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Date: Fri, 23 Jul 2010 09:10:27 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: linux-pci@...r.kernel.org, Jesse Barnes <jbarnes@...tuousgeek.org>
Cc: linux-kernel@...r.kernel.org, chrisw@...hat.com,
ddutile@...hat.com, bjorn.helgaas@...com, eike-kernel@...tec.de
Subject: Re: [PATCH v2] pci: Allow read/write access to sysfs I/O port
resources
On Mon, 2010-07-19 at 09:45 -0600, Alex Williamson wrote:
> PCI sysfs resource files currently only allow mmap'ing. On x86 this
> works fine for memory backed BARs, but doesn't work at all for I/O
> port backed BARs. Add read/write to I/O port PCI sysfs resource
> files to allow userspace access to these device regions.
>
> Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
> ---
Any thoughts on this for -next? Thanks,
Alex
> v2: hopefully better commit log, remove unneeded cast, use bool
>
> Documentation/filesystems/sysfs-pci.txt | 7 ++-
> drivers/pci/pci-sysfs.c | 68 +++++++++++++++++++++++++++++++
> 2 files changed, 73 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
> index 85354b3..74eaac2 100644
> --- a/Documentation/filesystems/sysfs-pci.txt
> +++ b/Documentation/filesystems/sysfs-pci.txt
> @@ -39,7 +39,7 @@ files, each with their own function.
> local_cpus nearby CPU mask (cpumask, ro)
> remove remove device from kernel's list (ascii, wo)
> resource PCI resource host addresses (ascii, ro)
> - resource0..N PCI resource N, if present (binary, mmap)
> + resource0..N PCI resource N, if present (binary, mmap, rw[1])
> resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap)
> rom PCI ROM resource, if present (binary, ro)
> subsystem_device PCI subsystem device (ascii, ro)
> @@ -54,13 +54,16 @@ files, each with their own function.
> binary - file contains binary data
> cpumask - file contains a cpumask type
>
> +[1] rw for RESOURCE_IO (I/O port) regions only
> +
> The read only files are informational, writes to them will be ignored, with
> the exception of the 'rom' file. Writable files can be used to perform
> actions on the device (e.g. changing config space, detaching a device).
> mmapable files are available via an mmap of the file at offset 0 and can be
> used to do actual device programming from userspace. Note that some platforms
> don't support mmapping of certain resources, so be sure to check the return
> -value from any attempted mmap.
> +value from any attempted mmap. The most notable of these are I/O port
> +resources, which also provide read/write access.
>
> The 'enable' file provides a counter that indicates how many times the device
> has been enabled. If the 'enable' file currently returns '4', and a '1' is
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 5935b85..f7692dc 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -778,6 +778,70 @@ pci_mmap_resource_wc(struct file *filp, struct kobject *kobj,
> return pci_mmap_resource(kobj, attr, vma, 1);
> }
>
> +static ssize_t
> +pci_resource_io(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *attr, char *buf,
> + loff_t off, size_t count, bool write)
> +{
> + struct pci_dev *pdev = to_pci_dev(container_of(kobj,
> + struct device, kobj));
> + struct resource *res = attr->private;
> + unsigned long port = off;
> + int i;
> +
> + for (i = 0; i < PCI_ROM_RESOURCE; i++)
> + if (res == &pdev->resource[i])
> + break;
> + if (i >= PCI_ROM_RESOURCE)
> + return -ENODEV;
> +
> + port += pci_resource_start(pdev, i);
> +
> + if (port > pci_resource_end(pdev, i))
> + return 0;
> +
> + if (port + count - 1 > pci_resource_end(pdev, i))
> + return -EINVAL;
> +
> + switch (count) {
> + case 1:
> + if (write)
> + outb(*(u8 *)buf, port);
> + else
> + *(u8 *)buf = inb(port);
> + return 1;
> + case 2:
> + if (write)
> + outw(*(u16 *)buf, port);
> + else
> + *(u16 *)buf = inw(port);
> + return 2;
> + case 4:
> + if (write)
> + outl(*(u32 *)buf, port);
> + else
> + *(u32 *)buf = inl(port);
> + return 4;
> + }
> + return -EINVAL;
> +}
> +
> +static ssize_t
> +pci_read_resource_io(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *attr, char *buf,
> + loff_t off, size_t count)
> +{
> + return pci_resource_io(filp, kobj, attr, buf, off, count, false);
> +}
> +
> +static ssize_t
> +pci_write_resource_io(struct file *filp, struct kobject *kobj,
> + struct bin_attribute *attr, char *buf,
> + loff_t off, size_t count)
> +{
> + return pci_resource_io(filp, kobj, attr, buf, off, count, true);
> +}
> +
> /**
> * pci_remove_resource_files - cleanup resource files
> * @pdev: dev to cleanup
> @@ -828,6 +892,10 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
> sprintf(res_attr_name, "resource%d", num);
> res_attr->mmap = pci_mmap_resource_uc;
> }
> + if (pci_resource_flags(pdev, num) & IORESOURCE_IO) {
> + res_attr->read = pci_read_resource_io;
> + res_attr->write = pci_write_resource_io;
> + }
> res_attr->attr.name = res_attr_name;
> res_attr->attr.mode = S_IRUSR | S_IWUSR;
> res_attr->size = pci_resource_len(pdev, num);
>
--
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