diff options
| -rw-r--r-- | Documentation/acpi/scan_handlers.txt | 77 | ||||
| -rw-r--r-- | drivers/acpi/scan.c | 60 | ||||
| -rw-r--r-- | include/acpi/acpi_bus.h | 14 |
3 files changed, 144 insertions, 7 deletions
diff --git a/Documentation/acpi/scan_handlers.txt b/Documentation/acpi/scan_handlers.txt new file mode 100644 index 000000000000..3246ccf15992 --- /dev/null +++ b/Documentation/acpi/scan_handlers.txt @@ -0,0 +1,77 @@ +ACPI Scan Handlers + +Copyright (C) 2012, Intel Corporation +Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com> + +During system initialization and ACPI-based device hot-add, the ACPI namespace +is scanned in search of device objects that generally represent various pieces +of hardware. This causes a struct acpi_device object to be created and +registered with the driver core for every device object in the ACPI namespace +and the hierarchy of those struct acpi_device objects reflects the namespace +layout (i.e. parent device objects in the namespace are represented by parent +struct acpi_device objects and analogously for their children). Those struct +acpi_device objects are referred to as "device nodes" in what follows, but they +should not be confused with struct device_node objects used by the Device Trees +parsing code (although their role is analogous to the role of those objects). + +During ACPI-based device hot-remove device nodes representing pieces of hardware +being removed are unregistered and deleted. + +The core ACPI namespace scanning code in drivers/acpi/scan.c carries out basic +initialization of device nodes, such as retrieving common configuration +information from the device objects represented by them and populating them with +appropriate data, but some of them require additional handling after they have +been registered. For example, if the given device node represents a PCI host +bridge, its registration should cause the PCI bus under that bridge to be +enumerated and PCI devices on that bus to be registered with the driver core. +Similarly, if the device node represents a PCI interrupt link, it is necessary +to configure that link so that the kernel can use it. + +Those additional configuration tasks usually depend on the type of the hardware +component represented by the given device node which can be determined on the +basis of the device node's hardware ID (HID). They are performed by objects +called ACPI scan handlers represented by the following structure: + +struct acpi_scan_handler { + const struct acpi_device_id *ids; + struct list_head list_node; + int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id); + void (*detach)(struct acpi_device *dev); +}; + +where ids is the list of IDs of device nodes the given handler is supposed to +take care of, list_node is the hook to the global list of ACPI scan handlers +maintained by the ACPI core and the .attach() and .detach() callbacks are +executed, respectively, after registration of new device nodes and before +unregistration of device nodes the handler attached to previously. + +The namespace scanning function, acpi_bus_scan(), first registers all of the +device nodes in the given namespace scope with the driver core. Then, it tries +to match a scan handler against each of them using the ids arrays of the +available scan handlers. If a matching scan handler is found, its .attach() +callback is executed for the given device node. If that callback returns 1, +that means that the handler has claimed the device node and is now responsible +for carrying out any additional configuration tasks related to it. It also will +be responsible for preparing the device node for unregistration in that case. +The device node's handler field is then populated with the address of the scan +handler that has claimed it. + +If the .attach() callback returns 0, it means that the device node is not +interesting to the given scan handler and may be matched against the next scan +handler in the list. If it returns a (negative) error code, that means that +the namespace scan should be terminated due to a serious error. The error code +returned should then reflect the type of the error. + +The namespace trimming function, acpi_bus_trim(), first executes .detach() +callbacks from the scan handlers of all device nodes in the given namespace +scope (if they have scan handlers). Next, it unregisters all of the device +nodes in that scope. + +ACPI scan handlers can be added to the list maintained by the ACPI core with the +help of the acpi_scan_add_handler() function taking a pointer to the new scan +handler as an argument. The order in which scan handlers are added to the list +is the order in which they are matched against device nodes during namespace +scans. + +All scan handles must be added to the list before acpi_bus_scan() is run for the +first time and they cannot be removed from it. diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index fe9f2c926663..1453cd0672fb 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -53,6 +53,7 @@ static const struct acpi_device_id acpi_platform_device_ids[] = { static LIST_HEAD(acpi_device_list); static LIST_HEAD(acpi_bus_id_list); static DEFINE_MUTEX(acpi_scan_lock); +static LIST_HEAD(acpi_scan_handlers_list); DEFINE_MUTEX(acpi_device_lock); LIST_HEAD(acpi_wakeup_device_list); @@ -62,6 +63,15 @@ struct acpi_device_bus_id{ struct list_head node; }; +int acpi_scan_add_handler(struct acpi_scan_handler *handler) +{ + if (!handler || !handler->attach) + return -EINVAL; + + list_add_tail(&handler->list_node, &acpi_scan_handlers_list); + return 0; +} + /* * Creates hid/cid(s) string needed for modalias and uevent * e.g. on a device with hid:IBM0001 and cid:ACPI0001 you get: @@ -1570,20 +1580,42 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used, return AE_OK; } +static int acpi_scan_attach_handler(struct acpi_device *device) +{ + struct acpi_scan_handler *handler; + int ret = 0; + + list_for_each_entry(handler, &acpi_scan_handlers_list, list_node) { + const struct acpi_device_id *id; + + id = __acpi_match_device(device, handler->ids); + if (!id) + continue; + + ret = handler->attach(device, id); + if (ret > 0) { + device->handler = handler; + break; + } else if (ret < 0) { + break; + } + } + return ret; +} + static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used, void *not_used, void **ret_not_used) { const struct acpi_device_id *id; - acpi_status status = AE_OK; struct acpi_device *device; unsigned long long sta_not_used; - int type_not_used; + int ret; /* * Ignore errors ignored by acpi_bus_check_add() to avoid terminating * namespace walks prematurely. */ - if (acpi_bus_type_and_status(handle, &type_not_used, &sta_not_used)) + if (acpi_bus_type_and_status(handle, &ret, &sta_not_used)) return AE_OK; if (acpi_bus_get_device(handle, &device)) @@ -1593,10 +1625,15 @@ static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used, if (id) { /* This is a known good platform device. */ acpi_create_platform_device(device, id->driver_data); - } else if (device_attach(&device->dev) < 0) { - status = AE_CTRL_DEPTH; + return AE_OK; } - return status; + + ret = acpi_scan_attach_handler(device); + if (ret) + return ret > 0 ? AE_OK : AE_CTRL_DEPTH; + + ret = device_attach(&device->dev); + return ret >= 0 ? AE_OK : AE_CTRL_DEPTH; } /** @@ -1639,8 +1676,17 @@ static acpi_status acpi_bus_device_detach(acpi_handle handle, u32 lvl_not_used, struct acpi_device *device = NULL; if (!acpi_bus_get_device(handle, &device)) { + struct acpi_scan_handler *dev_handler = device->handler; + device->removal_type = ACPI_BUS_REMOVAL_EJECT; - device_release_driver(&device->dev); + if (dev_handler) { + if (dev_handler->detach) + dev_handler->detach(device); + + device->handler = NULL; + } else { + device_release_driver(&device->dev); + } } return AE_OK; } diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index ad0a86ac5cce..41850cb21730 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -84,6 +84,18 @@ struct acpi_driver; struct acpi_device; /* + * ACPI Scan Handler + * ----------------- + */ + +struct acpi_scan_handler { + const struct acpi_device_id *ids; + struct list_head list_node; + int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id); + void (*detach)(struct acpi_device *dev); +}; + +/* * ACPI Driver * ----------- */ @@ -269,6 +281,7 @@ struct acpi_device { struct acpi_device_wakeup wakeup; struct acpi_device_perf performance; struct acpi_device_dir dir; + struct acpi_scan_handler *handler; struct acpi_driver *driver; void *driver_data; struct device dev; @@ -382,6 +395,7 @@ int acpi_bus_receive_event(struct acpi_bus_event *event); static inline int acpi_bus_generate_proc_event(struct acpi_device *device, u8 type, int data) { return 0; } #endif +int acpi_scan_add_handler(struct acpi_scan_handler *handler); int acpi_bus_register_driver(struct acpi_driver *driver); void acpi_bus_unregister_driver(struct acpi_driver *driver); int acpi_bus_scan(acpi_handle handle); |