linux-kernel - [PATCH v3 3/3] clk: spacemit: fix i2s clock

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Message-Id: <20250818-k1-clk-i2s-generation-v3-3-8139b22ae709@linux.spacemit.com>
Date: Mon, 18 Aug 2025 17:28:22 +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 v3 3/3] clk: spacemit: fix i2s clock

Defining i2s_bclk and i2s_sysclk as fixed-rate clocks is insufficient
for real I2S use cases.

Moreover, the current I2S clock configuration does not work as expected
due to missing parent clocks.

This patch adds the missing parent clocks, defines i2s_sysclk as
a DDN clock, and i2s_bclk as a DIV clock.

A special note for i2s_bclk:

>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   |
|   2   |   8   |

>From a software perspective, introducing i2s_bclk_factor as the
parent of i2s_bclk is sufficient to address the issue.

The I2S-related clock registers can be found here [1].

Link:
https://developer.spacemit.com/documentation?token=LCrKwWDasiJuROkVNusc2pWTnEb
[1]

Fixes: 1b72c59db0add ("clk: spacemit: Add clock support for SpacemiT K1 SoC")
Co-developer: Jinmei Wei <weijinmei@...ux.spacemit.com>
Suggested-by: Haylen Chu <heylenay@....org>
Signed-off-by: Jinmei Wei <weijinmei@...ux.spacemit.com>
Signed-off-by: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
---
 drivers/clk/spacemit/ccu-k1.c    | 29 +++++++++++++++++++++++++++--
 drivers/clk/spacemit/ccu_mix.h   |  2 +-
 include/soc/spacemit/k1-syscon.h |  1 +
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
index 7155824673fb450971439873b6b6163faf48c7e5..b2c426b629a37a9901bbced26fc55c5f1b34eba5 100644
--- a/drivers/clk/spacemit/ccu-k1.c
+++ b/drivers/clk/spacemit/ccu-k1.c
@@ -141,8 +141,29 @@ CCU_DDN_DEFINE(slow_uart2_48, pll1_d4_614p4, MPMU_SUCCR_1, 16, 13, 0, 13, 2, 0);
 
 CCU_GATE_DEFINE(wdt_clk, CCU_PARENT_HW(pll1_d96_25p6), MPMU_WDTPCR, BIT(1), 0);
 
-CCU_FACTOR_GATE_DEFINE(i2s_sysclk, CCU_PARENT_HW(pll1_d16_153p6), MPMU_ISCCR, BIT(31), 50, 1);
-CCU_FACTOR_GATE_DEFINE(i2s_bclk, CCU_PARENT_HW(i2s_sysclk), MPMU_ISCCR, BIT(29), 1, 1);
+CCU_FACTOR_DEFINE(i2s_153p6, CCU_PARENT_HW(pll1_d8_307p2), 2, 1);
+
+static const struct clk_parent_data i2s_153p6_base_parents[] = {
+	CCU_PARENT_HW(i2s_153p6),
+	CCU_PARENT_HW(pll1_d8_307p2),
+};
+CCU_MUX_DEFINE(i2s_153p6_base, i2s_153p6_base_parents, MPMU_FCCR, 29, 1, 0);
+
+static const struct clk_parent_data i2s_sysclk_src_parents[] = {
+	CCU_PARENT_HW(pll1_d96_25p6),
+	CCU_PARENT_HW(i2s_153p6_base)
+};
+CCU_MUX_GATE_DEFINE(i2s_sysclk_src, i2s_sysclk_src_parents, MPMU_ISCCR, 30, 1, BIT(31), 0);
+
+CCU_DDN_DEFINE(i2s_sysclk, i2s_sysclk_src, MPMU_ISCCR, 0, 15, 15, 12, 1, 0);
+
+CCU_FACTOR_DEFINE(i2s_bclk_factor, CCU_PARENT_HW(i2s_sysclk), 2, 1);
+/*
+ * i2s_bclk is a non-linear discrete divider clock.
+ * Using i2s_bclk_factor as its parent simplifies software handling
+ * and avoids dealing with the non-linear division directly.
+ */
+CCU_DIV_GATE_DEFINE(i2s_bclk, CCU_PARENT_HW(i2s_bclk_factor), MPMU_ISCCR, 27, 2, BIT(29), 0);
 
 static const struct clk_parent_data apb_parents[] = {
 	CCU_PARENT_HW(pll1_d96_25p6),
@@ -756,6 +777,10 @@ static struct clk_hw *k1_ccu_mpmu_hws[] = {
 	[CLK_I2S_BCLK]		= &i2s_bclk.common.hw,
 	[CLK_APB]		= &apb_clk.common.hw,
 	[CLK_WDT_BUS]		= &wdt_bus_clk.common.hw,
+	[CLK_I2S_153P6]		= &i2s_153p6.common.hw,
+	[CLK_I2S_153P6_BASE]	= &i2s_153p6_base.common.hw,
+	[CLK_I2S_SYSCLK_SRC]	= &i2s_sysclk_src.common.hw,
+	[CLK_I2S_BCLK_FACTOR]	= &i2s_bclk_factor.common.hw,
 };
 
 static const struct spacemit_ccu_data k1_ccu_mpmu_data = {
diff --git a/drivers/clk/spacemit/ccu_mix.h b/drivers/clk/spacemit/ccu_mix.h
index 54d40cd39b2752260f57d2a96eb8d3eed8116ecd..5b5c3bb958167a68736587e9097a1ca6f94d22fa 100644
--- a/drivers/clk/spacemit/ccu_mix.h
+++ b/drivers/clk/spacemit/ccu_mix.h
@@ -130,7 +130,7 @@ static struct ccu_mix _name = {							\
 }
 
 #define CCU_DIV_GATE_DEFINE(_name, _parent, _reg_ctrl, _shift, _width,		\
-			    _mask_gate,	_flags)					\
+			    _mask_gate, _flags)			\
 static struct ccu_mix _name = {							\
 	.gate	= CCU_GATE_INIT(_mask_gate),					\
 	.div	= CCU_DIV_INIT(_shift, _width),					\
diff --git a/include/soc/spacemit/k1-syscon.h b/include/soc/spacemit/k1-syscon.h
index c59bd7a38e5b4219121341b9c0d9ffda13a9c3e2..354751562c55523ef8a22be931ddd8aca9651084 100644
--- a/include/soc/spacemit/k1-syscon.h
+++ b/include/soc/spacemit/k1-syscon.h
@@ -30,6 +30,7 @@ to_spacemit_ccu_adev(struct auxiliary_device *adev)
 
 /* MPMU register offset */
 #define MPMU_POSR			0x0010
+#define MPMU_FCCR			0x0008
 #define  POSR_PLL1_LOCK			BIT(27)
 #define  POSR_PLL2_LOCK			BIT(28)
 #define  POSR_PLL3_LOCK			BIT(29)

-- 
2.50.1