Device driver question

Device driver question

[Bloch, Jack]

I am relatively new to Linux (< 6 months). We have designed an embedded
system (on compact PCI) running on a Pentium III 700Mhz cPCI machine. This
machine supports upt to 6 cPCI boards for specific functions (this is our
own HW). I have already written the device drivers for these boards and the
system is running. I have a specific case where our HW can generate a
special interrupt. In this case I simply want the ISR to halt the system
(i.e. take the same action as if I typed halt from the command line). How
can I from within my device driver cause a halt? Please CC me specifically
on any replies.

Thanks in advance. 

Jack Bloch
Siemens Carrier Networks
e-mail    : jack.bloch@icn.siemens.com
phone     : (561) 923-6550

Re: Device driver question

[Tommy Reynolds]

Uttered "Bloch, Jack" <Jack.Bloch@icn.siemens.com>, spoke thus:

> I have a specific case where our HW can generate a
>  special interrupt. In this case I simply want the ISR to halt the system
>  (i.e. take the same action as if I typed halt from the command line). How
>  can I from within my device driver cause a halt? Please CC me specifically
>  on any replies.

Check out the code for "sys_reboot" in "kernel/sys.c" for ideas on how to do
this.  I don't think you can invoke "sys_reboot" from inside an interrupt
handler, but you could probably do the same thing by calling the service
routines "sys_reboot" does.

If that doesn't shut your machine down gracefully, then you might resort to
"call_usermodehelper" in "kernel/kmod.c" to run "/sbin/shutdown -h now".  You
can't invoke "call_usermodehelper" from an interrupt top half, but it should
work find from a tasklett.

Re: Device driver question

[Joe deBlaquiere]

How about just write a driver that responds to the interrupt, and write
a program that does a blocking read from the driver. The driver read
routine stuff the program on a wait queue... until... interrupt occurs,
wake up the program, program does exec(/sbin/halt) ?

This could actually be made into a good demonstration of driver
programming in that you could hook the parport interrupt and do it with
any PC.... 

On Wed, 2002-05-15 at 08:36, Tommy Reynolds wrote:
> Uttered "Bloch, Jack" <Jack.Bloch@icn.siemens.com>, spoke thus:
> 
> > I have a specific case where our HW can generate a
> >  special interrupt. In this case I simply want the ISR to halt the system
> >  (i.e. take the same action as if I typed halt from the command line). How
> >  can I from within my device driver cause a halt? Please CC me specifically
> >  on any replies.
> 
> Check out the code for "sys_reboot" in "kernel/sys.c" for ideas on how to do
> this.  I don't think you can invoke "sys_reboot" from inside an interrupt
> handler, but you could probably do the same thing by calling the service
> routines "sys_reboot" does.
> 
> If that doesn't shut your machine down gracefully, then you might resort to
> "call_usermodehelper" in "kernel/kmod.c" to run "/sbin/shutdown -h now".  You
> can't invoke "call_usermodehelper" from an interrupt top half, but it should
> work find from a tasklett.
> -
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Joe deBlaquiere
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Re: Device driver question

[Tommy Reynolds]

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Uttered "Joe deBlaquiere" <jadb@redhat.com>, spoke thus:

>  How about just write a driver that responds to the interrupt, and write
>  a program that does a blocking read from the driver. The driver read
>  routine stuff the program on a wait queue... until... interrupt occurs,
>  wake up the program, program does exec(/sbin/halt) ?

Yup, that could work too. (Classic see-interrupt-from-user-space solution)  It
all depends on how urgently his embedded system needs to reboot.  Choices abound
for rebooting: the hard part is not rebooting until you want to reboot.

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Re: Device driver question

[Tommy Reynolds]

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Uttered "Joe deBlaquiere" <jadb@redhat.com>, spoke thus:

>  How about just write a driver that responds to the interrupt, and write
>  a program that does a blocking read from the driver.

Then there's the

	printk( KERN_EMERG "Hey, Y'all, let's reboot!\n" );

solution.

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Re: Device driver question

[jw schultz]

On Wed, May 15, 2002 at 09:17:21AM -0400, Bloch, Jack wrote:
> I am relatively new to Linux (< 6 months). We have designed an embedded
> system (on compact PCI) running on a Pentium III 700Mhz cPCI machine. This
> machine supports upt to 6 cPCI boards for specific functions (this is our
> own HW). I have already written the device drivers for these boards and the
> system is running. I have a specific case where our HW can generate a
> special interrupt. In this case I simply want the ISR to halt the system
> (i.e. take the same action as if I typed halt from the command line). How
> can I from within my device driver cause a halt? Please CC me specifically
> on any replies.
> 
> Thanks in advance. 

I am assuming you are running more than just the kernel.
You could just post a signal to init (pid 1).
SIGINT would be a top candidate.

Take a look at powerd, init and inittab.


-- 
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