[U-Boot] [PATCH v2 1/9] sunxi: initial sun7i clocks and timer support.

Ian Campbell
2014-03-27T22:12:38Z

On Thu, 2014-03-27 at 23:00 +0100, Marek Vasut wrote:
> On Thursday, March 27, 2014 at 10:29:56 PM, Ian Campbell wrote:
> > On Mon, 2014-03-24 at 21:52 +0100, Marek Vasut wrote:
> > > > +static struct sunxi_timer *timer_base =
> > > > + &((struct sunxi_timer_reg *)SUNXI_TIMER_BASE)->timer[TIMER_NUM];
> > > > +
> > > > +/* macro to read the 32 bit timer: since it decrements, we invert read
> > > > value */ +#define READ_TIMER() (~readl(&timer_base->val))
> > >
> > > This macro has to go, just use ~readl() in place. But still, why do you
> > > use that negation in "~readl()" anyway ?
> >
> > The comment right above it explains why: the timer counts backwards and
> > inverting it accounts for that.
> >
> > This is subtle enough that I don't think using ~readl() in place in the
> > 3 callers would be an improvement.
>
> Please do it, we don't want any implementers down the line using this
> "READ_TIMER()" call and getting hit by "timer_base undefined" . That macro hides
> the dependency on this symbol, while if you expanded it in-place, the dependency
> would be explicit. I really do want to see that macro gone, sorry.

How about a static inline instead of the macro? I'm thinking with a
body:
{
struct sunxi_timer *timers =
(struct sunxi_timer_reg *)SUNXI_TIMER_BASE;
return timers[TIMER_NUM]->val;
}
With something similar in timer_init then both the macro and the static
global timer_base can be dropped.

BTW this macro is in arch/arm/cpu/armv7/sunxi/timer.c not a header, so
I'm not sure which implementers down the line you were worried about
using it in some other context where it breaks.

Ian.