linux-kernel - [PATCH v2 3/4] clk: spacemit: introduce factor for div clock

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Message-Id: <20250811-k1-clk-i2s-generation-v2-3-e4d3ec268b7a@linux.spacemit.com>
Date: Mon, 11 Aug 2025 22:04:29 +0800
From: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
To: Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Yixun Lan <dlan@...too.org>, 
 Alex Elder <elder@...cstar.com>, Haylen Chu <heylenay@....org>, 
 Inochi Amaoto <inochiama@...look.com>
Cc: linux-clk@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, Jinmei Wei <weijinmei@...ux.spacemit.com>, 
 Troy Mitchell <troy.mitchell@...ux.spacemit.com>
Subject: [PATCH v2 3/4] clk: spacemit: introduce factor for div clock

>From the definition of register, The i2s_bclk is a non-linear,
discrete divider clock.

The following table shows the correspondence between index
and frequency division coefficients:

| index |  div  |
|-------|-------|
|   0   |   2   |
|   1   |   4   |
|   2   |   6   |
|   3   |   8   |

But from a software perspective and this table, dividing the
actual div value by 2 is sufficient to obtain a continuous
divider clock.

Rather than introducing a new clock type to handle this case,
a factor parameter has been added to CCU_DIV_GATE_DEFINE.

Suggested-by: Haylen Chu <heylenay@....org>
Signed-off-by: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
---
 drivers/clk/spacemit/ccu_mix.c | 7 ++++++-
 drivers/clk/spacemit/ccu_mix.h | 4 +++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/spacemit/ccu_mix.c b/drivers/clk/spacemit/ccu_mix.c
index 9b852aa61f78aed5256bfe6fc3b01932d6db6256..dbd2cf234bf81d8e110b19868ff9af7373e2ab55 100644
--- a/drivers/clk/spacemit/ccu_mix.c
+++ b/drivers/clk/spacemit/ccu_mix.c
@@ -56,7 +56,10 @@ static unsigned long ccu_div_recalc_rate(struct clk_hw *hw,
 	val = ccu_read(&mix->common, ctrl) >> div->shift;
 	val &= (1 << div->width) - 1;
 
-	return divider_recalc_rate(hw, parent_rate, val, NULL, 0, div->width);
+	if (!div->factor)
+		return divider_recalc_rate(hw, parent_rate, val, NULL, 0, div->width);
+
+	return divider_recalc_rate(hw, parent_rate, val, NULL, 0, div->width) / div->factor;
 }
 
 /*
@@ -115,6 +118,8 @@ ccu_mix_calc_best_rate(struct clk_hw *hw, unsigned long rate,
 
 		for (int j = 1; j <= div_max; j++) {
 			unsigned long tmp = DIV_ROUND_CLOSEST_ULL(parent_rate, j);
+			if (mix->div.factor)
+				tmp /= mix->div.factor;
 
 			if (abs(tmp - rate) < abs(best_rate - rate)) {
 				best_rate = tmp;
diff --git a/drivers/clk/spacemit/ccu_mix.h b/drivers/clk/spacemit/ccu_mix.h
index 54d40cd39b2752260f57d2a96eb8d3eed8116ecd..7dd00d24ec4b1dab70663b9cb7b9ebb02abeaecb 100644
--- a/drivers/clk/spacemit/ccu_mix.h
+++ b/drivers/clk/spacemit/ccu_mix.h
@@ -34,6 +34,7 @@ struct ccu_mux_config {
 struct ccu_div_config {
 	u8 shift;
 	u8 width;
+	unsigned int factor;
 };
 
 struct ccu_mix {
@@ -130,10 +131,11 @@ static struct ccu_mix _name = {							\
 }
 
 #define CCU_DIV_GATE_DEFINE(_name, _parent, _reg_ctrl, _shift, _width,		\
-			    _mask_gate,	_flags)					\
+			    _mask_gate,	_factor, _flags)			\
 static struct ccu_mix _name = {							\
 	.gate	= CCU_GATE_INIT(_mask_gate),					\
 	.div	= CCU_DIV_INIT(_shift, _width),					\
+	.div.factor = _factor,						\
 	.common = {								\
 		.reg_ctrl	= _reg_ctrl,					\
 		CCU_MIX_INITHW(_name, _parent, spacemit_ccu_div_gate_ops,	\

-- 
2.50.1