Re: unsigned long ioremap()?

Jonathan Lundell
2001-05-03T07:50:29Z

At 3:18 AM -0400 2001-05-03, Jeff Garzik wrote:
>"David S. Miller" wrote:
>> There is a school of thought which believes that:
>>
> > struct xdev_regs {
>> u32 reg1;
>> u32 reg2;
>> };
> >
>> val = readl(&regs->reg2);
>>
>> is cleaner than:
>>
>> #define REG1 0x00
>> #define REG2 0x04
>>
>> val = readl(regs + REG2);
>>
>> I'm personally ambivalent and believe that both cases should be allowed.
>
>Agreed... Tangent a bit, I wanted to plug using macros which IMHO make
>code even more readable:
>
> val = RTL_R32(REG2);
> RTL_W32(REG2, val);
>
>Since these are driver-private, if you are only dealing with one chip
>you could even shorten things to "R32" and "W32", if that doesn't offend
>any sensibilities :)

With a little arithmetic behind the scenes and a NULL pointer to the
struct xdev, you could have:

struct xdev_regs {
u32 reg1;
u32 reg2;
} *xdr = 0;

#define RTL_R32(REG) readl(cookie+(unsigned long)(&xdr->REG))

cookie = ioremap(blah, blah);

val = RTL_R32(reg2);

...and have the benefits of the R32 macro as well as the use of
structure members.
--
/Jonathan Lundell.