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 #include "drmP.h"
  21
  22 struct drm_sysfs_class {
  23         struct class_device_attribute attr;
  24         struct class class;
  25 };
  26 #define to_drm_sysfs_class(d) container_of(d, struct drm_sysfs_class, class)
  27
  28 struct simple_dev {
  29         struct list_head node;
  30         dev_t dev;
  31         struct class_device class_dev;
  32 };
  33 #define to_simple_dev(d) container_of(d, struct simple_dev, class_dev)
  34
  35 static LIST_HEAD(simple_dev_list);
  36 static DEFINE_SPINLOCK(simple_dev_list_lock);
  37
  38 static void release_simple_dev(struct class_device *class_dev)
  39 {
  40         struct simple_dev *s_dev = to_simple_dev(class_dev);
  41         kfree(s_dev);
  42 }
  43
  44 static ssize_t show_dev(struct class_device *class_dev, char *buf)
  45 {
  46         struct simple_dev *s_dev = to_simple_dev(class_dev);
  47         return print_dev_t(buf, s_dev->dev);
  48 }
  49
  50 static void drm_sysfs_class_release(struct class *class)
  51 {
  52         struct drm_sysfs_class *cs = to_drm_sysfs_class(class);
  53         kfree(cs);
  54 }
  55
  56 /* Display the version of drm_core. This doesn't work right in current design */
  57 static ssize_t version_show(struct class *dev, char *buf)
  58 {
  59         return sprintf(buf, "%s %d.%d.%d %s\n", CORE_NAME, CORE_MAJOR,
  60                        CORE_MINOR, CORE_PATCHLEVEL, CORE_DATE);
  61 }
  62
  63 static CLASS_ATTR(version, S_IRUGO, version_show, NULL);
  64
  65 /**
  66  * drm_sysfs_create - create a struct drm_sysfs_class structure
  67  * @owner: pointer to the module that is to "own" this struct drm_sysfs_class
  68  * @name: pointer to a string for the name of this class.
  69  *
  70  * This is used to create a struct drm_sysfs_class pointer that can then be used
  71  * in calls to drm_sysfs_device_add().
  72  *
  73  * Note, the pointer created here is to be destroyed when finished by making a
  74  * call to drm_sysfs_destroy().
  75  */
  76 struct drm_sysfs_class *drm_sysfs_create(struct module *owner, char *name)
  77 {
  78         struct drm_sysfs_class *cs;
  79         int retval;
  80
  81         cs = kmalloc(sizeof(*cs), GFP_KERNEL);
  82         if (!cs) {
  83                 retval = -ENOMEM;
  84                 goto error;
  85         }
  86         memset(cs, 0x00, sizeof(*cs));
  87
  88         cs->class.name = name;
  89         cs->class.class_release = drm_sysfs_class_release;
  90         cs->class.release = release_simple_dev;
  91
  92         cs->attr.attr.name = "dev";
  93         cs->attr.attr.mode = S_IRUGO;
  94         cs->attr.attr.owner = owner;
  95         cs->attr.show = show_dev;
  96         cs->attr.store = NULL;
  97
  98         retval = class_register(&cs->class);
  99         if (retval)
 100                 goto error;
 101         class_create_file(&cs->class, &class_attr_version);
 102
 103         return cs;
 104
 105       error:
 106         kfree(cs);
 107         return ERR_PTR(retval);
 108 }
 109
 110 /**
 111  * drm_sysfs_destroy - destroys a struct drm_sysfs_class structure
 112  * @cs: pointer to the struct drm_sysfs_class that is to be destroyed
 113  *
 114  * Note, the pointer to be destroyed must have been created with a call to
 115  * drm_sysfs_create().
 116  */
 117 void drm_sysfs_destroy(struct drm_sysfs_class *cs)
 118 {
 119         if ((cs == NULL) || (IS_ERR(cs)))
 120                 return;
 121
 122         class_unregister(&cs->class);
 123 }
 124
 125 /**
 126  * drm_sysfs_device_add - adds a class device to sysfs for a character driver
 127  * @cs: pointer to the struct drm_sysfs_class that this device should be registered to.
 128  * @dev: the dev_t for the device to be added.
 129  * @device: a pointer to a struct device that is assiociated with this class device.
 130  * @fmt: string for the class device's name
 131  *
 132  * A struct class_device will be created in sysfs, registered to the specified
 133  * class.  A "dev" file will be created, showing the dev_t for the device.  The
 134  * pointer to the struct class_device will be returned from the call.  Any further
 135  * sysfs files that might be required can be created using this pointer.
 136  * Note: the struct drm_sysfs_class passed to this function must have previously been
 137  * created with a call to drm_sysfs_create().
 138  */
 139 struct class_device *drm_sysfs_device_add(struct drm_sysfs_class *cs, dev_t dev,
 140                                           struct device *device,
 141                                           const char *fmt, ...)
 142 {
 143         va_list args;
 144         struct simple_dev *s_dev = NULL;
 145         int retval;
 146
 147         if ((cs == NULL) || (IS_ERR(cs))) {
 148                 retval = -ENODEV;
 149                 goto error;
 150         }
 151
 152         s_dev = kmalloc(sizeof(*s_dev), GFP_KERNEL);
 153         if (!s_dev) {
 154                 retval = -ENOMEM;
 155                 goto error;
 156         }
 157         memset(s_dev, 0x00, sizeof(*s_dev));
 158
 159         s_dev->dev = dev;
 160         s_dev->class_dev.dev = device;
 161         s_dev->class_dev.class = &cs->class;
 162
 163         va_start(args, fmt);
 164         vsnprintf(s_dev->class_dev.class_id, BUS_ID_SIZE, fmt, args);
 165         va_end(args);
 166         retval = class_device_register(&s_dev->class_dev);
 167         if (retval)
 168                 goto error;
 169
 170         class_device_create_file(&s_dev->class_dev, &cs->attr);
 171
 172         spin_lock(&simple_dev_list_lock);
 173         list_add(&s_dev->node, &simple_dev_list);
 174         spin_unlock(&simple_dev_list_lock);
 175
 176         return &s_dev->class_dev;
 177
 178       error:
 179         kfree(s_dev);
 180         return ERR_PTR(retval);
 181 }
 182
 183 /**
 184  * drm_sysfs_device_remove - removes a class device that was created with drm_sysfs_device_add()
 185  * @dev: the dev_t of the device that was previously registered.
 186  *
 187  * This call unregisters and cleans up a class device that was created with a
 188  * call to drm_sysfs_device_add()
 189  */
 190 void drm_sysfs_device_remove(dev_t dev)
 191 {
 192         struct simple_dev *s_dev = NULL;
 193         int found = 0;
 194
 195         spin_lock(&simple_dev_list_lock);
 196         list_for_each_entry(s_dev, &simple_dev_list, node) {
 197                 if (s_dev->dev == dev) {
 198                         found = 1;
 199                         break;
 200                 }
 201         }
 202         if (found) {
 203                 list_del(&s_dev->node);
 204                 spin_unlock(&simple_dev_list_lock);
 205                 class_device_unregister(&s_dev->class_dev);
 206         } else {
 207                 spin_unlock(&simple_dev_list_lock);
 208         }
 209 }