Rework SPI device interface

include/sta/spi_device.hpp

@@ -4,6 +4,7 @@
 #ifndef STA_SPI_DEVICE_HPP
 #define STA_SPI_DEVICE_HPP
 
+#include <sta/intf/gpio_pin.hpp>
 #include <sta/intf/spi_interface.hpp>
 
 #include <cstddef>
@@ -20,8 +21,9 @@ namespace sta
 	public:
 		/**
 		 * @param intf  SPI hardware interface
+		 * @param pin   Chip select pin
 		 */
-		SpiDevice(SpiInterface * intf);
+		SpiDevice(SpiInterface * intf, GpioPin * csPin);
 
 
 		/**
@@ -94,14 +96,15 @@ namespace sta
 		/**
 		 * @brief Activate device via CS pin.
 		 */
-		virtual void select() = 0;
+		void select();
 		/**
 		 * @brief Deactivate device via CS pin.
 		 */
-		virtual void deselect() = 0;
+		void deselect();
 
 	private:
 		SpiInterface * intf_;   /**< SPI hardware interface */
+		GpioPin *      csPin_;  /**< Chip select pin */
 	};
 } // namespace sta