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SubjectRe: [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:
> Currently we only use logical PIO low-level accessors for when
> CONFIG_INDIRECT_PIO is enabled.
>
> Otherwise we just use inb/out et all directly.
>
> It is useful to now use logical PIO accessors for all cases, so we can add
> legality checks to accesses. Such a check would be for ensuring that the
> PCI IO port has been IO remapped prior to the access.

IIUC, *this* patch doesn't actually add any additional checks, so no
need to mention that in this commit log.

One thing this patch *does* do is "#define inb logic_inb" whenever
PCI_IOBASE is defined (we used to do that #define only when
CONFIG_INDIRECT_PIO was defined). That's a pretty important change
and needs to be very clear in the commit log.

I'm not sure it's even safe, because CONFIG_INDIRECT_PIO depends on
ARM64, but PCI_IOBASE is defined on most arches via asm-generic/io.h,
so this potentially affects arches other than ARM64.

If possible, split out the cleanup patches as below and make the patch
that does this PCI_IOBASE change as small as possible so we can
evaluate that change by itself.

> Using the logical PIO accesses will add a little processing overhead, but
> that's ok as IO port accesses are relatively slow anyway.
>
> Some changes are also made to stop spilling so many lines under
> CONFIG_INDIRECT_PIO.

"Some changes are also made" is a good hint to me that this patch
might be able to be split up :)

> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
> include/linux/logic_pio.h | 7 ++--
> lib/logic_pio.c | 83 ++++++++++++++++++++++++++++-----------
> 2 files changed, 63 insertions(+), 27 deletions(-)
>
> diff --git a/include/linux/logic_pio.h b/include/linux/logic_pio.h
> index cbd9d8495690..06d22b2ec99f 100644
> --- a/include/linux/logic_pio.h
> +++ b/include/linux/logic_pio.h
> @@ -37,7 +37,7 @@ struct logic_pio_host_ops {
> size_t dwidth, unsigned int count);
> };
>
> -#ifdef CONFIG_INDIRECT_PIO
> +#if defined(PCI_IOBASE)

Why change the #ifdef style? I understand these are equivalent, but
unless there's a movement to change from "#ifdef X" to "#if defined(X)"
I wouldn't bother.

> u8 logic_inb(unsigned long addr);
> void logic_outb(u8 value, unsigned long addr);
> void logic_outw(u16 value, unsigned long addr);
> @@ -102,6 +102,7 @@ void logic_outsl(unsigned long addr, const void *buffer, unsigned int count);
> #define outsl logic_outsl
> #endif
>
> +#if defined(CONFIG_INDIRECT_PIO)
> /*
> * We reserve 0x4000 bytes for Indirect IO as so far this library is only
> * used by the HiSilicon LPC Host. If needed, we can reserve a wider IO
> @@ -109,10 +110,10 @@ void logic_outsl(unsigned long addr, const void *buffer, unsigned int count);
> */
> #define PIO_INDIRECT_SIZE 0x4000
> #define MMIO_UPPER_LIMIT (IO_SPACE_LIMIT - PIO_INDIRECT_SIZE)
> -#else
> +#else /* CONFIG_INDIRECT_PIO */
> #define MMIO_UPPER_LIMIT IO_SPACE_LIMIT
> #endif /* CONFIG_INDIRECT_PIO */
> -
> +#endif /* PCI_IOBASE */
> struct logic_pio_hwaddr *find_io_range_by_fwnode(struct fwnode_handle *fwnode);
> unsigned long logic_pio_trans_hwaddr(struct fwnode_handle *fwnode,
> resource_size_t hw_addr, resource_size_t size);
> diff --git a/lib/logic_pio.c b/lib/logic_pio.c
> index feea48fd1a0d..40d9428010e1 100644
> --- a/lib/logic_pio.c
> +++ b/lib/logic_pio.c
> @@ -191,7 +191,8 @@ unsigned long logic_pio_trans_cpuaddr(resource_size_t addr)
> return ~0UL;
> }
>
> -#if defined(CONFIG_INDIRECT_PIO) && defined(PCI_IOBASE)
> +#if defined(PCI_IOBASE)
> +#if defined(CONFIG_INDIRECT_PIO)
> #define BUILD_LOGIC_IO(bw, type) \
> type logic_in##bw(unsigned long addr) \
> { \
> @@ -200,11 +201,11 @@ type logic_in##bw(unsigned long addr) \
> 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); \

I don't mind changing "entry" to "range" and adding "sz". But that
could be done in a separate "no functional change" patch that is
trivial to review, which would make *this* patch smaller and easier to
review.

Another "no functional change" simplification patch would be to
replace this:

type ret = (type)~0;

if (addr < MMIO_UPPER_LIMIT) {
ret = read##bw(...);
} else if (...) {
if (range && range->ops)
ret = range->ops->in(...);
else
WARN_ON_ONCE();
}
return ret;

with this:

if (addr < MMIO_UPPER_LIMIT)
return read##bw(...);

if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) {
if (range && range->ops)
return range->ops->in(...);
else
WARN_ON_ONCE();
}

return (type)~0;

Finally, I think the end result would be a little easier to read if
you restructured the #ifdefs like this:

#ifdef PCI_IOBASE
#define BUILD_LOGIC_IO(...)
type logic_in##bw(...)
{
if (addr < MMIO_UPPER_LIMIT)
return read##bw(...);

#ifdef CONFIG_INDIRECT_PIO
if (addr >= MMIO_UPPER_LIMIT && addr < IO_SPACE_LIMIT) {
if (range && range->ops)
return range->ops->in(...);
else
WARN_ON_ONCE();
}
#endif

return (type)~0;
}

That does mean a CONFIG_INDIRECT_PIO #ifdef in each in/out/ins/outs
builder, but it's more localized so I think it's easier to understand
that INDIRECT_PIO is just adding a new case to the default path.

> - 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); \
> } \
> @@ -216,49 +217,83 @@ void logic_out##bw(type value, unsigned long addr) \
> if (addr < MMIO_UPPER_LIMIT) { \
> write##bw(value, 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) \
> - entry->ops->out(entry->hostdata, \
> - addr, value, sizeof(type)); \
> + if (range && range->ops) \
> + range->ops->out(range->hostdata, \
> + addr, value, sz); \
> else \
> WARN_ON_ONCE(1); \
> } \
> } \
> \
> -void logic_ins##bw(unsigned long addr, void *buffer, \
> - unsigned int count) \
> +void logic_ins##bw(unsigned long addr, void *buf, unsigned int cnt) \
> { \
> if (addr < MMIO_UPPER_LIMIT) { \
> - reads##bw(PCI_IOBASE + addr, buffer, count); \
> + reads##bw(PCI_IOBASE + addr, buf, cnt); \
> } 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) \
> - entry->ops->ins(entry->hostdata, \
> - addr, buffer, sizeof(type), count); \
> + if (range && range->ops) \
> + range->ops->ins(range->hostdata, \
> + addr, buf, sz, cnt); \
> else \
> WARN_ON_ONCE(1); \
> } \
> \
> } \
> \
> -void logic_outs##bw(unsigned long addr, const void *buffer, \
> - unsigned int count) \
> +void logic_outs##bw(unsigned long addr, const void *buf, \
> + unsigned int cnt) \
> { \
> if (addr < MMIO_UPPER_LIMIT) { \
> - writes##bw(PCI_IOBASE + addr, buffer, count); \
> + writes##bw(PCI_IOBASE + addr, buf, cnt); \
> } 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) \
> - entry->ops->outs(entry->hostdata, \
> - addr, buffer, sizeof(type), count); \
> + if (range && range->ops) \
> + range->ops->outs(range->hostdata, \
> + addr, buf, sz, cnt); \
> else \
> WARN_ON_ONCE(1); \
> } \
> }
>
> +#else /* CONFIG_INDIRECT_PIO */
> +
> +#define BUILD_LOGIC_IO(bw, type) \
> +type logic_in##bw(unsigned long addr) \
> +{ \
> + type ret = (type)~0; \
> + \
> + if (addr < MMIO_UPPER_LIMIT) \
> + ret = read##bw(PCI_IOBASE + addr); \
> + return ret; \
> +} \
> + \
> +void logic_out##bw(type value, unsigned long addr) \
> +{ \
> + if (addr < MMIO_UPPER_LIMIT) \
> + write##bw(value, PCI_IOBASE + addr); \
> +} \
> + \
> +void logic_ins##bw(unsigned long addr, void *buf, unsigned int cnt) \
> +{ \
> + if (addr < MMIO_UPPER_LIMIT) \
> + reads##bw(PCI_IOBASE + addr, buf, cnt); \
> +} \
> + \
> +void logic_outs##bw(unsigned long addr, const void *buf, \
> + unsigned int cnt) \
> +{ \
> + if (addr < MMIO_UPPER_LIMIT) \
> + writes##bw(PCI_IOBASE + addr, buf, cnt); \
> +}
> +#endif /* CONFIG_INDIRECT_PIO */
> +
> BUILD_LOGIC_IO(b, u8)
> EXPORT_SYMBOL(logic_inb);
> EXPORT_SYMBOL(logic_insb);
> @@ -277,4 +312,4 @@ EXPORT_SYMBOL(logic_insl);
> EXPORT_SYMBOL(logic_outl);
> EXPORT_SYMBOL(logic_outsl);
>
> -#endif /* CONFIG_INDIRECT_PIO && PCI_IOBASE */
> +#endif /* PCI_IOBASE */
> --
> 2.17.1
>

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