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