linux-kernel - [PATCH v2] clk: meson: Fix the determine rate error in clk_regmap_divider_ro

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Message-Id: <20241112-fix_childclk_of_roclk_has_been_tampered_with-v2-1-64f8009cdf2a@amlogic.com>
Date: Tue, 12 Nov 2024 20:57:13 +0800
From: Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org>
To: Neil Armstrong <neil.armstrong@...aro.org>, 
 Jerome Brunet <jbrunet@...libre.com>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Kevin Hilman <khilman@...libre.com>, 
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>, 
 Jian Hu <jian.hu@...ogic.com>, Dmitry Rokosov <ddrokosov@...rdevices.ru>, 
 Yu Tu <yu.tu@...ogic.com>
Cc: linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Chuan Liu <chuan.liu@...ogic.com>
Subject: [PATCH v2] clk: meson: Fix the determine rate error in
 clk_regmap_divider_ro_ops

From: Chuan Liu <chuan.liu@...ogic.com>

The rate determined by calling clk_regmap_divider_ro_ops with
clk_regmap_div_determine_rate is not RO, which will result in the
unexpected modification of the frequency of its children when setting
the rate of a clock that references clk_regmap_divider_ro_ops.

Fiexs: ea11dda9e091 ("clk: meson: add regmap clocks")
Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>
---
Background: During the execution of clk_set_rate(), the function 
clk_core_round_rate_nolock() is called to calculate the matching rate
and save it to 'core->new_rate'. At the same time, it recalculates and
updates its 'child->newrate'. Finally, clk_change_rate() is called to
set all 'new_rates'.
---
Changes in v2:
- Remove the CLK_DIVIDER_READ_ONLY judgment logic in
clk_regmap_div_determine_rate().
- Add clk_regmap_div_ro_determine_rate().
- Link to v1: https://lore.kernel.org/r/20241111-fix_childclk_of_roclk_has_been_tampered_with-v1-1-f8c1b6ffdcb0@amlogic.com
---
 drivers/clk/meson/clk-regmap.c | 36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/clk/meson/clk-regmap.c b/drivers/clk/meson/clk-regmap.c
index 07f7e441b916..edf65ca92c7a 100644
--- a/drivers/clk/meson/clk-regmap.c
+++ b/drivers/clk/meson/clk-regmap.c
@@ -80,21 +80,6 @@ static int clk_regmap_div_determine_rate(struct clk_hw *hw,
 {
 	struct clk_regmap *clk = to_clk_regmap(hw);
 	struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk);
-	unsigned int val;
-	int ret;
-
-	/* if read only, just return current value */
-	if (div->flags & CLK_DIVIDER_READ_ONLY) {
-		ret = regmap_read(clk->map, div->offset, &val);
-		if (ret)
-			return ret;
-
-		val >>= div->shift;
-		val &= clk_div_mask(div->width);
-
-		return divider_ro_determine_rate(hw, req, div->table,
-						 div->width, div->flags, val);
-	}
 
 	return divider_determine_rate(hw, req, div->table, div->width,
 				      div->flags);
@@ -127,9 +112,28 @@ const struct clk_ops clk_regmap_divider_ops = {
 };
 EXPORT_SYMBOL_NS_GPL(clk_regmap_divider_ops, CLK_MESON);
 
+static int clk_regmap_div_ro_determine_rate(struct clk_hw *hw,
+					    struct clk_rate_request *req)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(clk->map, div->offset, &val);
+	if (ret)
+		return ret;
+
+	val >>= div->shift;
+	val &= clk_div_mask(div->width);
+
+	return divider_ro_determine_rate(hw, req, div->table, div->width,
+					 div->flags, val);
+}
+
 const struct clk_ops clk_regmap_divider_ro_ops = {
 	.recalc_rate = clk_regmap_div_recalc_rate,
-	.determine_rate = clk_regmap_div_determine_rate,
+	.determine_rate = clk_regmap_div_ro_determine_rate,
 };
 EXPORT_SYMBOL_NS_GPL(clk_regmap_divider_ro_ops, CLK_MESON);
 

---
base-commit: 664988eb47dd2d6ae1d9e4188ec91832562f8f26
change-id: 20241111-fix_childclk_of_roclk_has_been_tampered_with-61dbcc623746

Best regards,
-- 
Chuan Liu <chuan.liu@...ogic.com>