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/*
* Greybus protocol handling
*
* Copyright 2014-2015 Google Inc.
* Copyright 2014-2015 Linaro Ltd.
*
* Released under the GPLv2 only.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include "greybus.h"
/* Global list of registered protocols */
static DEFINE_SPINLOCK(gb_protocols_lock);
static LIST_HEAD(gb_protocols);
/* Caller must hold gb_protocols_lock */
static struct gb_protocol *gb_protocol_find(u8 id, u8 major, u8 minor)
{
struct gb_protocol *protocol;
list_for_each_entry(protocol, &gb_protocols, links) {
if (protocol->id < id)
continue;
if (protocol->id > id)
break;
if (protocol->major > major)
continue;
if (protocol->major < major)
break;
if (protocol->minor > minor)
continue;
if (protocol->minor < minor)
break;
return protocol;
}
return NULL;
}
int __gb_protocol_register(struct gb_protocol *protocol, struct module *module)
{
struct gb_protocol *existing;
u8 id = protocol->id;
u8 major = protocol->major;
u8 minor = protocol->minor;
protocol->owner = module;
/*
* The protocols list is sorted first by protocol id (low to
* high), then by major version (high to low), and finally
* by minor version (high to low). Searching only by
* protocol id will produce the newest implemented version
* of the protocol.
*/
spin_lock_irq(&gb_protocols_lock);
list_for_each_entry(existing, &gb_protocols, links) {
if (existing->id < id)
continue;
if (existing->id > id)
break;
if (existing->major > major)
continue;
if (existing->major < major)
break;
if (existing->minor > minor)
continue;
if (existing->minor < minor)
break;
/* A matching protocol has already been registered */
spin_unlock_irq(&gb_protocols_lock);
return -EEXIST;
}
/*
* We need to insert the protocol here, before the existing one
* (or before the head if we searched the whole list)
*/
list_add_tail(&protocol->links, &existing->links);
spin_unlock_irq(&gb_protocols_lock);
pr_info("Registered %s protocol.\n", protocol->name);
/*
* Go try to bind any unbound connections, as we have a
* new protocol in the system
*/
gb_bundle_bind_protocols();
return 0;
}
EXPORT_SYMBOL_GPL(__gb_protocol_register);
/*
* De-register a previously registered protocol.
*
* XXX Currently this fails (and reports an error to the caller) if
* XXX the protocol is currently in use. We may want to forcefully
* XXX kill off a protocol and all its active users at some point.
* XXX But I think that's better handled by quiescing modules that
* XXX have users and having those users drop their reference.
*
* Returns true if successful, false otherwise.
*/
int gb_protocol_deregister(struct gb_protocol *protocol)
{
u8 protocol_count = 0;
if (!protocol)
return 0;
spin_lock_irq(&gb_protocols_lock);
protocol = gb_protocol_find(protocol->id, protocol->major,
protocol->minor);
if (protocol) {
protocol_count = protocol->count;
if (!protocol_count)
list_del(&protocol->links);
}
spin_unlock_irq(&gb_protocols_lock);
if (protocol)
pr_info("Deregistered %s protocol.\n", protocol->name);
return protocol && !protocol_count;
}
EXPORT_SYMBOL_GPL(gb_protocol_deregister);
/* Returns the requested protocol if available, or a null pointer */
struct gb_protocol *gb_protocol_get(u8 id, u8 major, u8 minor)
{
struct gb_protocol *protocol;
u8 protocol_count;
spin_lock_irq(&gb_protocols_lock);
protocol = gb_protocol_find(id, major, minor);
if (protocol) {
if (!try_module_get(protocol->owner)) {
protocol = NULL;
} else {
protocol_count = protocol->count;
if (protocol_count != U8_MAX)
protocol->count++;
}
}
spin_unlock_irq(&gb_protocols_lock);
if (protocol)
WARN_ON(protocol_count == U8_MAX);
else
pr_err("protocol id %hhu version %hhu.%hhu not found\n",
id, major, minor);
return protocol;
}
int gb_protocol_get_version(struct gb_connection *connection, int type,
void *request, int request_size,
struct gb_protocol_version_response *response,
__u8 major)
{
int retval;
retval = gb_operation_sync(connection, type, request, request_size,
response, sizeof(*response));
if (retval)
return retval;
if (response->major > major) {
dev_err(&connection->dev,
"unsupported major version (%hhu > %hhu)\n",
response->major, major);
return -ENOTSUPP;
}
dev_dbg(&connection->dev, "version_major = %u version_minor = %u\n",
response->major, response->minor);
return 0;
}
EXPORT_SYMBOL_GPL(gb_protocol_get_version);
void gb_protocol_put(struct gb_protocol *protocol)
{
u8 id;
u8 major;
u8 minor;
u8 protocol_count;
if (!protocol)
return;
id = protocol->id;
major = protocol->major;
minor = protocol->minor;
spin_lock_irq(&gb_protocols_lock);
protocol = gb_protocol_find(id, major, minor);
if (protocol) {
protocol_count = protocol->count;
if (protocol_count)
protocol->count--;
module_put(protocol->owner);
}
spin_unlock_irq(&gb_protocols_lock);
if (protocol)
WARN_ON(!protocol_count);
else
pr_err("protocol id %hhu version %hhu.%hhu not found\n",
id, major, minor);
}
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