[v4,04/68] clk: Introduce clk_hw_determine_rate_no_reparent()

Commit Message

Maxime Ripard May 5, 2023, 11:25 a.m. UTC

From: Stephen Boyd <[e-mail]>

Some clock drivers do not want to allow any reparenting on a given
clock, but usually do so by not providing any determine_rate
implementation.

Whenever we call clk_round_rate() or clk_set_rate(), this leads to
clk_core_can_round() returning false and thus the rest of the function
either forwarding the rate request to its current parent if
CLK_SET_RATE_PARENT is set, or just returning the current clock rate.

This behaviour happens implicitly, and as we move forward to making a
determine_rate implementation required for muxes, we need some way to
explicitly opt-in for that behaviour.

Fortunately, this is exactly what the clk_core_determine_rate_no_reparent()
function is doing, so we can simply make it available to drivers.

Cc: Abel Vesa <[e-mail]>
Cc: Alessandro Zummo <[e-mail]>
Cc: Alexandre Belloni <[e-mail]>
Cc: Alexandre Torgue <[e-mail]>
Cc: "Andreas Färber" <[e-mail]>
Cc: AngeloGioacchino Del Regno <[e-mail]>
Cc: Baolin Wang <[e-mail]>
Cc: Charles Keepax <[e-mail]>
Cc: Chen-Yu Tsai <[e-mail]>
Cc: Chen-Yu Tsai <[e-mail]>
Cc: Chunyan Zhang <[e-mail]>
Cc: Claudiu Beznea <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: David Lechner <[e-mail]>
Cc: Dinh Nguyen <[e-mail]>
Cc: Fabio Estevam <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Jaroslav Kysela <[e-mail]>
Cc: Jernej Skrabec <[e-mail]>
Cc: Jonathan Hunter <[e-mail]>
Cc: Kishon Vijay Abraham I <[e-mail]>
Cc: Liam Girdwood <[e-mail]>
Cc: Linus Walleij <[e-mail]>
Cc: Luca Ceresoli <[e-mail]>
Cc: Manivannan Sadhasivam <[e-mail]>
Cc: Mark Brown <[e-mail]>
Cc: Markus Schneider-Pargmann <[e-mail]>
Cc: Max Filippov <[e-mail]>
Cc: Maxime Coquelin <[e-mail]>
Cc: Mikko Perttunen <[e-mail]>
Cc: Miles Chen <[e-mail]>
Cc: Nicolas Ferre <[e-mail]>
Cc: Orson Zhai <[e-mail]>
Cc: Paul Cercueil <[e-mail]>
Cc: Peng Fan <[e-mail]>
Cc: Peter De Schrijver <[e-mail]>
Cc: Prashant Gaikwad <[e-mail]>
Cc: Richard Fitzgerald <[e-mail]>
Cc: Samuel Holland <[e-mail]>
Cc: Sascha Hauer <[e-mail]>
Cc: Sekhar Nori <[e-mail]>
Cc: Shawn Guo <[e-mail]>
Cc: Takashi Iwai <[e-mail]>
Cc: Thierry Reding <[e-mail]>
Cc: Ulf Hansson <[e-mail]>
Cc: Vinod Koul <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: NXP Linux Team <[e-mail]>
Cc: [e-mail]
Cc: Pengutronix Kernel Team <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>
Signed-off-by: Maxime Ripard <[e-mail]>
---
 drivers/clk/clk.c            |  18 +++++
 drivers/clk/clk_test.c       | 152 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/clk-provider.h |   2 +
 3 files changed, 172 insertions(+)

Patch

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index f57f821a5e5a..5365595433c8 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -783,6 +783,24 @@  int __clk_mux_determine_rate_closest(struct clk_hw *hw,
 }
 EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);
 
+/*
+ * clk_hw_determine_rate_no_reparent - clk_ops::determine_rate implementation for a clk that doesn't reparent
+ * @hw: mux type clk to determine rate on
+ * @req: rate request, also used to return preferred frequency
+ *
+ * Helper for finding best parent rate to provide a given frequency.
+ * This can be used directly as a determine_rate callback (e.g. for a
+ * mux), or from a more complex clock that may combine a mux with other
+ * operations.
+ *
+ * Returns: 0 on success, -EERROR value on error
+ */
+int clk_hw_determine_rate_no_reparent(struct clk_hw *hw,
+				      struct clk_rate_request *req)
+{
+	return clk_core_determine_rate_no_reparent(hw, req);
+}
+
 /***        clk api        ***/
 
 static void clk_core_rate_unprotect(struct clk_core *core)
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index 2cb51153750d..b3ed3b0e4c31 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -141,6 +141,12 @@  static const struct clk_ops clk_multiple_parents_mux_ops = {
 	.determine_rate = __clk_mux_determine_rate_closest,
 };
 
+static const struct clk_ops clk_multiple_parents_no_reparent_mux_ops = {
+	.determine_rate = clk_hw_determine_rate_no_reparent,
+	.get_parent = clk_multiple_parents_mux_get_parent,
+	.set_parent = clk_multiple_parents_mux_set_parent,
+};
+
 static int clk_test_init_with_ops(struct kunit *test, const struct clk_ops *ops)
 {
 	struct clk_dummy_context *ctx;
@@ -2395,10 +2401,156 @@  static struct kunit_suite clk_mux_notifier_test_suite = {
 	.test_cases = clk_mux_notifier_test_cases,
 };
 
+static int
+clk_mux_no_reparent_test_init(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx;
+	const char *parents[2] = { "parent-0", "parent-1"};
+	int ret;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	test->priv = ctx;
+
+	ctx->parents_ctx[0].hw.init = CLK_HW_INIT_NO_PARENT("parent-0",
+							    &clk_dummy_rate_ops,
+							    0);
+	ctx->parents_ctx[0].rate = DUMMY_CLOCK_RATE_1;
+	ret = clk_hw_register(NULL, &ctx->parents_ctx[0].hw);
+	if (ret)
+		return ret;
+
+	ctx->parents_ctx[1].hw.init = CLK_HW_INIT_NO_PARENT("parent-1",
+							    &clk_dummy_rate_ops,
+							    0);
+	ctx->parents_ctx[1].rate = DUMMY_CLOCK_RATE_2;
+	ret = clk_hw_register(NULL, &ctx->parents_ctx[1].hw);
+	if (ret)
+		return ret;
+
+	ctx->current_parent = 0;
+	ctx->hw.init = CLK_HW_INIT_PARENTS("test-mux", parents,
+					   &clk_multiple_parents_no_reparent_mux_ops,
+					   0);
+	ret = clk_hw_register(NULL, &ctx->hw);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void
+clk_mux_no_reparent_test_exit(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+
+	clk_hw_unregister(&ctx->hw);
+	clk_hw_unregister(&ctx->parents_ctx[0].hw);
+	clk_hw_unregister(&ctx->parents_ctx[1].hw);
+}
+
+/*
+ * Test that if the we have a mux that cannot change parent and we call
+ * clk_round_rate() on it with a rate that should cause it to change
+ * parent, it won't.
+ */
+static void clk_mux_no_reparent_round_rate(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+	struct clk_hw *hw = &ctx->hw;
+	struct clk *clk = clk_hw_get_clk(hw, NULL);
+	struct clk *other_parent, *parent;
+	unsigned long other_parent_rate;
+	unsigned long parent_rate;
+	long rounded_rate;
+
+	parent = clk_get_parent(clk);
+	KUNIT_ASSERT_PTR_NE(test, parent, NULL);
+
+	parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, parent_rate, 0);
+
+	other_parent = clk_hw_get_clk(&ctx->parents_ctx[1].hw, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, other_parent);
+	KUNIT_ASSERT_FALSE(test, clk_is_match(parent, other_parent));
+
+	other_parent_rate = clk_get_rate(other_parent);
+	KUNIT_ASSERT_GT(test, other_parent_rate, 0);
+	clk_put(other_parent);
+
+	rounded_rate = clk_round_rate(clk, other_parent_rate);
+	KUNIT_ASSERT_GT(test, rounded_rate, 0);
+	KUNIT_EXPECT_EQ(test, rounded_rate, parent_rate);
+
+	clk_put(clk);
+}
+
+/*
+ * Test that if the we have a mux that cannot change parent and we call
+ * clk_set_rate() on it with a rate that should cause it to change
+ * parent, it won't.
+ */
+static void clk_mux_no_reparent_set_rate(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+	struct clk_hw *hw = &ctx->hw;
+	struct clk *clk = clk_hw_get_clk(hw, NULL);
+	struct clk *other_parent, *parent;
+	unsigned long other_parent_rate;
+	unsigned long parent_rate;
+	unsigned long rate;
+	int ret;
+
+	parent = clk_get_parent(clk);
+	KUNIT_ASSERT_PTR_NE(test, parent, NULL);
+
+	parent_rate = clk_get_rate(parent);
+	KUNIT_ASSERT_GT(test, parent_rate, 0);
+
+	other_parent = clk_hw_get_clk(&ctx->parents_ctx[1].hw, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, other_parent);
+	KUNIT_ASSERT_FALSE(test, clk_is_match(parent, other_parent));
+
+	other_parent_rate = clk_get_rate(other_parent);
+	KUNIT_ASSERT_GT(test, other_parent_rate, 0);
+	clk_put(other_parent);
+
+	ret = clk_set_rate(clk, other_parent_rate);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	rate = clk_get_rate(clk);
+	KUNIT_ASSERT_GT(test, rate, 0);
+	KUNIT_EXPECT_EQ(test, rate, parent_rate);
+
+	clk_put(clk);
+}
+
+static struct kunit_case clk_mux_no_reparent_test_cases[] = {
+	KUNIT_CASE(clk_mux_no_reparent_round_rate),
+	KUNIT_CASE(clk_mux_no_reparent_set_rate),
+	{}
+};
+
+/*
+ * Test suite for a clock mux that isn't allowed to change parent, using
+ * the clk_hw_determine_rate_no_reparent() helper.
+ *
+ * These tests exercise that helper, and the proper selection of
+ * rates and parents.
+ */
+static struct kunit_suite clk_mux_no_reparent_test_suite = {
+	.name = "clk-mux-no-reparent",
+	.init = clk_mux_no_reparent_test_init,
+	.exit = clk_mux_no_reparent_test_exit,
+	.test_cases = clk_mux_no_reparent_test_cases,
+};
+
 kunit_test_suites(
 	&clk_leaf_mux_set_rate_parent_test_suite,
 	&clk_test_suite,
 	&clk_multiple_parents_mux_test_suite,
+	&clk_mux_no_reparent_test_suite,
 	&clk_mux_notifier_test_suite,
 	&clk_orphan_transparent_multiple_parent_mux_test_suite,
 	&clk_orphan_transparent_single_parent_test_suite,
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 28ff6f1a6ada..f8f220fb5dab 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -1333,6 +1333,8 @@  int __clk_mux_determine_rate_closest(struct clk_hw *hw,
 int clk_mux_determine_rate_flags(struct clk_hw *hw,
 				 struct clk_rate_request *req,
 				 unsigned long flags);
+int clk_hw_determine_rate_no_reparent(struct clk_hw *hw,
+				      struct clk_rate_request *req);
 void clk_hw_reparent(struct clk_hw *hw, struct clk_hw *new_parent);
 void clk_hw_get_rate_range(struct clk_hw *hw, unsigned long *min_rate,
 			   unsigned long *max_rate);