linux-kernel - [PATCH v2] clk: scmi: migrate round_rate() to determine

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Message-Id: <20250827-clk-scmi-round-rate-v2-1-3782a50835ed@redhat.com>
Date: Wed, 27 Aug 2025 13:12:07 -0400
From: Brian Masney <bmasney@...hat.com>
To: Sudeep Holla <sudeep.holla@....com>, 
 Cristian Marussi <cristian.marussi@....com>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>
Cc: arm-scmi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Brian Masney <bmasney@...hat.com>
Subject: [PATCH v2] clk: scmi: migrate round_rate() to determine_rate()

This driver implements both the determine_rate() and round_rate() clk
ops, and the round_rate() clk ops is deprecated. When both are defined,
clk_core_determine_round_nolock() from the clk core will only use the
determine_rate() clk ops.

The existing scmi_clk_determine_rate() is a noop implementation that
lets the firmware round the rate as appropriate. Drop the existing
determine_rate implementation and convert the existing round_rate()
implementation over to determine_rate().

scmi_clk_determine_rate() was added recently when the clock parent
support was added, so it's not expected that this change will regress
anything.

Signed-off-by: Brian Masney <bmasney@...hat.com>
---
Changes since v1:
- Split out individual patch from larger v1 114 patch series
- Drop noop determine_rate implementation; convert round_rate
---
 drivers/clk/clk-scmi.c | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index d2408403283fc72f0cf902e65f4c08bcbc7b4b0b..78dd2d9c7cabd18f2a05cffd0408cfefaf34fce0 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -54,8 +54,8 @@ static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
 	return rate;
 }
 
-static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
-				unsigned long *parent_rate)
+static int scmi_clk_determine_rate(struct clk_hw *hw,
+				   struct clk_rate_request *req)
 {
 	u64 fmin, fmax, ftmp;
 	struct scmi_clk *clk = to_scmi_clk(hw);
@@ -67,20 +67,27 @@ static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
 	 * running at then.
 	 */
 	if (clk->info->rate_discrete)
-		return rate;
+		return 0;
 
 	fmin = clk->info->range.min_rate;
 	fmax = clk->info->range.max_rate;
-	if (rate <= fmin)
-		return fmin;
-	else if (rate >= fmax)
-		return fmax;
+	if (req->rate <= fmin) {
+		req->rate = fmin;
+
+		return 0;
+	} else if (req->rate >= fmax) {
+		req->rate = fmax;
 
-	ftmp = rate - fmin;
+		return 0;
+	}
+
+	ftmp = req->rate - fmin;
 	ftmp += clk->info->range.step_size - 1; /* to round up */
 	do_div(ftmp, clk->info->range.step_size);
 
-	return ftmp * clk->info->range.step_size + fmin;
+	req->rate = ftmp * clk->info->range.step_size + fmin;
+
+	return 0;
 }
 
 static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -119,15 +126,6 @@ static u8 scmi_clk_get_parent(struct clk_hw *hw)
 	return p_idx;
 }
 
-static int scmi_clk_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
-{
-	/*
-	 * Suppose all the requested rates are supported, and let firmware
-	 * to handle the left work.
-	 */
-	return 0;
-}
-
 static int scmi_clk_enable(struct clk_hw *hw)
 {
 	struct scmi_clk *clk = to_scmi_clk(hw);
@@ -300,7 +298,6 @@ scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
 
 	/* Rate ops */
 	ops->recalc_rate = scmi_clk_recalc_rate;
-	ops->round_rate = scmi_clk_round_rate;
 	ops->determine_rate = scmi_clk_determine_rate;
 	if (feats_key & BIT(SCMI_CLK_RATE_CTRL_SUPPORTED))
 		ops->set_rate = scmi_clk_set_rate;

---
base-commit: 3c642997252eef4449cb6b6e02af3dc22515d817
change-id: 20250827-clk-scmi-round-rate-7e3d4099134a

Best regards,
-- 
Brian Masney <bmasney@...hat.com>