linux-kernel - [PATCH RFC v4 03/12] clk: test: introduce clk_dummy

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Message-Id: <20250923-clk-tests-docs-v4-3-9205cb3d3cba@redhat.com>
Date: Tue, 23 Sep 2025 10:39:22 -0400
From: Brian Masney <bmasney@...hat.com>
To: Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Maxime Ripard <mripard@...nel.org>, 
 Jonathan Corbet <corbet@....net>, Russell King <linux@...linux.org.uk>
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-doc@...r.kernel.org, Brian Masney <bmasney@...hat.com>
Subject: [PATCH RFC v4 03/12] clk: test: introduce clk_dummy_div for a mock
 divider

This is used to mock up a divider in the clk kunit tests.

Signed-off-by: Brian Masney <bmasney@...hat.com>
---
 drivers/clk/clk_test.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index 372dd289a7ba148a0725ea0643342ccda7196216..e1f72fcede1df1d486744b171728231ec8fa8836 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -137,6 +137,50 @@ static const struct clk_ops clk_dummy_single_parent_ops = {
 	.get_parent = clk_dummy_single_get_parent,
 };
 
+// 4 ought to be enough for anybody
+#define CLK_DUMMY_DIV_WIDTH 4
+#define CLK_DUMMY_DIV_FLAGS (CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ROUND_CLOSEST)
+
+struct clk_dummy_div {
+	struct clk_hw hw;
+	unsigned int div;
+};
+
+static unsigned long clk_dummy_div_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	struct clk_dummy_div *div = container_of(hw, struct clk_dummy_div, hw);
+
+	return divider_recalc_rate(hw, parent_rate, div->div, NULL,
+				   CLK_DUMMY_DIV_FLAGS, CLK_DUMMY_DIV_WIDTH);
+}
+
+static int clk_dummy_div_determine_rate(struct clk_hw *hw,
+					struct clk_rate_request *req)
+{
+	if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) && req->best_parent_rate < req->rate)
+		return -EINVAL;
+
+	return divider_determine_rate(hw, req, NULL, CLK_DUMMY_DIV_WIDTH, CLK_DUMMY_DIV_FLAGS);
+}
+
+static int clk_dummy_div_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct clk_dummy_div *div = container_of(hw, struct clk_dummy_div, hw);
+
+	div->div = divider_get_val(rate, parent_rate, NULL, CLK_DUMMY_DIV_WIDTH,
+				   CLK_DUMMY_DIV_FLAGS);
+
+	return 0;
+}
+
+static const struct clk_ops clk_dummy_div_ops = {
+	.recalc_rate = clk_dummy_div_recalc_rate,
+	.determine_rate = clk_dummy_div_determine_rate,
+	.set_rate = clk_dummy_div_set_rate,
+};
+
 struct clk_multiple_parent_ctx {
 	struct clk_dummy_context parents_ctx[2];
 	struct clk_hw hw;

-- 
2.51.0