boards: arm: nucleo_f756zg: Added SPI support

Added support for SPI 1 available from the arduino connector (plus an
extra gpio). Tested against samples/sensor/bme280.

Added warnings in documentation, pinmux and dts highlighting a potential
conflict if using SPI_1 and on-board ethernet at the same time.

Signed-off-by: AJ Palmer <ajpcode@hotmail.com>

boards/arm/nucleo_f756zg/Kconfig.defconfig

@@ -51,4 +51,11 @@ config PWM_STM32_1
 
 endif # PWM
 
+if SPI
+
+config SPI_1
+	default y
+
+endif # SPI
+
 endif # BOARD_NUCLEO_F756ZG

boards/arm/nucleo_f756zg/doc/nucleof756zg.rst

@@ -112,6 +112,8 @@ features:
 +-----------+------------+-------------------------------------+
 | PWM       | on-chip    | pwm                                 |
 +-----------+------------+-------------------------------------+
+| SPI       | on-chip    | spi                                 |
++-----------+------------+-------------------------------------+
 
 Other hardware features are not yet supported on this Zephyr port.
 
@@ -138,6 +140,10 @@ and a ST morpho connector. Board is configured as follows:
 - USB DP : PA12
 - I2C : PB8, PB9
 - PWM : PE13
+- SPI : PA4, PA5, PA6, PA7
+
+Note. The Arduino Uno v3 specified SPI device conflicts with the on-board ETH
+device on pin PA7.
 
 System Clock
 ------------

boards/arm/nucleo_f756zg/nucleo_f756zg.dts

@@ -52,6 +52,7 @@
 
 arduino_serial: &usart6 {};
 arduino_i2c: &i2c1 {};
+arduino_spi: &spi1 {};
 
 &usart2 {
 	current-speed = <115200>;
@@ -90,3 +91,11 @@ arduino_i2c: &i2c1 {};
 		status = "ok";
 	};
 };
+
+&spi1 {
+	/*
+	 * WARNING: The pin PA7 will conflict on selection of SPI_1 and
+	 *          ETH_STM32_HAL. See pinmux.c for further details.
+	 */
+	status = "ok";
+};

boards/arm/nucleo_f756zg/nucleo_f756zg.yaml

@@ -14,3 +14,4 @@ supported:
   - usb_device
   - i2c
   - pwm
+  - spi

boards/arm/nucleo_f756zg/pinmux.c

@@ -12,7 +12,13 @@
 
 #include <pinmux/stm32/pinmux_stm32.h>
 
-/* NUCLEO-F756ZG pin configurations  */
+/* NUCLEO-F756ZG pin configurations
+ *
+ * WARNING: The pin PA7 will conflict on selection of SPI_1 and ETH_STM32_HAL.
+ *          If you require both peripherals, and you do not need Arduino Uno v3
+ *          comaptability, the pin PB5 (also on ST Zio connector) can be used
+ *          for the SPI_1 MOSI signal.
+ */
 static const struct pin_config pinconf[] = {
 #ifdef CONFIG_UART_2
 	{ STM32_PIN_PD5, STM32F7_PINMUX_FUNC_PD5_USART2_TX },
@@ -50,6 +56,12 @@ static const struct pin_config pinconf[] = {
 #ifdef CONFIG_PWM_STM32_1
 	{ STM32_PIN_PE13, STM32F7_PINMUX_FUNC_PE13_PWM1_CH3 },
 #endif /* CONFIG_PWM_STM32_1 */
+#ifdef CONFIG_SPI_1
+	{ STM32_PIN_PA4, STM32F7_PINMUX_FUNC_PA4_SPI1_NSS },
+	{ STM32_PIN_PA5, STM32F7_PINMUX_FUNC_PA5_SPI1_SCK },
+	{ STM32_PIN_PA6, STM32F7_PINMUX_FUNC_PA6_SPI1_MISO },
+	{ STM32_PIN_PA7, STM32F7_PINMUX_FUNC_PA7_SPI1_MOSI },
+#endif	/* CONFIG_SPI_1 */
 };
 
 static int pinmux_stm32_init(struct device *port)