Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

6 files changed, 1835 insertions, 0 deletions

diff --git a/drivers/iio/test/Kconfig b/drivers/iio/test/Kconfig
new file mode 100644
index 000000000..4fc17dd0d
--- /dev/null
+++ b/drivers/iio/test/Kconfig
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Industrial I/O subsystem unit tests configuration
+#
+
+# Keep in alphabetical order
+config IIO_GTS_KUNIT_TEST
+	tristate "Test IIO gain-time-scale helpers" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	select IIO_GTS_HELPER
+	default KUNIT_ALL_TESTS
+	help
+	  build unit tests for the IIO light sensor gain-time-scale helpers.
+
+	  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. Keep in alphabetical order
+
+config IIO_RESCALE_KUNIT_TEST
+	tristate "Test IIO rescale conversion functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT && IIO_RESCALE
+	default KUNIT_ALL_TESTS
+	help
+	  Build unit tests for the iio-rescale code.
+
+	  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 IIO_FORMAT_KUNIT_TEST
+	tristate "Test IIO formatting functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  build unit tests for the IIO formatting functions.
+
+	  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 IIO_MULTIPLY_KUNIT_TEST
+	tristate "Test IIO multiply functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  build unit tests for the IIO multiply functions.
+
+	  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.
diff --git a/drivers/iio/test/Makefile b/drivers/iio/test/Makefile
new file mode 100644
index 000000000..0c846bc21
--- /dev/null
+++ b/drivers/iio/test/Makefile
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the industrial I/O unit tests.
+#
+
+# Keep in alphabetical order
+obj-$(CONFIG_IIO_RESCALE_KUNIT_TEST) += iio-test-rescale.o
+obj-$(CONFIG_IIO_FORMAT_KUNIT_TEST) += iio-test-format.o
+obj-$(CONFIG_IIO_GTS_KUNIT_TEST) += iio-test-gts.o
+obj-$(CONFIG_IIO_MULTIPLY_KUNIT_TEST) += iio-test-multiply.o
+CFLAGS_iio-test-format.o += $(DISABLE_STRUCTLEAK_PLUGIN)
diff --git a/drivers/iio/test/iio-test-format.c b/drivers/iio/test/iio-test-format.c
new file mode 100644
index 000000000..e5d0a2ac4
--- /dev/null
+++ b/drivers/iio/test/iio-test-format.c
@@ -0,0 +1,324 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Unit tests for IIO formatting functions
+ *
+ * Copyright (c) 2020 Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <kunit/test.h>
+#include <linux/iio/iio.h>
+
+#define IIO_TEST_FORMAT_EXPECT_EQ(_test, _buf, _ret, _val) do { \
+		KUNIT_EXPECT_EQ(_test, strlen(_buf), _ret); \
+		KUNIT_EXPECT_STREQ(_test, (_buf), (_val)); \
+	} while (0)
+
+static void iio_test_iio_format_value_integer(struct kunit *test)
+{
+	char *buf;
+	int val;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	val = 42;
+	ret = iio_format_value(buf, IIO_VAL_INT, 1, &val);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "42\n");
+
+	val = -23;
+	ret = iio_format_value(buf, IIO_VAL_INT, 1, &val);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-23\n");
+
+	val = 0;
+	ret = iio_format_value(buf, IIO_VAL_INT, 1, &val);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0\n");
+
+	val = INT_MAX;
+	ret = iio_format_value(buf, IIO_VAL_INT, 1, &val);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "2147483647\n");
+
+	val = INT_MIN;
+	ret = iio_format_value(buf, IIO_VAL_INT, 1, &val);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-2147483648\n");
+}
+
+static void iio_test_iio_format_value_fixedpoint(struct kunit *test)
+{
+	int values[2];
+	char *buf;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	/* positive >= 1 */
+	values[0] = 1;
+	values[1] = 10;
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1.000010\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO_DB, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1.000010 dB\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1.000000010\n");
+
+	/* positive < 1 */
+	values[0] = 0;
+	values[1] = 12;
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.000012\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO_DB, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.000012 dB\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.000000012\n");
+
+	/* negative <= -1 */
+	values[0] = -1;
+	values[1] = 10;
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-1.000010\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO_DB, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-1.000010 dB\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-1.000000010\n");
+
+	/* negative > -1 */
+	values[0] = 0;
+	values[1] = -123;
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-0.000123\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO_DB, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-0.000123 dB\n");
+
+	ret = iio_format_value(buf, IIO_VAL_INT_PLUS_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-0.000000123\n");
+}
+
+static void iio_test_iio_format_value_fractional(struct kunit *test)
+{
+	int values[2];
+	char *buf;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	/* positive < 1 */
+	values[0] = 1;
+	values[1] = 10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.100000000\n");
+
+	/* positive >= 1 */
+	values[0] = 100;
+	values[1] = 3;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "33.333333333\n");
+
+	/* negative > -1 */
+	values[0] = -1;
+	values[1] = 1000000000;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-0.000000001\n");
+
+	/* negative <= -1 */
+	values[0] = -200;
+	values[1] = 3;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-66.666666666\n");
+
+	/* Zero */
+	values[0] = 0;
+	values[1] = -10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.000000000\n");
+}
+
+static void iio_test_iio_format_value_fractional_log2(struct kunit *test)
+{
+	int values[2];
+	char *buf;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	/* positive < 1 */
+	values[0] = 123;
+	values[1] = 10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL_LOG2, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.120117187\n");
+
+	/* positive >= 1 */
+	values[0] = 1234567;
+	values[1] = 10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL_LOG2, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1205.631835937\n");
+
+	/* negative > -1 */
+	values[0] = -123;
+	values[1] = 10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL_LOG2, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-0.120117187\n");
+
+	/* negative <= -1 */
+	values[0] = -1234567;
+	values[1] = 10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL_LOG2, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-1205.631835937\n");
+
+	/* Zero */
+	values[0] = 0;
+	values[1] = 10;
+	ret = iio_format_value(buf, IIO_VAL_FRACTIONAL_LOG2, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.000000000\n");
+}
+
+static void iio_test_iio_format_value_multiple(struct kunit *test)
+{
+	int values[] = {1, -2, 3, -4, 5};
+	char *buf;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	ret = iio_format_value(buf, IIO_VAL_INT_MULTIPLE,
+			       ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1 -2 3 -4 5 \n");
+}
+
+static void iio_test_iio_format_value_integer_64(struct kunit *test)
+{
+	int values[2];
+	char *buf;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	iio_val_s64_decompose(24, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "24\n");
+
+	iio_val_s64_decompose(-24, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-24\n");
+
+	iio_val_s64_decompose(0, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0\n");
+
+	iio_val_s64_decompose(UINT_MAX, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "4294967295\n");
+
+	iio_val_s64_decompose(-((s64)UINT_MAX), &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-4294967295\n");
+
+	iio_val_s64_decompose(LLONG_MAX, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "9223372036854775807\n");
+
+	iio_val_s64_decompose(LLONG_MIN, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_INT_64, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-9223372036854775808\n");
+}
+
+static void iio_test_iio_format_value_decimal_64(struct kunit *test)
+{
+	int values[2];
+	char *buf;
+	int ret;
+
+	buf = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf);
+
+	/* DECIMAL64_MILLI: positive >= 1, value 1.234 */
+	iio_val_s64_decompose(1234, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MILLI, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1.234\n");
+
+	/* DECIMAL64_MICRO: positive >= 1, value 3.141592 */
+	iio_val_s64_decompose(3141592, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "3.141592\n");
+
+	/* DECIMAL64_MILLI: positive < 1, value 0.042 */
+	iio_val_s64_decompose(42, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MILLI, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.042\n");
+
+	/* DECIMAL64_MILLI: negative <= -1, value -1.234 */
+	iio_val_s64_decompose(-1234, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MILLI, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-1.234\n");
+
+	/* DECIMAL64_MILLI: negative > -1, value -0.123 */
+	iio_val_s64_decompose(-123, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MILLI, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-0.123\n");
+
+	/* DECIMAL64_MILLI: zero */
+	iio_val_s64_decompose(0, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MILLI, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "0.000\n");
+
+	/* DECIMAL64_NANO: value 1.000000001 */
+	iio_val_s64_decompose(1000000001, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "1.000000001\n");
+
+	/* DECIMAL64_MICRO: large value using upper 32 bits */
+	iio_val_s64_decompose(5000000000000042LL, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "5000000000.000042\n");
+
+	/* limits */
+	iio_val_s64_decompose(LLONG_MAX, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_PICO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "9223372.036854775807\n");
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "9223372036.854775807\n");
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "9223372036854.775807\n");
+
+	iio_val_s64_decompose(LLONG_MIN, &values[0], &values[1]);
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_PICO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-9223372.036854775808\n");
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_NANO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-9223372036.854775808\n");
+	ret = iio_format_value(buf, IIO_VAL_DECIMAL64_MICRO, ARRAY_SIZE(values), values);
+	IIO_TEST_FORMAT_EXPECT_EQ(test, buf, ret, "-9223372036854.775808\n");
+}
+
+static struct kunit_case iio_format_test_cases[] = {
+		KUNIT_CASE(iio_test_iio_format_value_integer),
+		KUNIT_CASE(iio_test_iio_format_value_fixedpoint),
+		KUNIT_CASE(iio_test_iio_format_value_fractional),
+		KUNIT_CASE(iio_test_iio_format_value_fractional_log2),
+		KUNIT_CASE(iio_test_iio_format_value_multiple),
+		KUNIT_CASE(iio_test_iio_format_value_integer_64),
+		KUNIT_CASE(iio_test_iio_format_value_decimal_64),
+		{ }
+};
+
+static struct kunit_suite iio_format_test_suite = {
+	.name = "iio-format",
+	.test_cases = iio_format_test_cases,
+};
+kunit_test_suite(iio_format_test_suite);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("Test IIO formatting functions");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/test/iio-test-gts.c b/drivers/iio/test/iio-test-gts.c
new file mode 100644
index 000000000..6ffff85ba
--- /dev/null
+++ b/drivers/iio/test/iio-test-gts.c
@@ -0,0 +1,515 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Unit tests for IIO light sensor gain-time-scale helpers
+ *
+ * Copyright (c) 2023 Matti Vaittinen <mazziesaccount@gmail.com>
+ */
+
+#include <kunit/device.h>
+#include <kunit/test.h>
+#include <linux/device.h>
+#include <linux/iio/iio-gts-helper.h>
+#include <linux/iio/types.h>
+
+/*
+ * Please, read the "rant" from the top of the lib/test_linear_ranges.c if
+ * you see a line of helper code which is not being tested.
+ *
+ * Then, please look at the line which is not being tested. Is this line
+ * somehow unusually complex? If answer is "no", then chances are that the
+ * "development inertia" caused by adding a test exceeds the benefits.
+ *
+ * If yes, then adding a test is probably a good idea but please stop for a
+ * moment and consider the effort of changing all the tests when code gets
+ * refactored. Eventually it needs to be.
+ */
+
+#define TEST_TSEL_50		1
+#define TEST_TSEL_X_MIN		TEST_TSEL_50
+#define TEST_TSEL_100		0
+#define TEST_TSEL_200		2
+#define TEST_TSEL_400		4
+#define TEST_TSEL_X_MAX		TEST_TSEL_400
+
+#define TEST_GSEL_1		0x00
+#define TEST_GSEL_X_MIN		TEST_GSEL_1
+#define TEST_GSEL_4		0x08
+#define TEST_GSEL_16		0x0a
+#define TEST_GSEL_32		0x0b
+#define TEST_GSEL_64		0x0c
+#define TEST_GSEL_256		0x18
+#define TEST_GSEL_512		0x19
+#define TEST_GSEL_1024		0x1a
+#define TEST_GSEL_2048		0x1b
+#define TEST_GSEL_4096		0x1c
+#define TEST_GSEL_X_MAX		TEST_GSEL_4096
+
+#define TEST_SCALE_1X		64
+#define TEST_SCALE_MIN_X	TEST_SCALE_1X
+#define TEST_SCALE_2X		32
+#define TEST_SCALE_4X		16
+#define TEST_SCALE_8X		8
+#define TEST_SCALE_16X		4
+#define TEST_SCALE_32X		2
+#define TEST_SCALE_64X		1
+
+#define TEST_SCALE_NANO_128X	500000000
+#define TEST_SCALE_NANO_256X	250000000
+#define TEST_SCALE_NANO_512X	125000000
+#define TEST_SCALE_NANO_1024X	62500000
+#define TEST_SCALE_NANO_2048X	31250000
+#define TEST_SCALE_NANO_4096X	15625000
+#define TEST_SCALE_NANO_4096X2	7812500
+#define TEST_SCALE_NANO_4096X4	3906250
+#define TEST_SCALE_NANO_4096X8	1953125
+
+#define TEST_SCALE_NANO_MAX_X TEST_SCALE_NANO_4096X8
+
+/*
+ * Can't have this allocated from stack because the kunit clean-up will
+ * happen only after the test function has already gone
+ */
+static struct iio_gts gts;
+
+/* Keep the gain and time tables unsorted to test the sorting */
+static const struct iio_gain_sel_pair gts_test_gains[] = {
+	GAIN_SCALE_GAIN(1, TEST_GSEL_1),
+	GAIN_SCALE_GAIN(4, TEST_GSEL_4),
+	GAIN_SCALE_GAIN(16, TEST_GSEL_16),
+	GAIN_SCALE_GAIN(32, TEST_GSEL_32),
+	GAIN_SCALE_GAIN(64, TEST_GSEL_64),
+	GAIN_SCALE_GAIN(256, TEST_GSEL_256),
+	GAIN_SCALE_GAIN(512, TEST_GSEL_512),
+	GAIN_SCALE_GAIN(1024, TEST_GSEL_1024),
+	GAIN_SCALE_GAIN(4096, TEST_GSEL_4096),
+	GAIN_SCALE_GAIN(2048, TEST_GSEL_2048),
+#define HWGAIN_MAX 4096
+};
+
+static const struct iio_itime_sel_mul gts_test_itimes[] = {
+	GAIN_SCALE_ITIME_US(100 * 1000, TEST_TSEL_100, 2),
+	GAIN_SCALE_ITIME_US(400 * 1000, TEST_TSEL_400, 8),
+	GAIN_SCALE_ITIME_US(400 * 1000, TEST_TSEL_400, 8),
+	GAIN_SCALE_ITIME_US(50 * 1000, TEST_TSEL_50, 1),
+	GAIN_SCALE_ITIME_US(200 * 1000, TEST_TSEL_200, 4),
+#define TIMEGAIN_MAX 8
+};
+#define TOTAL_GAIN_MAX	(HWGAIN_MAX * TIMEGAIN_MAX)
+#define IIO_GTS_TEST_DEV "iio-gts-test-dev"
+
+static struct device *__test_init_iio_gain_scale(struct kunit *test,
+		struct iio_gts *gts, const struct iio_gain_sel_pair *g_table,
+		int num_g, const struct iio_itime_sel_mul *i_table, int num_i)
+{
+	struct device *dev;
+	int ret;
+
+	dev = kunit_device_register(test, IIO_GTS_TEST_DEV);
+
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, dev);
+	if (IS_ERR_OR_NULL(dev))
+		return NULL;
+
+	ret = devm_iio_init_iio_gts(dev, TEST_SCALE_1X, 0, g_table, num_g,
+				    i_table, num_i, gts);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	if (ret)
+		return NULL;
+
+	return dev;
+}
+
+#define test_init_iio_gain_scale(test, gts)	\
+	__test_init_iio_gain_scale(test, gts, gts_test_gains, \
+				   ARRAY_SIZE(gts_test_gains), gts_test_itimes, \
+				   ARRAY_SIZE(gts_test_itimes))
+
+static void test_init_iio_gts_invalid(struct kunit *test)
+{
+	struct device *dev;
+	int ret;
+	const struct iio_itime_sel_mul itimes_neg[] = {
+		GAIN_SCALE_ITIME_US(-10, TEST_TSEL_400, 8),
+		GAIN_SCALE_ITIME_US(200 * 1000, TEST_TSEL_200, 4),
+	};
+	const struct iio_gain_sel_pair gains_neg[] = {
+		GAIN_SCALE_GAIN(1, TEST_GSEL_1),
+		GAIN_SCALE_GAIN(2, TEST_GSEL_4),
+		GAIN_SCALE_GAIN(-2, TEST_GSEL_16),
+	};
+	/* 55555 * 38656 = 2147534080 => overflows 32bit int */
+	const struct iio_itime_sel_mul itimes_overflow[] = {
+		GAIN_SCALE_ITIME_US(400 * 1000, TEST_TSEL_400, 55555),
+		GAIN_SCALE_ITIME_US(200 * 1000, TEST_TSEL_200, 4),
+	};
+	const struct iio_gain_sel_pair gains_overflow[] = {
+		GAIN_SCALE_GAIN(1, TEST_GSEL_1),
+		GAIN_SCALE_GAIN(2, TEST_GSEL_4),
+		GAIN_SCALE_GAIN(38656, TEST_GSEL_16),
+	};
+
+	dev = kunit_device_register(test, IIO_GTS_TEST_DEV);
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, dev);
+	if (!dev)
+		return;
+
+	/* Ok gains, negative time */
+	ret = devm_iio_init_iio_gts(dev, TEST_SCALE_1X, 0, gts_test_gains,
+				    ARRAY_SIZE(gts_test_gains), itimes_neg,
+				    ARRAY_SIZE(itimes_neg), &gts);
+	KUNIT_EXPECT_EQ(test, -EINVAL, ret);
+
+	/* Ok times, negative gain */
+	ret = devm_iio_init_iio_gts(dev, TEST_SCALE_1X, 0, gains_neg,
+				    ARRAY_SIZE(gains_neg), gts_test_itimes,
+				    ARRAY_SIZE(gts_test_itimes), &gts);
+	KUNIT_EXPECT_EQ(test, -EINVAL, ret);
+
+	/* gain * time overflow int */
+	ret = devm_iio_init_iio_gts(dev, TEST_SCALE_1X, 0, gains_overflow,
+				    ARRAY_SIZE(gains_overflow), itimes_overflow,
+				    ARRAY_SIZE(itimes_overflow), &gts);
+	KUNIT_EXPECT_EQ(test, -EOVERFLOW, ret);
+}
+
+static void test_iio_gts_find_gain_for_scale_using_time(struct kunit *test)
+{
+	struct device *dev;
+	int ret, gain_sel;
+
+	dev = test_init_iio_gain_scale(test, &gts);
+	if (!dev)
+		return;
+
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_100,
+						TEST_SCALE_8X, 0, &gain_sel);
+	/*
+	 * Meas time 100 => gain by time 2x
+	 * TEST_SCALE_8X matches total gain 8x
+	 * => required HWGAIN 4x
+	 */
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, TEST_GSEL_4, gain_sel);
+
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_200, 0,
+						TEST_SCALE_NANO_256X, &gain_sel);
+	/*
+	 * Meas time 200 => gain by time 4x
+	 * TEST_SCALE_256X matches total gain 256x
+	 * => required HWGAIN 256/4 => 64x
+	 */
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, TEST_GSEL_64, gain_sel);
+
+	/* Min time, Min gain */
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_X_MIN,
+						TEST_SCALE_MIN_X, 0, &gain_sel);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, TEST_GSEL_1, gain_sel);
+
+	/* Max time, Max gain */
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_X_MAX,
+					0, TEST_SCALE_NANO_MAX_X, &gain_sel);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, TEST_GSEL_4096, gain_sel);
+
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_100, 0,
+						TEST_SCALE_NANO_256X, &gain_sel);
+	/*
+	 * Meas time 100 => gain by time 2x
+	 * TEST_SCALE_256X matches total gain 256x
+	 * => required HWGAIN 256/2 => 128x (not in gain-table - unsupported)
+	 */
+	KUNIT_EXPECT_NE(test, 0, ret);
+
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_200, 0,
+						TEST_SCALE_NANO_MAX_X, &gain_sel);
+	/* We can't reach the max gain with integration time smaller than MAX */
+	KUNIT_EXPECT_NE(test, 0, ret);
+
+	ret = iio_gts_find_gain_sel_for_scale_using_time(&gts, TEST_TSEL_50, 0,
+						TEST_SCALE_NANO_MAX_X, &gain_sel);
+	/* We can't reach the max gain with integration time smaller than MAX */
+	KUNIT_EXPECT_NE(test, 0, ret);
+}
+
+static void test_iio_gts_find_new_gain_sel_by_old_gain_time(struct kunit *test)
+{
+	struct device *dev;
+	int ret, old_gain, new_gain, old_time_sel, new_time_sel;
+
+	dev = test_init_iio_gain_scale(test, &gts);
+	if (!dev)
+		return;
+
+	old_gain = 32;
+	old_time_sel = TEST_TSEL_200;
+	new_time_sel = TEST_TSEL_400;
+
+	ret = iio_gts_find_new_gain_sel_by_old_gain_time(&gts, old_gain,
+					old_time_sel, new_time_sel, &new_gain);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	/*
+	 * Doubling the integration time doubles the total gain - so old
+	 * (hw)gain must be divided by two to compensate. => 32 / 2 => 16
+	 */
+	KUNIT_EXPECT_EQ(test, 16, new_gain);
+
+	old_gain = 4;
+	old_time_sel = TEST_TSEL_50;
+	new_time_sel = TEST_TSEL_200;
+	ret = iio_gts_find_new_gain_sel_by_old_gain_time(&gts, old_gain,
+					old_time_sel, new_time_sel, &new_gain);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	/*
+	 * gain by time 1x => 4x - (hw)gain 4x => 1x
+	 */
+	KUNIT_EXPECT_EQ(test, 1, new_gain);
+
+	old_gain = 512;
+	old_time_sel = TEST_TSEL_400;
+	new_time_sel = TEST_TSEL_50;
+	ret = iio_gts_find_new_gain_sel_by_old_gain_time(&gts, old_gain,
+					old_time_sel, new_time_sel, &new_gain);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	/*
+	 * gain by time 8x => 1x - (hw)gain 512x => 4096x)
+	 */
+	KUNIT_EXPECT_EQ(test, 4096, new_gain);
+
+	/* Unsupported gain 2x */
+	old_gain = 4;
+	old_time_sel = TEST_TSEL_200;
+	new_time_sel = TEST_TSEL_400;
+	ret = iio_gts_find_new_gain_sel_by_old_gain_time(&gts, old_gain,
+					old_time_sel, new_time_sel, &new_gain);
+	KUNIT_EXPECT_NE(test, 0, ret);
+
+	/* Too small gain */
+	old_gain = 4;
+	old_time_sel = TEST_TSEL_50;
+	new_time_sel = TEST_TSEL_400;
+	ret = iio_gts_find_new_gain_sel_by_old_gain_time(&gts, old_gain,
+					old_time_sel, new_time_sel, &new_gain);
+	KUNIT_EXPECT_NE(test, 0, ret);
+
+	/* Too big gain */
+	old_gain = 1024;
+	old_time_sel = TEST_TSEL_400;
+	new_time_sel = TEST_TSEL_50;
+	ret = iio_gts_find_new_gain_sel_by_old_gain_time(&gts, old_gain,
+					old_time_sel, new_time_sel, &new_gain);
+	KUNIT_EXPECT_NE(test, 0, ret);
+
+}
+
+static void test_iio_find_closest_gain_low(struct kunit *test)
+{
+	struct device *dev;
+	bool in_range;
+	int ret;
+
+	const struct iio_gain_sel_pair gts_test_gains_gain_low[] = {
+		GAIN_SCALE_GAIN(4, TEST_GSEL_4),
+		GAIN_SCALE_GAIN(16, TEST_GSEL_16),
+		GAIN_SCALE_GAIN(32, TEST_GSEL_32),
+	};
+
+	dev = test_init_iio_gain_scale(test, &gts);
+	if (!dev)
+		return;
+
+	ret = iio_find_closest_gain_low(&gts, 2, &in_range);
+	KUNIT_EXPECT_EQ(test, 1, ret);
+	KUNIT_EXPECT_EQ(test, true, in_range);
+
+	ret = iio_find_closest_gain_low(&gts, 1, &in_range);
+	KUNIT_EXPECT_EQ(test, 1, ret);
+	KUNIT_EXPECT_EQ(test, true, in_range);
+
+	ret = iio_find_closest_gain_low(&gts, 4095, &in_range);
+	KUNIT_EXPECT_EQ(test, 2048, ret);
+	KUNIT_EXPECT_EQ(test, true, in_range);
+
+	ret = iio_find_closest_gain_low(&gts, 4097, &in_range);
+	KUNIT_EXPECT_EQ(test, 4096, ret);
+	KUNIT_EXPECT_EQ(test, false, in_range);
+
+	kunit_device_unregister(test, dev);
+
+	dev = __test_init_iio_gain_scale(test, &gts, gts_test_gains_gain_low,
+				ARRAY_SIZE(gts_test_gains_gain_low),
+				gts_test_itimes, ARRAY_SIZE(gts_test_itimes));
+	if (!dev)
+		return;
+
+	ret = iio_find_closest_gain_low(&gts, 3, &in_range);
+	KUNIT_EXPECT_EQ(test, -EINVAL, ret);
+	KUNIT_EXPECT_EQ(test, false, in_range);
+}
+
+static void test_iio_gts_total_gain_to_scale(struct kunit *test)
+{
+	struct device *dev;
+	int ret, scale_int, scale_nano;
+
+	dev = test_init_iio_gain_scale(test, &gts);
+	if (!dev)
+		return;
+
+	ret = iio_gts_total_gain_to_scale(&gts, 1, &scale_int, &scale_nano);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, TEST_SCALE_1X, scale_int);
+	KUNIT_EXPECT_EQ(test, 0, scale_nano);
+
+	ret = iio_gts_total_gain_to_scale(&gts, 1, &scale_int, &scale_nano);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, TEST_SCALE_1X, scale_int);
+	KUNIT_EXPECT_EQ(test, 0, scale_nano);
+
+	ret = iio_gts_total_gain_to_scale(&gts, 4096 * 8, &scale_int,
+					  &scale_nano);
+	KUNIT_EXPECT_EQ(test, 0, ret);
+	KUNIT_EXPECT_EQ(test, 0, scale_int);
+	KUNIT_EXPECT_EQ(test, TEST_SCALE_NANO_4096X8, scale_nano);
+}
+
+static void test_iio_gts_chk_times(struct kunit *test, const int *vals)
+{
+	static const int expected[] = {0, 50000, 0, 100000, 0, 200000, 0, 400000};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(expected); i++)
+		KUNIT_EXPECT_EQ(test, expected[i], vals[i]);
+}
+
+static void test_iio_gts_chk_scales_all(struct kunit *test, struct iio_gts *gts,
+					const int *vals, int len)
+{
+	static const int gains[] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512,
+				    1024, 2048, 4096, 4096 * 2, 4096 * 4,
+				    4096 * 8};
+	int expected[ARRAY_SIZE(gains) * 2];
+	int i, ret;
+	int exp_len = ARRAY_SIZE(gains) * 2;
+
+	KUNIT_EXPECT_EQ(test, exp_len, len);
+	if (len != exp_len)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(gains); i++) {
+		ret = iio_gts_total_gain_to_scale(gts, gains[i],
+						  &expected[2 * i],
+						  &expected[2 * i + 1]);
+		KUNIT_EXPECT_EQ(test, 0, ret);
+		if (ret)
+			return;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(expected); i++)
+		KUNIT_EXPECT_EQ(test, expected[i], vals[i]);
+}
+
+static void test_iio_gts_chk_scales_t200(struct kunit *test, struct iio_gts *gts,
+					 const int *vals, int len)
+{
+	/* The gain caused by time 200 is 4x */
+	static const int gains[] = {
+		1 * 4,
+		4 * 4,
+		16 * 4,
+		32 * 4,
+		64 * 4,
+		256 * 4,
+		512 * 4,
+		1024 * 4,
+		2048 * 4,
+		4096 * 4
+	};
+	int expected[ARRAY_SIZE(gains) * 2];
+	int i, ret;
+
+	KUNIT_EXPECT_EQ(test, 2 * ARRAY_SIZE(gains), len);
+	if (len < 2 * ARRAY_SIZE(gains))
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(gains); i++) {
+		ret = iio_gts_total_gain_to_scale(gts, gains[i],
+						  &expected[2 * i],
+						  &expected[2 * i + 1]);
+		KUNIT_EXPECT_EQ(test, 0, ret);
+		if (ret)
+			return;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(expected); i++)
+		KUNIT_EXPECT_EQ(test, expected[i], vals[i]);
+}
+
+static void test_iio_gts_avail_test(struct kunit *test)
+{
+	struct device *dev;
+	int ret;
+	int type, len;
+	const int *vals;
+
+	dev = test_init_iio_gain_scale(test, &gts);
+	if (!dev)
+		return;
+
+	/* test table building for times and iio_gts_avail_times() */
+	ret = iio_gts_avail_times(&gts, &vals, &type, &len);
+	KUNIT_EXPECT_EQ(test, IIO_AVAIL_LIST, ret);
+	if (ret)
+		return;
+
+	KUNIT_EXPECT_EQ(test, IIO_VAL_INT_PLUS_MICRO, type);
+	KUNIT_EXPECT_EQ(test, 8, len);
+	if (len < 8)
+		return;
+
+	test_iio_gts_chk_times(test, vals);
+
+	/* Test table building for all scales and iio_gts_all_avail_scales() */
+	ret = iio_gts_all_avail_scales(&gts, &vals, &type, &len);
+	KUNIT_EXPECT_EQ(test, IIO_AVAIL_LIST, ret);
+	if (ret)
+		return;
+
+	KUNIT_EXPECT_EQ(test, IIO_VAL_INT_PLUS_NANO, type);
+
+	test_iio_gts_chk_scales_all(test, &gts, vals, len);
+
+	/*
+	 * Test table building for scales/time and
+	 * iio_gts_avail_scales_for_time()
+	 */
+	ret = iio_gts_avail_scales_for_time(&gts, 200000, &vals, &type, &len);
+	KUNIT_EXPECT_EQ(test, IIO_AVAIL_LIST, ret);
+	if (ret)
+		return;
+
+	KUNIT_EXPECT_EQ(test, IIO_VAL_INT_PLUS_NANO, type);
+	test_iio_gts_chk_scales_t200(test, &gts, vals, len);
+}
+
+static struct kunit_case iio_gts_test_cases[] = {
+	KUNIT_CASE(test_init_iio_gts_invalid),
+	KUNIT_CASE(test_iio_gts_find_gain_for_scale_using_time),
+	KUNIT_CASE(test_iio_gts_find_new_gain_sel_by_old_gain_time),
+	KUNIT_CASE(test_iio_find_closest_gain_low),
+	KUNIT_CASE(test_iio_gts_total_gain_to_scale),
+	KUNIT_CASE(test_iio_gts_avail_test),
+	{ }
+};
+
+static struct kunit_suite iio_gts_test_suite = {
+	.name = "iio-gain-time-scale",
+	.test_cases = iio_gts_test_cases,
+};
+
+kunit_test_suite(iio_gts_test_suite);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
+MODULE_DESCRIPTION("Test IIO light sensor gain-time-scale helpers");
+MODULE_IMPORT_NS("IIO_GTS_HELPER");
diff --git a/drivers/iio/test/iio-test-multiply.c b/drivers/iio/test/iio-test-multiply.c
new file mode 100644
index 000000000..432e279ff
--- /dev/null
+++ b/drivers/iio/test/iio-test-multiply.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Unit tests for IIO multiply functions
+ *
+ * Copyright (c) 2025 Hans de Goede <hans@hansg.org>
+ * Based on iio-test-format.c which is:
+ * Copyright (c) 2020 Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <kunit/test.h>
+#include <linux/iio/consumer.h>
+#include <linux/math64.h>
+#include <linux/types.h>
+
+static void __iio_test_iio_multiply_value_integer(struct kunit *test, s64 multiplier)
+{
+	int ret, result, val;
+
+	val = 42;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT, val, 0);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, multiplier * val);
+
+	val = -23;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT, val, 0);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, multiplier * val);
+
+	val = 0;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT, val, 0);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, multiplier * val);
+}
+
+static void iio_test_iio_multiply_value_integer(struct kunit *test)
+{
+	__iio_test_iio_multiply_value_integer(test, 20);
+	__iio_test_iio_multiply_value_integer(test, -20);
+}
+
+static void __iio_test_iio_multiply_value_fixedpoint(struct kunit *test, s64 multiplier)
+{
+	int ret, result, val, val2;
+
+	/* positive >= 1 (1.5) */
+	val = 1;
+	val2 = 500000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_MICRO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * 15, 10));
+
+	val = 1;
+	val2 = 500000000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_NANO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * 15, 10));
+
+	/* positive < 1 (0.5) */
+	val = 0;
+	val2 = 500000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_MICRO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * 5, 10));
+
+	val = 0;
+	val2 = 500000000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_NANO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * 5, 10));
+
+	/* negative <= -1 (-1.5) */
+	val = -1;
+	val2 = 500000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_MICRO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * -15, 10));
+
+	val = -1;
+	val2 = 500000000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_NANO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * -15, 10));
+
+	/* negative > -1 (-0.5) */
+	val = 0;
+	val2 = -500000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_MICRO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * -5, 10));
+
+	val = 0;
+	val2 = -500000000;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_INT_PLUS_NANO, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * -5, 10));
+}
+
+static void iio_test_iio_multiply_value_fixedpoint(struct kunit *test)
+{
+	__iio_test_iio_multiply_value_fixedpoint(test, 20);
+	__iio_test_iio_multiply_value_fixedpoint(test, -20);
+}
+
+static void __iio_test_iio_multiply_value_fractional(struct kunit *test, s64 multiplier)
+{
+	int ret, result, val, val2;
+
+	/* positive < 1 (1/10)*/
+	val = 1;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * val, val2));
+
+	/* positive >= 1 (100/3)*/
+	val = 100;
+	val2 = 3;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * val, val2));
+
+	/* negative > -1 (-1/10) */
+	val = -1;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * val, val2));
+
+	/* negative <= -1 (-200/3)*/
+	val = -200;
+	val2 = 3;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * val, val2));
+
+	/* Zero (0/-10) */
+	val = 0;
+	val2 = -10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, div_s64(multiplier * val, val2));
+}
+
+static void iio_test_iio_multiply_value_fractional(struct kunit *test)
+{
+	__iio_test_iio_multiply_value_fractional(test, 20);
+	__iio_test_iio_multiply_value_fractional(test, -20);
+}
+
+static void __iio_test_iio_multiply_value_fractional_log2(struct kunit *test, s64 multiplier)
+{
+	int ret, result, val, val2;
+
+	/* positive < 1 (123/1024) */
+	val = 123;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL_LOG2, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, (multiplier * val) >> val2);
+
+	/* positive >= 1 (1234567/1024) */
+	val = 1234567;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL_LOG2, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, (multiplier * val) >> val2);
+
+	/* negative > -1 (-123/1024) */
+	val = -123;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL_LOG2, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, (multiplier * val) >> val2);
+
+	/* negative <= -1 (-1234567/1024) */
+	val = -1234567;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL_LOG2, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, (multiplier * val) >> val2);
+
+	/* Zero (0/1024) */
+	val = 0;
+	val2 = 10;
+	ret = iio_multiply_value(&result, multiplier, IIO_VAL_FRACTIONAL_LOG2, val, val2);
+	KUNIT_EXPECT_EQ(test, ret, IIO_VAL_INT);
+	KUNIT_EXPECT_EQ(test, result, (multiplier * val) >> val2);
+}
+
+static void iio_test_iio_multiply_value_fractional_log2(struct kunit *test)
+{
+	__iio_test_iio_multiply_value_fractional_log2(test, 20);
+	__iio_test_iio_multiply_value_fractional_log2(test, -20);
+}
+
+static struct kunit_case iio_multiply_test_cases[] = {
+		KUNIT_CASE(iio_test_iio_multiply_value_integer),
+		KUNIT_CASE(iio_test_iio_multiply_value_fixedpoint),
+		KUNIT_CASE(iio_test_iio_multiply_value_fractional),
+		KUNIT_CASE(iio_test_iio_multiply_value_fractional_log2),
+		{ }
+};
+
+static struct kunit_suite iio_multiply_test_suite = {
+	.name = "iio-multiply",
+	.test_cases = iio_multiply_test_cases,
+};
+kunit_test_suite(iio_multiply_test_suite);
+
+MODULE_AUTHOR("Hans de Goede <hans@hansg.org>");
+MODULE_DESCRIPTION("Test IIO multiply functions");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_UNIT_TEST");
diff --git a/drivers/iio/test/iio-test-rescale.c b/drivers/iio/test/iio-test-rescale.c
new file mode 100644
index 000000000..bcd4a607b
--- /dev/null
+++ b/drivers/iio/test/iio-test-rescale.c
@@ -0,0 +1,719 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kunit tests for IIO rescale conversions
+ *
+ * Copyright (c) 2021 Liam Beguin <liambeguin@gmail.com>
+ */
+
+#include <linux/gcd.h>
+#include <linux/overflow.h>
+
+#include <linux/iio/afe/rescale.h>
+#include <linux/iio/iio.h>
+
+#include <kunit/test.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;
+};
+
+static 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",
+	},
+};
+
+static 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)
+{
+	strscpy(desc, t->name, KUNIT_PARAM_DESC_SIZE);
+}
+
+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 tmp, tmp2;
+	int ret = 0;
+
+	/*
+	 * iio_str_to_fixpoint() uses 10^8 here instead of 10^9 as fract_mult is
+	 * the multiplier for the first decimal place.
+	 */
+	ret = iio_str_to_fixpoint(str, 100000000, &tmp, &tmp2);
+	if (ret < 0)
+		return ret;
+
+	if (tmp < 0)
+		tmp2 *= -1;
+
+	*nano = (s64)tmp * 1000000000UL + 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 = 1000000UL * abs(exp - real);
+
+	return (int)div64_u64(err, abs(exp));
+}
+
+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;
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buff);
+
+	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;
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buff_off);
+
+	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);
+
+MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>");
+MODULE_DESCRIPTION("Test IIO rescale conversion functions");
+MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_RESCALE");