/*
 * 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;

/* The default amount of time a request is given to complete */
#define GB_OPERATION_TIMEOUT_DEFAULT    1000    /* milliseconds */

/*
 * 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_MESSAGE_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,
};

#define GB_OPERATION_MESSAGE_SIZE_MIN   sizeof(struct gb_operation_msg_hdr)
#define GB_OPERATION_MESSAGE_SIZE_MAX   U16_MAX

/*
 * Protocol code should only examine the payload and payload_size fields, and
 * host-controller drivers may use the hcpriv field. All other fields are
 * intended to be private to the operations core code.
 */
struct gb_message {
        struct gb_operation             *operation;
        struct gb_operation_msg_hdr     *header;

        void                            *payload;
        size_t                          payload_size;

        void                            *buffer;

        void                            *hcpriv;
};

#define GB_OPERATION_FLAG_INCOMING              BIT(0)
#define GB_OPERATION_FLAG_UNIDIRECTIONAL        BIT(1)
#define GB_OPERATION_FLAG_SHORT_RESPONSE        BIT(2)
#define GB_OPERATION_FLAG_CORE                  BIT(3)

#define GB_OPERATION_FLAG_USER_MASK     (GB_OPERATION_FLAG_SHORT_RESPONSE | \
                                         GB_OPERATION_FLAG_UNIDIRECTIONAL)

/*
 * 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;

        unsigned long           flags;
        u8                      type;
        u16                     id;
        int                     errno;          /* Operation result */

        struct work_struct      work;
        gb_operation_callback   callback;
        struct completion       completion;
        struct timer_list       timer;

        struct kref             kref;
        atomic_t                waiters;

        int                     active;
        struct list_head        links;          /* connection->operations */
};

static inline bool
gb_operation_is_incoming(struct gb_operation *operation)
{
        return operation->flags & GB_OPERATION_FLAG_INCOMING;
}

static inline bool
gb_operation_is_unidirectional(struct gb_operation *operation)
{
        return operation->flags & GB_OPERATION_FLAG_UNIDIRECTIONAL;
}

static inline bool
gb_operation_short_response_allowed(struct gb_operation *operation)
{
        return operation->flags & GB_OPERATION_FLAG_SHORT_RESPONSE;
}

static inline bool gb_operation_is_core(struct gb_operation *operation)
{
        return operation->flags & GB_OPERATION_FLAG_CORE;
}

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

int gb_operation_result(struct gb_operation *operation);

size_t gb_operation_get_payload_size_max(struct gb_connection *connection);
struct gb_operation *
gb_operation_create_flags(struct gb_connection *connection,
                                u8 type, size_t request_size,
                                size_t response_size, unsigned long flags,
                                gfp_t gfp);

static inline struct gb_operation *
gb_operation_create(struct gb_connection *connection,
                                u8 type, size_t request_size,
                                size_t response_size, gfp_t gfp)
{
        return gb_operation_create_flags(connection, type, request_size,
                                                response_size, 0, gfp);
}

struct gb_operation *
gb_operation_create_core(struct gb_connection *connection,
                                u8 type, size_t request_size,
                                size_t response_size, unsigned long flags,
                                gfp_t gfp);

void gb_operation_get(struct gb_operation *operation);
void gb_operation_put(struct gb_operation *operation);

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

int gb_operation_request_send(struct gb_operation *operation,
                                gb_operation_callback callback,
                                unsigned int timeout,
                                gfp_t gfp);
int gb_operation_request_send_sync_timeout(struct gb_operation *operation,
                                                unsigned int timeout);
static inline int
gb_operation_request_send_sync(struct gb_operation *operation)
{
        return gb_operation_request_send_sync_timeout(operation,
                        GB_OPERATION_TIMEOUT_DEFAULT);
}

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

void greybus_message_sent(struct gb_host_device *hd,
                                struct gb_message *message, int status);

int gb_operation_sync_timeout(struct gb_connection *connection, int type,
                                void *request, int request_size,
                                void *response, int response_size,
                                unsigned int timeout);
int gb_operation_unidirectional_timeout(struct gb_connection *connection,
                                int type, void *request, int request_size,
                                unsigned int timeout);

static inline int gb_operation_sync(struct gb_connection *connection, int type,
                      void *request, int request_size,
                      void *response, int response_size)
{
        return gb_operation_sync_timeout(connection, type,
                        request, request_size, response, response_size,
                        GB_OPERATION_TIMEOUT_DEFAULT);
}

static inline int gb_operation_unidirectional(struct gb_connection *connection,
                                int type, void *request, int request_size)
{
        return gb_operation_unidirectional_timeout(connection, type,
                        request, request_size, GB_OPERATION_TIMEOUT_DEFAULT);
}

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

#endif /* !__OPERATION_H */