大家帮我看看clk_get究竟是怎么实现的。谢谢

linux-2.6.21.5/arch/arm/plat-s3c24xx/clock.c

/* Clock API calls */



struct clk *(struct device *dev, const char *id)

{

    struct clk *p;

    struct clk *clk = ERR_PTR(-ENOENT);

    int idno;



    if (dev == NULL || dev->bus != &platform_bus_type)

        idno = -1;

    else

        idno = to_platform_device(dev)->id;



    mutex_lock(&clocks_mutex);



    list_for_each_entry(p, & clocks, list) {

        if (p->id == idno &&

            strcmp(id, p->name) == 0 &&

            try_module_get(p->owner)) {

            clk = p;

            break;

        }

    }



    /* check for the case where a device was supplied, but the

     * clock that was being searched for is not device specific */



    if (IS_ERR(clk)) {

        list_for_each_entry(p, &clocks, list) {

            if (p->id == -1 && strcmp(id, p->name) == 0 &&

                try_module_get(p->owner)) {

                clk = p;

                break;

            }

        }

    }



    mutex_unlock(&clocks_mutex);

    return clk;

}

#define list_for_each_entry(pos, head, member)                \

for (pos = list_entry((head)->next, typeof(*pos), member);    \

prefetch(pos->member.next), &pos->member != (head);     \

pos = list_entry(pos->member.next, typeof(*pos), member))



说白了define list_for_each_entry 就是一个for循环。。。。

struct clk clk_xtal = {

.name   = "xtal",

.id   = -1,

.rate   = 0,

.parent   = NULL,

.ctrlbit = 0,

};