drivers/char/drm/drm_sysfs.c

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