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