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>

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>
Alex Williamson · Jesse Barnes
1 parent 2491762cfb
Showing 2 changed files with 73 additions and 2 deletions Side-by-side Diff
Documentation/filesystems/sysfs-pci.txt
drivers/pci/pci-sysfs.c
@@ -39,7 +39,7 @@
        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 @@
   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
@@ -778,6 +778,70 @@
 	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
@@ -827,6 +891,10 @@
 			pdev->res_attr[num] = res_attr;
 			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;
...	...	@@ -39,7 +39,7 @@
39	39	local_cpus nearby CPU mask (cpumask, ro)
40	40	remove remove device from kernel's list (ascii, wo)
41	41	resource PCI resource host addresses (ascii, ro)
42		- resource0..N PCI resource N, if present (binary, mmap)
	42	+ resource0..N PCI resource N, if present (binary, mmap, rw[1])
43	43	resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap)
44	44	rom PCI ROM resource, if present (binary, ro)
45	45	subsystem_device PCI subsystem device (ascii, ro)
46	46
...	...	@@ -54,13 +54,16 @@
54	54	binary - file contains binary data
55	55	cpumask - file contains a cpumask type
56	56
	57	+[1] rw for RESOURCE_IO (I/O port) regions only
	58	+
57	59	The read only files are informational, writes to them will be ignored, with
58	60	the exception of the 'rom' file. Writable files can be used to perform
59	61	actions on the device (e.g. changing config space, detaching a device).
60	62	mmapable files are available via an mmap of the file at offset 0 and can be
61	63	used to do actual device programming from userspace. Note that some platforms
62	64	don't support mmapping of certain resources, so be sure to check the return
63		-value from any attempted mmap.
	65	+value from any attempted mmap. The most notable of these are I/O port
	66	+resources, which also provide read/write access.
64	67
65	68	The 'enable' file provides a counter that indicates how many times the device
66	69	has been enabled. If the 'enable' file currently returns '4', and a '1' is
...	...	@@ -778,6 +778,70 @@
778	778	return pci_mmap_resource(kobj, attr, vma, 1);
779	779	}
780	780
	781	+static ssize_t
	782	+pci_resource_io(struct file filp, struct kobject kobj,
	783	+ struct bin_attribute attr, char buf,
	784	+ loff_t off, size_t count, bool write)
	785	+{
	786	+ struct pci_dev *pdev = to_pci_dev(container_of(kobj,
	787	+ struct device, kobj));
	788	+ struct resource *res = attr->private;
	789	+ unsigned long port = off;
	790	+ int i;
	791	+
	792	+ for (i = 0; i < PCI_ROM_RESOURCE; i++)
	793	+ if (res == &pdev->resource[i])
	794	+ break;
	795	+ if (i >= PCI_ROM_RESOURCE)
	796	+ return -ENODEV;
	797	+
	798	+ port += pci_resource_start(pdev, i);
	799	+
	800	+ if (port > pci_resource_end(pdev, i))
	801	+ return 0;
	802	+
	803	+ if (port + count - 1 > pci_resource_end(pdev, i))
	804	+ return -EINVAL;
	805	+
	806	+ switch (count) {
	807	+ case 1:
	808	+ if (write)
	809	+ outb((u8 )buf, port);
	810	+ else
	811	+ (u8 )buf = inb(port);
	812	+ return 1;
	813	+ case 2:
	814	+ if (write)
	815	+ outw((u16 )buf, port);
	816	+ else
	817	+ (u16 )buf = inw(port);
	818	+ return 2;
	819	+ case 4:
	820	+ if (write)
	821	+ outl((u32 )buf, port);
	822	+ else
	823	+ (u32 )buf = inl(port);
	824	+ return 4;
	825	+ }
	826	+ return -EINVAL;
	827	+}
	828	+
	829	+static ssize_t
	830	+pci_read_resource_io(struct file filp, struct kobject kobj,
	831	+ struct bin_attribute attr, char buf,
	832	+ loff_t off, size_t count)
	833	+{
	834	+ return pci_resource_io(filp, kobj, attr, buf, off, count, false);
	835	+}
	836	+
	837	+static ssize_t
	838	+pci_write_resource_io(struct file filp, struct kobject kobj,
	839	+ struct bin_attribute attr, char buf,
	840	+ loff_t off, size_t count)
	841	+{
	842	+ return pci_resource_io(filp, kobj, attr, buf, off, count, true);
	843	+}
	844	+
781	845	/**
782	846	* pci_remove_resource_files - cleanup resource files
783	847	* @pdev: dev to cleanup
...	...	@@ -827,6 +891,10 @@
827	891	pdev->res_attr[num] = res_attr;
828	892	sprintf(res_attr_name, "resource%d", num);
829	893	res_attr->mmap = pci_mmap_resource_uc;
	894	+ }
	895	+ if (pci_resource_flags(pdev, num) & IORESOURCE_IO) {
	896	+ res_attr->read = pci_read_resource_io;
	897	+ res_attr->write = pci_write_resource_io;
830	898	}
831	899	res_attr->attr.name = res_attr_name;
832	900	res_attr->attr.mode = S_IRUSR \| S_IWUSR;