boards: nucleo_h755zi_q: add CAN support on M7

Add CAN support by configuring fdcan1 in the device tree for the M7
core. As with other H7xx boards, it will be clocked by pll2 which is
also turned on.

Updated documentation.

Tested on nucleo_h755zi_q board.

Signed-off-by: Martin Thiede <[email protected]>

Author: mthiede-acn2

boards/st/nucleo_h755zi_q/doc/index.rst

@@ -93,6 +93,7 @@ and a ST morpho connector. Board is configured as follows:
 - LD2 : PE1
 - LD3 : PB14
 - I2C : PB8, PB9
+- CAN/CANFD : PD0, PD1
 
 System Clock
 ------------
@@ -107,6 +108,11 @@ Serial Port
 Nucleo H755ZI-Q board has 4 UARTs and 4 USARTs. The Zephyr console output is
 assigned to USART3. Default settings are 115200 8N1.
 
+CAN, CANFD
+----------
+
+Requires an external CAN or CANFD transceiver.
+
 Resources sharing
 -----------------
 

boards/st/nucleo_h755zi_q/nucleo_h755zi_q_stm32h755xx_m7.dts

@@ -26,6 +26,7 @@
 		zephyr,dtcm = &dtcm;
 		zephyr,sram = &sram0;
 		zephyr,flash = &flash0;
+		zephyr,canbus = &fdcan1;
 	};
 
 	pwmleds {
@@ -68,6 +69,24 @@
 	status = "okay";
 };
 
+&pll2 {
+	div-m = <4>;
+	mul-n = <120>;
+	div-p = <2>;
+	div-q = <3>; /* gives 80MHz to the FDCAN */
+	div-r = <2>;
+	clocks = <&clk_hse>;
+	status = "okay";
+};
+
+&fdcan1 {
+	clocks = <&rcc STM32_CLOCK_BUS_APB1_2 0x00000100>,
+		 <&rcc STM32_SRC_PLL2_Q FDCAN_SEL(2)>;
+	pinctrl-0 = <&fdcan1_rx_pd0 &fdcan1_tx_pd1>;
+	pinctrl-names = "default";
+	status = "okay";
+};
+
 &rcc {
 	clocks = <&pll>;
 	clock-frequency = <DT_FREQ_M(480)>;

boards/st/nucleo_h755zi_q/nucleo_h755zi_q_stm32h755xx_m7.yaml

@@ -17,4 +17,5 @@ supported:
   - pwm
   - netif:eth
   - usb_device
+  - can
 vendor: st