From: Liam Beguin <lvb@xxxxxxxxxx>
The iio-rescale driver supports various combinations of scale types and
offsets. These can often result in large integer multiplications. Make
sure these calculations are done right by adding a set of kunit test
cases that build on top of iio-test-format.
To run these tests, add the following to .kunitconfig
$ cat .kunitconfig
CONFIG_IIO=y
CONFIG_IIO_RESCALE_KUNIT_TEST=y
CONFIG_KUNIT=y
Then run:
$ ./tools/testing/kunit/kunit.py run --kunitconfig .kunitconfig
Signed-off-by: Liam Beguin <lvb@xxxxxxxxxx>
---
drivers/iio/test/Kconfig | 10 +
drivers/iio/test/Makefile | 1 +
drivers/iio/test/iio-test-rescale.c | 705 ++++++++++++++++++++++++++++
3 files changed, 716 insertions(+)
create mode 100644 drivers/iio/test/iio-test-rescale.c
diff --git a/drivers/iio/test/Kconfig b/drivers/iio/test/Kconfig
index 679a7794af20..872ed4ed140a 100644
--- a/drivers/iio/test/Kconfig
+++ b/drivers/iio/test/Kconfig
@@ -4,6 +4,16 @@
#
# Keep in alphabetical order
+config IIO_RESCALE_KUNIT_TEST
+ bool "Test IIO rescale conversion functions"
+ depends on KUNIT && !IIO_RESCALE
+ default KUNIT_ALL_TESTS
+ help
+ If you want to run tests on the iio-rescale code say Y here.
+
+ This takes advantage of ARCH=um to run tests and should be used by
+ developers to tests their changes to the rescaling logic.
+
config IIO_TEST_FORMAT
bool "Test IIO formatting functions"
depends on KUNIT=y
diff --git a/drivers/iio/test/Makefile b/drivers/iio/test/Makefile
index 467519a2027e..f15ae0a6394f 100644
--- a/drivers/iio/test/Makefile
+++ b/drivers/iio/test/Makefile
@@ -4,5 +4,6 @@
#
# Keep in alphabetical order
+obj-$(CONFIG_IIO_RESCALE_KUNIT_TEST) += iio-test-rescale.o ../afe/iio-rescale.o
obj-$(CONFIG_IIO_TEST_FORMAT) += iio-test-format.o
CFLAGS_iio-test-format.o += $(DISABLE_STRUCTLEAK_PLUGIN)
diff --git a/drivers/iio/test/iio-test-rescale.c b/drivers/iio/test/iio-test-rescale.c
new file mode 100644
index 000000000000..526f87fa3514
--- /dev/null
+++ b/drivers/iio/test/iio-test-rescale.c
@@ -0,0 +1,705 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kunit tests for IIO rescale conversions
+ *
+ * Copyright (c) 2021 Liam Beguin <liambeguin@xxxxxxxxx>
+ */
+
+#include <kunit/test.h>
+#include <linux/gcd.h>
+#include <linux/iio/afe/rescale.h>
+#include <linux/iio/iio.h>
+#include <linux/overflow.h>
+
+struct rescale_tc_data {
+ const char *name;
+
+ const s32 numerator;
+ const s32 denominator;
+ const s32 offset;
+
+ const int schan_val;
+ const int schan_val2;
+ const int schan_off;
+ const int schan_scale_type;
+
+ const char *expected;
+ const char *expected_off;
+};
+
+const struct rescale_tc_data scale_cases[] = {
+ /*
+ * Typical use cases
+ */
+ {
+ .name = "typical IIO_VAL_INT, positive",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT,
+ .schan_val = 42,
+ .expected = "5210.918114143",
+ },
+ {
+ .name = "typical IIO_VAL_INT, negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT,
+ .schan_val = 42,
+ .expected = "-5210.918114143",
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL, positive",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 42,
+ .schan_val2 = 20,
+ .expected = "260.545905707",
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL, negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 42,
+ .schan_val2 = 20,
+ .expected = "-260.545905707",
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL_LOG2, positive",
+ .numerator = 42,
+ .denominator = 53,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 4096,
+ .schan_val2 = 16,
+ .expected = "0.049528301",
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL_LOG2, negative",
+ .numerator = -42,
+ .denominator = 53,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 4096,
+ .schan_val2 = 16,
+ .expected = "-0.049528301",
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_NANO, positive",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = 123456,
+ .expected = "1240.710106203",
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_NANO, negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = 123456,
+ .expected = "-1240.710106203",
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_MICRO, positive",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = 1234,
+ .expected = "1240.84789",
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_MICRO, negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = 1234,
+ .expected = "-1240.84789",
+ },
+ /*
+ * Use cases with small scales involving divisions
+ */
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 261/509 scaled by 90/1373754273",
+ .numerator = 261,
+ .denominator = 509,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 90,
+ .schan_val2 = 1373754273,
+ .expected = "0.000000033594",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 90/1373754273 scaled by 261/509",
+ .numerator = 90,
+ .denominator = 1373754273,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 261,
+ .schan_val2 = 509,
+ .expected = "0.000000033594",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 760/1373754273 scaled by 427/2727",
+ .numerator = 760,
+ .denominator = 1373754273,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 427,
+ .schan_val2 = 2727,
+ .expected = "0.000000086626",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 761/1373754273 scaled by 427/2727",
+ .numerator = 761,
+ .denominator = 1373754273,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 427,
+ .schan_val2 = 2727,
+ .expected = "0.000000086740",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 5/32768 scaled by 3/10000",
+ .numerator = 5,
+ .denominator = 32768,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 3,
+ .schan_val2 = 10000,
+ .expected = "0.0000000457763671875",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 0 < scale < 1",
+ .numerator = 6,
+ .denominator = 6,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 1,
+ .schan_val2 = 3,
+ .expected = "0.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, -1 < scale < 0",
+ .numerator = -6,
+ .denominator = 6,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 1,
+ .schan_val2 = 3,
+ .expected = "-0.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, 0 < scale < 2",
+ .numerator = 8,
+ .denominator = 2,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 1,
+ .schan_val2 = 3,
+ .expected = "1.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL, -2 < scale < 0",
+ .numerator = -8,
+ .denominator = 2,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 1,
+ .schan_val2 = 3,
+ .expected = "-1.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL_LOG2, 760/32768 scaled by 15/22",
+ .numerator = 760,
+ .denominator = 32768,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 15,
+ .schan_val2 = 22,
+ .expected = "0.000000082946",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL_LOG2, 761/32768 scaled by 15/22",
+ .numerator = 761,
+ .denominator = 32768,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 15,
+ .schan_val2 = 22,
+ .expected = "0.000000083055",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL_LOG2, 0 < scale < 1",
+ .numerator = 16,
+ .denominator = 3,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 1,
+ .schan_val2 = 4,
+ .expected = "0.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL_LOG2, -1 < scale < 0",
+ .numerator = -16,
+ .denominator = 3,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 1,
+ .schan_val2 = 4,
+ .expected = "-0.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL_LOG2, 0 < scale < 2",
+ .numerator = 8,
+ .denominator = 3,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 1,
+ .schan_val2 = 1,
+ .expected = "1.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_FRACTIONAL_LOG2, -2 < scale < 0",
+ .numerator = -8,
+ .denominator = 3,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 1,
+ .schan_val2 = 1,
+ .expected = "-1.3333333333333333",
+ },
+ {
+ .name = "small IIO_VAL_INT_PLUS_MICRO, positive",
+ .numerator = 1,
+ .denominator = 2,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 5,
+ .schan_val2 = 1234,
+ .expected = "2.500617",
+ },
+ {
+ .name = "small IIO_VAL_INT_PLUS_MICRO, negative",
+ .numerator = -1,
+ .denominator = 2,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 5,
+ .schan_val2 = 1234,
+ .expected = "-2.500617",
+ },
+ /*
+ * INT_PLUS_{MICRO,NANO} positive/negative corner cases
+ */
+ {
+ .name = "negative IIO_VAL_INT_PLUS_NANO, negative schan",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = -10,
+ .schan_val2 = 123456,
+ .expected = "-1240.710106203",
+ },
+ {
+ .name = "negative IIO_VAL_INT_PLUS_NANO, both negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = -10,
+ .schan_val2 = 123456,
+ .expected = "1240.710106203",
+ },
+ {
+ .name = "negative IIO_VAL_INT_PLUS_NANO, 3 negative",
+ .numerator = -1000000,
+ .denominator = -8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = -10,
+ .schan_val2 = 123456,
+ .expected = "-1240.710106203",
+ },
+ {
+ .name = "negative IIO_VAL_INT_PLUS_NANO, 4 negative",
+ .numerator = -1000000,
+ .denominator = -8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = -10,
+ .schan_val2 = -123456,
+ .expected = "-1240.710106203",
+ },
+ {
+ .name = "negative IIO_VAL_INT_PLUS_NANO, negative, *val = 0",
+ .numerator = 1,
+ .denominator = -10,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 0,
+ .schan_val2 = 123456789,
+ .expected = "-0.012345678",
+ },
+ /*
+ * INT_PLUS_{MICRO,NANO} decimal part overflow
+ */
+ {
+ .name = "decimal overflow IIO_VAL_INT_PLUS_NANO, positive",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .expected = "1256.01200856",
+ },
+ {
+ .name = "decimal overflow IIO_VAL_INT_PLUS_NANO, negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .expected = "-1256.01200856",
+ },
+ {
+ .name = "decimal overflow IIO_VAL_INT_PLUS_NANO, negative schan",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = -10,
+ .schan_val2 = 123456789,
+ .expected = "-1256.01200856",
+ },
+ {
+ .name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, positive",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .expected = "16557.914267",
+ },
+ {
+ .name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, negative",
+ .numerator = -1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .expected = "-16557.914267",
+ },
+ {
+ .name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, negative schan",
+ .numerator = 1000000,
+ .denominator = 8060,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = -10,
+ .schan_val2 = 123456789,
+ .expected = "-16557.914267",
+ },
+ /*
+ * 32-bit overflow conditions
+ */
+ {
+ .name = "overflow IIO_VAL_FRACTIONAL, positive",
+ .numerator = 2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = S32_MAX,
+ .schan_val2 = 1,
+ .expected = "214748364.7",
+ },
+ {
+ .name = "overflow IIO_VAL_FRACTIONAL, negative",
+ .numerator = -2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = S32_MAX,
+ .schan_val2 = 1,
+ .expected = "-214748364.7",
+ },
+ {
+ .name = "overflow IIO_VAL_FRACTIONAL_LOG2, positive",
+ .numerator = S32_MAX,
+ .denominator = 4096,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 4096,
+ .schan_val2 = 16,
+ .expected = "32767.99998474121",
+ },
+ {
+ .name = "overflow IIO_VAL_FRACTIONAL_LOG2, negative",
+ .numerator = S32_MAX,
+ .denominator = 4096,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = -4096,
+ .schan_val2 = 16,
+ .expected = "-32767.99998474121",
+ },
+ {
+ .name = "overflow IIO_VAL_INT_PLUS_NANO, positive",
+ .numerator = 2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = S32_MAX,
+ .expected = "1.214748364",
+ },
+ {
+ .name = "overflow IIO_VAL_INT_PLUS_NANO, negative",
+ .numerator = -2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = S32_MAX,
+ .expected = "-1.214748364",
+ },
+ {
+ .name = "overflow IIO_VAL_INT_PLUS_NANO, negative schan",
+ .numerator = 2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = -10,
+ .schan_val2 = S32_MAX,
+ .expected = "-1.214748364",
+ },
+ {
+ .name = "overflow IIO_VAL_INT_PLUS_MICRO, positive",
+ .numerator = 2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = S32_MAX,
+ .expected = "215.748364",
+ },
+ {
+ .name = "overflow IIO_VAL_INT_PLUS_MICRO, negative",
+ .numerator = -2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = S32_MAX,
+ .expected = "-215.748364",
+ },
+ {
+ .name = "overflow IIO_VAL_INT_PLUS_MICRO, negative schan",
+ .numerator = 2,
+ .denominator = 20,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = -10,
+ .schan_val2 = S32_MAX,
+ .expected = "-215.748364",
+ },
+};
+
+const struct rescale_tc_data offset_cases[] = {
+ /*
+ * Typical use cases
+ */
+ {
+ .name = "typical IIO_VAL_INT, positive",
+ .offset = 1234,
+ .schan_scale_type = IIO_VAL_INT,
+ .schan_val = 123,
+ .schan_val2 = 0,
+ .schan_off = 14,
+ .expected_off = "24", /* 23.872 */
+ },
+ {
+ .name = "typical IIO_VAL_INT, negative",
+ .offset = -1234,
+ .schan_scale_type = IIO_VAL_INT,
+ .schan_val = 12,
+ .schan_val2 = 0,
+ .schan_off = 14,
+ .expected_off = "-88", /* -88.83333333333333 */
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL, positive",
+ .offset = 1234,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 12,
+ .schan_val2 = 34,
+ .schan_off = 14,
+ .expected_off = "3510", /* 3510.333333333333 */
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL, negative",
+ .offset = -1234,
+ .schan_scale_type = IIO_VAL_FRACTIONAL,
+ .schan_val = 12,
+ .schan_val2 = 34,
+ .schan_off = 14,
+ .expected_off = "-3482", /* -3482.333333333333 */
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL_LOG2, positive",
+ .offset = 1234,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 12,
+ .schan_val2 = 16,
+ .schan_off = 14,
+ .expected_off = "6739299", /* 6739299.333333333 */
+ },
+ {
+ .name = "typical IIO_VAL_FRACTIONAL_LOG2, negative",
+ .offset = -1234,
+ .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
+ .schan_val = 12,
+ .schan_val2 = 16,
+ .schan_off = 14,
+ .expected_off = "-6739271", /* -6739271.333333333 */
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_NANO, positive",
+ .offset = 1234,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .schan_off = 14,
+ .expected_off = "135", /* 135.8951219647469 */
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_NANO, negative",
+ .offset = -1234,
+ .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .schan_off = 14,
+ .expected_off = "-107", /* -107.89512196474689 */
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_MICRO, positive",
+ .offset = 1234,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .schan_off = 14,
+ .expected_off = "23", /* 23.246438560723952 */
+ },
+ {
+ .name = "typical IIO_VAL_INT_PLUS_MICRO, negative",
+ .offset = -12345,
+ .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
+ .schan_val = 10,
+ .schan_val2 = 123456789,
+ .schan_off = 14,
+ .expected_off = "-78", /* -78.50185091745313 */
+ },
+};
+
+static void case_to_desc(const struct rescale_tc_data *t, char *desc)
+{
+ strcpy(desc, t->name);
+}
+
+KUNIT_ARRAY_PARAM(iio_rescale_scale, scale_cases, case_to_desc);
+KUNIT_ARRAY_PARAM(iio_rescale_offset, offset_cases, case_to_desc);
+
+/**
+ * iio_str_to_nano() - Parse a fixed-point string to get an
+ * IIO_VAL_INT_PLUS_NANO value
+ * @str: The string to parse
+ * @nano: The number as an integer
+ *
+ * Returns 0 on success, or a negative error code if the string cound not be
+ * parsed.
+ */
+static int iio_str_to_nano(const char *str, s64 *nano)
+{
+ int fract_mult = 100000000LL;
+ int tmp, tmp2;
+ int ret = 0;
+
+ ret = iio_str_to_fixpoint(str, fract_mult, &tmp, &tmp2);
+ if (ret < 0)
+ return ret;
+
+ if (tmp < 0)
+ tmp2 *= -1;
+
+ *nano = (s64)tmp * 10 * fract_mult + tmp2;
+
+ return ret;
+}
+
+/**
+ * iio_test_relative_error_ppm() - Compute relative error (in parts-per-million)
+ * between two fixed-point strings
+ * @real_str: The real value as a string
+ * @exp_str: The expected value as a string
+ *
+ * Returns a negative error code if the strings cound not be parsed, or the
+ * relative error in parts-per-million.
+ */
+static int iio_test_relative_error_ppm(const char *real_str, const char *exp_str)
+{
+ s64 real, exp, err;
+ int ret;
+
+ ret = iio_str_to_nano(real_str, &real);
+ if (ret < 0)
+ return ret;
+
+ ret = iio_str_to_nano(exp_str, &exp);
+ if (ret < 0)
+ return ret;
+
+ if (!exp) {
+ pr_err("Expected value is null, relative error is undefined\n");
+ return -EINVAL;
+ }
+
+ err = 1000000 * abs(exp - real);
+ err = div64_u64(err, abs(exp));
+ return (int)err;
+}
+
+static void iio_rescale_test_scale(struct kunit *test)
+{
+ struct rescale_tc_data *t = (struct rescale_tc_data *)test->param_value;
+ char *buff = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+ struct rescale rescale;
+ int values[2];
+ int rel_ppm;
+ int ret;
+
+ rescale.numerator = t->numerator;
+ rescale.denominator = t->denominator;
+ rescale.offset = t->offset;
+ values[0] = t->schan_val;
+ values[1] = t->schan_val2;
+
+ ret = rescale_process_scale(&rescale, t->schan_scale_type,
+ &values[0], &values[1]);
+
+ ret = iio_format_value(buff, ret, 2, values);
+ KUNIT_EXPECT_EQ(test, (int)strlen(buff), ret);
+
+ rel_ppm = iio_test_relative_error_ppm(buff, t->expected);
+ KUNIT_EXPECT_GE_MSG(test, rel_ppm, 0, "failed to compute ppm\n");
+
+ KUNIT_EXPECT_EQ_MSG(test, rel_ppm, 0,
+ "\t real=%s"
+ "\texpected=%s\n",
+ buff, t->expected);
+}
+
+static void iio_rescale_test_offset(struct kunit *test)
+{
+ struct rescale_tc_data *t = (struct rescale_tc_data *)test->param_value;
+ char *buff_off = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+ struct rescale rescale;
+ int values[2];
+ int ret;
+
+ rescale.numerator = t->numerator;
+ rescale.denominator = t->denominator;
+ rescale.offset = t->offset;
+ values[0] = t->schan_val;
+ values[1] = t->schan_val2;
+
+ ret = rescale_process_offset(&rescale, t->schan_scale_type,
+ t->schan_val, t->schan_val2, t->schan_off,
+ &values[0], &values[1]);
+
+ ret = iio_format_value(buff_off, ret, 2, values);
+ KUNIT_EXPECT_EQ(test, (int)strlen(buff_off), ret);
+
+ KUNIT_EXPECT_STREQ(test, strim(buff_off), t->expected_off);
+}
+
+static struct kunit_case iio_rescale_test_cases[] = {
+ KUNIT_CASE_PARAM(iio_rescale_test_scale, iio_rescale_scale_gen_params),
+ KUNIT_CASE_PARAM(iio_rescale_test_offset, iio_rescale_offset_gen_params),
+ {}
+};
+
+static struct kunit_suite iio_rescale_test_suite = {
+ .name = "iio-rescale",
+ .test_cases = iio_rescale_test_cases,
+};
+kunit_test_suite(iio_rescale_test_suite);
--
2.34.0
