Commit 75568f80 authored by Alex Chiang's avatar Alex Chiang Committed by Jesse Barnes
Browse files

PCI: create function symlinks in /sys/bus/pci/slots/N/ 



Create convenience symlinks in sysfs, linking slots to device
functions, and vice versa. These links make it easier for users to
figure out which devices actually live in what slots.

For example:

sapphire:/sys/bus/pci/slots # ls
1  10  2  3  4  5  6  7  8  9

sapphire:/sys/bus/pci/slots # ls -l 3
total 0
-r--r--r-- 1 root root 65536 Aug 18 14:10 address
lrwxrwxrwx 1 root root     0 Aug 18 14:10 function0 ->
../../../../devices/pci0000:23/0000:23:01.0
lrwxrwxrwx 1 root root     0 Aug 18 14:10 function1 ->
../../../../devices/pci0000:23/0000:23:01.1

sapphire:/sys/bus/pci/slots # ls -l 3/function0/slot
lrwxrwxrwx 1 root root 0 Aug 18 14:13 3/function0/slot ->
../../../bus/pci/slots/3

The original form of this patch was written by Matthew Wilcox,
and was enhanced to include links from the sysfs slots/ directory
pointing back at the device functions.

Cc: willy@linux.intel.com
Signed-off-by: default avatarAlex Chiang <achiang@hp.com>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent fc2a093e

Documentation/ABI/testing/sysfs-bus-pci

+40 −0
Original line number Diff line number Diff line
@@ -133,6 +133,46 @@ Description: 
		The symbolic link points to the PCI device sysfs entry of the

		Physical Function this device associates with.





What:		/sys/bus/pci/slots/...

Date:		April 2005 (possibly older)

KernelVersion:	2.6.12 (possibly older)

Contact:	linux-pci@vger.kernel.org

Description:

		When the appropriate driver is loaded, it will create a

		directory per claimed physical PCI slot in

		/sys/bus/pci/slots/.  The names of these directories are

		specific to the driver, which in turn, are specific to the

		platform, but in general, should match the label on the

		machine's physical chassis.



		The drivers that can create slot directories include the

		PCI hotplug drivers, and as of 2.6.27, the pci_slot driver.



		The slot directories contain, at a minimum, a file named

		'address' which contains the PCI bus:device:function tuple.

		Other files may appear as well, but are specific to the

		driver.



What:		/sys/bus/pci/slots/.../function[0-7]

Date:		March 2010

KernelVersion:	2.6.35

Contact:	linux-pci@vger.kernel.org

Description:

		If PCI slot directories (as described above) are created,

		and the physical slot is actually populated with a device,

		symbolic links in the slot directory pointing to the

		device's PCI functions are created as well.



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

Date:		March 2010

KernelVersion:	2.6.35

Contact:	linux-pci@vger.kernel.org

Description:

		If PCI slot directories (as described above) are created,

		a symbolic link pointing to the slot directory will be

		created as well.



What:		/sys/bus/pci/slots/.../module

Date:		June 2009

Contact:	linux-pci@vger.kernel.org

drivers/pci/pci-sysfs.c

+37 −0
Original line number Diff line number Diff line
@@ -1011,6 +1011,39 @@ error: 
	return retval;

}



static void pci_remove_slot_links(struct pci_dev *dev)

{

	char func[10];

	struct pci_slot *slot;



	sysfs_remove_link(&dev->dev.kobj, "slot");

	list_for_each_entry(slot, &dev->bus->slots, list) {

		if (slot->number != PCI_SLOT(dev->devfn))

			continue;

		snprintf(func, 10, "function%d", PCI_FUNC(dev->devfn));

		sysfs_remove_link(&slot->kobj, func);

	}

}



static int pci_create_slot_links(struct pci_dev *dev)

{

	int result = 0;

	char func[10];

	struct pci_slot *slot;



	list_for_each_entry(slot, &dev->bus->slots, list) {

		if (slot->number != PCI_SLOT(dev->devfn))

			continue;

		result = sysfs_create_link(&dev->dev.kobj, &slot->kobj, "slot");

		if (result)

			goto out;

		snprintf(func, 10, "function%d", PCI_FUNC(dev->devfn));

		result = sysfs_create_link(&slot->kobj, &dev->dev.kobj, func);

	}

out:

	return result;

}



int __must_check pci_create_sysfs_dev_files (struct pci_dev *pdev)

{

	int retval;
@@ -1073,6 +1106,8 @@ int __must_check pci_create_sysfs_dev_files (struct pci_dev *pdev) 
	if (retval)

		goto err_vga_file;



	pci_create_slot_links(pdev);



	return 0;



err_vga_file:
@@ -1122,6 +1157,8 @@ void pci_remove_sysfs_dev_files(struct pci_dev *pdev) 
	if (!sysfs_initialized)

		return;



	pci_remove_slot_links(pdev);



	pci_remove_capabilities_sysfs(pdev);



	if (pdev->cfg_size < PCI_CFG_SPACE_EXP_SIZE)

drivers/pci/slot.c

+48 −0
Original line number Diff line number Diff line
@@ -97,6 +97,50 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf) 
	return bus_speed_read(slot->bus->cur_bus_speed, buf);

}



static void remove_sysfs_files(struct pci_slot *slot)

{

	char func[10];

	struct list_head *tmp;



	list_for_each(tmp, &slot->bus->devices) {

		struct pci_dev *dev = pci_dev_b(tmp);

		if (PCI_SLOT(dev->devfn) != slot->number)

			continue;

		sysfs_remove_link(&dev->dev.kobj, "slot");



		snprintf(func, 10, "function%d", PCI_FUNC(dev->devfn));

		sysfs_remove_link(&slot->kobj, func);

	}

}



static int create_sysfs_files(struct pci_slot *slot)

{

	int result;

	char func[10];

	struct list_head *tmp;



	list_for_each(tmp, &slot->bus->devices) {

		struct pci_dev *dev = pci_dev_b(tmp);

		if (PCI_SLOT(dev->devfn) != slot->number)

			continue;



		result = sysfs_create_link(&dev->dev.kobj, &slot->kobj, "slot");

		if (result)

			goto fail;



		snprintf(func, 10, "function%d", PCI_FUNC(dev->devfn));

		result = sysfs_create_link(&slot->kobj, &dev->dev.kobj, func);

		if (result)

			goto fail;

	}



	return 0;



fail:

	remove_sysfs_files(slot);

	return result;

}



static void pci_slot_release(struct kobject *kobj)

{

	struct pci_dev *dev;
@@ -109,6 +153,8 @@ static void pci_slot_release(struct kobject *kobj) 
		if (PCI_SLOT(dev->devfn) == slot->number)

			dev->slot = NULL;



	remove_sysfs_files(slot);



	list_del(&slot->list);



	kfree(slot);
@@ -300,6 +346,8 @@ placeholder: 
	INIT_LIST_HEAD(&slot->list);

	list_add(&slot->list, &parent->slots);



	create_sysfs_files(slot);



	list_for_each_entry(dev, &parent->devices, bus_list)

		if (PCI_SLOT(dev->devfn) == slot_nr)

			dev->slot = slot;

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