PCI: Allow read/write access to sysfs I/O port resources

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.

Acked-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 68 insertions, 0 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 5935b854917f..f7692dc531e4 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);