imxrt:app: Support ramfs for imxrt1052-nxp-evk

Add ramfs (8MB size) support for imxrt1052-nxp-evk board.
Signed-off-by: NGavin Liu <gavin-liugang@outlook.com>

bsp/imxrt/imxrt1052-nxp-evk/applications/mnt.c

+/*
+ * Copyright (c) 2019, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2019-09-19     Gavin        first version
+ *
+ */
+
+#include <rtthread.h>
+#ifdef RT_USING_DFS_RAMFS
+#include <dfs_fs.h>
+
+extern struct dfs_ramfs *dfs_ramfs_create(rt_uint8_t *pool, rt_size_t size);
+
+int mnt_init(void)
+{
+	rt_uint8_t *pool = RT_NULL;
+	rt_size_t size = 8*1024*1024;
+
+	pool = rt_malloc(size);
+	if (pool == RT_NULL)
+		return 0;
+
+	if (dfs_mount(RT_NULL, "/", "ram", 0, (const void *)dfs_ramfs_create(pool, size)) == 0)
+		rt_kprintf("RAM file system initializated!\n");
+	else
+		rt_kprintf("RAM file system initializate failed!\n");
+
+	return 0;
+}
+INIT_ENV_EXPORT(mnt_init);
+#endif