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    SubjectRe: [PATCH RFC 2/5] s390: add pci_iomap_range
    On Mon, 15 Dec 2014, Michael S. Tsirkin wrote:
    > From: Michael S Tsirkin <mst@redhat.com>
    >
    > Virtio drivers should map the part of the range they need, not
    > necessarily all of it.
    > To this end, support mapping ranges within BAR on s390.
    > Since multiple ranges can now be mapped within a BAR, we keep track of
    > the number of mappings created, and only clear out the mapping for a BAR
    > when this number reaches 0.
    >

    I can't say much about the users of this interface but in principle I'm
    OK with such a change.

    > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
    > ---
    > arch/s390/include/asm/pci_io.h | 1 +
    > arch/s390/pci/pci.c | 34 +++++++++++++++++++++++++++-------
    > 2 files changed, 28 insertions(+), 7 deletions(-)
    >
    > diff --git a/arch/s390/include/asm/pci_io.h b/arch/s390/include/asm/pci_io.h
    > index d194d54..25228b3 100644
    > --- a/arch/s390/include/asm/pci_io.h
    > +++ b/arch/s390/include/asm/pci_io.h
    > @@ -16,6 +16,7 @@
    > struct zpci_iomap_entry {
    > u32 fh;
    > u8 bar;
    > + u16 count;
    > };
    >
    > extern struct zpci_iomap_entry *zpci_iomap_start;
    > diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
    > index 2fa7b14..51cb653 100644
    > --- a/arch/s390/pci/pci.c
    > +++ b/arch/s390/pci/pci.c
    > @@ -259,7 +259,10 @@ void __iowrite64_copy(void __iomem *to, const void *from, size_t count)
    > }
    >
    > /* Create a virtual mapping cookie for a PCI BAR */
    > -void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
    > +void __iomem *pci_iomap_range(struct pci_dev *pdev,
    > + int bar,
    > + unsigned long offset,
    > + unsigned long max)
    > {
    > struct zpci_dev *zdev = get_zdev(pdev);
    > u64 addr;
    > @@ -270,14 +273,27 @@ void __iomem *pci_iomap(struct pci_dev *pdev, int bar, unsigned long max)
    >
    > idx = zdev->bars[bar].map_idx;
    > spin_lock(&zpci_iomap_lock);
    > - zpci_iomap_start[idx].fh = zdev->fh;
    > - zpci_iomap_start[idx].bar = bar;
    > + if (zpci_iomap_start[idx].count++) {
    > + BUG_ON(zpci_iomap_start[idx].fh != zdev->fh ||
    > + zpci_iomap_start[idx].bar != bar);
    > + } else {
    > + zpci_iomap_start[idx].fh = zdev->fh;
    > + zpci_iomap_start[idx].bar = bar;
    > + }
    > + /* Detect overrun */
    > + BUG_ON(!zpci_iomap_start[idx].count);
    > spin_unlock(&zpci_iomap_lock);
    >
    > addr = ZPCI_IOMAP_ADDR_BASE | ((u64) idx << 48);
    > - return (void __iomem *) addr;
    > + return (void __iomem *) addr + offset;
    > }
    > -EXPORT_SYMBOL_GPL(pci_iomap);
    > +EXPORT_SYMBOL_GPL(pci_iomap_range);
    > +
    > +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);

    This was EXPORT_SYMBOL_GPL. I guess, for this patch, it should stay that
    way. ...Hm, everyone else has this stuff as EXPORT_SYMBOL looks like we
    should use that too.

    Regards,
    Sebastian

    >
    > void pci_iounmap(struct pci_dev *pdev, void __iomem *addr)
    > {
    > @@ -285,8 +301,12 @@ void pci_iounmap(struct pci_dev *pdev, void __iomem *addr)
    >
    > idx = (((__force u64) addr) & ~ZPCI_IOMAP_ADDR_BASE) >> 48;
    > spin_lock(&zpci_iomap_lock);
    > - zpci_iomap_start[idx].fh = 0;
    > - zpci_iomap_start[idx].bar = 0;
    > + /* Detect underrun */
    > + BUG_ON(!zpci_iomap_start[idx].count);
    > + if (!--zpci_iomap_start[idx].count) {
    > + zpci_iomap_start[idx].fh = 0;
    > + zpci_iomap_start[idx].bar = 0;
    > + }
    > spin_unlock(&zpci_iomap_lock);
    > }
    > EXPORT_SYMBOL_GPL(pci_iounmap);
    > --
    > MST
    >
    >



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