/*
 * Greybus operations
 *
 * Copyright 2014 Google Inc.
 * Copyright 2014 Linaro Ltd.
 *
 * Released under the GPLv2 only.
 */

#ifndef __OPERATION_H
#define __OPERATION_H

#include <linux/completion.h>

struct gb_operation;

/*
 * No protocol may define an operation that has numeric value 0x00.
 * It is reserved as an explicitly invalid value.
 */
#define GB_OPERATION_TYPE_INVALID	((u8)0x00)

/*
 * 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	((u8)0x80)

enum gb_operation_result {
	GB_OP_SUCCESS		= 0x00,
	GB_OP_INTERRUPTED	= 0x01,
	GB_OP_TIMEOUT		= 0x02,
	GB_OP_NO_MEMORY		= 0x03,
	GB_OP_PROTOCOL_BAD	= 0x04,
	GB_OP_OVERFLOW		= 0x05,
	GB_OP_INVALID		= 0x06,
	GB_OP_RETRY		= 0x07,
	GB_OP_NONEXISTENT	= 0x08,
	GB_OP_UNKNOWN_ERROR	= 0xfe,
	GB_OP_MALFUNCTION	= 0xff,
};

/*
 * Protocol code should only examine the payload and payload_size
 * fields.  All other fields are intended to be private to the
 * operations core code.
 */
struct gb_message {
	struct gb_operation		*operation;
	void				*cookie;
	struct gb_operation_msg_hdr	*header;

	void				*payload;
	size_t				payload_size;

	u8				buffer[];
};

/*
 * A Greybus operation is a remote procedure call performed over a
 * connection between two UniPro interfaces.
 *
 * Every operation consists of a request message sent to the other
 * end of the connection coupled with a reply message returned to
 * the sender.  Every operation has a type, whose interpretation is
 * dependent on the protocol associated with the connection.
 *
 * Only four things in an operation structure are intended to be
 * directly usable by protocol handlers:  the operation's connection
 * pointer; the operation type; the request message payload (and
 * size); and the response message payload (and size).  Note that a
 * message with a 0-byte payload has a null message payload pointer.
 *
 * In addition, every operation has a result, which is an errno
 * value.  Protocol handlers access the operation result using
 * gb_operation_result().
 */
typedef void (*gb_operation_callback)(struct gb_operation *);
struct gb_operation {
	struct gb_connection	*connection;
	struct gb_message	*request;
	struct gb_message	*response;
	u8			type;

	u16			id;
	int			errno;		/* Operation result */

	struct work_struct	work;
	gb_operation_callback	callback;	/* If asynchronous */
	struct completion	completion;	/* Used if no callback */

	struct kref		kref;
	struct list_head	links;		/* connection->operations */
};

void gb_connection_recv(struct gb_connection *connection,
					void *data, size_t size);

int gb_operation_result(struct gb_operation *operation);

struct gb_operation *gb_operation_create(struct gb_connection *connection,
					u8 type, size_t request_size,
					size_t response_size);
void gb_operation_get(struct gb_operation *operation);
void gb_operation_put(struct gb_operation *operation);
static inline void gb_operation_destroy(struct gb_operation *operation)
{
	gb_operation_put(operation);
}

bool gb_operation_response_alloc(struct gb_operation *operation,
					size_t response_size);

int gb_operation_request_send(struct gb_operation *operation,
				gb_operation_callback callback);
int gb_operation_request_send_sync(struct gb_operation *operation);
int gb_operation_response_send(struct gb_operation *operation, int errno);

void gb_operation_cancel(struct gb_operation *operation, int errno);

void greybus_data_sent(struct greybus_host_device *hd,
				void *header, int status);

int gb_operation_sync(struct gb_connection *connection, int type,
		      void *request, int request_size,
		      void *response, int response_size);

int gb_operation_init(void);
void gb_operation_exit(void);

#endif /* !__OPERATION_H */