drivers: can: sam: use UPLL clock instead of PLLA clock

drivers/can/Kconfig.sam

@@ -8,15 +8,3 @@ config CAN_SAM
 	bool "Atmel SAM CAN driver"
 	default $(dt_compat_enabled,$(DT_COMPAT_ATMEL_SAM_CAN))
 	select CAN_MCAN
-
-if CAN_SAM
-
-config CAN_SAM_CKDIV
-	int "Clock divider"
-	range 0 255
-	default 0
-	depends on CAN_SAM
-	help
-	  Clock divider for the MCAN core clock.
-
-endif #CAN_SAM

drivers/can/can_sam.c

@@ -21,6 +21,7 @@ struct can_sam_config {
 	void (*config_irq)(void);
 	const struct pinctrl_dev_config *pcfg;
 	uint8_t pmc_id;
+	int divider;
 };
 
 struct can_sam_data {
@@ -29,18 +30,20 @@ struct can_sam_data {
 
 static int can_sam_get_core_clock(const struct device *dev, uint32_t *rate)
 {
-	ARG_UNUSED(dev);
+	const struct can_mcan_config *mcan_cfg = dev->config;
+	const struct can_sam_config *sam_cfg = mcan_cfg->custom;
 
-	*rate = SOC_ATMEL_SAM_MCK_FREQ_HZ / (CONFIG_CAN_SAM_CKDIV + 1);
+	*rate = SOC_ATMEL_SAM_UPLLCK_FREQ_HZ / (sam_cfg->divider);
 
 	return 0;
 }
 
-static void can_sam_clock_enable(const struct can_sam_config *cfg)
+static void can_sam_clock_enable(const struct can_sam_config *sam_cfg)
 {
-	REG_PMC_PCK5 = PMC_PCK_CSS_PLLA_CLK | PMC_PCK_PRES(CONFIG_CAN_SAM_CKDIV);
+	REG_PMC_PCK5 = PMC_PCK_CSS_UPLL_CLK | PMC_PCK_PRES(sam_cfg->divider - 1);
 	PMC->PMC_SCER |= PMC_SCER_PCK5;
-	soc_pmc_peripheral_enable(cfg->pmc_id);
+
+	soc_pmc_peripheral_enable(sam_cfg->pmc_id);
 }
 
 static int can_sam_init(const struct device *dev)
@@ -129,6 +132,7 @@ static void config_can_##inst##_irq(void)
 #define CAN_SAM_CFG_INST(inst)						\
 	static const struct can_sam_config can_sam_cfg_##inst = {	\
 		.pmc_id = DT_INST_PROP(inst, peripheral_id),		\
+		.divider = DT_INST_PROP(inst, divider),			\
 		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(inst),		\
 		.config_irq = config_can_##inst##_irq,			\
 	};								\

dts/arm/atmel/same70.dtsi

@@ -438,13 +438,12 @@
 
 			can0: can@40030000 {
 				compatible = "atmel,sam-can";
-				#address-cells = <1>;
-				#size-cells = <0>;
 				reg = <0x40030000 0x100>;
 				reg-names = "m_can";
 				interrupts = <35 0>, <36 0>;
 				interrupt-names = "LINE_0", "LINE_1";
 				peripheral-id = <35>;
+				divider = <6>;
 				sjw = <1>;
 				sample-point = <875>;
 				sjw-data = <1>;
@@ -455,13 +454,12 @@
 
 			can1: can@40034000 {
 				compatible = "atmel,sam-can";
-				#address-cells = <1>;
-				#size-cells = <0>;
 				reg = <0x40034000 0x100>;
 				reg-names = "m_can";
 				interrupts = <37 0>, <38 0>;
 				interrupt-names = "LINE_0", "LINE_1";
 				peripheral-id = <37>;
+				divider = <6>;
 				sjw = <1>;
 				sample-point = <875>;
 				sjw-data = <1>;

dts/bindings/can/atmel,sam-can.yaml

@@ -17,3 +17,12 @@ properties:
       type: int
       required: true
       description: peripheral ID
+
+    divider:
+      type: int
+      required: true
+      enum:
+        - 6
+        - 12
+        - 24
+      description: Clock divider for the CAN core clock

soc/arm/atmel_sam/same70/soc.c

@@ -177,6 +177,14 @@ static ALWAYS_INLINE void clock_init(void)
 		;
 	}
 
+	/* Setup UPLL */
+	PMC->CKGR_UCKR = CKGR_UCKR_UPLLCOUNT(0x3Fu) | CKGR_UCKR_UPLLEN;
+
+	/* Wait for PLL lock */
+	while (!(PMC->PMC_SR & PMC_SR_LOCKU)) {
+		;
+	}
+
 	/*
 	 * Final setup of the Master Clock
 	 */

soc/arm/atmel_sam/same70/soc.h

@@ -73,6 +73,9 @@
 #define SOC_ATMEL_SAM_MCK_FREQ_HZ \
 	(SOC_ATMEL_SAM_HCLK_FREQ_HZ / CONFIG_SOC_ATMEL_SAME70_MDIV)
 
+/** UTMI PLL clock (UPLLCK) Frequency */
+#define SOC_ATMEL_SAM_UPLLCK_FREQ_HZ MHZ(480)
+
 #endif /* _ASMLANGUAGE */
 
 #endif /* _ATMEL_SAME70_SOC_H_ */

soc/arm/atmel_sam/samv71/soc.c

@@ -178,6 +178,14 @@ static ALWAYS_INLINE void clock_init(void)
 		;
 	}
 
+	/* Setup UPLL */
+	PMC->CKGR_UCKR = CKGR_UCKR_UPLLCOUNT(0x3Fu) | CKGR_UCKR_UPLLEN;
+
+	/* Wait for PLL lock */
+	while (!(PMC->PMC_SR & PMC_SR_LOCKU)) {
+		;
+	}
+
 	/*
 	 * Final setup of the Master Clock
 	 */

soc/arm/atmel_sam/samv71/soc.h

@@ -74,6 +74,9 @@
 #define SOC_ATMEL_SAM_MCK_FREQ_HZ \
 	(SOC_ATMEL_SAM_HCLK_FREQ_HZ / CONFIG_SOC_ATMEL_SAMV71_MDIV)
 
+/** UTMI PLL clock (UPLLCK) Frequency */
+#define SOC_ATMEL_SAM_UPLLCK_FREQ_HZ MHZ(480)
+
 #endif /* _ASMLANGUAGE */
 
 #include "pwm_fixup.h"