/*
* 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
#define OPERATION_TIMEOUT_DEFAULT 1000 /* milliseconds */
/*
* XXX This needs to be coordinated with host driver parameters
* XXX May need to reduce to allow for message header within a page
*/
#define GB_OPERATION_MESSAGE_SIZE_MAX 4096
static struct kmem_cache *gb_operation_cache;
/* Workqueue to handle Greybus operation completions. */
static struct workqueue_struct *gb_operation_workqueue;
/*
* All operation messages (both requests and responses) begin with
* a 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. The header contains an
* operation type field, whose interpretation is dependent on what
* type of protocol is used over the connection.
*
* The high bit (0x80) of the operation type field is used to
* indicate whether the message is a request (clear) or a response
* (set).
*
* Response messages include an additional status byte, which
* communicates the result of the corresponding request. A zero
* status value means the operation completed successfully. Any
* other value indicates an error; in this case, the payload of the
* response message (if any) is ignored. The status byte must be
* zero in the header for a request message.
*
* 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 operation_id; /* Operation unique id */
__u8 type; /* E.g GB_I2C_TYPE_* or GB_GPIO_TYPE_* */
__u8 result; /* Result of request (in responses only) */
/* 2 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_pending_operation_insert(struct gb_operation *operation)
{
struct gb_connection *connection = operation->connection;
struct gb_operation_msg_hdr *header;
/*
* Assign the operation's id and move it into its
* connection's pending list.
*/
spin_lock_irq(&gb_operations_lock);
operation->id = ++connection->op_cycle;
list_move_tail(&operation->links, &connection->pending);
spin_unlock_irq(&gb_operations_lock);
/* Store the operation id in the request header */
header = operation->request->header;
header->operation_id = cpu_to_le16(operation->id);
}
static void gb_pending_operation_remove(struct gb_operation *operation)
{
struct gb_connection *connection = operation->connection;
/* Take us off of the list of pending operations */
spin_lock_irq(&gb_operations_lock);
list_move_tail(&operation->links, &connection->operations);
spin_unlock_irq(&gb_operations_lock);
}
static struct gb_operation *
gb_pending_operation_find(struct gb_connection *connection, u16 operation_id)
{
struct gb_operation *operation;
bool found = false;
spin_lock_irq(&gb_operations_lock);
list_for_each_entry(operation, &connection->pending, links)
if (operation->id == operation_id) {
found = true;
break;
}
spin_unlock_irq(&gb_operations_lock);
return found ? operation : NULL;
}
static int gb_message_send(struct gb_message *message, gfp_t gfp_mask)
{
struct gb_connection *connection = message->operation->connection;
u16 dest_cport_id = connection->interface_cport_id;
int ret = 0;
message->cookie = connection->hd->driver->buffer_send(connection->hd,
dest_cport_id,
message->header,
message->size,
gfp_mask);
if (IS_ERR(message->cookie)) {
ret = PTR_ERR(message->cookie);
message->cookie = NULL;
}
return ret;
}
/*
* Cancel a message whose buffer we have passed to the host device
* layer to be sent.
*/
static void gb_message_cancel(struct gb_message *message)
{
struct greybus_host_device *hd;
if (!message->cookie)
return; /* Don't bother if the message isn't in flight */
hd = message->operation->connection->hd;
hd->driver->buffer_cancel(message->cookie);
}
/*
* An operation'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.
*/
static void gb_operation_complete(struct gb_operation *operation)
{
if (operation->callback)
operation->callback(operation);
else
complete_all(&operation->completion);
gb_operation_put(operation);
}
/*
* Wait for a submitted operation to complete. Returns the result
* of the operation; this will be -EINTR if the wait was interrupted.
*/
static int gb_operation_wait(struct gb_operation *operation)
{
int ret;
ret = wait_for_completion_interruptible(&operation->completion);
if (ret < 0)
gb_operation_cancel(operation, -EINTR);
return operation->errno;
}
#if 0
static void gb_operation_request_handle(struct gb_operation *operation)
{
struct gb_protocol *protocol = operation->connection->protocol;
struct gb_operation_msg_hdr *header;
header = operation->request->header;
/*
* If the protocol has no incoming request handler, report
* an error and mark the request bad.
*/
if (protocol->request_recv) {
protocol->request_recv(header->type, operation);
return;
}
gb_connection_err(operation->connection,
"unexpected incoming request type 0x%02hhx\n", header->type);
operation->errno = -EPROTONOSUPPORT;
}
#endif
/*
* Complete an operation in non-atomic context. The operation's
* result value should have been set before queueing this.
*/
static void gb_operation_work(struct work_struct *work)
{
struct gb_operation *operation;
operation = container_of(work, struct gb_operation, work);
gb_operation_complete(operation);
}
/*
* Timeout call for the operation.
*/
static void gb_operation_timeout(struct work_struct *work)
{
struct gb_operation *operation;
operation = container_of(work, struct gb_operation, timeout_work.work);
gb_operation_cancel(operation, -ETIMEDOUT);
}
/*
* Given a pointer to the header in a message sent on a given host
* device, return the associated message structure. (This "header"
* is just the buffer pointer we supply to the host device for
* sending.)
*/
static struct gb_message *
gb_hd_message_find(struct greybus_host_device *hd, void *header)
{
struct gb_message *message;
u8 *result;
result = (u8 *)header - hd->buffer_headroom - sizeof(*message);
message = (struct gb_message *)result;
return message;
}
/*
* Allocate a message to be used for an operation request or
* response. 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).
*
* Our message structure consists of:
* message structure
* headroom
* message header \_ these combined are
* message payload / the message size
*/
static struct gb_message *
gb_operation_message_alloc(struct greybus_host_device *hd, u8 type,
size_t payload_size, gfp_t gfp_flags)
{
struct gb_message *message;
struct gb_operation_msg_hdr *header;
size_t message_size = payload_size + sizeof(*header);
size_t size;
u8 *buffer;
if (message_size > hd->buffer_size_max)
return NULL;
size = sizeof(*message) + hd->buffer_headroom + message_size;
message = kzalloc(size, gfp_flags);
if (!message)
return NULL;
buffer = &message->buffer[0];
header = (struct gb_operation_msg_hdr *)(buffer + hd->buffer_headroom);
/* Fill in the header structure */
header->size = cpu_to_le16(message_size);
header->operation_id = 0; /* Filled in when submitted */
header->type = type;
message->header = header;
message->payload = header + 1;
message->size = message_size;
return message;
}
static void gb_operation_message_free(struct gb_message *message)
{
kfree(message);
}
/*
* Map an enum gb_operation_status value (which is represented in a
* message as a single byte) to an appropriate Linux negative errno.
*/
int gb_operation_status_map(u8 status)
{
switch (status) {
case GB_OP_SUCCESS:
return 0;
case GB_OP_INVALID:
return -EINVAL;
case GB_OP_NO_MEMORY:
return -ENOMEM;
case GB_OP_INTERRUPTED:
return -EINTR;
case GB_OP_RETRY:
return -EAGAIN;
case GB_OP_PROTOCOL_BAD:
return -EPROTONOSUPPORT;
case GB_OP_OVERFLOW:
return -E2BIG;
case GB_OP_TIMEOUT:
return -ETIMEDOUT;
default:
return -EIO;
}
}
/*
* Create a Greybus operation to be sent over the given connection.
* The request buffer will be 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.
*/
static struct gb_operation *
gb_operation_create_common(struct gb_connection *connection, bool outgoing,
u8 type, size_t request_size,
size_t response_size)
{
struct greybus_host_device *hd = connection->hd;
struct gb_operation *operation;
gfp_t gfp_flags = response_size ? GFP_KERNEL : GFP_ATOMIC;
operation = kmem_cache_zalloc(gb_operation_cache, gfp_flags);
if (!operation)
return NULL;
operation->connection = connection;
operation->request = gb_operation_message_alloc(hd, type, request_size,
gfp_flags);
if (!operation->request)
goto err_cache;
operation->request->operation = operation;
if (outgoing) {
type |= GB_OPERATION_TYPE_RESPONSE;
operation->response = gb_operation_message_alloc(hd, type,
response_size, GFP_KERNEL);
if (!operation->response)
goto err_request;
operation->response->operation = operation;
}
INIT_WORK(&operation->work, gb_operation_work);
operation->callback = NULL; /* set at submit time */
init_completion(&operation->completion);
INIT_DELAYED_WORK(&operation->timeout_work, gb_operation_timeout);
kref_init(&operation->kref);
spin_lock_irq(&gb_operations_lock);
list_add_tail(&operation->links, &connection->operations);
spin_unlock_irq(&gb_operations_lock);
return operation;
err_request:
gb_operation_message_free(operation->request);
err_cache:
kmem_cache_free(gb_operation_cache, operation);
return NULL;
}
struct gb_operation *gb_operation_create(struct gb_connection *connection,
u8 type, size_t request_size,
size_t response_size)
{
return gb_operation_create_common(connection, true, type,
request_size, response_size);
}
static struct gb_operation *
gb_operation_create_incoming(struct gb_connection *connection,
u8 type, size_t request_size,
size_t response_size)
{
return gb_operation_create_common(connection, false, type,
request_size, response_size);
}
/*
* Get an additional reference on an operation.
*/
void gb_operation_get(struct gb_operation *operation)
{
kref_get(&operation->kref);
}
/*
* Destroy a previously created operation.
*/
static void _gb_operation_destroy(struct kref *kref)
{
struct gb_operation *operation;
operation = container_of(kref, struct gb_operation, kref);
/* XXX Make sure it's not in flight */
spin_lock_irq(&gb_operations_lock);
list_del(&operation->links);
spin_unlock_irq(&gb_operations_lock);
gb_operation_message_free(operation->response);
gb_operation_message_free(operation->request);
kmem_cache_free(gb_operation_cache, operation);
}
/*
* Drop a reference on an operation, and destroy it when the last
* one is gone.
*/
void gb_operation_put(struct gb_operation *operation)
{
if (!WARN_ON(!operation))
kref_put(&operation->kref, _gb_operation_destroy);
}
/*
* 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)
{
unsigned long timeout;
int ret;
if (operation->connection->state != GB_CONNECTION_STATE_ENABLED)
return -ENOTCONN;
/*
* First, get an extra reference on the operation.
* It'll be dropped when the operation completes.
*/
gb_operation_get(operation);
operation->callback = callback;
gb_pending_operation_insert(operation);
/*
* We impose a time limit for requests to complete. We need
* to set the timer before we send the request though, so we
* don't lose a race with the receipt of the resposne.
*/
timeout = msecs_to_jiffies(OPERATION_TIMEOUT_DEFAULT);
schedule_delayed_work(&operation->timeout_work, timeout);
/* All set, send the request */
ret = gb_message_send(operation->request, GFP_KERNEL);
if (ret || callback)
return ret;
return gb_operation_wait(operation);
}
/*
* Send a response for an incoming operation request.
*/
int gb_operation_response_send(struct gb_operation *operation)
{
gb_operation_destroy(operation);
return 0;
}
/*
* This function is called when a buffer send request has completed.
* The "header" is the message header--the beginning of what we
* asked to have sent.
*/
void
greybus_data_sent(struct greybus_host_device *hd, void *header, int status)
{
struct gb_message *message;
struct gb_operation *operation;
/* If there's no error, there's really nothing to do */
if (!status)
return; /* Mark it complete? */
/* XXX Right now we assume we're an outgoing request */
message = gb_hd_message_find(hd, header);
operation = message->operation;
operation->errno = status;
queue_work(gb_operation_workqueue, &operation->work);
}
EXPORT_SYMBOL_GPL(greybus_data_sent);
/*
* We've received data on a connection, and it doesn't look like a
* response, so we assume it's a request.
*
* This is called in interrupt context, so just copy the incoming
* data into the request buffer and handle the rest via workqueue.
*/
void gb_connection_recv_request(struct gb_connection *connection,
u16 operation_id, u8 type, void *data, size_t size)
{
struct gb_operation *operation;
operation = gb_operation_create_incoming(connection, type, size, 0);
if (!operation) {
gb_connection_err(connection, "can't create operation");
return; /* XXX Respond with pre-allocated ENOMEM */
}
operation->id = operation_id;
memcpy(operation->request->header, data, size);
/* XXX Right now this will just complete the operation */
operation->errno = -ENOSYS;
queue_work(gb_operation_workqueue, &operation->work);
}
/*
* We've received data that appears to be an operation response
* message. Look up the operation, and record that we've received
* its response.
*
* This is called in interrupt context, so just copy the incoming
* data into the response buffer and handle the rest via workqueue.
*/
static void gb_connection_recv_response(struct gb_connection *connection,
u16 operation_id, void *data, size_t size)
{
struct gb_operation *operation;
struct gb_message *message;
struct gb_operation_msg_hdr *header;
int result;
operation = gb_pending_operation_find(connection, operation_id);
if (!operation) {
gb_connection_err(connection, "operation not found");
return;
}
cancel_delayed_work(&operation->timeout_work);
gb_pending_operation_remove(operation);
message = operation->response;
if (size <= message->size) {
/* Transfer the operation result from the response header */
header = message->header;
result = gb_operation_status_map(header->result);
} else {
gb_connection_err(connection, "recv buffer too small");
result = -E2BIG;
}
/* We must ignore the payload if a bad status is returned */
if (!result)
memcpy(message->header, data, size);
/* The rest will be handled in work queue context */
operation->errno = result;
queue_work(gb_operation_workqueue, &operation->work);
}
/*
* Handle data arriving on a connection. As soon as we return the
* supplied data buffer will be reused (so unless we do something
* with, it's effectively dropped).
*/
void gb_connection_recv(struct gb_connection *connection,
void *data, size_t size)
{
struct gb_operation_msg_hdr *header;
size_t msg_size;
u16 operation_id;
if (connection->state != GB_CONNECTION_STATE_ENABLED) {
gb_connection_err(connection, "dropping %zu received bytes",
size);
return;
}
if (size < sizeof(*header)) {
gb_connection_err(connection, "message too small");
return;
}
header = data;
msg_size = (size_t)le16_to_cpu(header->size);
if (msg_size > size) {
gb_connection_err(connection, "incomplete message");
return; /* XXX Should still complete operation */
}
operation_id = le16_to_cpu(header->operation_id);
if (header->type & GB_OPERATION_TYPE_RESPONSE)
gb_connection_recv_response(connection, operation_id,
data, msg_size);
else
gb_connection_recv_request(connection, operation_id,
header->type, data, msg_size);
}
/*
* Cancel an operation, and record the given error to indicate why.
*/
void gb_operation_cancel(struct gb_operation *operation, int errno)
{
operation->errno = errno;
gb_message_cancel(operation->request);
gb_message_cancel(operation->response);
}
int gb_operation_init(void)
{
gb_operation_cache = kmem_cache_create("gb_operation_cache",
sizeof(struct gb_operation), 0, 0, NULL);
if (!gb_operation_cache)
return -ENOMEM;
gb_operation_workqueue = alloc_workqueue("greybus_operation", 0, 1);
if (!gb_operation_workqueue) {
kmem_cache_destroy(gb_operation_cache);
gb_operation_cache = NULL;
return -ENOMEM;
}
return 0;
}
void gb_operation_exit(void)
{
destroy_workqueue(gb_operation_workqueue);
gb_operation_workqueue = NULL;
kmem_cache_destroy(gb_operation_cache);
gb_operation_cache = NULL;
}
