PCI: Introduce /sys/bus/pci/devices/.../rescan

This interface allows the user to force a rescan of the device's
parent bus and all subordinate buses, and rediscover devices removed
earlier from this part of the device tree.

Cc: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 29 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index daa791a9e85e..97ad190e13af 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -74,6 +74,16 @@ Description:
                 hot-remove the PCI device and any of its children.
                 Depends on CONFIG_HOTPLUG.
 
+What:           /sys/bus/pci/devices/.../rescan
+Date:           January 2009
+Contact:        Linux PCI developers <linux-pci@vger.kernel.org>
+Description:
+                Writing a non-zero value to this attribute will
+                force a rescan of the device's parent bus and all
+                child buses, and re-discover devices removed earlier
+                from this part of the device tree.
+                Depends on CONFIG_HOTPLUG.
+
 What:           /sys/bus/pci/devices/.../vpd
 Date:           February 2008
 Contact:        Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index e16990ecc024..e9a8706a6401 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -244,6 +244,24 @@ struct bus_attribute pci_bus_attrs[] = {
         __ATTR_NULL
 };
 
+static ssize_t
+dev_rescan_store(struct device *dev, struct device_attribute *attr,
+                 const char *buf, size_t count)
+{
+        unsigned long val;
+        struct pci_dev *pdev = to_pci_dev(dev);
+
+        if (strict_strtoul(buf, 0, &val) < 0)
+                return -EINVAL;
+
+        if (val) {
+                mutex_lock(&pci_remove_rescan_mutex);
+                pci_rescan_bus(pdev->bus);
+                mutex_unlock(&pci_remove_rescan_mutex);
+        }
+        return count;
+}
+
 static void remove_callback(struct device *dev)
 {
         struct pci_dev *pdev = to_pci_dev(dev);
@@ -298,6 +316,7 @@ struct device_attribute pci_dev_attrs[] = {
         __ATTR(msi_bus, 0644, msi_bus_show, msi_bus_store),
 #ifdef CONFIG_HOTPLUG
         __ATTR(remove, (S_IWUSR|S_IWGRP), NULL, remove_store),
+        __ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, dev_rescan_store),
 #endif
         __ATTR_NULL,
 };