linux-kernel - Re: [PATCH v4 1/3] lib: logic_pio: Use logical PIO low-level accessors for !CONFIG_INDIRECT

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Message-ID: <20190613135825.GG13533@google.com>
Date:   Thu, 13 Jun 2019 08:58:25 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     John Garry <john.garry@...wei.com>
Cc:     lorenzo.pieralisi@....com, arnd@...db.de,
        linux-pci@...r.kernel.org, rjw@...ysocki.net,
        linux-arm-kernel@...ts.infradead.org, will.deacon@....com,
        wangkefeng.wang@...wei.com, linuxarm@...wei.com,
        andriy.shevchenko@...ux.intel.com, linux-kernel@...r.kernel.org,
        catalin.marinas@....com
Subject: Re: [PATCH v4 1/3] lib: logic_pio: Use logical PIO low-level
 accessors for !CONFIG_INDIRECT_PIO

On Tue, Jun 11, 2019 at 10:12:52PM +0800, John Garry wrote:
Another thought here:

>  	if (addr < MMIO_UPPER_LIMIT) {					\
>  		ret = read##bw(PCI_IOBASE + addr);			\
>  	} else if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) { \
> -		struct logic_pio_hwaddr *entry = find_io_range(addr);	\
> +		struct logic_pio_hwaddr *range = find_io_range(addr);	\
> +		size_t sz = sizeof(type);				\
>  									\
> -		if (entry && entry->ops)				\
> -			ret = entry->ops->in(entry->hostdata,		\
> -					addr, sizeof(type));		\
> +		if (range && range->ops)				\
> +			ret = range->ops->in(range->hostdata, addr, sz);\
>  		else							\
>  			WARN_ON_ONCE(1);				\

Could this be simplified a little by requiring callers to set
range->ops for LOGIC_PIO_INDIRECT ranges *before* calling
logic_pio_register_range()?  E.g.,

  hisi_lpc_probe(...)
  {
    range = devm_kzalloc(...);
    range->flags = LOGIC_PIO_INDIRECT;
    range->ops = &hisi_lpc_ops;
    logic_pio_register_range(range);
    ...

and

  logic_pio_register_range(struct logic_pio_hwaddr *new_range)
  {
    if (new_range->flags == LOGIC_PIO_INDIRECT && !new_range->ops)
      return -EINVAL;
    ...

Then maybe you wouldn't need to check range->ops in the accessors.

Bjorn