| /* |
| * 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 -RESTARTSYS |
| * if the wait was interrupted. Otherwise returns the result of the |
| * operation. |
| */ |
| 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) |
| gb_message_cancel(operation->request); |
| else |
| ret = operation->errno; |
| return ret; |
| } |
| |
| #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. |
| * |
| * If this fires, something went wrong, so mark the result as timed out, and |
| * run the completion handler, which (hopefully) should clean up the operation |
| * properly. |
| */ |
| static void operation_timeout(struct work_struct *work) |
| { |
| struct gb_operation *operation; |
| |
| operation = container_of(work, struct gb_operation, timeout_work.work); |
| pr_debug("%s: timeout!\n", __func__); |
| |
| operation->errno = -ETIMEDOUT; |
| gb_operation_complete(operation); |
| } |
| |
| /* |
| * 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, 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. |
| */ |
| void gb_operation_cancel(struct gb_operation *operation) |
| { |
| operation->canceled = true; |
| 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; |
| } |