spi: Get basic SPI commands working

spi.c

@@ -0,0 +1,36 @@
+#include <stdint.h>
+#include <string.h>
+#include "printf.h"
+#include "bionic.h"
+#include "memio.h"
+#include "spi.h"
+#include "fernvale-spi.h"
+#include "scriptic.h"
+
+static void spi_init(void)
+{
+	static int spi_initted = 0;
+
+	if (spi_initted)
+		return;
+
+	spi_initted = 1;
+	scriptic_run("spi_init");
+}
+
+int spi_cmd_txrx(uint8_t tx_size, uint8_t rx_size,
+		 uint8_t *tx_buf, uint8_t *rx_buf)
+{
+	spi_init();
+
+	_memcpy(SPI_DATA, tx_buf, tx_size);
+
+	writel(tx_size, SPI_WRITE_COUNT);
+	writel(rx_size, SPI_READ_COUNT);
+
+	scriptic_run("spi_run");
+
+	_memcpy(rx_buf, SPI_DATA + tx_size, rx_size);
+
+	return 0;
+}