clk: Add clk_drop_range

In order to reset the range on a clock, we need to call
clk_set_rate_range with a minimum of 0 and a maximum of ULONG_MAX. Since
it's fairly inconvenient, let's introduce a clk_drop_range() function
that will do just this.

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220225143534.405820-8-maxime@cerno.tech
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: mripard

drivers/clk/clk_test.c

@@ -645,7 +645,7 @@ static void clk_range_test_multiple_set_range_rate_maximized(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, rate, DUMMY_CLOCK_RATE_1);
 
 	KUNIT_ASSERT_EQ(test,
-			clk_set_rate_range(user2, 0, ULONG_MAX),
+			clk_drop_range(user2),
 			0);
 
 	rate = clk_get_rate(clk);
@@ -762,7 +762,7 @@ static void clk_range_test_multiple_set_range_rate_minimized(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, rate, DUMMY_CLOCK_RATE_2);
 
 	KUNIT_ASSERT_EQ(test,
-			clk_set_rate_range(user2, 0, ULONG_MAX),
+			clk_drop_range(user2),
 			0);
 
 	rate = clk_get_rate(clk);

include/linux/clk.h

@@ -986,6 +986,17 @@ static inline void clk_bulk_disable_unprepare(int num_clks,
 	clk_bulk_unprepare(num_clks, clks);
 }
 
+/**
+ * clk_drop_range - Reset any range set on that clock
+ * @clk: clock source
+ *
+ * Returns success (0) or negative errno.
+ */
+static inline int clk_drop_range(struct clk *clk)
+{
+	return clk_set_rate_range(clk, 0, ULONG_MAX);
+}
+
 /**
  * clk_get_optional - lookup and obtain a reference to an optional clock
  *		      producer.