[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 05/47] pci: add pci_iomap_wc() variants
On Fri, Mar 20, 2015 at 04:17:55PM -0700, Luis R. Rodriguez wrote: > From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx> > > This allows drivers to take advantage of write-combining > when possible. Ideally we'd have pci_read_bases() just > peg an IORESOURCE_WC flag for us but where exactly > video devices memory lie varies *largely* and at times things > are mixed with MMIO registers, sometimes we can address > the changes in drivers, other times the change requires > intrusive changes. > > Although there is also arch_phys_wc_add() that makes use of > architecture specific write-combinging alternatives (MTRR on combinging? > x86 when a system does not have PAT) we void polluting > pci_iomap() space with it and force drivers and subsystems > that want to use it to be explicit. > > There are a few motivations for this: > > a) Take advantage of PAT when available > > b) Help bury MTRR code away, MTRR is architecture specific and on > x86 its replaced by PAT > > c) Help with the goal of eventually using _PAGE_CACHE_UC over > _PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (de33c442e) > > Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> > Cc: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> > Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Juergen Gross <jgross@xxxxxxxx> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > Cc: Dave Airlie <airlied@xxxxxxxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: Antonino Daplas <adaplas@xxxxxxxxx> > Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx> > Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx> > Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxx> > Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> > Cc: venkatesh.pallipadi@xxxxxxxxx > Cc: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> > Cc: konrad.wilk@xxxxxxxxxx > Cc: ville.syrjala@xxxxxxxxxxxxxxx > Cc: david.vrabel@xxxxxxxxxx > Cc: jbeulich@xxxxxxxx > Cc: toshi.kani@xxxxxx > Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx> > Cc: linux-fbdev@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx > Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx> > --- > include/asm-generic/pci_iomap.h | 14 ++++++++++ > lib/pci_iomap.c | 61 > +++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 75 insertions(+) > > diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h > index 7389c87..b1e17fc 100644 > --- a/include/asm-generic/pci_iomap.h > +++ b/include/asm-generic/pci_iomap.h > @@ -15,9 +15,13 @@ struct pci_dev; > #ifdef CONFIG_PCI > /* Create a virtual mapping cookie for a PCI BAR (memory or IO) */ > extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long > max); > +extern void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned > long max); > extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, > unsigned long offset, > unsigned long maxlen); > +extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, > + unsigned long offset, > + unsigned long maxlen); > /* Create a virtual mapping cookie for a port on a given PCI device. > * Do not call this directly, it exists to make it easier for architectures > * to override */ > @@ -34,12 +38,22 @@ static inline void __iomem *pci_iomap(struct pci_dev > *dev, int bar, unsigned lon > return NULL; > } > > +static inline void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, > unsigned long max) > +{ > + return NULL; > +} > static inline void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, > unsigned long offset, > unsigned long maxlen) > { > return NULL; > } > +static inline void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, > + unsigned long offset, > + unsigned long maxlen) > +{ > + return NULL; > +} > #endif > > #endif /* __ASM_GENERIC_IO_H */ > diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c > index bcce5f1..30b65ae 100644 > --- a/lib/pci_iomap.c > +++ b/lib/pci_iomap.c > @@ -52,6 +52,46 @@ void __iomem *pci_iomap_range(struct pci_dev *dev, > EXPORT_SYMBOL(pci_iomap_range); > > /** > + * pci_iomap_wc_range - create a virtual WC mapping cookie for a PCI BAR > + * @dev: PCI device that owns the BAR > + * @bar: BAR number > + * @offset: map memory at the given offset in BAR > + * @maxlen: max length of the memory to map > + * > + * Using this function you will get a __iomem address to your device BAR. > + * You can access it using ioread*() and iowrite*(). These functions hide > + * the details if this is a MMIO or PIO address space and will just do what > + * you expect from them in the correct way. When possible write combining > + * is used. > + * > + * @maxlen specifies the maximum length to map. If you want to get access to > + * the complete BAR from offset to the end, pass %0 here. s/%0/0 ? Or is that some special syntax? > + * */ > +void __iomem *pci_iomap_wc_range(struct pci_dev *dev, > + int bar, > + unsigned long offset, > + unsigned long maxlen) > +{ > + resource_size_t start = pci_resource_start(dev, bar); > + resource_size_t len = pci_resource_len(dev, bar); > + unsigned long flags = pci_resource_flags(dev, bar); > + > + if (len <= offset || !start) > + return NULL; > + len -= offset; > + start += offset; > + if (maxlen && len > maxlen) > + len = maxlen; > + if (flags & IORESOURCE_IO) > + return __pci_ioport_map(dev, start, len); > + if (flags & IORESOURCE_MEM) > + return ioremap_wc(start, len); > + /* What? */ > + return NULL; > +} > +EXPORT_SYMBOL_GPL(pci_iomap_wc_range); > + > +/** > * pci_iomap - create a virtual mapping cookie for a PCI BAR > * @dev: PCI device that owns the BAR > * @bar: BAR number > @@ -70,4 +110,25 @@ void __iomem *pci_iomap(struct pci_dev *dev, int bar, > unsigned long maxlen) > return pci_iomap_range(dev, bar, 0, maxlen); > } > EXPORT_SYMBOL(pci_iomap); > + > +/** > + * pci_iomap_wc - create a virtual WC mapping cookie for a PCI BAR > + * @dev: PCI device that owns the BAR > + * @bar: BAR number > + * @maxlen: length of the memory to map > + * > + * Using this function you will get a __iomem address to your device BAR. > + * You can access it using ioread*() and iowrite*(). These functions hide > + * the details if this is a MMIO or PIO address space and will just do what > + * you expect from them in the correct way. When possible write combining > + * is used. > + * > + * @maxlen specifies the maximum length to map. If you want to get access to > + * the complete BAR without checking for its length first, pass %0 here. > + * */ > +void __iomem *pci_iomap_wc(struct pci_dev *dev, int bar, unsigned long > maxlen) > +{ > + return pci_iomap_wc_range(dev, bar, 0, maxlen); > +} > +EXPORT_SYMBOL_GPL(pci_iomap_wc); > #endif /* CONFIG_PCI */ > -- > 2.3.2.209.gd67f9d5.dirty > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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