add spi driver

Signed-off-by: liangkangnan <liangkangnan@163.com>

tests/example/include/spi.h

@@ -0,0 +1,18 @@
+#ifndef _SPI_H_
+#define _SPI_H_
+
+#define SPI_BASE      (0x50000000)
+#define SPI_CTRL      (SPI_BASE + (0x00))
+#define SPI_DATA      (SPI_BASE + (0x04))
+#define SPI_STATUS    (SPI_BASE + (0x08))
+
+#define SPI_REG(addr) (*((volatile uint32_t *)addr))
+
+void spi_init();
+void spi_set_ss(uint8_t level);
+void spi_write_byte(uint8_t data);
+void spi_write_bytes(uint8_t data[], uint32_t len);
+uint8_t spi_read_byte();
+void spi_read_bytes(uint8_t data[], uint32_t len);
+
+#endif

tests/example/lib/spi.c

@@ -0,0 +1,51 @@
+#include <stdint.h>
+
+#include "../include/spi.h"
+
+
+void spi_init()
+{
+    SPI_REG(SPI_CTRL) = 0x06;              // CPOL = 1, CPHA = 1
+}
+
+void spi_set_ss(uint8_t level)
+{
+    if (!level)
+        SPI_REG(SPI_CTRL) |= 1 << 3;
+    else
+        SPI_REG(SPI_CTRL) &= ~(1 << 3);
+}
+
+void spi_write_byte(uint8_t data)
+{
+    SPI_REG(SPI_DATA) = data;
+    SPI_REG(SPI_CTRL) |= 1 << 0;           // start
+    while (SPI_REG(SPI_STATUS) & 0x1);     // wait transfer complete
+}
+
+void spi_write_bytes(uint8_t data[], uint32_t len)
+{
+    uint32_t i;
+
+    for (i = 0; i < len; i++)
+        spi_write_byte(data[i]);
+}
+
+uint8_t spi_read_byte()
+{
+    uint8_t data;
+
+    SPI_REG(SPI_CTRL) |= 1 << 0;           // start
+    while (SPI_REG(SPI_STATUS) & 0x1);     // wait transfer complete
+    data = SPI_REG(SPI_DATA) & 0xff;       // readback data
+
+    return data;
+}
+
+void spi_read_bytes(uint8_t data[], uint32_t len)
+{
+    uint32_t i;
+
+    for (i = 0; i < len; i++)
+        data[i] = spi_read_byte();
+}