drivers/base/class_simple.c

   1 /*
   2  * class_simple.c - a "simple" interface for classes for simple char devices.
   3  *
   4  * Copyright (c) 2003-2004 Greg Kroah-Hartman <greg@kroah.com>
   5  * Copyright (c) 2003-2004 IBM Corp.
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/device.h>
  13 #include <linux/kdev_t.h>
  14 #include <linux/err.h>
  15
  16 struct class_simple {
  17         struct class_device_attribute attr;
  18         struct class class;
  19 };
  20 #define to_class_simple(d) container_of(d, struct class_simple, class)
  21
  22 struct simple_dev {
  23         struct list_head node;
  24         dev_t dev;
  25         struct class_device class_dev;
  26 };
  27 #define to_simple_dev(d) container_of(d, struct simple_dev, class_dev)
  28
  29 static LIST_HEAD(simple_dev_list);
  30 static spinlock_t simple_dev_list_lock = SPIN_LOCK_UNLOCKED;
  31
  32 static void release_simple_dev(struct class_device *class_dev)
  33 {
  34         struct simple_dev *s_dev = to_simple_dev(class_dev);
  35         kfree(s_dev);
  36 }
  37
  38 static ssize_t show_dev(struct class_device *class_dev, char *buf)
  39 {
  40         struct simple_dev *s_dev = to_simple_dev(class_dev);
  41         return print_dev_t(buf, s_dev->dev);
  42 }
  43
  44 static void class_simple_release(struct class *class)
  45 {
  46         struct class_simple *cs = to_class_simple(class);
  47         kfree(cs);
  48 }
  49
  50 /**
  51  * class_simple_create - create a struct class_simple structure
  52  * @owner: pointer to the module that is to "own" this struct class_simple
  53  * @name: pointer to a string for the name of this class.
  54  *
  55  * This is used to create a struct class_simple pointer that can then be used
  56  * in calls to class_simple_device_add().  This is used when you do not wish to
  57  * create a full blown class support for a type of char devices.
  58  *
  59  * Note, the pointer created here is to be destroyed when finished by making a
  60  * call to class_simple_destroy().
  61  */
  62 struct class_simple *class_simple_create(struct module *owner, char *name)
  63 {
  64         struct class_simple *cs;
  65         int retval;
  66
  67         cs = kmalloc(sizeof(*cs), GFP_KERNEL);
  68         if (!cs) {
  69                 retval = -ENOMEM;
  70                 goto error;
  71         }
  72         memset(cs, 0x00, sizeof(*cs));
  73
  74         cs->class.name = name;
  75         cs->class.class_release = class_simple_release;
  76         cs->class.release = release_simple_dev;
  77
  78         cs->attr.attr.name = "dev";
  79         cs->attr.attr.mode = S_IRUGO;
  80         cs->attr.attr.owner = owner;
  81         cs->attr.show = show_dev;
  82         cs->attr.store = NULL;
  83
  84         retval = class_register(&cs->class);
  85         if (retval)
  86                 goto error;
  87
  88         return cs;
  89
  90 error:
  91         kfree(cs);
  92         return ERR_PTR(retval);
  93 }
  94 EXPORT_SYMBOL(class_simple_create);
  95
  96 /**
  97  * class_simple_destroy - destroys a struct class_simple structure
  98  * @cs: pointer to the struct class_simple that is to be destroyed
  99  *
 100  * Note, the pointer to be destroyed must have been created with a call to
 101  * class_simple_create().
 102  */
 103 void class_simple_destroy(struct class_simple *cs)
 104 {
 105         if ((cs == NULL) || (IS_ERR(cs)))
 106                 return;
 107
 108         class_unregister(&cs->class);
 109 }
 110 EXPORT_SYMBOL(class_simple_destroy);
 111
 112 /**
 113  * class_simple_device_add - adds a class device to sysfs for a character driver
 114  * @cs: pointer to the struct class_simple that this device should be registered to.
 115  * @dev: the dev_t for the device to be added.
 116  * @device: a pointer to a struct device that is assiociated with this class device.
 117  * @fmt: string for the class device's name
 118  *
 119  * This function can be used by simple char device classes that do not
 120  * implement their own class device registration.  A struct class_device will
 121  * be created in sysfs, registered to the specified class.  A "dev" file will
 122  * be created, showing the dev_t for the device.  The pointer to the struct
 123  * class_device will be returned from the call.  Any further sysfs files that
 124  * might be required can be created using this pointer.
 125  * Note: the struct class_device passed to this function must have previously been
 126  * created with a call to class_simple_create().
 127  */
 128 struct class_device *class_simple_device_add(struct class_simple *cs, dev_t dev, struct device *device, const char *fmt, ...)
 129 {
 130         va_list args;
 131         struct simple_dev *s_dev = NULL;
 132         int retval;
 133
 134         if ((cs == NULL) || (IS_ERR(cs))) {
 135                 retval = -ENODEV;
 136                 goto error;
 137         }
 138
 139         s_dev = kmalloc(sizeof(*s_dev), GFP_KERNEL);
 140         if (!s_dev) {
 141                 retval = -ENOMEM;
 142                 goto error;
 143         }
 144         memset(s_dev, 0x00, sizeof(*s_dev));
 145
 146         s_dev->dev = dev;
 147         s_dev->class_dev.dev = device;
 148         s_dev->class_dev.class = &cs->class;
 149
 150         va_start(args, fmt);
 151         vsnprintf(s_dev->class_dev.class_id, BUS_ID_SIZE, fmt, args);
 152         va_end(args);
 153         retval = class_device_register(&s_dev->class_dev);
 154         if (retval)
 155                 goto error;
 156
 157         class_device_create_file(&s_dev->class_dev, &cs->attr);
 158
 159         spin_lock(&simple_dev_list_lock);
 160         list_add(&s_dev->node, &simple_dev_list);
 161         spin_unlock(&simple_dev_list_lock);
 162
 163         return &s_dev->class_dev;
 164
 165 error:
 166         kfree(s_dev);
 167         return ERR_PTR(retval);
 168 }
 169 EXPORT_SYMBOL(class_simple_device_add);
 170
 171 /**
 172  * class_simple_set_hotplug - set the hotplug callback in the embedded struct class
 173  * @cs: pointer to the struct class_simple to hold the pointer
 174  * @hotplug: function pointer to the hotplug function
 175  *
 176  * Implement and set a hotplug function to add environment variables specific to this
 177  * class on the hotplug event.
 178  */
 179 int class_simple_set_hotplug(struct class_simple *cs,
 180         int (*hotplug)(struct class_device *dev, char **envp, int num_envp, char *buffer, int buffer_size))
 181 {
 182         if ((cs == NULL) || (IS_ERR(cs)))
 183                 return -ENODEV;
 184         cs->class.hotplug = hotplug;
 185         return 0;
 186 }
 187 EXPORT_SYMBOL(class_simple_set_hotplug);
 188
 189 /**
 190  * class_simple_device_remove - removes a class device that was created with class_simple_device_add()
 191  * @dev: the dev_t of the device that was previously registered.
 192  *
 193  * This call unregisters and cleans up a class device that was created with a
 194  * call to class_device_simple_add()
 195  */
 196 void class_simple_device_remove(dev_t dev)
 197 {
 198         struct simple_dev *s_dev = NULL;
 199         int found = 0;
 200
 201         spin_lock(&simple_dev_list_lock);
 202         list_for_each_entry(s_dev, &simple_dev_list, node) {
 203                 if (s_dev->dev == dev) {
 204                         found = 1;
 205                         break;
 206                 }
 207         }
 208         if (found) {
 209                 list_del(&s_dev->node);
 210                 spin_unlock(&simple_dev_list_lock);
 211                 class_device_unregister(&s_dev->class_dev);
 212         } else {
 213                 spin_unlock(&simple_dev_list_lock);
 214         }
 215 }
 216 EXPORT_SYMBOL(class_simple_device_remove);