@@ -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
@@ -310,3 +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
new file mode 100644
@@ -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");