--- /dev/null
+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.
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);
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:
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))
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;
}
/**
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;
}
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
* -----------
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;
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);
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff