clk: fractional-divider: tests: Add test suite for edge cases

In light of the recent discovery that the fractional divisor
approximation does not utilize the full available range for clocks that
are flagged CLK_FRAC_DIVIDER_ZERO_BASED [1], implement tests for the
edge cases of this clock type.

Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
Link: https://lore.kernel.org/lkml/20230529133433.56215-1-frank@oltmanns.dev [1]
Link: https://lore.kernel.org/r/20230617131041.18313-3-frank@oltmanns.dev
[sboyd@kernel.org: Rename suite and tests slightly, drop unused
includes, store parent rate to compare instead of repeating equation]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: explicitly disable CONFIG_UML_PCI_OVER_VIRTIO in .kunitconfig

CONFIG_UML_PCI_OVER_VIRTIO=y is needed to enable CONFIG_PCI=y on UML.
However, this causes test failures when running the clk tests, i.e.
$ ./tools/testing/kunit/kunit.py run --kunitconfig=drivers/clk

A snippet of the particular error is:
> ok 1 - clk_gate_test_parent_rate
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 45 at lib/logic_iomem.c:141 __raw_readl+0x9f/0xd0

This is triggered by this cast in the test:
143 ctx->fake_mem = (void __force __iomem *)&ctx->fake_reg;
this seems to work except when logic iomem is enabled, i.e.
CONFIG_INDIRECT_IOMEM=y.

As a short-term fix, explicitly disable CONFIG_UML_PCI_OVER_VIRTIO in
drivers/clk/.kunitconfig so we can enable it for everyone else by
default in kunit.py.

The long-term fix probably requires something more complicated, like
#ifdef CONFIG_INDIRECT_IOMEM
logic_iomem_add_region(...);
#endif

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reported-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Reviewed-by: David Gow <davidgow@google.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

clk: Introduce Kunit Tests for the framework

Let's test various parts of the rate-related clock API with the kunit
testing framework.

Cc: kunit-dev@googlegroups.com
Tested-by: Daniel Latypov <dlatypov@google.com>
Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220225143534.405820-3-maxime@cerno.tech
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: gate: Add some kunit test suites

Test various parts of the clk gate implementation with the kunit testing
framework.

Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Daniel Latypov <dlatypov@google.com>
Cc: <kunit-dev@googlegroups.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20220120175902.2165958-1-sboyd@kernel.org