Message-ID: <20161109165044.GE10219@e106497-lin.cambridge.arm.com>
Date:   Wed, 9 Nov 2016 16:50:44 +0000
From:   "liviu.dudau@....com" <liviu.dudau@....com>
To:     Gabriele Paoloni <gabriele.paoloni@...wei.com>
Cc:     Yuanzhichang <yuanzhichang@...ilicon.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "olof@...om.net" <olof@...om.net>, "arnd@...db.de" <arnd@...db.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "minyard@....org" <minyard@....org>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "zourongrong@...il.com" <zourongrong@...il.com>,
        John Garry <john.garry@...wei.com>,
        "zhichang.yuan02@...il.com" <zhichang.yuan02@...il.com>,
        "kantyzc@....com" <kantyzc@....com>,
        "xuwei (O)" <xuwei5@...ilicon.com>
Subject: Re: [PATCH V5 2/3] ARM64 LPC: Add missing range exception for
 special ISA

On Wed, Nov 09, 2016 at 04:16:17PM +0000, Gabriele Paoloni wrote:
> Hi Liviu
> 
> Thanks for reviewing
> 

[removed some irrelevant part of discussion, avoid crazy formatting]

> > > +/**
> > > + * addr_is_indirect_io - check whether the input taddr is for
> > indirectIO.
> > > + * @taddr: the io address to be checked.
> > > + *
> > > + * Returns 1 when taddr is in the range; otherwise return 0.
> > > + */
> > > +int addr_is_indirect_io(u64 taddr)
> > > +{
> > > +	if (arm64_extio_ops->start > taddr || arm64_extio_ops->end <
> > taddr)
> > 
> > start >= taddr ?
> 
> Nope... if  (taddr < arm64_extio_ops->start || taddr > arm64_extio_ops->end)
> then taddr is outside the range [start; end] and will return 0; otherwise
> it will return 1...

Oops, sorry, did not pay attention to the returned value. The check is
correct as it is, no need to change then.

> 
> > 
> > > +		return 0;
> > > +
> > > +	return 1;
> > > +}
> > >
> > >  BUILD_EXTIO(b, u8)
> > >
> > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > index 02b2903..cc2a05d 100644
> > > --- a/drivers/of/address.c
> > > +++ b/drivers/of/address.c
> > > @@ -479,6 +479,50 @@ static int of_empty_ranges_quirk(struct
> > device_node *np)
> > >  	return false;
> > >  }
> > >
> > > +
> > > +/*
> > > + * of_isa_indirect_io - get the IO address from some isa reg
> > property value.
> > > + *	For some isa/lpc devices, no ranges property in ancestor node.
> > > + *	The device addresses are described directly in their regs
> > property.
> > > + *	This fixup function will be called to get the IO address of
> > isa/lpc
> > > + *	devices when the normal of_translation failed.
> > > + *
> > > + * @parent:	points to the parent dts node;
> > > + * @bus:		points to the of_bus which can be used to parse
> > address;
> > > + * @addr:	the address from reg property;
> > > + * @na:		the address cell counter of @addr;
> > > + * @presult:	store the address paresed from @addr;
> > > + *
> > > + * return 1 when successfully get the I/O address;
> > > + * 0 will return for some failures.
> > 
> > Bah, you are returning a signed int, why 0 for failure? Return a
> > negative value with
> > error codes. Otherwise change the return value into a bool.
> 
> Yes we'll move to bool
> 
> > 
> > > + */
> > > +static int of_get_isa_indirect_io(struct device_node *parent,
> > > +				struct of_bus *bus, __be32 *addr,
> > > +				int na, u64 *presult)
> > > +{
> > > +	unsigned int flags;
> > > +	unsigned int rlen;
> > > +
> > > +	/* whether support indirectIO */
> > > +	if (!indirect_io_enabled())
> > > +		return 0;
> > > +
> > > +	if (!of_bus_isa_match(parent))
> > > +		return 0;
> > > +
> > > +	flags = bus->get_flags(addr);
> > > +	if (!(flags & IORESOURCE_IO))
> > > +		return 0;
> > > +
> > > +	/* there is ranges property, apply the normal translation
> > directly. */
> > 
> > s/there is ranges/if we have a 'ranges'/
> 
> Thanks for spotting this
> 
> > 
> > > +	if (of_get_property(parent, "ranges", &rlen))
> > > +		return 0;
> > > +
> > > +	*presult = of_read_number(addr + 1, na - 1);
> > > +	/* this fixup is only valid for specific I/O range. */
> > > +	return addr_is_indirect_io(*presult);
> > > +}
> > > +
> > >  static int of_translate_one(struct device_node *parent, struct
> > of_bus *bus,
> > >  			    struct of_bus *pbus, __be32 *addr,
> > >  			    int na, int ns, int pna, const char *rprop)
> > > @@ -595,6 +639,15 @@ static u64 __of_translate_address(struct
> > device_node *dev,
> > >  			result = of_read_number(addr, na);
> > >  			break;
> > >  		}
> > > +		/*
> > > +		 * For indirectIO device which has no ranges property, get
> > > +		 * the address from reg directly.
> > > +		 */
> > > +		if (of_get_isa_indirect_io(dev, bus, addr, na, &result)) {
> > > +			pr_debug("isa indirectIO matched(%s)..addr =
> > 0x%llx\n",
> > > +				of_node_full_name(dev), result);
> > > +			break;
> > > +		}
> > >
> > >  		/* Get new parent bus and counts */
> > >  		pbus = of_match_bus(parent);
> > > @@ -688,8 +741,9 @@ static int __of_address_to_resource(struct
> > device_node *dev,
> > >  	if (taddr == OF_BAD_ADDR)
> > >  		return -EINVAL;
> > >  	memset(r, 0, sizeof(struct resource));
> > > -	if (flags & IORESOURCE_IO) {
> > > +	if (flags & IORESOURCE_IO && taddr >= PCIBIOS_MIN_IO) {
> > >  		unsigned long port;
> > > +
> > >  		port = pci_address_to_pio(taddr);
> > >  		if (port == (unsigned long)-1)
> > >  			return -EINVAL;
> > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > > index ba34907..1a08511 100644
> > > --- a/drivers/pci/pci.c
> > > +++ b/drivers/pci/pci.c
> > > @@ -3263,7 +3263,7 @@ int __weak pci_register_io_range(phys_addr_t
> > addr, resource_size_t size)
> > >
> > >  #ifdef PCI_IOBASE
> > >  	struct io_range *range;
> > > -	resource_size_t allocated_size = 0;
> > > +	resource_size_t allocated_size = PCIBIOS_MIN_IO;
> > >
> > >  	/* check if the range hasn't been previously recorded */
> > >  	spin_lock(&io_range_lock);
> > > @@ -3312,7 +3312,7 @@ phys_addr_t pci_pio_to_address(unsigned long
> > pio)
> > >
> > >  #ifdef PCI_IOBASE
> > >  	struct io_range *range;
> > > -	resource_size_t allocated_size = 0;
> > > +	resource_size_t allocated_size = PCIBIOS_MIN_IO;
> > 
> > Have you checked that pci_pio_to_address still returns valid values
> > after this? I know that
> > you are trying to take into account PCIBIOS_MIN_IO limit when
> > allocating reserving the IO ranges,
> > but the values added in the io_range_list are still starting from zero,
> > no from PCIBIOS_MIN_IO,
> 
> I think you're wrong here as in pci_address_to_pio we have:
> +	resource_size_t offset = PCIBIOS_MIN_IO;
> 
> This should be enough to guarantee that the PIOs start at
> PCIBIOS_MIN_IO...right?

I don't think you can guarantee that the pio value that gets passed into
pci_pio_to_address() always comes from a previously returned value by
pci_address_to_pio(). Maybe you can add a check in pci_pio_to_address()

	if (pio < PCIBIOS_MIN_IO)
		return address;

to avoid adding more checks in the list_for_each_entry() loop.

Best regards,
Liviu

> 
> 
> > so the calculation of the address in this function could return
> > negative values casted to pci_addr_t.
> > 
> > Maybe you want to adjust the range->start value in
> > pci_register_io_range() as well to have it
> > offset by PCIBIOS_MIN_IO as well.
> > 
> > Best regards,
> > Liviu
> > 
> > >
> > >  	if (pio > IO_SPACE_LIMIT)
> > >  		return address;
> > > @@ -3335,7 +3335,7 @@ unsigned long __weak
> > pci_address_to_pio(phys_addr_t address)
> > >  {
> > >  #ifdef PCI_IOBASE
> > >  	struct io_range *res;
> > > -	resource_size_t offset = 0;
> > > +	resource_size_t offset = PCIBIOS_MIN_IO;
> > >  	unsigned long addr = -1;
> > >
> > >  	spin_lock(&io_range_lock);
> > > diff --git a/include/linux/of_address.h b/include/linux/of_address.h
> > > index 3786473..deec469 100644
> > > --- a/include/linux/of_address.h
> > > +++ b/include/linux/of_address.h
> > > @@ -24,6 +24,23 @@ struct of_pci_range {
> > >  #define for_each_of_pci_range(parser, range) \
> > >  	for (; of_pci_range_parser_one(parser, range);)
> > >
> > > +
> > > +#ifndef indirect_io_enabled
> > > +#define indirect_io_enabled indirect_io_enabled
> > > +static inline bool indirect_io_enabled(void)
> > > +{
> > > +	return false;
> > > +}
> > > +#endif
> > > +
> > > +#ifndef addr_is_indirect_io
> > > +#define addr_is_indirect_io addr_is_indirect_io
> > > +static inline int addr_is_indirect_io(u64 taddr)
> > > +{
> > > +	return 0;
> > > +}
> > > +#endif
> > > +
> > >  /* Translate a DMA address from device space to CPU space */
> > >  extern u64 of_translate_dma_address(struct device_node *dev,
> > >  				    const __be32 *in_addr);
> > > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > > index 0e49f70..7f6bbb6 100644
> > > --- a/include/linux/pci.h
> > > +++ b/include/linux/pci.h
> > > @@ -2130,4 +2130,12 @@ static inline bool pci_ari_enabled(struct
> > pci_bus *bus)
> > >  /* provide the legacy pci_dma_* API */
> > >  #include <linux/pci-dma-compat.h>
> > >
> > > +/*
> > > + * define this macro here to refrain from compilation error for some
> > > + * platforms. Please keep this macro at the end of this header file.
> > > + */
> > > +#ifndef PCIBIOS_MIN_IO
> > > +#define PCIBIOS_MIN_IO		0
> > > +#endif
> > > +
> > >  #endif /* LINUX_PCI_H */
> > > --
> > > 1.9.1
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-pci"
> > in
> > > the body of a message to majordomo@...r.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

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