Re: [PATCHv2 1/4] net: fec: do not use readl()/writel() for ColdFire

[Andrew Lunn]

On Wed, Jun 10, 2026 at 12:12:58AM +1000, Greg Ungerer wrote:
> Modify the FEC driver to not directly use readl() and writel() to access
> hardware registers but instead local fec_readl() and fec_writel() methods.
> This allows for different architecture users of this driver to have
> different underlying access functions - to support both little and big
> endian hardware.
> 
> The FEC hardware block in ColdFire SoC parts is accessed big-endian.
> The usual kernel readl()/writel() IO memory access methods are defined to
> access little endian data. Change access for ColdFire to use __raw_readl()
> and __raw_writel() access methods - which do not modify or swap bytes
> on access.
> 
> The FEC driver works today because the m68k architecture io.h has a
> kludge in the definitions of the readl() and writel() functions for
> ColdFire that allow big-endian access if the address of the register to
> access is within the SoC's internal peripheral registers. This is being
> fixed in the near future to define readl() and writel() correctly - with
> no byte swapping. Thus the motivation for this fix here.
> 
> __raw_readl()/__raw_writel() access methods are used instead of the more
> commonly used ioread32be()/iowrite32be() here because those are broken too,
> because of the current readl()/writel() kludge. They are implemented in
> asm-generic/io.h in terms of readl()/writel().
> 
> Note that even when readl() and writel() are fixed on ColdFire they will
> not be the right thing to use within the FEC driver on ColdFire hardware.
> 
> Signed-off-by: Greg Ungerer <gerg@xxxxxxxxxxxxxx>

Reviewed-by: Andrew Lunn <andrew@xxxxxxx>

    Andrew