[4/6] arm: Clean up asm/io.h

asm/io.h is the header file containing the central MMIO accessor macros.
Judging by the header and the comments, it was apparently once copied
from the Linux kernel, but has deviated since then *heavily*. There is
absolutely no point in staying close to the original Linux code anymore,
so just remove the old cruft, by:
- removing pointless Linux history
- removing commented code
- removing outdated comments
- removing unused definitions (for mem_isa)

This massively improves the readability of the file.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 arch/arm/include/asm/io.h | 98 +--------------------------------------
 1 file changed, 2 insertions(+), 96 deletions(-)

On Sun,  9 Jan 2022 17:30:07 +0000
Andre Przywara <andre.przywara@arm.com> wrote:

Hi Rick, Leo:

> asm/io.h is the header file containing the central MMIO accessor macros.
> Judging by the header and the comments, it was apparently once copied
> from the Linux kernel, but has deviated since then *heavily*. There is
> absolutely no point in staying close to the original Linux code anymore,
> so just remove the old cruft, by:
> - removing pointless Linux history
> - removing commented code
> - removing outdated comments
> - removing unused definitions (for mem_isa)
> 
> This massively improves the readability of the file.

it looks like arch/risc-v/include/asm/io.h is a copy of the ARM
version, and includes the same pointless legacy. You might want to
remove those parts there as well.

Cheers,
Andre

> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  arch/arm/include/asm/io.h | 98 +--------------------------------------
>  1 file changed, 2 insertions(+), 96 deletions(-)
> 
> diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
> index 36b840378a9..89b1015bc4d 100644
> --- a/arch/arm/include/asm/io.h
> +++ b/arch/arm/include/asm/io.h
> @@ -1,45 +1,26 @@
>  /*
> - *  linux/include/asm-arm/io.h
> + * I/O device access primitives. Based on early versions from the Linux kernel.
>   *
>   *  Copyright (C) 1996-2000 Russell King
>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License version 2 as
>   * published by the Free Software Foundation.
> - *
> - * Modifications:
> - *  16-Sep-1996	RMK	Inlined the inx/outx functions & optimised for both
> - *			constant addresses and variable addresses.
> - *  04-Dec-1997	RMK	Moved a lot of this stuff to the new architecture
> - *			specific IO header files.
> - *  27-Mar-1999	PJB	Second parameter of memcpy_toio is const..
> - *  04-Apr-1999	PJB	Added check_signature.
> - *  12-Dec-1999	RMK	More cleanups
> - *  18-Jun-2000 RMK	Removed virt_to_* and friends definitions
>   */
>  #ifndef __ASM_ARM_IO_H
>  #define __ASM_ARM_IO_H
>  
> -#ifdef __KERNEL__
> -
>  #include <linux/types.h>
>  #include <linux/kernel.h>
>  #include <asm/byteorder.h>
>  #include <asm/memory.h>
>  #include <asm/barriers.h>
> -#if 0	/* XXX###XXX */
> -#include <asm/arch/hardware.h>
> -#endif	/* XXX###XXX */
>  
>  static inline void sync(void)
>  {
>  }
>  
> -/*
> - * Generic virtual read/write.  Note that we don't support half-word
> - * read/writes.  We define __arch_*[bl] here, and leave __arch_*w
> - * to the architecture specific code.
> - */
> +/* Generic virtual read/write. */
>  #define __arch_getb(a)			(*(volatile unsigned char *)(a))
>  #define __arch_getw(a)			(*(volatile unsigned short *)(a))
>  #define __arch_getl(a)			(*(volatile unsigned int *)(a))
> @@ -247,13 +228,6 @@ static inline void __raw_readsl(unsigned long addr, void *data, int longlen)
>  #define setbits_64(addr, set) setbits(64, addr, set)
>  #define clrsetbits_64(addr, clear, set) clrsetbits(64, addr, clear, set)
>  
> -/*
> - * Now, pick up the machine-defined IO definitions
> - */
> -#if 0	/* XXX###XXX */
> -#include <asm/arch/io.h>
> -#endif	/* XXX###XXX */
> -
>  /*
>   *  IO port access primitives
>   *  -------------------------
> @@ -317,16 +291,6 @@ static inline void __raw_readsl(unsigned long addr, void *data, int longlen)
>  #define writesb(a, d, s)	__raw_writesb((unsigned long)a, d, s)
>  #define readsb(a, d, s)		__raw_readsb((unsigned long)a, d, s)
>  
> -/*
> - * DMA-consistent mapping functions.  These allocate/free a region of
> - * uncached, unwrite-buffered mapped memory space for use with DMA
> - * devices.  This is the "generic" version.  The PCI specific version
> - * is in pci.h
> - */
> -extern void *consistent_alloc(int gfp, size_t size, dma_addr_t *handle);
> -extern void consistent_free(void *vaddr, size_t size, dma_addr_t handle);
> -extern void consistent_sync(void *vaddr, size_t size, int rw);
> -
>  /*
>   * String version of IO memory access ops:
>   */
> @@ -334,8 +298,6 @@ extern void _memcpy_fromio(void *, unsigned long, size_t);
>  extern void _memcpy_toio(unsigned long, const void *, size_t);
>  extern void _memset_io(unsigned long, int, size_t);
>  
> -extern void __readwrite_bug(const char *fn);
> -
>  /* Optimized copy functions to read from/write to IO sapce */
>  #ifdef CONFIG_ARM64
>  #include <cpu_func.h>
> @@ -441,62 +403,6 @@ void __memset_io(volatile void __iomem *dst, int c, size_t count)
>  #define memcpy_toio(a, b, c)		memcpy((void *)(a), (b), (c))
>  #endif
>  
> -/*
> - * If this architecture has ISA IO, then define the isa_read/isa_write
> - * macros.
> - */
> -#ifdef __mem_isa
> -
> -#define isa_readb(addr)			__raw_readb(__mem_isa(addr))
> -#define isa_readw(addr)			__raw_readw(__mem_isa(addr))
> -#define isa_readl(addr)			__raw_readl(__mem_isa(addr))
> -#define isa_writeb(val,addr)		__raw_writeb(val,__mem_isa(addr))
> -#define isa_writew(val,addr)		__raw_writew(val,__mem_isa(addr))
> -#define isa_writel(val,addr)		__raw_writel(val,__mem_isa(addr))
> -#define isa_memset_io(a,b,c)		_memset_io(__mem_isa(a),(b),(c))
> -#define isa_memcpy_fromio(a,b,c)	_memcpy_fromio((a),__mem_isa(b),(c))
> -#define isa_memcpy_toio(a,b,c)		_memcpy_toio(__mem_isa((a)),(b),(c))
> -
> -#define isa_eth_io_copy_and_sum(a,b,c,d) \
> -				eth_copy_and_sum((a),__mem_isa(b),(c),(d))
> -
> -static inline int
> -isa_check_signature(unsigned long io_addr, const unsigned char *signature,
> -		    int length)
> -{
> -	int retval = 0;
> -	do {
> -		if (isa_readb(io_addr) != *signature)
> -			goto out;
> -		io_addr++;
> -		signature++;
> -		length--;
> -	} while (length);
> -	retval = 1;
> -out:
> -	return retval;
> -}
> -
> -#else	/* __mem_isa */
> -
> -#define isa_readb(addr)			(__readwrite_bug("isa_readb"),0)
> -#define isa_readw(addr)			(__readwrite_bug("isa_readw"),0)
> -#define isa_readl(addr)			(__readwrite_bug("isa_readl"),0)
> -#define isa_writeb(val,addr)		__readwrite_bug("isa_writeb")
> -#define isa_writew(val,addr)		__readwrite_bug("isa_writew")
> -#define isa_writel(val,addr)		__readwrite_bug("isa_writel")
> -#define isa_memset_io(a,b,c)		__readwrite_bug("isa_memset_io")
> -#define isa_memcpy_fromio(a,b,c)	__readwrite_bug("isa_memcpy_fromio")
> -#define isa_memcpy_toio(a,b,c)		__readwrite_bug("isa_memcpy_toio")
> -
> -#define isa_eth_io_copy_and_sum(a,b,c,d) \
> -				__readwrite_bug("isa_eth_io_copy_and_sum")
> -
> -#define isa_check_signature(io,sig,len)	(0)
> -
> -#endif	/* __mem_isa */
> -#endif	/* __KERNEL__ */
> -
>  #include <asm-generic/io.h>
>  #include <iotrace.h>
>

On Sun, Jan 09, 2022 at 09:39:03PM +0000, Andre Przywara wrote:
> On Sun,  9 Jan 2022 17:30:07 +0000
> Andre Przywara <andre.przywara@arm.com> wrote:
> 
> Hi Rick, Leo:
> 
> > asm/io.h is the header file containing the central MMIO accessor macros.
> > Judging by the header and the comments, it was apparently once copied
> > from the Linux kernel, but has deviated since then *heavily*. There is
> > absolutely no point in staying close to the original Linux code anymore,
> > so just remove the old cruft, by:
> > - removing pointless Linux history
> > - removing commented code
> > - removing outdated comments
> > - removing unused definitions (for mem_isa)
> > 
> > This massively improves the readability of the file.
> 
> it looks like arch/risc-v/include/asm/io.h is a copy of the ARM
> version, and includes the same pointless legacy. You might want to
> remove those parts there as well.
> 
> Cheers,
> Andre
> 
> > Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> > ---
> >  arch/arm/include/asm/io.h | 98 +--------------------------------------
> >  1 file changed, 2 insertions(+), 96 deletions(-)

Hi Andre,

Thanks for the reminder!
Will do ASAP!

Best regards,
Leo