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authorPhilippe Bergheaud <felix@linux.vnet.ibm.com>2016-06-23 15:03:53 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2016-06-28 18:34:56 +1000
commitb810253bd9342f863a86ec7dfff4a5a7a0394d2f (patch)
treed5432cdb249bf3c83ab5583f4485353e26c869f4 /include/misc
parent6e8a9279a85abd07d05e9322844b0f254e8437ac (diff)
cxl: Add mechanism for delivering AFU driver specific events
This adds an afu_driver_ops structure with fetch_event() and event_delivered() callbacks. An AFU driver such as cxlflash can fill this out and associate it with a context to enable passing custom AFU specific events to userspace. This also adds a new kernel API function cxl_context_pending_events(), that the AFU driver can use to notify the cxl driver that new specific events are ready to be delivered, and wake up anyone waiting on the context wait queue. The current count of AFU driver specific events is stored in the field afu_driver_events of the context structure. The cxl driver checks the afu_driver_events count during poll, select, read, etc. calls to check if an AFU driver specific event is pending, and calls fetch_event() to obtain and deliver that event. This way, the cxl driver takes care of all the usual locking semantics around these calls and handles all the generic cxl events, so that the AFU driver only needs to worry about it's own events. fetch_event() return a struct cxl_event_afu_driver_reserved, allocated by the AFU driver, and filled in with the specific event information and size. Total event size (header + data) should not be greater than CXL_READ_MIN_SIZE (4K). Th cxl driver prepends an appropriate cxl event header, copies the event to userspace, and finally calls event_delivered() to return the status of the operation to the AFU driver. The event is identified by the context and cxl_event_afu_driver_reserved pointers. Since AFU drivers provide their own means for userspace to obtain the AFU file descriptor (i.e. cxlflash uses an ioctl on their scsi file descriptor to obtain the AFU file descriptor) and the generic cxl driver will never use this event, the ABI of the event is up to each individual AFU driver. Signed-off-by: Philippe Bergheaud <felix@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'include/misc')
-rw-r--r--include/misc/cxl.h48
1 files changed, 48 insertions, 0 deletions
diff --git a/include/misc/cxl.h b/include/misc/cxl.h
index 56560c5781b4..17419f61e611 100644
--- a/include/misc/cxl.h
+++ b/include/misc/cxl.h
@@ -220,4 +220,52 @@ void cxl_perst_reloads_same_image(struct cxl_afu *afu,
*/
ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);
+/*
+ * AFU driver ops allow an AFU driver to create their own events to pass to
+ * userspace through the file descriptor as a simpler alternative to overriding
+ * the read() and poll() calls that works with the generic cxl events. These
+ * events are given priority over the generic cxl events, so they will be
+ * delivered first if multiple types of events are pending.
+ *
+ * The AFU driver must call cxl_context_events_pending() to notify the cxl
+ * driver that new events are ready to be delivered for a specific context.
+ * cxl_context_events_pending() will adjust the current count of AFU driver
+ * events for this context, and wake up anyone waiting on the context wait
+ * queue.
+ *
+ * The cxl driver will then call fetch_event() to get a structure defining
+ * the size and address of the driver specific event data. The cxl driver
+ * will build a cxl header with type and process_element fields filled in,
+ * and header.size set to sizeof(struct cxl_event_header) + data_size.
+ * The total size of the event is limited to CXL_READ_MIN_SIZE (4K).
+ *
+ * fetch_event() is called with a spin lock held, so it must not sleep.
+ *
+ * The cxl driver will then deliver the event to userspace, and finally
+ * call event_delivered() to return the status of the operation, identified
+ * by cxl context and AFU driver event data pointers.
+ * 0 Success
+ * -EFAULT copy_to_user() has failed
+ * -EINVAL Event data pointer is NULL, or event size is greater than
+ * CXL_READ_MIN_SIZE.
+ */
+struct cxl_afu_driver_ops {
+ struct cxl_event_afu_driver_reserved *(*fetch_event) (
+ struct cxl_context *ctx);
+ void (*event_delivered) (struct cxl_context *ctx,
+ struct cxl_event_afu_driver_reserved *event,
+ int rc);
+};
+
+/*
+ * Associate the above driver ops with a specific context.
+ * Reset the current count of AFU driver events.
+ */
+void cxl_set_driver_ops(struct cxl_context *ctx,
+ struct cxl_afu_driver_ops *ops);
+
+/* Notify cxl driver that new events are ready to be delivered for context */
+void cxl_context_events_pending(struct cxl_context *ctx,
+ unsigned int new_events);
+
#endif /* _MISC_CXL_H */

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