From b41a60eca833d76593d4dac8a59f5c38714194ee Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Wed, 30 May 2007 15:39:33 -0400 Subject: USB: add power/persist device attribute This patch (as920) adds an extra level of protection to the USB-Persist facility. Now it will apply by default only to hubs; for all other devices the user must enable it explicitly by setting the power/persist device attribute. The disconnect_all_children() routine in hub.c has been removed and its code placed inline. This is the way it was originally as part of hub_pre_reset(); the revised usage in hub_reset_resume() is sufficiently different that the code can no longer be shared. Likewise, mark_children_for_reset() is now inline as part of hub_reset_resume(). The end result looks much cleaner than before. The sysfs interface is updated to add the new attribute file, and there are corresponding documentation updates. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/Kconfig | 13 ++++---- drivers/usb/core/hub.c | 78 ++++++++++++++++++------------------------------ drivers/usb/core/sysfs.c | 75 ++++++++++++++++++++++++++++++++++++++++++++-- 3 files changed, 110 insertions(+), 56 deletions(-) (limited to 'drivers/usb/core') diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig index 5113ef4cb7f..97b09f28270 100644 --- a/drivers/usb/core/Kconfig +++ b/drivers/usb/core/Kconfig @@ -91,12 +91,15 @@ config USB_PERSIST depends on USB && PM && EXPERIMENTAL default n help - If you say Y here, USB device data structures will remain + + If you say Y here and enable the "power/persist" attribute + for a USB device, the device's data structures will remain persistent across system suspend, even if the USB bus loses - power. (This includes software-suspend, also known as swsusp, - or suspend-to-disk.) The devices will reappear as if by magic - when the system wakes up, with no need to unmount USB filesystems, - rmmod host-controller drivers, or do anything else. + power. (This includes hibernation, also known as swsusp or + suspend-to-disk.) The devices will reappear as if by magic + when the system wakes up, with no need to unmount USB + filesystems, rmmod host-controller drivers, or do anything + else. WARNING: This option can be dangerous! diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index c4cdb69a6e9..50e79010401 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -596,27 +596,18 @@ static void hub_port_logical_disconnect(struct usb_hub *hub, int port1) kick_khubd(hub); } -static void disconnect_all_children(struct usb_hub *hub, int logical) -{ - struct usb_device *hdev = hub->hdev; - int port1; - - for (port1 = 1; port1 <= hdev->maxchild; ++port1) { - if (hdev->children[port1-1]) { - if (logical) - hub_port_logical_disconnect(hub, port1); - else - usb_disconnect(&hdev->children[port1-1]); - } - } -} - /* caller has locked the hub device */ static int hub_pre_reset(struct usb_interface *intf) { struct usb_hub *hub = usb_get_intfdata(intf); + struct usb_device *hdev = hub->hdev; + int i; - disconnect_all_children(hub, 0); + /* Disconnect all the children */ + for (i = 0; i < hdev->maxchild; ++i) { + if (hdev->children[i]) + usb_disconnect(&hdev->children[i]); + } hub_quiesce(hub); return 0; } @@ -1872,50 +1863,39 @@ static int hub_resume(struct usb_interface *intf) return 0; } -#ifdef CONFIG_USB_PERSIST - -/* For "persistent-device" resets we must mark the child devices for reset - * and turn off a possible connect-change status (so khubd won't disconnect - * them later). - */ -static void mark_children_for_reset_resume(struct usb_hub *hub) +static int hub_reset_resume(struct usb_interface *intf) { + struct usb_hub *hub = usb_get_intfdata(intf); struct usb_device *hdev = hub->hdev; int port1; + hub_power_on(hub); + for (port1 = 1; port1 <= hdev->maxchild; ++port1) { struct usb_device *child = hdev->children[port1-1]; if (child) { - child->reset_resume = 1; - clear_port_feature(hdev, port1, - USB_PORT_FEAT_C_CONNECTION); + + /* For "USB_PERSIST"-enabled children we must + * mark the child device for reset-resume and + * turn off the connect-change status to prevent + * khubd from disconnecting it later. + */ + if (USB_PERSIST && child->persist_enabled) { + child->reset_resume = 1; + clear_port_feature(hdev, port1, + USB_PORT_FEAT_C_CONNECTION); + + /* Otherwise we must disconnect the child, + * but as we may not lock the child device here + * we have to do a "logical" disconnect. + */ + } else { + hub_port_logical_disconnect(hub, port1); + } } } -} - -#else - -static inline void mark_children_for_reset_resume(struct usb_hub *hub) -{ } - -#endif /* CONFIG_USB_PERSIST */ - -static int hub_reset_resume(struct usb_interface *intf) -{ - struct usb_hub *hub = usb_get_intfdata(intf); - hub_power_on(hub); - if (USB_PERSIST) - mark_children_for_reset_resume(hub); - else { - /* Reset-resume doesn't call pre_reset, so we have to - * disconnect the children here. But we may not lock - * the child devices, so we have to do a "logical" - * disconnect. - */ - disconnect_all_children(hub, 1); - } hub_activate(hub); return 0; } diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index be37c863fdf..5dfe31bc32b 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -169,6 +169,73 @@ show_quirks(struct device *dev, struct device_attribute *attr, char *buf) } static DEVICE_ATTR(quirks, S_IRUGO, show_quirks, NULL); + +#if defined(CONFIG_USB_PERSIST) || defined(CONFIG_USB_SUSPEND) +static const char power_group[] = "power"; +#endif + +#ifdef CONFIG_USB_PERSIST + +static ssize_t +show_persist(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct usb_device *udev = to_usb_device(dev); + + return sprintf(buf, "%d\n", udev->persist_enabled); +} + +static ssize_t +set_persist(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct usb_device *udev = to_usb_device(dev); + int value; + + /* Hubs are always enabled for USB_PERSIST */ + if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) + return -EPERM; + + if (sscanf(buf, "%d", &value) != 1) + return -EINVAL; + usb_pm_lock(udev); + udev->persist_enabled = !!value; + usb_pm_unlock(udev); + return count; +} + +static DEVICE_ATTR(persist, S_IRUGO | S_IWUSR, show_persist, set_persist); + +static int add_persist_attributes(struct device *dev) +{ + int rc = 0; + + if (is_usb_device(dev)) { + struct usb_device *udev = to_usb_device(dev); + + /* Hubs are automatically enabled for USB_PERSIST */ + if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) + udev->persist_enabled = 1; + rc = sysfs_add_file_to_group(&dev->kobj, + &dev_attr_persist.attr, + power_group); + } + return rc; +} + +static void remove_persist_attributes(struct device *dev) +{ + sysfs_remove_file_from_group(&dev->kobj, + &dev_attr_persist.attr, + power_group); +} + +#else + +#define add_persist_attributes(dev) 0 +#define remove_persist_attributes(dev) do {} while (0) + +#endif /* CONFIG_USB_PERSIST */ + #ifdef CONFIG_USB_SUSPEND static ssize_t @@ -276,8 +343,6 @@ set_level(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR(level, S_IRUGO | S_IWUSR, show_level, set_level); -static char power_group[] = "power"; - static int add_power_attributes(struct device *dev) { int rc = 0; @@ -311,6 +376,7 @@ static void remove_power_attributes(struct device *dev) #endif /* CONFIG_USB_SUSPEND */ + /* Descriptor fields */ #define usb_descriptor_attr_le16(field, format_string) \ static ssize_t \ @@ -384,6 +450,10 @@ int usb_create_sysfs_dev_files(struct usb_device *udev) if (retval) return retval; + retval = add_persist_attributes(dev); + if (retval) + goto error; + retval = add_power_attributes(dev); if (retval) goto error; @@ -421,6 +491,7 @@ void usb_remove_sysfs_dev_files(struct usb_device *udev) device_remove_file(dev, &dev_attr_product); device_remove_file(dev, &dev_attr_serial); remove_power_attributes(dev); + remove_persist_attributes(dev); sysfs_remove_group(&dev->kobj, &dev_attr_grp); } -- cgit v1.2.3