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    SubjectRe: [PATCH v9 03/12] PCI: Introduce helper functions to deal with PCI I/O ranges.
    On Tue, Aug 12, 2014 at 11:25 AM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
    > Some architectures do not have a simple view of the PCI I/O space
    > and instead use a range of CPU addresses that map to bus addresses.
    > For some architectures these ranges will be expressed by OF bindings
    > in a device tree file.
    >
    > This patch introduces a pci_register_io_range() helper function with
    > a generic implementation that can be used by such architectures to
    > keep track of the I/O ranges described by the PCI bindings. If the
    > PCI_IOBASE macro is not defined that signals lack of support for PCI
    > and we return an error.
    >
    > In order to retrieve the CPU address associated with an I/O port, a
    > new helper function pci_pio_to_address() is introduced. This will
    > search in the list of ranges registered with pci_register_io_range()
    > and return the CPU address that corresponds to the given port.
    >
    > Cc: Grant Likely <grant.likely@linaro.org>
    > Cc: Rob Herring <robh+dt@kernel.org>
    > Cc: Arnd Bergmann <arnd@arndb.de>
    > Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>

    Acked-by: Rob Herring <robh@kernel.org>


    > ---
    > drivers/of/address.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++
    > include/linux/of_address.h | 2 +
    > 2 files changed, 97 insertions(+)
    >
    > diff --git a/drivers/of/address.c b/drivers/of/address.c
    > index 5edfcb0..4dab700 100644
    > --- a/drivers/of/address.c
    > +++ b/drivers/of/address.c
    > @@ -5,6 +5,7 @@
    > #include <linux/module.h>
    > #include <linux/of_address.h>
    > #include <linux/pci_regs.h>
    > +#include <linux/slab.h>
    > #include <linux/string.h>
    >
    > /* Max address size we deal with */
    > @@ -601,12 +602,106 @@ const __be32 *of_get_address(struct device_node *dev, int index, u64 *size,
    > }
    > EXPORT_SYMBOL(of_get_address);
    >
    > +#ifdef PCI_IOBASE
    > +struct io_range {
    > + struct list_head list;
    > + phys_addr_t start;
    > + resource_size_t size;
    > +};
    > +
    > +static LIST_HEAD(io_range_list);
    > +static DEFINE_SPINLOCK(io_range_lock);
    > +#endif
    > +
    > +/*
    > + * Record the PCI IO range (expressed as CPU physical address + size).
    > + * Return a negative value if an error has occured, zero otherwise
    > + */
    > +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;
    > +
    > + /* check if the range hasn't been previously recorded */
    > + spin_lock(&io_range_lock);
    > + list_for_each_entry(range, &io_range_list, list) {
    > + if (addr >= range->start && addr + size <= range->start + size)
    > + return 0;
    > + allocated_size += range->size;
    > + }
    > + spin_unlock(&io_range_lock);
    > +
    > + /* range not registed yet, check for available space */
    > + if (allocated_size + size - 1 > IO_SPACE_LIMIT) {
    > + /* if it's too big check if 64K space can be reserved */
    > + if (allocated_size + SZ_64K - 1 > IO_SPACE_LIMIT)
    > + return -E2BIG;
    > +
    > + size = SZ_64K;
    > + pr_warn("Requested IO range too big, new size set to 64K\n");
    > + }
    > +
    > + /* add the range to the list */
    > + range = kzalloc(sizeof(*range), GFP_KERNEL);
    > + if (!range)
    > + return -ENOMEM;
    > +
    > + range->start = addr;
    > + range->size = size;
    > +
    > + list_add_tail(&range->list, &io_range_list);
    > +#endif
    > +
    > + return 0;
    > +}
    > +
    > +phys_addr_t pci_pio_to_address(unsigned long pio)
    > +{
    > + phys_addr_t address = (phys_addr_t)OF_BAD_ADDR;
    > +
    > +#ifdef PCI_IOBASE
    > + struct io_range *range;
    > + resource_size_t allocated_size = 0;
    > +
    > + if (pio > IO_SPACE_LIMIT)
    > + return address;
    > +
    > + spin_lock(&io_range_lock);
    > + list_for_each_entry(range, &io_range_list, list) {
    > + if (pio >= allocated_size && pio < allocated_size + range->size) {
    > + address = range->start + pio - allocated_size;
    > + break;
    > + }
    > + allocated_size += range->size;
    > + }
    > + spin_unlock(&io_range_lock);
    > +#endif
    > +
    > + return address;
    > +}
    > +
    > unsigned long __weak pci_address_to_pio(phys_addr_t address)
    > {
    > +#ifdef PCI_IOBASE
    > + struct io_range *res;
    > + resource_size_t offset = 0;
    > +
    > + list_for_each_entry(res, &io_range_list, list) {
    > + if (address >= res->start &&
    > + address < res->start + res->size) {
    > + return res->start - address + offset;
    > + }
    > + offset += res->size;
    > + }
    > +
    > + return (unsigned long)-1;
    > +#else
    > if (address > IO_SPACE_LIMIT)
    > return (unsigned long)-1;
    >
    > return (unsigned long) address;
    > +#endif
    > }
    >
    > static int __of_address_to_resource(struct device_node *dev,
    > diff --git a/include/linux/of_address.h b/include/linux/of_address.h
    > index c13b878..28e6836 100644
    > --- a/include/linux/of_address.h
    > +++ b/include/linux/of_address.h
    > @@ -55,7 +55,9 @@ extern void __iomem *of_iomap(struct device_node *device, int index);
    > extern const __be32 *of_get_address(struct device_node *dev, int index,
    > u64 *size, unsigned int *flags);
    >
    > +extern int pci_register_io_range(phys_addr_t addr, resource_size_t size);
    > extern unsigned long pci_address_to_pio(phys_addr_t addr);
    > +extern phys_addr_t pci_pio_to_address(unsigned long pio);
    >
    > extern int of_pci_range_parser_init(struct of_pci_range_parser *parser,
    > struct device_node *node);
    > --
    > 2.0.4
    >
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


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