Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

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 <gregkh@suse.de>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent 5228a828

Documentation/ABI/testing/sysfs-bus-pci

+10 −0
Original line number Diff line number Diff line
@@ -84,6 +84,16 @@ Description: 
		from this part of the device tree.

		Depends on CONFIG_HOTPLUG.



What:		/sys/bus/pci/devices/.../reset

Date:		July 2009

Contact:	Michael S. Tsirkin <mst@redhat.com>

Description:

		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 <bhutchings@solarflare.com>

drivers/pci/pci-sysfs.c

+37 −0
Original line number Diff line number Diff line
@@ -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 */

	pcie_aspm_create_sysfs_dev_files(dev);



	if (!pci_probe_reset_function(dev)) {

		retval = device_create_file(&dev->dev, &reset_attr);

		if (retval)

			goto error;

		dev->reset_fn = 1;

	}

	return 0;



error:

	pcie_aspm_remove_sysfs_dev_files(dev);

	if (dev->vpd && dev->vpd->attr) {

		sysfs_remove_bin_file(&dev->dev.kobj, dev->vpd->attr);

		kfree(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) 
	}



	pcie_aspm_remove_sysfs_dev_files(dev);

	if (dev->reset_fn) {

		device_remove_file(&dev->dev, &reset_attr);

		dev->reset_fn = 0;

	}

}



/**

drivers/pci/pci.c

+16 −0
Original line number Diff line number Diff line
@@ -2261,6 +2261,22 @@ int __pci_reset_function(struct pci_dev *dev) 
}

EXPORT_SYMBOL_GPL(__pci_reset_function);



/**

 * 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

drivers/pci/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

#endif

int pci_probe_reset_function(struct pci_dev *dev);



/**

 * struct pci_platform_pm_ops - Firmware PM callbacks

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */