Commit 711d5779 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Jesse Barnes
Browse files

PCI: expose function reset capability in sysfs

Some devices allow an individual function to be reset without affecting
other functions in the same device: that's what pci_reset_function does.
For devices that have this support, expose reset attribite in sysfs.

This is useful e.g. for virtualization, where a qemu userspace
process wants to reset the device when the guest is reset,
to emulate machine reboot as closely as possible.
Acked-by: default avatarGreg Kroah-Hartman <>
Signed-off-by: default avatarMichael S. Tsirkin <>
Signed-off-by: default avatarJesse Barnes <>
parent 5228a828
......@@ -84,6 +84,16 @@ Description:
from this part of the device tree.
What: /sys/bus/pci/devices/.../reset
Date: July 2009
Contact: Michael S. Tsirkin <>
Some devices allow an individual function to be reset
without affecting other functions in the same device.
For devices that have this support, a file named reset
will be present in sysfs. Writing 1 to this file
will perform reset.
What: /sys/bus/pci/devices/.../vpd
Date: February 2008
Contact: Ben Hutchings <>
......@@ -916,6 +916,24 @@ int __attribute__ ((weak)) pcibios_add_platform_entries(struct pci_dev *dev)
return 0;
static ssize_t reset_store(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
struct pci_dev *pdev = to_pci_dev(dev);
unsigned long val;
ssize_t result = strict_strtoul(buf, 0, &val);
if (result < 0)
return result;
if (val != 1)
return -EINVAL;
return pci_reset_function(pdev);
static struct device_attribute reset_attr = __ATTR(reset, 0200, NULL, reset_store);
static int pci_create_capabilities_sysfs(struct pci_dev *dev)
int retval;
......@@ -943,7 +961,22 @@ static int pci_create_capabilities_sysfs(struct pci_dev *dev)
/* Active State Power Management */
if (!pci_probe_reset_function(dev)) {
retval = device_create_file(&dev->dev, &reset_attr);
if (retval)
goto error;
dev->reset_fn = 1;
return 0;
if (dev->vpd && dev->vpd->attr) {
sysfs_remove_bin_file(&dev->dev.kobj, dev->vpd->attr);
return retval;
int __must_check pci_create_sysfs_dev_files (struct pci_dev *pdev)
......@@ -1037,6 +1070,10 @@ static void pci_remove_capabilities_sysfs(struct pci_dev *dev)
if (dev->reset_fn) {
device_remove_file(&dev->dev, &reset_attr);
dev->reset_fn = 0;
......@@ -2261,6 +2261,22 @@ int __pci_reset_function(struct pci_dev *dev)
* pci_probe_reset_function - check whether the device can be safely reset
* @dev: PCI device to reset
* Some devices allow an individual function to be reset without affecting
* other functions in the same device. The PCI device must be responsive
* to PCI config space in order to use this function.
* Returns 0 if the device function can be reset or negative if the
* device doesn't support resetting a single function.
int pci_probe_reset_function(struct pci_dev *dev)
return pci_dev_reset(dev, 1);
* pci_reset_function - quiesce and reset a PCI device function
* @dev: PCI device to reset
......@@ -16,6 +16,7 @@ extern void pci_cleanup_rom(struct pci_dev *dev);
extern int pci_mmap_fits(struct pci_dev *pdev, int resno,
struct vm_area_struct *vma);
int pci_probe_reset_function(struct pci_dev *dev);
* struct pci_platform_pm_ops - Firmware PM callbacks
......@@ -276,6 +276,7 @@ struct pci_dev {
unsigned int state_saved:1;
unsigned int is_physfn:1;
unsigned int is_virtfn:1;
unsigned int reset_fn:1;
pci_dev_flags_t dev_flags;
atomic_t enable_cnt; /* pci_enable_device has been called */
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