How can i use a function in multiple drivers?

Question

I want to call do_input_boost function in another driver but I couldn't find the way to call the function.

static void do_input_boost(struct kthread_work *work)
{
    unsigned int i, ret;
    struct cpu_sync *i_sync_info;

    /* Set the input_boost_min for all CPUs in the system */
    pr_debug("Setting input boost min for all CPUs\n");
    for_each_possible_cpu(i) {
        i_sync_info = &per_cpu(sync_info, i);
        i_sync_info->input_boost_min = i_sync_info->input_boost_freq;
    }

    queue_delayed_work(system_power_efficient_wq,
        &input_boost_rem, msecs_to_jiffies(input_boost_ms));
}

I also added EXPORT_SYMBOL(do_input_boost) but couldn't find the proper prototype definition for calling this function, like

do_input_boost();

EDIT: i added a hear and linked in target driver

#ifdef CONFIG_CPU_BOOST
extern void do_input_boost(void);
#else
extern void do_input_boost(void)
{
}
#endif

Remove `static` ? Add a [function declaration](https://en.cppreference.com/w/c/language/function_declaration) before calling the function? — KamilCuk, Sep 09 '18 at 09:54

Gaurav · Accepted Answer · 2018-09-09T10:49:06.417

1

IMO you'll have to remove static as it limits the visibility of this function to the current translational unit (provided the other driver is not in the same .c file).

Removing static will make that function global and from other .c files it will be accessible using extern declaration.

lets say that this function of ours do_input_boost is defined in a.c file and your driver is in b.c file (where you want to call that function), then:

in b.c you'll declare that function: extern void do_input_boost(struct kthread_work*); and then you can call that.

edited Sep 09 '18 at 10:49

answered Sep 09 '18 at 10:02

Gaurav

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thank you, i edited my post with added a header. now i can call the function with that way. is it correct? – Mostafa Zarghami Sep 09 '18 at 10:43
@MostafaZarghami Edited my answer. – Gaurav Sep 09 '18 at 10:49
by this way how can i call the function? do_input_boost(); ? b.c is compiling if i set "extern void do_input_boost(void);" and "do_input_boost();" – Mostafa Zarghami Sep 09 '18 at 11:05
@MostafaZarghami check this link: https://stackoverflow.com/questions/856636/effects-of-the-extern-keyword-on-c-functions – Gaurav Sep 09 '18 at 11:15

How can i use a function in multiple drivers?

1 Answers1