drivers: i2s: stm32 sai add mclk-divider property

This property enables the user to configure the Master Clock Divider.

Signed-off-by: Mario Paja <mariopaja@hotmail.com>

Author: mariopaja

drivers/i2s/i2s_stm32_sai.c

@@ -25,6 +25,12 @@
 #include <zephyr/irq.h>
 LOG_MODULE_REGISTER(i2s_stm32_sai, CONFIG_I2S_LOG_LEVEL);
 
+enum mclk_divider {
+	MCLK_NO_DIV,
+	MCLK_DIV_256,
+	MCLK_DIV_512
+};
+
 struct queue_item {
 	void *buffer;
 	size_t size;
@@ -66,8 +72,8 @@ struct i2s_stm32_sai_cfg {
 	size_t pclk_len;
 	const struct pinctrl_dev_config *pcfg;
 
-	bool mclk_div_enable;
 	bool mclk_enable;
+	enum mclk_divider mclk_div;
 	bool synchronous;
 };
 
@@ -427,10 +433,15 @@ static int i2s_stm32_sai_configure(const struct device *dev, enum i2s_dir dir,
 		hsai->Init.MckOutput = SAI_MCK_OUTPUT_DISABLE;
 	}
 
-	if (cfg->mclk_div_enable) {
-		hsai->Init.NoDivider = SAI_MASTERDIVIDER_ENABLE;
-	} else {
+	if (cfg->mclk_div == (enum mclk_divider)MCLK_NO_DIV) {
 		hsai->Init.NoDivider = SAI_MASTERDIVIDER_DISABLED;
+	} else {
+		hsai->Init.NoDivider = SAI_MASTERDIVIDER_ENABLE;
+		if (cfg->mclk_div == (enum mclk_divider)MCLK_DIV_256) {
+			hsai->Init.MckOverSampling = SAI_MCK_OVERSAMPLING_DISABLE;
+		} else {
+			hsai->Init.MckOverSampling = SAI_MCK_OVERSAMPLING_ENABLE;
+		}
 	}
 
 	/* AudioFrequency */
@@ -761,7 +772,6 @@ static DEVICE_API(i2s, i2s_stm32_driver_api) = {
 	.trigger = i2s_stm32_sai_trigger,
 	.write = i2s_stm32_sai_write,
 	.read = i2s_stm32_sai_read,
-
 };
 
 #define SAI_DMA_CHANNEL_INIT(index, dir, src_dev, dest_dev)                                        \
@@ -806,7 +816,7 @@ static DEVICE_API(i2s, i2s_stm32_driver_api) = {
 		.pclk_len = DT_INST_NUM_CLOCKS(index),                                             \
 		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(index),                                     \
 		.mclk_enable = DT_INST_PROP(index, mclk_enable),                                   \
-		.mclk_div_enable = DT_INST_PROP(index, mclk_div_enable),                           \
+		.mclk_div = (enum mclk_divider)DT_ENUM_IDX(DT_DRV_INST(index), mclk_divider),      \
 		.synchronous = DT_INST_PROP(index, synchronous),                                   \
 	};                                                                                         \
                                                                                                    \

dts/bindings/i2s/st,stm32-sai.yaml

@@ -25,18 +25,30 @@ properties:
   pinctrl-names:
     required: true
 
-  mclk-div-enable:
-    type: boolean
-    description: |
-      SAI NODIV property.
-      When property is not present, oversampling is enabled @ 256.
-
   mclk-enable:
     type: boolean
     description: |
       Master Clock Output function.
       An mck pin must be listed within pinctrl-0 when enabling this property.
 
+  mclk-divider:
+    type: string
+    default: "no-div"
+    description: |
+      Master Clock Divider Configuration.
+
+      When no-div property is present:
+      - MCKDIV = SAI_CK_x / (FS * (FRL + 1))
+      Otherwise:
+      - MCKDIV = SAI_CK_x / (FS * (OSR + 1) * 256)
+
+      When div-256 is present OSR is set to 0.
+      When div-512 is present OSR is set to 1.
+    enum:
+      - "no-div"
+      - "div-256"
+      - "div-512"
+
   synchronous:
     type: boolean
     description: |

samples/drivers/i2s/output/boards/nucleo_u575zi_q.overlay

@@ -28,6 +28,6 @@
 	pinctrl-names = "default";
 	status = "okay";
 	mclk-enable;
-	mclk-div-enable;
+	mclk-divider = "div-256";
 	dma-names = "tx";
 };