/**
 * bitmap_from_u64 - Check and swap words within u64.
 *  @mask: source bitmap
 *  @dst:  destination bitmap
 *
 * In 32-bit Big Endian kernel, when using ``(u32 *)(&val)[*]``
 * to read u64 mask, we will get the wrong word.
 * That is ``(u32 *)(&val)[0]`` gets the upper 32 bits,
 * but we expect the lower 32-bits of u64.
 */
static inline void bitmap_from_u64(unsigned long *dst, u64 mask)
{
        dst[0] = mask & ULONG_MAX;

        if (sizeof(mask) > sizeof(unsigned long))
                dst[1] = mask >> 32;
}

/*
 * Bitmap.
 *
 * (C) 2019.06.10 <buddy.zhang@aliyun.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/init.h>

/* header of bitmap */
#include <linux/bitmap.h>

static __init int bitmap_demo_init(void)
{

	unsigned long bitmap[2] = {0};
	u64 map = 0x123456789abcdef;

	/* Cover u64 to bitmap */
	bitmap_from_u64(bitmap, map);
	printk("%#llx cover to [0]%#lx [1]%#lx\n", map,
						bitmap[0], bitmap[1]);

	return 0;
}
device_initcall(bitmap_demo_init);

diff --git a/drivers/BiscuitOS/Kconfig b/drivers/BiscuitOS/Kconfig
index 4edc5a5..1a9abee 100644
--- a/drivers/BiscuitOS/Kconfig
+++ b/drivers/BiscuitOS/Kconfig
@@ -6,4 +6,14 @@ if BISCUITOS_DRV
config BISCUITOS_MISC
        bool "BiscuitOS misc driver"
+config BISCUITOS_BITMAP
+       bool "bitmap"
+
+if BISCUITOS_BITMAP
+
+config DEBUG_BISCUITOS_BITMAP
+       bool "bitmap_from_u64"
+
+endif # BISCUITOS_BITMAP
+
endif # BISCUITOS_DRV

diff --git a/drivers/BiscuitOS/Makefile b/drivers/BiscuitOS/Makefile
index 82004c9..9909149 100644
--- a/drivers/BiscuitOS/Makefile
+++ b/drivers/BiscuitOS/Makefile
@@ -1 +1,2 @@
obj-$(CONFIG_BISCUITOS_MISC)     += BiscuitOS_drv.o
+obj-$(CONFIG_BISCUITOS_BITMAP)     += bitmap.o
--

Device Driver--->
    [*]BiscuitOS Driver--->
        [*]bitmap
            [*]bitmap_from_u64()

usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
0x123456789abcdef cover to [0]0x89abcdef [1]0x1234567
aaci-pl041 10004000.aaci: ARM AC'97 Interface PL041 rev0 at 0x10004000, irq 24
aaci-pl041 10004000.aaci: FIFO 512 entries
oprofile: using arm/armv7-ca9