Subject: Re: MI bus ops(Re: 16bit aligned NS16550 variant)
To: None <>
From: TAKEMURA Shin <>
List: tech-kern
Date: 11/11/2001 00:09:30
----- Original Message -----
From: "Jason R Thorpe" <>
To: "TAKEMURA Shin" <>
Cc: <>; <>;
<>; <>
Sent: Saturday, November 10, 2001 1:01 AM
Subject: Re: MI bus ops(Re: 16bit aligned NS16550 variant)

> On Sun, Nov 04, 2001 at 11:24:41AM +0900, TAKEMURA Shin wrote:
>  > In the last discussion, I found that function vector definition of
>  > bus_space method should be michine independent.

> So, the bus_space_ops, while independent, don't actually contain enough
> info for MI code to construct its own bus_space_tag_t's.  This is because
> bus_space_tag_t's still have a machine-dependent definition.
> I think what I'd really like to see here is for <machine/bus.h> to be
> replaced by:

Okay... I've wrote rough draft of sys/bus.h (attached).
The file describes abstract class of bus object. To implement a conclete
bus space with the sys/bus.h, you should define a new bus_space_tag
derived from the bus_space_tag. This is similar to what you do with the
device structure in sys/device.h.
For example,

machine/bus_mainbus.h --------
    #include <sys/bus.h>

    struct mainbus_bus_space_tag {
        struct bus_space_tag bs_bs;
        u_int32_t baseaddr;

mainbus.c --------
    #include <machine/bus_mainbus.h>


    mainbus_bs_r_1(bus_space_tag_t t, bus_space_handle_t bsh, bus_size_t
        struct mainbus_bus_space_tag *ht = (struct hpcmips_bus_space_tag*)t;
        return (*(volatile u_int8_t *)(ht->baseaddr + bsh + offset));

other points:

  - I use BUS_SPACE_MD_CALLS instead of
    __BUS_SPACE_MC_CALLS because the macro might be referd
    somewhere MI code. You can't override a bus method nor create
    new MI bus space if the macro was defined.
  - A machine/bus_types.h below will provide compatibility. I think
    it's too hard to rewrite all bus_space stuff of all ports at once.
        #define BUS_SPACE_MD_CALLS
        #deinfe BUS_SPACE_MD_TYPES
        #define BUS_DMA_MD_CALLS
        #define BUS_DMA_MD_TYPES
    With this bus_types.h, sys/bus.h will do nothing but including

How do you think abous this ? I'm going to write concrete (compilable)
version of new bus.h and hpcmips' main bus.If you object, please let
me know ASAP. I don't like to write more code only to throw it away.