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 register definition, the i2s_bclk divider always implies
an additional 1/2 factor.

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

| index | div |
|-------|-------|
| 0 | 2 |
| 1 | 4 |
| 2 | 6 |
| 3 | 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 <[e-mail]>
Suggested-by: Haylen Chu <[e-mail]>
Signed-off-by: Jinmei Wei <[e-mail]>
Signed-off-by: Troy Mitchell <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/spacemit/ccu-k1.c

···
 
 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);
+/*
+ * Divider of i2s_bclk always implies a 1/2 factor, which is
+ * described by i2s_bclk_factor.
+ */
+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),
···
 	[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 = {

include/soc/spacemit/k1-syscon.h

···
 
 /* 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)