Re: EPIC Vs OpenPIC (RFC)

quoted

And it really makes for an even more simple
xxx_setup.c for the different ports.

At the same time I would like to suggest an inclusion
of the registration of the i8259 interrupts to
i8259_init().
At the momenty everyone of the drivers are doing exactly
the same thing:
for ( vec = 0 ; vec < NUM_8259_INTERRUPTS  ; vec++ )
        irq_desc[vec].handler = &i8259_pic;

  Why should all drivers populate irq_desc ??
I dont get this. It is done once in life time,
right ? That too, even before driver's init
routine come into picture.

Sorry for talking about drivers, did get a little
confusing, what I meant is that every
port (see the xxx_setup.c stuff) is doing
the same thing.

quoted

Moving this to i8259_init() and giving the routine a
parameter startvec (even if everyone is starting from 0
at the moment) would get rid of even more code from
the machine-specific stuff.

   The best thing is allow the 8259 to retain
its vector space from 0-15. Program EPIC
to generate interrupts from 16-40. ( By
passing "offset" value of 16 to openpic_init)
That should clear things up and seperate the
vector spaces of EPIC and PIC.

I am not sure it the i8259 (or similar) will always
have vectors 0-15, what if we have two cascades ?
I think we need to make sure not limiting this
too much by giving the i8259() routing the extra
argument for the first vector.

   May I know whats the semantics of the
"regOffset" ?

Well, that was from the first draft, when I wasn't
sure if we still needed it.

Now the interface looks like this:

typedef enum irq_polarity_en {
    OP_IRQ_POS = 1,
    OP_IRQ_NEG = 0
} irq_polarity_type;

typedef enum irq_sense_en {
    OP_IRQ_LEVEL = 1,
    OP_IRQ_EDGE  = 0
} irq_sense_type;

typedef struct openpic_irq_def_str {
    u_int               PICIrq;
    u_int               Vector;
    u_char              Priority;
    irq_sense_type      IrqSense;
    irq_polarity_type   IrqPolarity;
    /* This can be used for cascade, but should work well for the chrp
specials too */
    int                 (*CascadeAckHandler)(int);
} openpic_irq_def;

typedef struct openpic_def_str {
    volatile struct OpenPIC *OpenPIC_Addr;
    int             slave_pic;
    openpic_irq_def *IRQdef;    /* The lovest vector first in the table !!! */
} openpic_def;

Good Luck

Thanks

Dag


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