From owner-cvs-all  Tue Sep 28  6:54:34 1999
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To: imp@village.org
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Subject: Re: cvs commit: src/sys/conf files src/sys/i386/conf files.i386 
In-Reply-To: <199909270628.AAA08033@harmony.village.org>
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	<199909270628.AAA08033@harmony.village.org>
From: Takahashi Yoshihiro <nyan@FreeBSD.org>
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In article <199909270628.AAA08033@harmony.village.org>
Warner Losh <imp@village.org> writes:

> I'd also like to get some feedback on a related issue.  I'd like to
> know what people think of adding a third space to the I386 port.  The
> third I/O space would be I386_BUS_SPACE_IO_INDIRECT.  The code for it
> would look like the following.  In a nutshel, its bsh is a pointer to
> an array of I/O ports, and the offset is an index into that array.  So 
> you'd effectively replace bsh+offset with bsh[offset].  The driver
> would be responsible for managing the bsh array for the _INDIRECT
> case.

I agree this method. But, your code requires some ugly casts.
I suggest the following way to fix this problem.

bus_space_handle_t is the union instead of u_int.

	union bus_space_handle {
		bus_addr_t bsh_base;
		bus_addr_t *bsh_iat;
	};
	typedef union bus_space_handle bus_space_handle_t;

and, for example, bus_space_write_1 is the following:

static __inline void
bus_space_write_1(bus_space_tag_t tag, bus_space_handle_t bsh,
		       bus_size_t offset, u_int8_t value)
{
#if defined(_I386_BUS_PIO_H_)
#if defined(_I386_BUS_MEMIO_H_) || defined(_I386_BUS_PIOI_H_)
	if (tag == I386_BUS_SPACE_IO)
#endif
		outb(bsh.bsh_base + offset, value);
#endif
#if defined(_I386_BUS_MEMIO_H_)
#if defined(_I386_BUS_PIO_H_) || defined(_I386_BUS_PIOI_H_)
	else if (tag == I386_BUS_SPACE_MEM)
#endif
		*(volatile u_int8_t *)(bsh.bsh_base + offset) = value;
#endif
#if defined(_I386_BUS_PIOI_H_)
#if defined(_I386_BUS_PIO_H_) || defined(_I386_BUS_MEMIO_H_)
	else if (tag == I386_BUS_SPACE_IO_INDIRECT)
#endif
		outb(bsh.bsh_iat[offset], value);
#endif
}


It is unnecessary to do the ugly casts by changing like this.
I think that there is no problem with this method.

---
Takahashi Yoshihiro / nyan@FreeBSD.org


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