/**
 * atomic_add_negative - add and test if negative
 * @i: integer value to add
 * @v: pointer of type atomic_t
 *
 * Atomically adds @i to @v and returns true
 * if the result is negative, or false when
 * result is greater than or equal to zero.
 */
#ifndef atomic_add_negative
static inline bool atomic_add_negative(int i, atomic_t *v)
{
        return atomic_add_return(i, v) < 0;
}
#endif

/*
 * atomic
 *
 * (C) 2019.05.05 <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.
 */

/* Memory access
 *
 *
 *      +----------+
 *      |          |
 *      | Register |                                         +--------+
 *      |          |                                         |        |
 *      +----------+                                         |        |
 *            A                                              |        |
 *            |                                              |        |
 * +-----+    |      +----------+        +----------+        |        |
 * |     |<---o      |          |        |          |        |        |
 * | CPU |<--------->| L1 Cache |<------>| L2 Cache |<------>| Memory |
 * |     |<---o      |          |        |          |        |        |
 * +-----+    |      +----------+        +----------+        |        |
 *            |                                              |        |
 *            o--------------------------------------------->|        |
 *                         volatile/atomic                   |        |
 *                                                           |        |
 *                                                           +--------+
 */

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

static atomic_t BiscuitOS_counter = ATOMIC_INIT(-6);

/* atomic_* */
static __init int atomic_demo_init(void)
{
	/* Legacy data */
	printk("[0]Atomic: %d\n", atomic_read(&BiscuitOS_counter));

	if (atomic_add_negative(2, &BiscuitOS_counter))
		printk("Atomic is negative\n");
	else
		printk("Atomic is no negative\n");

	return 0;
}
device_initcall(atomic_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_ATOMIC
+       bool "atomic"
+
+if BISCUITOS_ATOMIC
+
+config DEBUG_BISCUITOS_ATOMIC
+       bool "atomic_add_negative"
+
+endif # BISCUITOS_ATOMIC
+
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_ATOMIC)  += atomic.o
--

Device Driver--->
    [*]BiscuitOS Driver--->
        [*]atomic
            [*]atomic_add_negative()

usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
[0]Atomic: -6
Atomic is negative
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