/*
* 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"
/*
* The top bit of the type in an operation message header indicates
* whether the message is a request (bit clear) or response (bit set)
*/
#define GB_OPERATION_TYPE_RESPONSE 0x80
/*
* XXX This needs to be coordinated with host driver parameters
*/
#define GB_OPERATION_MESSAGE_SIZE_MAX 4096
/* Workqueue to handle Greybus operation completions. */
static struct workqueue_struct *gb_operation_recv_workqueue;
/*
* 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);
static void gb_operation_insert(struct gb_operation *operation)
{
struct gb_connection *connection = operation->connection;
struct rb_root *root = &connection->pending;
struct rb_node *node = &operation->node;
struct rb_node **link = &root->rb_node;
struct rb_node *above = NULL;
struct gb_operation_msg_hdr *header;
__le16 wire_id;
/*
* Assign the operation's id, and store it in the header of
* both request and response message headers.
*/
operation->id = gb_connection_operation_id(connection);
wire_id = cpu_to_le16(operation->id);
header = operation->request->transfer_buffer;
header->id = wire_id;
/* OK, insert the operation into its connection's tree */
spin_lock_irq(&gb_operations_lock);
while (*link) {
struct gb_operation *other;
above = *link;
other = rb_entry(above, struct gb_operation, node);
header = other->request->transfer_buffer;
if (other->id > operation->id)
link = &above->rb_left;
else if (other->id < operation->id)
link = &above->rb_right;
}
rb_link_node(node, above, link);
rb_insert_color(node, root);
spin_unlock_irq(&gb_operations_lock);
}
static void gb_operation_remove(struct gb_operation *operation)
{
spin_lock_irq(&gb_operations_lock);
rb_erase(&operation->node, &operation->connection->pending);
spin_unlock_irq(&gb_operations_lock);
}
static struct gb_operation *
gb_operation_find(struct gb_connection *connection, u16 id)
{
struct gb_operation *operation = NULL;
struct rb_node *node;
bool found = false;
spin_lock_irq(&gb_operations_lock);
node = connection->pending.rb_node;
while (node && !found) {
operation = rb_entry(node, struct gb_operation, node);
if (operation->id > id)
node = node->rb_left;
else if (operation->id < id)
node = node->rb_right;
else
found = true;
}
spin_unlock_irq(&gb_operations_lock);
return found ? operation : NULL;
}
/*
* 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 operation 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->request);
return ret;
}
/*
* This handler is used if no operation response messages are ever
* expected for a given protocol.
*/
static void gb_operation_recv_none(struct gb_operation *operation)
{
/* Nothing to do! */
}
typedef void (*gb_operation_recv_handler)(struct gb_operation *operation);
static gb_operation_recv_handler gb_operation_recv_handlers[] = {
[GREYBUS_PROTOCOL_CONTROL] = NULL,
[GREYBUS_PROTOCOL_AP] = NULL,
[GREYBUS_PROTOCOL_GPIO] = NULL,
[GREYBUS_PROTOCOL_I2C] = gb_operation_recv_none,
[GREYBUS_PROTOCOL_UART] = NULL,
[GREYBUS_PROTOCOL_HID] = NULL,
[GREYBUS_PROTOCOL_VENDOR] = NULL,
};
static void gb_operation_request_handle(struct gb_operation *operation)
{
u8 protocol = operation->connection->protocol;
/* Subtract one from array size to stay within u8 range */
if (protocol <= (u8)(ARRAY_SIZE(gb_operation_recv_handlers) - 1)) {
gb_operation_recv_handler handler;
handler = gb_operation_recv_handlers[protocol];
if (handler) {
handler(operation); /* Handle the request */
return;
}
}
gb_connection_err(operation->connection, "unrecognized protocol %u\n",
(unsigned int)protocol);
operation->result = GB_OP_PROTOCOL_BAD;
gb_operation_complete(operation);
}
/*
* Either this operation contains an incoming request, or its
* response has arrived. An incoming request will have a null
* response buffer pointer (it is the responsibility of the request
* handler to allocate and fill in the response buffer).
*/
static void gb_operation_recv_work(struct work_struct *recv_work)
{
struct gb_operation *operation;
bool incoming_request;
operation = container_of(recv_work, struct gb_operation, recv_work);
incoming_request = operation->response == NULL;
if (incoming_request)
gb_operation_request_handle(operation);
gb_operation_complete(operation);
/* We're finished with the buffer we read into */
if (incoming_request)
greybus_gbuf_finished(operation->request);
else
greybus_gbuf_finished(operation->response);
}
/*
* Buffer completion function. We get notified whenever any buffer
* completes. For outbound messages, this tells us that the message
* has been sent. For inbound messages, it means the data has
* landed in the buffer and is ready to be processed.
*
* Either way, we don't do anything. We don't really care when an
* outbound message has been sent, and for incoming messages we
* we'll be done with everything we need to do before we mark it
* finished.
*
* XXX We may want to record that a request is (or is no longer) in flight.
*/
static void gb_operation_gbuf_complete(struct gbuf *gbuf)
{
if (gbuf->status) {
struct gb_operation *operation = gbuf->context;
struct gb_operation_msg_hdr *header;
int id;
int type;
if (gbuf == operation->request)
header = operation->request_payload;
else if (gbuf == operation->response)
header = operation->response_payload;
else
header = NULL;
id = header ? (int)header->id : -1;
type = header ? (int)header->type : -1;
gb_connection_err(operation->connection,
"operation %d type %d gbuf error %d",
id, type, gbuf->status);
}
return;
}
/*
* Allocate a buffer to be used for an operation request or response
* message. For outgoing messages, both types of message contain a
* common header, which is filled in here. Incoming requests or
* responses also contain the same header, but there's no need to
* initialize it here (it'll be overwritten by the incoming
* message).
*/
struct gbuf *gb_operation_gbuf_create(struct gb_operation *operation,
u8 type, size_t size, bool data_out)
{
struct gb_connection *connection = operation->connection;
struct gb_operation_msg_hdr *header;
struct gbuf *gbuf;
gfp_t gfp_flags = data_out ? GFP_KERNEL : GFP_ATOMIC;
size += sizeof(*header);
gbuf = greybus_alloc_gbuf(connection, gb_operation_gbuf_complete,
size, data_out, gfp_flags, operation);
if (!gbuf)
return NULL;
/* Fill in the header structure */
header = (struct gb_operation_msg_hdr *)gbuf->transfer_buffer;
header->size = cpu_to_le16(size);
header->id = 0; /* Filled in when submitted */
header->type = type;
return gbuf;
}
/*
* Create a Greybus operation to be sent over the given connection.
* The request buffer will big enough for a payload of the given
* size. Outgoing requests must specify the size of the response
* buffer size, which must be sufficient to hold all expected
* response data.
*
* Incoming requests will supply a response size of 0, and in that
* case no response buffer is allocated. (A response always
* includes a status byte, so 0 is not a valid size.) Whatever
* handles the operation request is responsible for allocating the
* response buffer.
*
* Returns a pointer to the new operation or a null pointer if an
* error occurs.
*/
struct gb_operation *gb_operation_create(struct gb_connection *connection,
u8 type, size_t request_size,
size_t response_size)
{
struct gb_operation *operation;
gfp_t gfp_flags = response_size ? GFP_KERNEL : GFP_ATOMIC;
bool outgoing = response_size != 0;
/* XXX Use a slab cache */
operation = kzalloc(sizeof(*operation), gfp_flags);
if (!operation)
return NULL;
operation->connection = connection; /* XXX refcount? */
operation->request = gb_operation_gbuf_create(operation, type,
request_size,
outgoing);
if (!operation->request) {
kfree(operation);
return NULL;
}
operation->request_payload = operation->request->transfer_buffer +
sizeof(struct gb_operation_msg_hdr);
/* We always use the full request buffer */
operation->request->actual_length = request_size;
if (outgoing) {
type |= GB_OPERATION_TYPE_RESPONSE;
operation->response = gb_operation_gbuf_create(operation,
type, response_size,
false);
if (!operation->response) {
greybus_free_gbuf(operation->request);
kfree(operation);
return NULL;
}
operation->response_payload =
operation->response->transfer_buffer +
sizeof(struct gb_operation_msg_hdr);
}
INIT_WORK(&operation->recv_work, gb_operation_recv_work);
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->response);
greybus_free_gbuf(operation->request);
kfree(operation);
}
/*
* Send an operation request message. 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_request_send(struct gb_operation *operation,
gb_operation_callback callback)
{
int ret;
/*
* XXX
* I think the order of operations is going to be
* significant, and if so, we may need a mutex to surround
* setting the operation id and submitting the gbuf.
*/
operation->callback = callback;
gb_operation_insert(operation);
ret = greybus_submit_gbuf(operation->request, GFP_KERNEL);
if (ret)
return ret;
if (!callback)
ret = gb_operation_wait(operation);
return ret;
}
/*
* Send a response for an incoming operation request.
*/
int gb_operation_response_send(struct gb_operation *operation)
{
/* XXX
* Caller needs to have set operation->response->actual_length
*/
gb_operation_remove(operation);
gb_operation_destroy(operation);
return 0;
}
/*
* Handle data arriving on a connection. This is called in
* interrupt context, so just copy the incoming data into a buffer
* and do remaining handling via a work queue.
*/
void gb_connection_operation_recv(struct gb_connection *connection,
void *data, size_t size)
{
struct gb_operation_msg_hdr *header;
struct gb_operation *operation;
struct gbuf *gbuf;
u16 msg_size;
if (size > GB_OPERATION_MESSAGE_SIZE_MAX) {
gb_connection_err(connection, "message too big");
return;
}
header = data;
msg_size = le16_to_cpu(header->size);
if (header->type & GB_OPERATION_TYPE_RESPONSE) {
u16 id = le16_to_cpu(header->id);
operation = gb_operation_find(connection, id);
if (!operation) {
gb_connection_err(connection, "operation not found");
return;
}
gb_operation_remove(operation);
gbuf = operation->response;
gbuf->status = GB_OP_SUCCESS; /* If we got here we're good */
if (size > gbuf->transfer_buffer_length) {
gb_connection_err(connection, "recv buffer too small");
return;
}
} else {
WARN_ON(msg_size != size);
operation = gb_operation_create(connection, header->type,
msg_size, 0);
if (!operation) {
gb_connection_err(connection, "can't create operation");
return;
}
gbuf = operation->request;
}
memcpy(gbuf->transfer_buffer, data, msg_size);
gbuf->actual_length = msg_size;
/* The rest will be handled in work queue context */
queue_work(gb_operation_recv_workqueue, &operation->recv_work);
}
int gb_operation_init(void)
{
gb_operation_recv_workqueue = alloc_workqueue("greybus_recv", 0, 1);
if (!gb_operation_recv_workqueue)
return -ENOMEM;
return 0;
}
void gb_operation_exit(void)
{
destroy_workqueue(gb_operation_recv_workqueue);
}
