+ *
+ * Return: the amount of values in range pointed by @r
+ */
+unsigned int linear_range_values_in_range(const struct linear_range *r)
+{
+ if (!r)
+ return 0;
+ return r->max_sel - r->min_sel + 1;
+}
+EXPORT_SYMBOL_GPL(linear_range_values_in_range);
+
+/**
+ * linear_range_values_in_range_array - return the amount of values in ranges
+ * @r: pointer to array of linear ranges where values are counted
+ * @ranges: amount of ranges we include in computation.
+ *
+ * Compute the amount of values in ranges pointed by @r. Note, values can
+ * be all equal - range with selectors 0,...,2 with step 0 still contains
+ * 3 values even though they are all equal.
+ *
+ * Return: the amount of values in first @ranges ranges pointed by @r
+ */
+unsigned int linear_range_values_in_range_array(const struct linear_range *r,
+ int ranges)
+{
+ int i, values_in_range = 0;
+
+ for (i = 0; i < ranges; i++) {
+ int values;
+
+ values = linear_range_values_in_range(&r[i]);
+ if (!values)
+ return values;
+
+ values_in_range += values;
+ }
+ return values_in_range;
+}
+EXPORT_SYMBOL_GPL(linear_range_values_in_range_array);
+
+/**
+ * linear_range_get_max_value - return the largest value in a range
+ * @r: pointer to linear range where value is looked from
+ *
+ * Return: the largest value in the given range
+ */
+unsigned int linear_range_get_max_value(const struct linear_range *r)
+{
+ return r->min + (r->max_sel - r->min_sel) * r->step;
+}
+EXPORT_SYMBOL_GPL(linear_range_get_max_value);
+
+/**
+ * linear_range_get_value - fetch a value from given range
+ * @r: pointer to linear range where value is looked from
+ * @selector: selector for which the value is searched
+ * @val: address where found value is updated
+ *
+ * Search given ranges for value which matches given selector.
+ *
+ * Return: 0 on success, -EINVAL given selector is not found from any of the
+ * ranges.
+ */
+int linear_range_get_value(const struct linear_range *r, unsigned int selector,
+ unsigned int *val)
+{
+ if (r->min_sel > selector || r->max_sel < selector)
+ return -EINVAL;
+
+ *val = r->min + (selector - r->min_sel) * r->step;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(linear_range_get_value);
+
+/**
+ * linear_range_get_value_array - fetch a value from array of ranges
+ * @r: pointer to array of linear ranges where value is looked from
+ * @ranges: amount of ranges in an array
+ * @selector: selector for which the value is searched
+ * @val: address where found value is updated
+ *
+ * Search through an array of ranges for value which matches given selector.
+ *
+ * Return: 0 on success, -EINVAL given selector is not found from any of the
+ * ranges.
+ */
+int linear_range_get_value_array(const struct linear_range *r, int ranges,
+ unsigned int selector, unsigned int *val)
+{
+ int i;
+
+ for (i = 0; i < ranges; i++)
+ if (r[i].min_sel <= selector && r[i].max_sel >= selector)
+ return linear_range_get_value(&r[i], selector, val);
+
+ return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(linear_range_get_value_array);
+
+/**
+ * linear_range_get_selector_low - return linear range selector for value
+ * @r: pointer to linear range where selector is looked from
+ * @val: value for which the selector is searched
+ * @selector: address where found selector value is updated
+ * @found: flag to indicate that given value was in the range
+ *
+ * Return selector which which range value is closest match for given
+ * input value. Value is matching if it is equal or smaller than given
+ * value. If given value is in the range, then @found is set true.
+ *
+ * Return: 0 on success, -EINVAL if range is invalid or does not contain
+ * value smaller or equal to given value
+ */
+int linear_range_get_selector_low(const struct linear_range *r,
+ unsigned int val, unsigned int *selector,
+ bool *found)
+{
+ *found = false;
+
+ if (r->min > val)
+ return -EINVAL;
+
+ if (linear_range_get_max_value(r) < val) {
+ *selector = r->max_sel;
+ return 0;
+ }
+
+ *found = true;
+
+ if (r->step == 0)
+ *selector = r->min_sel;
+ else
+ *selector = (val - r->min) / r->step + r->min_sel;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(linear_range_get_selector_low);
+
+/**
+ * linear_range_get_selector_low_array - return linear range selector for value
+ * @r: pointer to array of linear ranges where selector is looked from
+ * @ranges: amount of ranges to scan from array
+ * @val: value for which the selector is searched
+ * @selector: address where found selector value is updated
+ * @found: flag to indicate that given value was in the range
+ *
+ * Scan array of ranges for selector which which range value matches given
+ * input value. Value is matching if it is equal or smaller than given
+ * value. If given value is found to be in a range scanning is stopped and
+ * @found is set true. If a range with values smaller than given value is found
+ * but the range max is being smaller than given value, then the ranges
+ * biggest selector is updated to @selector but scanning ranges is continued
+ * and @found is set to false.
+ *
+ * Return: 0 on success, -EINVAL if range array is invalid or does not contain
+ * range with a value smaller or equal to given value
+ */
+int linear_range_get_selector_low_array(const struct linear_range *r,
+ int ranges, unsigned int val,
+ unsigned int *selector, bool *found)
+{
+ int i;
+ int ret = -EINVAL;
+
+ for (i = 0; i < ranges; i++) {
+ int tmpret;
+
+ tmpret = linear_range_get_selector_low(&r[i], val, selector,
+ found);
+ if (!tmpret)
+ ret = 0;
+
+ if (*found)
+ break;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(linear_range_get_selector_low_array);
+
+/**
+ * linear_range_get_selector_high - return linear range selector for value
+ * @r: pointer to linear range where selector is looked from
+ * @val: value for which the selector is searched
+ * @selector: address where found selector value is updated
+ * @found: flag to indicate that given value was in the range
+ *
+ * Return selector which which range value is closest match for given
+ * input value. Value is matching if it is equal or higher than given
+ * value. If given value is in the range, then @found is set true.
+ *
+ * Return: 0 on success, -EINVAL if range is invalid or does not contain
+ * value greater or equal to given value
+ */
+int linear_range_get_selector_high(const struct linear_range *r,
+ unsigned int val, unsigned int *selector,
+ bool *found)
+{
+ *found = false;
+
+ if (linear_range_get_max_value(r) < val)
+ return -EINVAL;
+
+ if (r->min > val) {
+ *selector = r->min_sel;
+ return 0;
+ }
+
+ *found = true;
+
+ if (r->step == 0)
+ *selector = r->max_sel;
+ else
+ *selector = DIV_ROUND_UP(val - r->min, r->step) + r->min_sel;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(linear_range_get_selector_high);
+
+MODULE_DESCRIPTION("linear-ranges helper");
+MODULE_LICENSE("GPL");
diff --git a/lib/test_linear_ranges.c b/lib/test_linear_ranges.c
new file mode 100644
index 000000000000..676e0b8abcdd
--- /dev/null
+++ b/lib/test_linear_ranges.c
@@ -0,0 +1,228 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for the linear_ranges helper.
+ *
+ * Copyright (C) 2020, ROHM Semiconductors.
+ * Author: Matti Vaittinen <matti.vaittien@fi.rohmeurope.com>
+ */
+#include <kunit/test.h>
+
+#include <linux/linear_range.h>
+
+/* First things first. I deeply dislike unit-tests. I have seen all the hell
+ * breaking loose when people who think the unit tests are "the silver bullet"
+ * to kill bugs get to decide how a company should implement testing strategy...
+ *
+ * Believe me, it may get _really_ ridiculous. It is tempting to think that
+ * walking through all the possible execution branches will nail down 100% of
+ * bugs. This may lead to ideas about demands to get certain % of "test
+ * coverage" - measured as line coverage. And that is one of the worst things
+ * you can do.
+ *
+ * Ask people to provide line coverage and they do. I've seen clever tools
+ * which generate test cases to test the existing functions - and by default
+ * these tools expect code to be correct and just generate checks which are
+ * passing when ran against current code-base. Run this generator and you'll get
+ * tests that do not test code is correct but just verify nothing changes.
+ * Problem is that testing working code is pointless. And if it is not
+ * working, your test must not assume it is working. You won't catch any bugs
+ * by such tests. What you can do is to generate a huge amount of tests.
+ * Especially if you were are asked to proivde 100% line-coverage x_x. So what
+ * does these tests - which are not finding any bugs now - do?
+ *
+ * They add inertia to every future development. I think it was Terry Pratchet
+ * who wrote someone having same impact as thick syrup has to chronometre.
+ * Excessive amount of unit-tests have this effect to development. If you do
+ * actually find _any_ bug from code in such environment and try fixing it...
+ * ...chances are you also need to fix the test cases. In sunny day you fix one
+ * test. But I've done refactoring which resulted 500+ broken tests (which had
+ * really zero value other than proving to managers that we do do "quality")...
+ *
+ * After this being said - there are situations where UTs can be handy. If you
+ * have algorithms which take some input and should produce output - then you
+ * can implement few, carefully selected simple UT-cases which test this. I've
+ * previously used this for example for netlink and device-tree data parsing
+ * functions. Feed some data examples to functions and verify the output is as
+ * expected. I am not covering all the cases but I will see the logic should be
+ * working.
+ *
+ * Here we also do some minor testing. I don't want to go through all branches
+ * or test more or less obvious things - but I want to see the main logic is
+ * working. And I definitely don't want to add 500+ test cases that break when
+ * some simple fix is done x_x. So - let's only add few, well selected tests
+ * which ensure as much logic is good as possible.
+ */
+
+/*
+ * Test Range 1:
+ * selectors: 2 3 4 5 6
+ * values (5): 10 20 30 40 50
+ *
+ * Test Range 2:
+ * selectors: 7 8 9 10
+ * values (4): 100 150 200 250
+ */
+
+#define RANGE1_MIN 10
+#define RANGE1_MIN_SEL 2
+#define RANGE1_STEP 10
+
+/* 2, 3, 4, 5, 6 */
+static const unsigned int range1_sels[] = { RANGE1_MIN_SEL, RANGE1_MIN_SEL + 1,
+ RANGE1_MIN_SEL + 2,
+ RANGE1_MIN_SEL + 3,
+ RANGE1_MIN_SEL + 4 };
+/* 10, 20, 30, 40, 50 */
+static const unsigned int range1_vals[] = { RANGE1_MIN, RANGE1_MIN +
+ RANGE1_STEP,
+ RANGE1_MIN + RANGE1_STEP * 2,
+ RANGE1_MIN + RANGE1_STEP * 3,
+ RANGE1_MIN + RANGE1_STEP * 4 };
+
+#define RANGE2_MIN 100
+#define RANGE2_MIN_SEL 7
+#define RANGE2_STEP 50
+
+/* 7, 8, 9, 10 */
+static const unsigned int range2_sels[] = { RANGE2_MIN_SEL, RANGE2_MIN_SEL + 1,
+ RANGE2_MIN_SEL + 2,
+ RANGE2_MIN_SEL + 3 };
+/* 100, 150, 200, 250 */
+static const unsigned int range2_vals[] = { RANGE2_MIN, RANGE2_MIN +
+ RANGE2_STEP,
+ RANGE2_MIN + RANGE2_STEP * 2,
+ RANGE2_MIN + RANGE2_STEP * 3 };
+
+#define RANGE1_NUM_VALS (ARRAY_SIZE(range1_vals))
+#define RANGE2_NUM_VALS (ARRAY_SIZE(range2_vals))
+#define RANGE_NUM_VALS (RANGE1_NUM_VALS + RANGE2_NUM_VALS)
+
+#define RANGE1_MAX_SEL (RANGE1_MIN_SEL + RANGE1_NUM_VALS - 1)
+#define RANGE1_MAX_VAL (range1_vals[RANGE1_NUM_VALS - 1])
+
+#define RANGE2_MAX_SEL (RANGE2_MIN_SEL + RANGE2_NUM_VALS - 1)
+#define RANGE2_MAX_VAL (range2_vals[RANGE2_NUM_VALS - 1])
+
+#define SMALLEST_SEL RANGE1_MIN_SEL
+#define SMALLEST_VAL RANGE1_MIN
+
+static struct linear_range testr[] = {
+ {
+ .min = RANGE1_MIN,
+ .min_sel = RANGE1_MIN_SEL,
+ .max_sel = RANGE1_MAX_SEL,
+ .step = RANGE1_STEP,
+ }, {
+ .min = RANGE2_MIN,
+ .min_sel = RANGE2_MIN_SEL,
+ .max_sel = RANGE2_MAX_SEL,
+ .step = RANGE2_STEP
+ },
+};
+
+static void range_test_get_value(struct kunit *test)
+{
+ int ret, i;
+ unsigned int sel, val;
+
+ for (i = 0; i < RANGE1_NUM_VALS; i++) {
+ sel = range1_sels[i];
+ ret = linear_range_get_value_array(&testr[0], 2, sel, &val);
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_EQ(test, val, range1_vals[i]);
+ }
+ for (i = 0; i < RANGE2_NUM_VALS; i++) {
+ sel = range2_sels[i];
+ ret = linear_range_get_value_array(&testr[0], 2, sel, &val);
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_EQ(test, val, range2_vals[i]);
+ }
+ ret = linear_range_get_value_array(&testr[0], 2, sel + 1, &val);
+ KUNIT_EXPECT_NE(test, 0, ret);
+}
+
+static void range_test_get_selector_high(struct kunit *test)
+{
+ int ret, i;
+ unsigned int sel;
+ bool found;
+
+ for (i = 0; i < RANGE1_NUM_VALS; i++) {
+ ret = linear_range_get_selector_high(&testr[0], range1_vals[i],
+ &sel, &found);
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_EQ(test, sel, range1_sels[i]);
+ KUNIT_EXPECT_TRUE(test, found);
+ }
+
+ ret = linear_range_get_selector_high(&testr[0], RANGE1_MAX_VAL + 1,
+ &sel, &found);
+ KUNIT_EXPECT_LE(test, ret, 0);
+
+ ret = linear_range_get_selector_high(&testr[0], RANGE1_MIN - 1,
+ &sel, &found);
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_FALSE(test, found);
+ KUNIT_EXPECT_EQ(test, sel, range1_sels[0]);
+}
+
+static void range_test_get_value_amount(struct kunit *test)
+{
+ int ret;
+
+ ret = linear_range_values_in_range_array(&testr[0], 2);
+ KUNIT_EXPECT_EQ(test, (int)RANGE_NUM_VALS, ret);
+}
+
+static void range_test_get_selector_low(struct kunit *test)
+{
+ int i, ret;
+ unsigned int sel;
+ bool found;
+
+ for (i = 0; i < RANGE1_NUM_VALS; i++) {
+ ret = linear_range_get_selector_low_array(&testr[0], 2,
+ range1_vals[i], &sel,
+ &found);
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_EQ(test, sel, range1_sels[i]);
+ KUNIT_EXPECT_TRUE(test, found);
+ }
+ for (i = 0; i < RANGE2_NUM_VALS; i++) {
+ ret = linear_range_get_selector_low_array(&testr[0], 2,
+ range2_vals[i], &sel,
+ &found);
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_EQ(test, sel, range2_sels[i]);
+ KUNIT_EXPECT_TRUE(test, found);
+ }
+
+ /*
+ * Seek value greater than range max => get_selector_*_low should
+ * return Ok - but set found to false as value is not in range
+ */
+ ret = linear_range_get_selector_low_array(&testr[0], 2,
+ range2_vals[RANGE2_NUM_VALS - 1] + 1,
+ &sel, &found);
+
+ KUNIT_EXPECT_EQ(test, 0, ret);
+ KUNIT_EXPECT_EQ(test, sel, range2_sels[RANGE2_NUM_VALS - 1]);
+ KUNIT_EXPECT_FALSE(test, found);
+}
+
+static struct kunit_case range_test_cases[] = {
+ KUNIT_CASE(range_test_get_value_amount),
+ KUNIT_CASE(range_test_get_selector_high),
+ KUNIT_CASE(range_test_get_selector_low),
+ KUNIT_CASE(range_test_get_value),
+ {},
+};
+
+static struct kunit_suite range_test_module = {
+ .name = "linear-ranges-test",
+ .test_cases = range_test_cases,
+};
+
+kunit_test_suites(&range_test_module);
+
+MODULE_LICENSE("GPL");