/******************************************************************************
 * xenbus.h
 *
 * Talks to Xen Store to figure out what devices we have.
 *
 * Copyright (C) 2005 Rusty Russell, IBM Corporation
 * Copyright (C) 2005 XenSource Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#ifndef _XEN_XENBUS_H
#define _XEN_XENBUS_H

#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/mutex.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/completion.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/semaphore.h>
#include <xen/interface/xen.h>
#include <xen/interface/grant_table.h>
#include <xen/interface/io/xenbus.h>
#include <xen/interface/io/xs_wire.h>
#include <xen/interface/event_channel.h>

#define XENBUS_MAX_RING_GRANT_ORDER 4
#define XENBUS_MAX_RING_GRANTS      (1U << XENBUS_MAX_RING_GRANT_ORDER)

/* Register callback to watch this node. */
struct xenbus_watch
{
        struct list_head list;

        /* Path being watched. */
        const char *node;

        unsigned int nr_pending;

        /*
         * Called just before enqueing new event while a spinlock is held.
         * The event will be discarded if this callback returns false.
         */
        bool (*will_handle)(struct xenbus_watch *,
                              const char *path, const char *token);

        /* Callback (executed in a process context with no locks held). */
        void (*callback)(struct xenbus_watch *,
                         const char *path, const char *token);
};


/* A xenbus device. */
struct xenbus_device {
        const char *devicetype;
        const char *nodename;
        const char *otherend;
        bool vanished;
        int otherend_id;
        struct xenbus_watch otherend_watch;
        struct device dev;
        enum xenbus_state state;
        struct completion down;
        struct work_struct work;
        struct semaphore reclaim_sem;

        /* Event channel based statistics and settings. */
        atomic_t event_channels;
        atomic_t events;
        atomic_t spurious_events;
        atomic_t jiffies_eoi_delayed;
        unsigned int spurious_threshold;
};

#define to_xenbus_device(__dev) container_of_const(__dev, struct xenbus_device, dev)

struct xenbus_device_id
{
        /* .../device/<device_type>/<identifier> */
        char devicetype[32];    /* General class of device. */
};

/* A xenbus driver. */
struct xenbus_driver {
        const char *name;       /* defaults to ids[0].devicetype */
        const struct xenbus_device_id *ids;
        bool allow_rebind; /* avoid setting xenstore closed during remove */
        bool not_essential;     /* is not mandatory for boot progress */
        int (*probe)(struct xenbus_device *dev,
                     const struct xenbus_device_id *id);
        void (*otherend_changed)(struct xenbus_device *dev,
                                 enum xenbus_state backend_state);
        void (*remove)(struct xenbus_device *dev);
        int (*suspend)(struct xenbus_device *dev);
        int (*resume)(struct xenbus_device *dev);
        int (*uevent)(const struct xenbus_device *, struct kobj_uevent_env *);
        struct device_driver driver;
        int (*read_otherend_details)(struct xenbus_device *dev);
        int (*is_ready)(struct xenbus_device *dev);
        void (*reclaim_memory)(struct xenbus_device *dev);
};

#define to_xenbus_driver(__drv) container_of_const(__drv, struct xenbus_driver, driver)

int __must_check __xenbus_register_frontend(struct xenbus_driver *drv,
                                            struct module *owner,
                                            const char *mod_name);
int __must_check __xenbus_register_backend(struct xenbus_driver *drv,
                                           struct module *owner,
                                           const char *mod_name);

#define xenbus_register_frontend(drv) \
        __xenbus_register_frontend(drv, THIS_MODULE, KBUILD_MODNAME)
#define xenbus_register_backend(drv) \
        __xenbus_register_backend(drv, THIS_MODULE, KBUILD_MODNAME)

void xenbus_unregister_driver(struct xenbus_driver *drv);

struct xenbus_transaction
{
        u32 id;
};

/* Nil transaction ID. */
#define XBT_NIL ((struct xenbus_transaction) { 0 })

char **xenbus_directory(struct xenbus_transaction t,
                        const char *dir, const char *node, unsigned int *num);
void *xenbus_read(struct xenbus_transaction t,
                  const char *dir, const char *node, unsigned int *len);
int xenbus_write(struct xenbus_transaction t,
                 const char *dir, const char *node, const char *string);
int xenbus_exists(struct xenbus_transaction t,
                  const char *dir, const char *node);
int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node);
int xenbus_transaction_start(struct xenbus_transaction *t);
int xenbus_transaction_end(struct xenbus_transaction t, bool abort);

/* Single read and scanf: returns -errno or num scanned if > 0. */
__scanf(4, 5)
int xenbus_scanf(struct xenbus_transaction t,
                 const char *dir, const char *node, const char *fmt, ...);

/* Read an (optional) unsigned value. */
unsigned int xenbus_read_unsigned(const char *dir, const char *node,
                                  unsigned int default_val);

/* Single printf and write: returns -errno or 0. */
__printf(4, 5)
int xenbus_printf(struct xenbus_transaction t,
                  const char *dir, const char *node, const char *fmt, ...);

/* Generic read function: NULL-terminated triples of name,
 * sprintf-style type string, and pointer. Returns 0 or errno.*/
int xenbus_gather(struct xenbus_transaction t, const char *dir, ...);

/* notifier routines for when the xenstore comes up */
extern int xenstored_ready;
int register_xenstore_notifier(struct notifier_block *nb);
void unregister_xenstore_notifier(struct notifier_block *nb);

int register_xenbus_watch(struct xenbus_watch *watch);
void unregister_xenbus_watch(struct xenbus_watch *watch);
void xs_suspend(void);
void xs_resume(void);
void xs_suspend_cancel(void);

struct work_struct;

#define XENBUS_IS_ERR_READ(str) ({                      \
        if (!IS_ERR(str) && strlen(str) == 0) {         \
                kfree(str);                             \
                str = ERR_PTR(-ERANGE);                 \
        }                                               \
        IS_ERR(str);                                    \
})

#define XENBUS_EXIST_ERR(err) ((err) == -ENOENT || (err) == -ERANGE)

int xenbus_watch_path(struct xenbus_device *dev, const char *path,
                      struct xenbus_watch *watch,
                      bool (*will_handle)(struct xenbus_watch *,
                                          const char *, const char *),
                      void (*callback)(struct xenbus_watch *,
                                       const char *, const char *));
__printf(5, 6)
int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
                         bool (*will_handle)(struct xenbus_watch *,
                                             const char *, const char *),
                         void (*callback)(struct xenbus_watch *,
                                          const char *, const char *),
                         const char *pathfmt, ...);

int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
                      unsigned int nr_pages, grant_ref_t *grefs);
void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages,
                          grant_ref_t *grefs);
int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
                           unsigned int nr_grefs, void **vaddr);

int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr);

int xenbus_alloc_evtchn(struct xenbus_device *dev, evtchn_port_t *port);
int xenbus_free_evtchn(struct xenbus_device *dev, evtchn_port_t port);

enum xenbus_state xenbus_read_driver_state(const struct xenbus_device *dev,
                                           const char *path);

__printf(3, 4)
void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...);
__printf(3, 4)
void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...);

const char *xenbus_strstate(enum xenbus_state state);
int xenbus_dev_is_online(struct xenbus_device *dev);
int xenbus_frontend_closed(struct xenbus_device *dev);

extern const struct file_operations xen_xenbus_fops;
extern struct xenstore_domain_interface *xen_store_interface;
extern int xen_store_evtchn;

#endif /* _XEN_XENBUS_H */