[ECOS] driver development, how to make timeouts?

[Sergei Gavrikov]

On Sat, 28 May 2011, Richard Rauch wrote:

> Hi all,
> 
> How I have to implement a timeout inside an eCos Driver?
> 
> I have following code, which is waiting on an interrupt event:
> 
>     cyg_drv_mutex_lock(&(extra->i2c_lock));
>     cyg_drv_dsr_lock();
>     while (!extra->i2c_completed) {
>         cyg_drv_cond_wait(&(extra->i2c_wait));
>     }
>     cyg_drv_dsr_unlock();
>     cyg_drv_mutex_unlock(&(extra->i2c_lock));
> 
> 
> The cyg_drv_cond_wait() never returns, as long as no interrupt occurs. But
> in special cases (if the hardware is not wired properly), there will be
> never an interrupt.
> 
> How can I break in this function after a while?
> 
> In normal user API, there is a function cyg_cond_timed_wait() which is able
> to return in case of timeout.
> I haven't found a similar function in driver's kernel API!
>
> Who knows a solution?

Hi,

There is such a precedent in io/can/current/src/can.c:

69 #ifdef CYGOPT_IO_CAN_SUPPORT_TIMEOUTS
70 #define CYG_DRV_COND_WAIT(_cond, _time) cyg_cond_timed_wait(_cond, cyg_current_time() + (_time))
71 #else
72 #define CYG_DRV_COND_WAIT(_cond, _time) cyg_drv_cond_wait(_cond)

But, keep in a mind that needs eCos kernel packages:

    cdl_component CYGOPT_IO_CAN_SUPPORT_TIMEOUTS {
        display       "Support read/write timeouts"
        flavor        bool
        default_value 0
        active_if     CYGPKG_KERNEL
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^
        ...

HTH

Sergei

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