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Message-ID: <20140930085933.GM841@e106497-lin.cambridge.arm.com>
Date: Tue, 30 Sep 2014 09:59:33 +0100
From: Liviu Dudau <Liviu.Dudau@....com>
To: Al Stone <ahs3@...hat.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>,
Rob Herring <robh+dt@...nel.org>,
Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Catalin Marinas <Catalin.Marinas@....com>,
Will Deacon <Will.Deacon@....com>,
Russell King <linux@....linux.org.uk>,
linux-pci <linux-pci@...r.kernel.org>,
Linus Walleij <linus.walleij@...aro.org>,
linux-arch <linux-arch@...r.kernel.org>,
Sinan Kaya <okaya@...eaurora.org>,
Kukjin Kim <kgene.kim@...sung.com>,
Device Tree ML <devicetree@...r.kernel.org>,
Jingoo Han <jg1.han@...sung.com>,
LKML <linux-kernel@...r.kernel.org>,
Grant Likely <grant.likely@...retlab.ca>,
Tanmay Inamdar <tinamdar@....com>,
Suravee Suthikulanit <suravee.suthikulpanit@....com>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Yinghai Lu <yinghai@...nel.org>,
Jiang Liu <jiang.liu@...ux.intel.com>,
LAKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v13 02/12] of/pci: Add pci_register_io_range() and
pci_pio_to_address()
On Mon, Sep 29, 2014 at 08:20:30PM +0100, Al Stone wrote:
> On 09/29/2014 08:29 AM, Liviu Dudau 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.
> >
> > Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
> > Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> > Reviewed-by: Catalin Marinas <catalin.marinas@....com>
> > Acked-by: Rob Herring <robh@...nel.org>
> > CC: Grant Likely <grant.likely@...aro.org>
> > CC: Arnd Bergmann <arnd@...db.de>
> > ---
> > drivers/of/address.c | 109 +++++++++++++++++++++++++++++++++++++++++++++
> > include/linux/of_address.h | 2 +
> > 2 files changed, 111 insertions(+)
> >
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index e371825..758d4f0 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -5,6 +5,8 @@
> > #include <linux/module.h>
> > #include <linux/of_address.h>
> > #include <linux/pci_regs.h>
> > +#include <linux/sizes.h>
> > +#include <linux/slab.h>
> > #include <linux/string.h>
> >
> > /* Max address size we deal with */
> > @@ -601,12 +603,119 @@ 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)
> > +{
> > + int err = 0;
> > +
> > +#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) {
> > + /* range already registered, bail out */
> > + goto end_register;
> > + }
> > + allocated_size += range->size;
> > + }
> > +
> > + /* 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) {
> > + err = -E2BIG;
> > + goto end_register;
> > + }
> > +
> > + 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) {
> > + err = -ENOMEM;
> > + goto end_register;
> > + }
> > +
> > + range->start = addr;
> > + range->size = size;
> > +
> > + list_add_tail(&range->list, &io_range_list);
> > +
> > +end_register:
> > + spin_unlock(&io_range_lock);
> > +#endif
> > +
> > + return err;
> > +}
> > +
> > +phys_addr_t pci_pio_to_address(unsigned long pio)
> > +{
> > + phys_addr_t address = (phys_addr_t)OF_BAD_ADDR;
Hi Al,
>
> This reference to OF_BAD_ADDR is the only thing I'm seeing in this
> patch that is DT specific.
>
> Couldn't these helper functions be more useful if provided outside
> of DT, perhaps in the PCI code instead? I was giving some thought
> to re-using them for ACPI support of PCI but don't want to have to
> build DT if I'm not really going to use it.
The reason why I've put it (now) in drivers/of is that the code is only
used by DT specific code. At some moment one of the older series put
it into drivers/pci but I was trying to make it more clear that this
is DT specific.
If you find this useful for ACPI (and this series lands in v3.18) then
I suggest you send a patch to move it into drivers/pci?
Best regards,
Liviu
>
> > +#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;
> > + unsigned long addr = -1;
> > +
> > + spin_lock(&io_range_lock);
> > + list_for_each_entry(res, &io_range_list, list) {
> > + if (address >= res->start && address < res->start + res->size) {
> > + addr = res->start - address + offset;
> > + break;
> > + }
> > + offset += res->size;
> > + }
> > + spin_unlock(&io_range_lock);
> > +
> > + return addr;
> > +#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 fb7b722..f8cc7da 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);
> >
>
>
> --
> ciao,
> al
> -----------------------------------
> Al Stone
> Software Engineer
> Red Hat, Inc.
> ahs3@...hat.com
> -----------------------------------
>
--
====================
| I would like to |
| fix the world, |
| but they're not |
| giving me the |
\ source code! /
---------------
¯\_(ツ)_/¯
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