1/********************************************************************* 2 * 3 * sir_dongle.c: manager for serial dongle protocol drivers 4 * 5 * Copyright (c) 2002 Martin Diehl 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation; either version 2 of 10 * the License, or (at your option) any later version. 11 * 12 ********************************************************************/ 13 14#include <linux/module.h> 15#include <linux/kernel.h> 16#include <linux/init.h> 17#include <linux/kmod.h> 18#include <linux/mutex.h> 19 20#include <net/irda/irda.h> 21 22#include "sir-dev.h" 23 24/************************************************************************** 25 * 26 * dongle registration and attachment 27 * 28 */ 29 30static LIST_HEAD(dongle_list); /* list of registered dongle drivers */ 31static DEFINE_MUTEX(dongle_list_lock); /* protects the list */ 32 33int irda_register_dongle(struct dongle_driver *new) 34{ 35 struct list_head *entry; 36 struct dongle_driver *drv; 37 38 IRDA_DEBUG(0, "%s : registering dongle \"%s\" (%d).\n", 39 __func__, new->driver_name, new->type); 40 41 mutex_lock(&dongle_list_lock); 42 list_for_each(entry, &dongle_list) { 43 drv = list_entry(entry, struct dongle_driver, dongle_list); 44 if (new->type == drv->type) { 45 mutex_unlock(&dongle_list_lock); 46 return -EEXIST; 47 } 48 } 49 list_add(&new->dongle_list, &dongle_list); 50 mutex_unlock(&dongle_list_lock); 51 return 0; 52} 53EXPORT_SYMBOL(irda_register_dongle); 54 55int irda_unregister_dongle(struct dongle_driver *drv) 56{ 57 mutex_lock(&dongle_list_lock); 58 list_del(&drv->dongle_list); 59 mutex_unlock(&dongle_list_lock); 60 return 0; 61} 62EXPORT_SYMBOL(irda_unregister_dongle); 63 64int sirdev_get_dongle(struct sir_dev *dev, IRDA_DONGLE type) 65{ 66 struct list_head *entry; 67 const struct dongle_driver *drv = NULL; 68 int err = -EINVAL; 69 70 request_module("irda-dongle-%d", type); 71 72 if (dev->dongle_drv != NULL) 73 return -EBUSY; 74 75 /* serialize access to the list of registered dongles */ 76 mutex_lock(&dongle_list_lock); 77 78 list_for_each(entry, &dongle_list) { 79 drv = list_entry(entry, struct dongle_driver, dongle_list); 80 if (drv->type == type) 81 break; 82 else 83 drv = NULL; 84 } 85 86 if (!drv) { 87 err = -ENODEV; 88 goto out_unlock; /* no such dongle */ 89 } 90 91 /* handling of SMP races with dongle module removal - three cases: 92 * 1) dongle driver was already unregistered - then we haven't found the 93 * requested dongle above and are already out here 94 * 2) the module is already marked deleted but the driver is still 95 * registered - then the try_module_get() below will fail 96 * 3) the try_module_get() below succeeds before the module is marked 97 * deleted - then sys_delete_module() fails and prevents the removal 98 * because the module is in use. 99 */ 100 101 if (!try_module_get(drv->owner)) { 102 err = -ESTALE; 103 goto out_unlock; /* rmmod already pending */ 104 } 105 dev->dongle_drv = drv; 106 107 if (!drv->open || (err=drv->open(dev))!=0) 108 goto out_reject; /* failed to open driver */ 109 110 mutex_unlock(&dongle_list_lock); 111 return 0; 112 113out_reject: 114 dev->dongle_drv = NULL; 115 module_put(drv->owner); 116out_unlock: 117 mutex_unlock(&dongle_list_lock); 118 return err; 119} 120 121int sirdev_put_dongle(struct sir_dev *dev) 122{ 123 const struct dongle_driver *drv = dev->dongle_drv; 124 125 if (drv) { 126 if (drv->close) 127 drv->close(dev); /* close this dongle instance */ 128 129 dev->dongle_drv = NULL; /* unlink the dongle driver */ 130 module_put(drv->owner);/* decrement driver's module refcount */ 131 } 132 133 return 0; 134} 135