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Date: Sun, 18 Jul 2010 21:15:48 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
chrisw@...hat.com, ddutile@...hat.com, bjorn.helgaas@...com
Subject: [PATCH] pci: Allow read/write access to I/O port resources
PCI sysfs resource files currently only allow mmap'ing, which doesn't
work on all architectures, particularly x86. Add read/write to
allow access to these device regions using sysfs.
Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
---
I intend to use this for KVM PCI device assignment to avoid raw in/out
in the code and allow permissions based on pci sysfs files rather than
iopl/ioperm.
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..c98ea15 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, int write)
+{
+ struct pci_dev *pdev = to_pci_dev(container_of(kobj,
+ struct device, kobj));
+ struct resource *res = (struct resource *)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, 0);
+}
+
+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, 1);
+}
+
/**
* 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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