[PATCH 6/7] MPIC MSI allocator

[Michael Ellerman]

On Sat, 2007-04-21 at 18:17 -0500, Milton Miller wrote:
> On Apr 19, 2007, Michael Ellerman wrote:
> > To support MSI on MPIC we need a way to reserve and allocate hardware 
> > irq
> > numbers, this patch implements an allocator for that.
> 
> > Index: msi-new/arch/powerpc/sysdev/mpic_msi.c
> > ===================================================================
> > --- /dev/null
> > +++ msi-new/arch/powerpc/sysdev/mpic_msi.c
> ...
> > +irq_hw_number_t mpic_msi_alloc_hwirqs(struct mpic *mpic, int num)
> > +{
> > +	unsigned long flags;
> > +	int offset, order = fls(num) - 1;
> 
> get_count_order would be more clear.  Also it has
> a correction factor.  (Applies several places).

I was hoping someone would point out something better than fls, fixed.

> > +#ifdef CONFIG_MPIC_BROKEN_U3
> > +static int mpic_msi_reserve_u3_hwirqs(struct mpic *mpic)
> > +{
> > +	irq_hw_number_t hwirq;
> > +	struct irq_host_ops *ops = mpic->irqhost->ops;
> > +	struct device_node *np;
> > +	int flags, index, i;
> > +	struct of_irq oirq;
> > +
> > +	pr_debug("mpic: found U3, guessing msi allocator setup\n");
> > +
> > +	/* Reserve source numbers we know are reserved in the HW */
> > +	for (i = 0;   i < 8;   i++) __mpic_msi_reserve_hwirq(mpic, i);
> > +	for (i = 42;  i < 46;  i++) __mpic_msi_reserve_hwirq(mpic, i);
> > +	for (i = 100; i < 105; i++) __mpic_msi_reserve_hwirq(mpic, i);
> 
> More lines please.
> 
> > +#else
> > +static int mpic_msi_reserve_u3_hwirqs(struct mpic *mpic) { return -1; 
> > }
> 
> and here.

Blank lines aren't free you know!

> 
> > +	if (len % 8 != 0) {
> > +		printk(KERN_WARNING "mpic: Malformed msi-available-ranges "
> > +		       "property on %s\n", mpic->of_node->full_name);
> > +		return -EINVAL;
> > +	}
> > +
> > +	bitmap_allocate_region(mpic->hwirq_bitmap, 0,
> > +			       fls(mpic->irq_count) - 1);
> > +
> > +	/* Format is: (<u32 start> <u32 count>)+ */
> > +	len /= sizeof(u32);
> > +	for (i = 0; i < len / 2; i++, p += 2)
> 
> how about just dividing by the calculated 8 above?  or use
> count = len / 8.

I'm not sure I follow. If you can think of a clearer way I'm all ears,
or are you just trying to save a divide :)

> 
> > +		mpic_msi_free_hwirqs(mpic, *p, *(p + 1));
> > +
> > +	return 0;
> > +}
> > +
> > +int mpic_msi_init_allocator(struct mpic *mpic)
> > +{
> > +	int rc, size;
> > +
> > +	BUG_ON(mpic->hwirq_bitmap);
> > +	spin_lock_init(&mpic->bitmap_lock);
> > +
> > +	size = mpic->irq_count / 8;
> > +	pr_debug("mpic: allocator bitmap size is 0x%x bytes\n", size);
> 
> BITS_TO_LONGS() * sizeof(long).   We need to round up to longs to
> use bitmask_*, especially being a big endian architecture.

Eww, sorry that's horrible. Fixed.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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