linux-kernel - [PATCH v3 1/3] clk: samsung: introduce nMUX for MUX clks that can reparented

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Date: Thu, 28 Mar 2024 12:34:38 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: peter.griffin@...aro.org,
	krzysztof.kozlowski@...aro.org
Cc: alim.akhtar@...sung.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	andre.draszik@...aro.org,
	willmcvicker@...gle.com,
	kernel-team@...roid.com,
	s.nawrocki@...sung.com,
	cw00.choi@...sung.com,
	mturquette@...libre.com,
	sboyd@...nel.org,
	semen.protsenko@...aro.org,
	linux-clk@...r.kernel.org,
	jaewon02.kim@...sung.com,
	Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH v3 1/3] clk: samsung: introduce nMUX for MUX clks that can reparented

All samsung MUX clocks that are defined with MUX() set the
CLK_SET_RATE_NO_REPARENT flag in __MUX(), which prevents MUXes to be
reparented during clk_set_rate().

Introduce nMUX() for MUX clocks that can be reparented on clock rate
change. "nMUX" comes from "n-to-1 selector", hopefully emphasising that
the selector can change on clock rate changes. Ideally MUX/MUX_F()
should change to not have the CLK_SET_RATE_NO_REPARENT flag set by
default, and all their users to be updated to add the flag back
(like in the case of DIV and GATE). But this is a very intrusive change
and because for now only GS101 allows MUX reparenting on clock rate
change, stick with nMUX().

One user of nMUX() will be GS101. GS101 defines MUX clocks that
are dedicated for each instance of an IP (see MUX USI). The reparenting
of these MUX clocks will not affect other instances of the same IP or
different IPs altogether.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
 drivers/clk/samsung/clk.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/samsung/clk.h b/drivers/clk/samsung/clk.h
index a70bd7cce39f..fb06caa71f0a 100644
--- a/drivers/clk/samsung/clk.h
+++ b/drivers/clk/samsung/clk.h
@@ -133,7 +133,7 @@ struct samsung_mux_clock {
 		.name		= cname,			\
 		.parent_names	= pnames,			\
 		.num_parents	= ARRAY_SIZE(pnames),		\
-		.flags		= (f) | CLK_SET_RATE_NO_REPARENT, \
+		.flags		= f,				\
 		.offset		= o,				\
 		.shift		= s,				\
 		.width		= w,				\
@@ -141,9 +141,16 @@ struct samsung_mux_clock {
 	}

 #define MUX(_id, cname, pnames, o, s, w)			\
-	__MUX(_id, cname, pnames, o, s, w, 0, 0)
+	__MUX(_id, cname, pnames, o, s, w, CLK_SET_RATE_NO_REPARENT, 0)

 #define MUX_F(_id, cname, pnames, o, s, w, f, mf)		\
+	__MUX(_id, cname, pnames, o, s, w, (f) | CLK_SET_RATE_NO_REPARENT, mf)
+
+/* Used by MUX clocks where reparenting on clock rate change is allowed. */
+#define nMUX(_id, cname, pnames, o, s, w)			\
+	__MUX(_id, cname, pnames, o, s, w, 0, 0)
+
+#define nMUX_F(_id, cname, pnames, o, s, w, f, mf)		\
 	__MUX(_id, cname, pnames, o, s, w, f, mf)

 /**
-- 
2.44.0.396.g6e790dbe36-goog