clk: Add KUnit tests for clk fixed rate basic type

Test that the fixed rate basic type clk works as intended.

Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20240718210513.3801024-8-sboyd@kernel.org

drivers/clk/.kunitconfig

 CONFIG_KUNIT=y
+CONFIG_OF=y
 CONFIG_COMMON_CLK=y
 CONFIG_CLK_KUNIT_TEST=y
+CONFIG_CLK_FIXED_RATE_KUNIT_TEST=y
 CONFIG_CLK_GATE_KUNIT_TEST=y
 CONFIG_CLK_FD_KUNIT_TEST=y
 CONFIG_UML_PCI_OVER_VIRTIO=n

drivers/clk/Kconfig

@@ -512,6 +512,15 @@ config CLK_KUNIT_TEST
 	help
 	  Kunit tests for the common clock framework.
 
+config CLK_FIXED_RATE_KUNIT_TEST
+	tristate "Basic fixed rate clk type KUnit test" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	select OF_OVERLAY if OF
+	select DTC
+	help
+	  KUnit tests for the basic fixed rate clk type.
+
 config CLK_GATE_KUNIT_TEST
 	tristate "Basic gate type Kunit test" if !KUNIT_ALL_TESTS
 	depends on KUNIT

drivers/clk/Makefile

@@ -6,6 +6,8 @@ obj-$(CONFIG_CLK_KUNIT_TEST)	+= clk_test.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-divider.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-factor.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-rate.o
+obj-$(CONFIG_CLK_FIXED_RATE_KUNIT_TEST)	+= clk-fixed-rate-test.o
+clk-fixed-rate-test-y		:= clk-fixed-rate_test.o kunit_clk_fixed_rate_test.dtbo.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-gate.o
 obj-$(CONFIG_CLK_GATE_KUNIT_TEST) += clk-gate_test.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-multiplier.o

drivers/clk/clk-fixed-rate_test.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _CLK_FIXED_RATE_TEST_H
+#define _CLK_FIXED_RATE_TEST_H
+
+#define TEST_FIXED_FREQUENCY	50000000
+#define TEST_FIXED_ACCURACY	300
+
+#endif

drivers/clk/kunit_clk_fixed_rate_test.dtso

+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+#include "clk-fixed-rate_test.h"
+
+&{/} {
+	fixed_50MHz: kunit-clock {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <TEST_FIXED_FREQUENCY>;
+		clock-accuracy = <TEST_FIXED_ACCURACY>;
+	};
+
+	kunit-clock-consumer {
+		compatible = "test,single-clk-consumer";
+		clocks = <&fixed_50MHz>;
+	};
+};