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authorSaravana Kannan <saravanak@google.com>2019-09-04 14:11:23 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-10-04 17:30:19 +0200
commitfc5a251d0fd7ca9038bab78a8c97932c8c6ca23b (patch)
tree2c4275c295cc293a6df7d5218b3953776a4683dd /include/linux/device.h
parenta3e1d1a7f5fcccaf1d252278425fea9a4a553100 (diff)
downloadlwn-fc5a251d0fd7ca9038bab78a8c97932c8c6ca23b.tar.gz
lwn-fc5a251d0fd7ca9038bab78a8c97932c8c6ca23b.zip
driver core: Add sync_state driver/bus callback
This sync_state driver/bus callback is called once all the consumers of a supplier have probed successfully. This allows the supplier device's driver/bus to sync the supplier device's state to the software state with the guarantee that all the consumers are actively managing the resources provided by the supplier device. To maintain backwards compatibility and ease transition from existing frameworks and resource cleanup schemes, late_initcall_sync is the earliest when the sync_state callback might be called. There is no upper bound on the time by which the sync_state callback has to be called. This is because if a consumer device never probes, the supplier has to maintain its resources in the state left by the bootloader. For example, if the bootloader leaves the display backlight at a fixed voltage and the backlight driver is never probed, you don't want the backlight to ever be turned off after boot up. Also, when multiple devices are added after kernel init, some suppliers could be added before their consumer devices get added. In these instances, the supplier devices could get their sync_state callback called right after they probe because the consumers devices haven't had a chance to create device links to the suppliers. To handle this correctly, this change also provides APIs to pause/resume sync state callbacks so that when multiple devices are added, their sync_state callback evaluation can be postponed to happen after all of them are added. kbuild test robot reported missing documentation for device.state_synced Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Saravana Kannan <saravanak@google.com> Link: https://lore.kernel.org/r/20190904211126.47518-5-saravanak@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/device.h')
-rw-r--r--include/linux/device.h24
1 files changed, 24 insertions, 0 deletions
diff --git a/include/linux/device.h b/include/linux/device.h
index c6fb5b3431b7..6978bb471567 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -80,6 +80,13 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
* that generate uevents to add the environment variables.
* @probe: Called when a new device or driver add to this bus, and callback
* the specific driver's probe to initial the matched device.
+ * @sync_state: Called to sync device state to software state after all the
+ * state tracking consumers linked to this device (present at
+ * the time of late_initcall) have successfully bound to a
+ * driver. If the device has no consumers, this function will
+ * be called at late_initcall_sync level. If the device has
+ * consumers that are never bound to a driver, this function
+ * will never get called until they do.
* @remove: Called when a device removed from this bus.
* @shutdown: Called at shut-down time to quiesce the device.
*
@@ -123,6 +130,7 @@ struct bus_type {
int (*match)(struct device *dev, struct device_driver *drv);
int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
int (*probe)(struct device *dev);
+ void (*sync_state)(struct device *dev);
int (*remove)(struct device *dev);
void (*shutdown)(struct device *dev);
@@ -340,6 +348,13 @@ enum probe_type {
* @probe: Called to query the existence of a specific device,
* whether this driver can work with it, and bind the driver
* to a specific device.
+ * @sync_state: Called to sync device state to software state after all the
+ * state tracking consumers linked to this device (present at
+ * the time of late_initcall) have successfully bound to a
+ * driver. If the device has no consumers, this function will
+ * be called at late_initcall_sync level. If the device has
+ * consumers that are never bound to a driver, this function
+ * will never get called until they do.
* @remove: Called when the device is removed from the system to
* unbind a device from this driver.
* @shutdown: Called at shut-down time to quiesce the device.
@@ -379,6 +394,7 @@ struct device_driver {
const struct acpi_device_id *acpi_match_table;
int (*probe) (struct device *dev);
+ void (*sync_state)(struct device *dev);
int (*remove) (struct device *dev);
void (*shutdown) (struct device *dev);
int (*suspend) (struct device *dev, pm_message_t state);
@@ -1136,12 +1152,14 @@ enum dl_dev_state {
* @suppliers: List of links to supplier devices.
* @consumers: List of links to consumer devices.
* @needs_suppliers: Hook to global list of devices waiting for suppliers.
+ * @defer_sync: Hook to global list of devices that have deferred sync_state.
* @status: Driver status information.
*/
struct dev_links_info {
struct list_head suppliers;
struct list_head consumers;
struct list_head needs_suppliers;
+ struct list_head defer_sync;
enum dl_dev_state status;
};
@@ -1217,6 +1235,9 @@ struct dev_links_info {
* @offline: Set after successful invocation of bus type's .offline().
* @of_node_reused: Set if the device-tree node is shared with an ancestor
* device.
+ * @state_synced: The hardware state of this device has been synced to match
+ * the software state of this device by calling the driver/bus
+ * sync_state() callback.
* @dma_coherent: this particular device is dma coherent, even if the
* architecture supports non-coherent devices.
*
@@ -1313,6 +1334,7 @@ struct device {
bool offline_disabled:1;
bool offline:1;
bool of_node_reused:1;
+ bool state_synced:1;
#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
@@ -1655,6 +1677,8 @@ struct device_link *device_link_add(struct device *consumer,
struct device *supplier, u32 flags);
void device_link_del(struct device_link *link);
void device_link_remove(void *consumer, struct device *supplier);
+void device_links_supplier_sync_state_pause(void);
+void device_links_supplier_sync_state_resume(void);
#ifndef dev_fmt
#define dev_fmt(fmt) fmt