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d90c25b0a2
Give the operation layer a chance to examine incoming data so that it can handle it appropriately. Treat the data as an operation message header. If it's a response, look up the operation it's associated with. If it's not, create a new operation. Copy the incoming data into the request or response buffer. The next patch adds a work queue to pick up handling the request or response from there. Get rid of gb_operation_submit(). Instead, we have two functions, one for sending an operation's request message, the other for sending an operation's response message. Not fully functional yet, still just filling things in... Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
380 lines
10 KiB
C
380 lines
10 KiB
C
/*
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* Greybus operations
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*
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* Copyright 2014 Google Inc.
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*
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* Released under the GPLv2 only.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/workqueue.h>
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#include "greybus.h"
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/*
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* The top bit of the type in an operation message header indicates
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* whether the message is a request (bit clear) or response (bit set)
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*/
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#define GB_OPERATION_TYPE_RESPONSE 0x80
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/*
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* XXX This needs to be coordinated with host driver parameters
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*/
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#define GB_OPERATION_MESSAGE_SIZE_MAX 4096
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/*
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* All operation messages (both requests and responses) begin with
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* a common header that encodes the size of the data (header
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* included). This header also contains a unique identifier, which
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* is used to keep track of in-flight operations. Finally, the
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* header contains a operation type field, whose interpretation is
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* dependent on what type of device lies on the other end of the
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* connection. Response messages are distinguished from request
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* messages by setting the high bit (0x80) in the operation type
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* value.
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*
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* The wire format for all numeric fields in the header is little
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* endian. Any operation-specific data begins immediately after the
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* header, and is 64-bit aligned.
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*/
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struct gb_operation_msg_hdr {
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__le16 size; /* Size in bytes of header + payload */
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__le16 id; /* Operation unique id */
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__u8 type; /* E.g GB_I2C_TYPE_* or GB_GPIO_TYPE_* */
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/* 3 bytes pad, must be zero (ignore when read) */
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} __aligned(sizeof(u64));
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/* XXX Could be per-host device, per-module, or even per-connection */
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static DEFINE_SPINLOCK(gb_operations_lock);
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static void gb_operation_insert(struct gb_operation *operation)
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{
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struct gb_connection *connection = operation->connection;
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struct rb_root *root = &connection->pending;
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struct rb_node *node = &operation->node;
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struct rb_node **link = &root->rb_node;
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struct rb_node *above = NULL;
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struct gb_operation_msg_hdr *header;
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__le16 wire_id;
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/*
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* Assign the operation's id, and store it in the header of
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* both request and response message headers.
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*/
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operation->id = gb_connection_operation_id(connection);
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wire_id = cpu_to_le16(operation->id);
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header = operation->request->transfer_buffer;
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header->id = wire_id;
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/* OK, insert the operation into its connection's tree */
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spin_lock_irq(&gb_operations_lock);
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while (*link) {
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struct gb_operation *other;
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above = *link;
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other = rb_entry(above, struct gb_operation, node);
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header = other->request->transfer_buffer;
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if (other->id > operation->id)
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link = &above->rb_left;
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else if (other->id < operation->id)
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link = &above->rb_right;
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}
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rb_link_node(node, above, link);
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rb_insert_color(node, root);
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spin_unlock_irq(&gb_operations_lock);
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}
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static void gb_operation_remove(struct gb_operation *operation)
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{
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spin_lock_irq(&gb_operations_lock);
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rb_erase(&operation->node, &operation->connection->pending);
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spin_unlock_irq(&gb_operations_lock);
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}
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static struct gb_operation *
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gb_operation_find(struct gb_connection *connection, u16 id)
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{
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struct gb_operation *operation = NULL;
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struct rb_node *node;
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bool found = false;
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spin_lock_irq(&gb_operations_lock);
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node = connection->pending.rb_node;
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while (node && !found) {
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operation = rb_entry(node, struct gb_operation, node);
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if (operation->id > id)
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node = node->rb_left;
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else if (operation->id < id)
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node = node->rb_right;
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else
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found = true;
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}
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spin_unlock_irq(&gb_operations_lock);
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return found ? operation : NULL;
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}
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/*
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* An operations's response message has arrived. If no callback was
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* supplied it was submitted for asynchronous completion, so we notify
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* any waiters. Otherwise we assume calling the completion is enough
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* and nobody else will be waiting.
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*/
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void gb_operation_complete(struct gb_operation *operation)
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{
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/* XXX Should probably report bad status if no callback */
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if (operation->callback)
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operation->callback(operation);
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else
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complete_all(&operation->completion);
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gb_operation_destroy(operation);
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}
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/*
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* Wait for a submitted operatnoi to complete */
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int gb_operation_wait(struct gb_operation *operation)
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{
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int ret;
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ret = wait_for_completion_interruptible(&operation->completion);
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/* If interrupted, cancel the in-flight buffer */
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if (ret < 0)
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ret = greybus_kill_gbuf(operation->request);
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return ret;
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}
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/*
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* Called when an operation buffer completes.
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*/
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static void gb_operation_gbuf_complete(struct gbuf *gbuf)
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{
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/* Don't do anything */
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struct gb_operation *operation;
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struct gb_operation_msg_hdr *header;
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u16 id;
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/*
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* This isn't right, but it keeps things balanced until we
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* can set up operation response handling.
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*/
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header = gbuf->transfer_buffer;
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id = le16_to_cpu(header->id);
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operation = gb_operation_find(gbuf->connection, id);
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if (operation)
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gb_operation_remove(operation);
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else
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gb_connection_err(gbuf->connection, "operation not found");
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}
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/*
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* Allocate a buffer to be used for an operation request or response
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* message. Both types of message contain a header, which is filled
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* in here. W
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*/
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struct gbuf *gb_operation_gbuf_create(struct gb_operation *operation,
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u8 type, size_t size, bool outbound)
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{
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struct gb_connection *connection = operation->connection;
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struct gb_operation_msg_hdr *header;
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struct gbuf *gbuf;
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gfp_t gfp_flags = outbound ? GFP_KERNEL : GFP_ATOMIC;
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/* Operation buffers hold a header in addition to their payload */
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size += sizeof(*header);
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gbuf = greybus_alloc_gbuf(connection, gb_operation_gbuf_complete,
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size, outbound, gfp_flags, operation);
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if (!gbuf)
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return NULL;
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/* Fill in the header structure */
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header = (struct gb_operation_msg_hdr *)gbuf->transfer_buffer;
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header->size = cpu_to_le16(size);
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header->id = 0; /* Filled in when submitted */
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header->type = type;
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return gbuf;
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}
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/*
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* Create a Greybus operation to be sent over the given connection.
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* The request buffer will big enough for a payload of the given
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* size. Outgoing requests must specify the size of the response
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* buffer size, which must be sufficient to hold all expected
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* response data.
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*
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* Incoming requests will supply a response size of 0, and in that
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* case no response buffer is allocated. (A response always
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* includes a status byte, so 0 is not a valid size.) Whatever
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* handles the operation request is responsible for allocating the
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* response buffer.
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*
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* Returns a pointer to the new operation or a null pointer if an
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* error occurs.
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*/
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struct gb_operation *gb_operation_create(struct gb_connection *connection,
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u8 type, size_t request_size,
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size_t response_size)
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{
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struct gb_operation *operation;
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gfp_t gfp_flags = response_size ? GFP_KERNEL : GFP_ATOMIC;
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if (!request_size) {
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gb_connection_err(connection, "zero-sized request");
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return NULL;
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}
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/* XXX Use a slab cache */
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operation = kzalloc(sizeof(*operation), gfp_flags);
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if (!operation)
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return NULL;
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operation->connection = connection; /* XXX refcount? */
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operation->request = gb_operation_gbuf_create(operation, type,
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request_size, true);
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if (!operation->request) {
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kfree(operation);
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return NULL;
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}
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operation->request_payload = operation->request->transfer_buffer +
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sizeof(struct gb_operation_msg_hdr);
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/* We always use the full request buffer */
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operation->request->actual_length = request_size;
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if (response_size) {
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type |= GB_OPERATION_TYPE_RESPONSE;
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operation->response = gb_operation_gbuf_create(operation,
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type, response_size, false);
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if (!operation->response) {
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greybus_free_gbuf(operation->request);
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kfree(operation);
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return NULL;
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}
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operation->response_payload =
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operation->response->transfer_buffer +
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sizeof(struct gb_operation_msg_hdr);
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}
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operation->callback = NULL; /* set at submit time */
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init_completion(&operation->completion);
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spin_lock_irq(&gb_operations_lock);
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list_add_tail(&operation->links, &connection->operations);
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spin_unlock_irq(&gb_operations_lock);
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return operation;
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}
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/*
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* Destroy a previously created operation.
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*/
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void gb_operation_destroy(struct gb_operation *operation)
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{
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if (WARN_ON(!operation))
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return;
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/* XXX Make sure it's not in flight */
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spin_lock_irq(&gb_operations_lock);
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list_del(&operation->links);
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spin_unlock_irq(&gb_operations_lock);
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greybus_free_gbuf(operation->response);
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greybus_free_gbuf(operation->request);
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kfree(operation);
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}
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/*
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* Send an operation request message. The caller has filled in
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* any payload so the request message is ready to go. If non-null,
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* the callback function supplied will be called when the response
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* message has arrived indicating the operation is complete. A null
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* callback function is used for a synchronous request; return from
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* this function won't occur until the operation is complete (or an
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* interrupt occurs).
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*/
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int gb_operation_request_send(struct gb_operation *operation,
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gb_operation_callback callback)
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{
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int ret;
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/*
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* XXX
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* I think the order of operations is going to be
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* significant, and if so, we may need a mutex to surround
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* setting the operation id and submitting the gbuf.
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*/
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operation->callback = callback;
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gb_operation_insert(operation);
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ret = greybus_submit_gbuf(operation->request, GFP_KERNEL);
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if (ret)
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return ret;
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if (!callback)
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ret = gb_operation_wait(operation);
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return ret;
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}
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/*
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* Send a response for an incoming operation request.
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*/
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int gb_operation_response_send(struct gb_operation *operation)
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{
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/* XXX
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* Caller needs to have set operation->response->actual_length
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*/
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gb_operation_remove(operation);
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gb_operation_destroy(operation);
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return 0;
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}
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void gb_connection_operation_recv(struct gb_connection *connection,
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void *data, size_t size)
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{
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struct gb_operation_msg_hdr *header;
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struct gb_operation *operation;
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struct gbuf *gbuf;
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u16 msg_size;
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if (size > GB_OPERATION_MESSAGE_SIZE_MAX) {
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gb_connection_err(connection, "message too big");
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return;
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}
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header = data;
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msg_size = le16_to_cpu(header->size);
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if (header->type & GB_OPERATION_TYPE_RESPONSE) {
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u16 id = le16_to_cpu(header->id);
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operation = gb_operation_find(connection, id);
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if (!operation) {
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gb_connection_err(connection, "operation not found");
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return;
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}
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gb_operation_remove(operation);
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gbuf = operation->response;
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if (size > gbuf->transfer_buffer_length) {
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gb_connection_err(connection, "recv buffer too small");
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return;
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}
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} else {
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WARN_ON(msg_size != size);
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operation = gb_operation_create(connection, header->type,
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msg_size, 0);
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if (!operation) {
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gb_connection_err(connection, "can't create operation");
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return;
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}
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gbuf = operation->request;
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}
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memcpy(gbuf->transfer_buffer, data, msg_size);
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gbuf->actual_length = msg_size;
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/* XXX And now we let a work queue handle the rest */
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}
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