[PATCH 3/3] PCI: Legacy fakephp driver

Trent Piepho
2009-01-29T10:56:23Z

This module's interface is compatible with what fakephp's interface has
been.

It puts entries in /sys/bus/pci/slots with the names of all PCI
devices/functions. Each one has a "power" attribute, which works the same
way as the fakephp driver's power attribute has worked.

There are a few improvements over fakephp, which couldn't handle PCI
devices being added or removed via a means other than fakephp's actions.
If a device is added another way, fakephp doesn't notice it and doesn't
create the fake slot for it. If a device was removed another way, fakephp
doesn't delete the fake slot for it (and accessing the stale slot will
cause an oops). These problems are fixed. As a consequence of this,
removing a bridge with other devices behind it works as well, which is
something else fakephp couldn't do.

This patch duplicates a tiny bit of the code in the PCI core that does this
same function. Re-using that code ends up being more complex than
duplicating it, and it makes code in the PCI core more ugly just to support
this legacy fakephp interface compatibility layer.
---
drivers/pci/hotplug/Kconfig | 5 +
drivers/pci/hotplug/Makefile | 1 +
drivers/pci/hotplug/legacy_fakephp.c | 168 ++++++++++++++++++++++++++++++++++
3 files changed, 174 insertions(+), 0 deletions(-)
create mode 100644 drivers/pci/hotplug/legacy_fakephp.c

diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
index eacfb13..d26bc68 100644
--- a/drivers/pci/hotplug/Kconfig
+++ b/drivers/pci/hotplug/Kconfig
@@ -39,6 +39,11 @@ config HOTPLUG_PCI_FAKE

When in doubt, say N.

+config HOTPLUG_PCI_LEGACY_FAKE
+ tristate "Legacy Fake PCI Hotplug driver"
+ help
+ Provides an interface like the fakephp driver used to.
+
config HOTPLUG_PCI_COMPAQ
tristate "Compaq PCI Hotplug driver"
depends on X86 && PCI_BIOS && PCI_LEGACY
diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
index 9bdbe1a..9ad009d 100644
--- a/drivers/pci/hotplug/Makefile
+++ b/drivers/pci/hotplug/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_HOTPLUG_PCI_SHPC) += shpchp.o
obj-$(CONFIG_HOTPLUG_PCI_RPA) += rpaphp.o
obj-$(CONFIG_HOTPLUG_PCI_RPA_DLPAR) += rpadlpar_io.o
obj-$(CONFIG_HOTPLUG_PCI_SGI) += sgi_hotplug.o
+obj-$(CONFIG_HOTPLUG_PCI_LEGACY_FAKE) += legacy_fakephp.o

# Link this last so it doesn't claim devices that have a real hotplug driver
obj-$(CONFIG_HOTPLUG_PCI_FAKE) += fakephp.o
diff --git a/drivers/pci/hotplug/legacy_fakephp.c b/drivers/pci/hotplug/legacy_fakephp.c
new file mode 100644
index 0000000..696b156
--- /dev/null
+++ b/drivers/pci/hotplug/legacy_fakephp.c
@@ -0,0 +1,168 @@
+/* Works like the fakephp driver used to, except a little better.
+ *
+ * - It's possible to remove devices with subordinate busses.
+ * - New PCI devices that appear via any method, not just a fakephp triggered
+ * rescan, will be noticed.
+ * - Devices that are removed via any method, not just a fakephp triggered
+ * removal, will also be noticed.
+ *
+ * Uses nothing from the pci-hotplug subsystem.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include "../pci.h"
+
+struct legacy_slot {
+ struct kobject kobj;
+ struct pci_dev *dev;
+ struct list_head list;
+};
+
+static LIST_HEAD(legacy_list);
+
+static ssize_t legacy_show(struct kobject *kobj, struct attribute *attr,
+ char *buf)
+{
+ struct legacy_slot *slot = container_of(kobj, typeof(*slot), kobj);
+ strcpy(buf, "1\n");
+ return 2;
+}
+
+static void remove_callback(void *data)
+{
+ pci_remove_bus_device((struct pci_dev *)data);
+}
+
+/* pci_rescan_busses is __devinit, which is why this driver requires HOTPLUG to
+ * be on. */
+static void __ref rescan(void)
+{
+ pci_rescan_busses();
+}
+
+static ssize_t legacy_store(struct kobject *kobj, struct attribute *attr,
+ const char *buf, size_t len)
+{
+ struct legacy_slot *slot = container_of(kobj, typeof(*slot), kobj);
+ unsigned long val;
+
+ if (strict_strtoul(buf, 0, &val) < 0)
+ return -EINVAL;
+
+ if (val)
+ rescan();
+ else
+ sysfs_schedule_callback(&slot->dev->dev.kobj, remove_callback,
+ slot->dev, THIS_MODULE);
+ return len;
+}
+
+static struct attribute *legacy_attrs[] = {
+ &(struct attribute){ .name = "power", .mode = 0644 },
+ NULL,
+};
+
+static void legacy_release(struct kobject *kobj)
+{
+ struct legacy_slot *slot = container_of(kobj, typeof(*slot), kobj);
+
+ pci_dev_put(slot->dev);
+ kfree(slot);
+}
+
+static struct kobj_type legacy_ktype = {
+ .sysfs_ops = &(struct sysfs_ops){
+ .store = legacy_store, .show = legacy_show
+ },
+ .release = &legacy_release,
+ .default_attrs = legacy_attrs,
+};
+
+static int legacy_add_slot(struct pci_dev *pdev)
+{
+ struct legacy_slot *slot = kzalloc(sizeof(*slot), GFP_KERNEL);
+
+ if (!slot)
+ return -ENOMEM;
+
+ if (kobject_init_and_add(&slot->kobj, &legacy_ktype,
+ &pci_slots_kset->kobj, "%s",
+ pdev->dev.bus_id)) {
+ dev_warn(&pdev->dev, "Failed to created legacy fake slot\n");
+ return -EINVAL;
+ }
+ slot->dev = pci_dev_get(pdev);
+
+ list_add(&slot->list, &legacy_list);
+
+ return 0;
+}
+
+static int legacy_notify(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct pci_dev *pdev = to_pci_dev(data);
+
+ if (action == BUS_NOTIFY_ADD_DEVICE) {
+ legacy_add_slot(pdev);
+ } else if (action == BUS_NOTIFY_DEL_DEVICE) {
+ struct legacy_slot *slot;
+
+ list_for_each_entry(slot, &legacy_list, list)
+ if (slot->dev == pdev)
+ goto found;
+
+ dev_warn(&pdev->dev, "Missing legacy fake slot?");
+ return -ENODEV;
+found:
+ kobject_del(&slot->kobj);
+ list_del(&slot->list);
+ kobject_put(&slot->kobj);
+ }
+
+ return 0;
+}
+
+static struct notifier_block legacy_notifier = {
+ .notifier_call = legacy_notify
+};
+
+static int __init init_legacy(void)
+{
+ struct pci_dev *pdev = NULL;
+
+ /* Add existing devices */
+ while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev)))
+ legacy_add_slot(pdev);
+
+ /* Be alerted of any new ones */
+ bus_register_notifier(&pci_bus_type, &legacy_notifier);
+ return 0;
+}
+module_init(init_legacy);
+
+static void __exit remove_legacy(void)
+{
+ struct legacy_slot *slot, *tmp;
+
+ bus_unregister_notifier(&pci_bus_type, &legacy_notifier);
+
+ list_for_each_entry_safe(slot, tmp, &legacy_list, list) {
+ list_del(&slot->list);
+ kobject_del(&slot->kobj);
+ kobject_put(&slot->kobj);
+ }
+}
+module_exit(remove_legacy);
+
+
+MODULE_AUTHOR("Trent Piepho <xyzzy@speakeasy.org>");
+MODULE_DESCRIPTION("Legacy version of the fakephp interface");
+MODULE_LICENSE("GPL");
--
1.5.4.3