--- /dev/null
+/*
+ * Greybus operations
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+
+#include "greybus.h"
+
+/*
+ * All operation messages (both requests and responses) begin with
+ * a common header that encodes the size of the data (header
+ * included). This header also contains a unique identifier, which
+ * is used to keep track of in-flight operations. Finally, the
+ * header contains a operation type field, whose interpretation is
+ * dependent on what type of device lies on the other end of the
+ * connection. Response messages are distinguished from request
+ * messages by setting the high bit (0x80) in the operation type
+ * value.
+ *
+ * The wire format for all numeric fields in the header is little
+ * endian. Any operation-specific data begins immediately after the
+ * header, and is 64-bit aligned.
+ */
+struct gb_operation_msg_hdr {
+ __le16 size; /* Size in bytes of header + payload */
+ __le16 id; /* Operation unique id */
+ __u8 type; /* E.g GB_I2C_TYPE_* or GB_GPIO_TYPE_* */
+ /* 3 bytes pad, must be zero (ignore when read) */
+} __aligned(sizeof(u64));
+
+/* XXX Could be per-host device, per-module, or even per-connection */
+static DEFINE_SPINLOCK(gb_operations_lock);
+
+/*
+ * An operations's response message has arrived. If no callback was
+ * supplied it was submitted for asynchronous completion, so we notify
+ * any waiters. Otherwise we assume calling the completion is enough
+ * and nobody else will be waiting.
+ */
+void gb_operation_complete(struct gb_operation *operation)
+{
+ if (operation->callback)
+ operation->callback(operation);
+ else
+ complete_all(&operation->completion);
+}
+
+/*
+ * Wait for a submitted operatnoi to complete */
+int gb_operation_wait(struct gb_operation *operation)
+{
+ int ret;
+
+ ret = wait_for_completion_interruptible(&operation->completion);
+ /* If interrupted, cancel the in-flight buffer */
+ if (ret < 0)
+ ret = greybus_kill_gbuf(operation->gbuf);
+ return ret;
+
+}
+
+/*
+ * Submit an outbound operation. The caller has filled in any
+ * payload so the request message is ready to go. If non-null,
+ * the callback function supplied will be called when the response
+ * message has arrived indicating the operation is complete. A null
+ * callback function is used for a synchronous request; return from
+ * this function won't occur until the operation is complete (or an
+ * interrupt occurs).
+ */
+int gb_operation_submit(struct gb_operation *operation,
+ gb_operation_callback callback)
+{
+ int ret;
+
+ /* XXX
+ * gfp is probably GFP_ATOMIC but really I think
+ * the gfp mask should go away.
+ */
+ operation->callback = callback;
+ ret = greybus_submit_gbuf(operation->gbuf, GFP_KERNEL);
+ if (ret)
+ return ret;
+ if (!callback)
+ ret = gb_operation_wait(operation);
+
+ return ret;
+}
+
+/*
+ * Called when a greybus request message has actually been sent.
+ */
+static void gbuf_out_callback(struct gbuf *gbuf)
+{
+ /* Record it's been submitted; need response now */
+}
+
+/*
+ * Create a Greybus operation having a buffer big enough for an
+ * outgoing payload of the given size to be sent over the given
+ * connection.
+ *
+ * Returns a pointer to the new operation or a null pointer if a
+ * failure occurs due to memory exhaustion.
+ */
+struct gb_operation *gb_operation_create(struct gb_connection *connection,
+ size_t size)
+{
+ struct gb_operation *operation;
+ struct gb_operation_msg_hdr *header;
+ struct gbuf *gbuf;
+
+ /* XXX Use a slab cache */
+ operation = kzalloc(sizeof(*operation), GFP_KERNEL);
+ if (!operation)
+ return NULL;
+
+ /* Our buffer holds a header in addition to the requested payload */
+ size += sizeof(*header);
+ gbuf = greybus_alloc_gbuf(connection->function->interface->gmod,
+ connection->cport_id,
+ gbuf_out_callback, size,
+ GFP_KERNEL, operation);
+ if (gbuf) {
+ kfree(operation);
+ return NULL;
+ }
+
+ operation->connection = connection; /* XXX refcount? */
+
+ /* Fill in the header structure and payload pointer */
+ operation->gbuf = gbuf;
+ header = (struct gb_operation_msg_hdr *)&gbuf->transfer_buffer;
+ header->id = 0;
+ header->size = size;
+ operation->payload = (char *)header + sizeof(*header);
+
+ operation->callback = NULL; /* set at submit time */
+ init_completion(&operation->completion);
+
+ spin_lock_irq(&gb_operations_lock);
+ list_add_tail(&operation->links, &connection->operations);
+ spin_unlock_irq(&gb_operations_lock);
+
+ return operation;
+}
+
+/*
+ * Destroy a previously created operation.
+ */
+void gb_operation_destroy(struct gb_operation *operation)
+{
+ if (WARN_ON(!operation))
+ return;
+
+ /* XXX Make sure it's not in flight */
+ spin_lock_irq(&gb_operations_lock);
+ list_del(&operation->links);
+ spin_unlock_irq(&gb_operations_lock);
+
+ greybus_free_gbuf(operation->gbuf);
+
+ kfree(operation);
+}
--- /dev/null
+/*
+ * Greybus operations
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#ifndef __OPERATION_H
+#define __OPERATION_H
+
+#include <linux/completion.h>
+
+enum gb_operation_status {
+ GB_OP_SUCCESS = 0,
+ GB_OP_INVALID = 1,
+ GB_OP_NO_MEMORY = 2,
+ GB_OP_INTERRUPTED = 3,
+};
+
+/*
+ * A Greybus operation is a remote procedure call performed over a
+ * connection between the AP and a function on Greybus module.
+ * Every operation consists of a request message sent to the other
+ * end of the connection coupled with a reply returned to the
+ * sender.
+ *
+ * The state for managing active requests on a connection is held in
+ * the connection structure.
+ *
+ * YADA YADA
+ *
+ * submitting each request and providing its matching response to
+ * the caller when it arrives. Operations normally complete
+ * asynchronously, and when an operation's response arrives its
+ * callback function is executed. The callback pointer is supplied
+ * at the time the operation is submitted; a null callback pointer
+ * causes synchronous operation--the caller is blocked until
+ * the response arrives. In addition, it is possible to await
+ * the completion of a submitted asynchronous operation.
+ *
+ * A Greybus device operation includes a Greybus buffer to hold the
+ * data sent to the device. The only field within a Greybus
+ * operation that should be used by a caller is the payload pointer,
+ * which should be used to populate the request data. This pointer
+ * is guaranteed to be 64-bit aligned.
+ * XXX and callback?
+ */
+struct gb_operation;
+typedef void (*gb_operation_callback)(struct gb_operation *);
+struct gb_operation {
+ struct gb_connection *connection;
+ struct gbuf *gbuf;
+ void *payload; /* sender data */
+ gb_operation_callback callback; /* If asynchronous */
+ struct completion completion; /* Used if no callback */
+ u8 result;
+
+ struct list_head links; /* connection->operations */
+};
+
+struct gb_operation *gb_operation_create(struct gb_connection *connection,
+ size_t size);
+void gb_operation_destroy(struct gb_operation *operation);
+
+int gb_operation_wait(struct gb_operation *operation);
+void gb_operation_complete(struct gb_operation *operation);
+
+#endif /* !__OPERATION_H */
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