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 #include <linux/slab.h>
  19 #include <linux/string.h>
  20
  21 #include "drm_core.h"
  22 #include "drmP.h"
  23
  24 struct drm_sysfs_class {
  25         struct class_device_attribute attr;
  26         struct class class;
  27 };
  28 #define to_drm_sysfs_class(d) container_of(d, struct drm_sysfs_class, class)
  29
  30 struct simple_dev {
  31         struct list_head node;
  32         dev_t dev;
  33         struct class_device class_dev;
  34 };
  35 #define to_simple_dev(d) container_of(d, struct simple_dev, class_dev)
  36
  37 static LIST_HEAD(simple_dev_list);
  38 static DEFINE_SPINLOCK(simple_dev_list_lock);
  39
  40 static void release_simple_dev(struct class_device *class_dev)
  41 {
  42         struct simple_dev *s_dev = to_simple_dev(class_dev);
  43         kfree(s_dev);
  44 }
  45
  46 static ssize_t show_dev(struct class_device *class_dev, char *buf)
  47 {
  48         struct simple_dev *s_dev = to_simple_dev(class_dev);
  49         return print_dev_t(buf, s_dev->dev);
  50 }
  51
  52 static void drm_sysfs_class_release(struct class *class)
  53 {
  54         struct drm_sysfs_class *cs = to_drm_sysfs_class(class);
  55         kfree(cs);
  56 }
  57
  58 /* Display the version of drm_core. This doesn't work right in current design */
  59 static ssize_t version_show(struct class *dev, char *buf)
  60 {
  61         return sprintf(buf, "%s %d.%d.%d %s\n", CORE_NAME, CORE_MAJOR,
  62                        CORE_MINOR, CORE_PATCHLEVEL, CORE_DATE);
  63 }
  64
  65 static CLASS_ATTR(version, S_IRUGO, version_show, NULL);
  66
  67 /**
  68  * drm_sysfs_create - create a struct drm_sysfs_class structure
  69  * @owner: pointer to the module that is to "own" this struct drm_sysfs_class
  70  * @name: pointer to a string for the name of this class.
  71  *
  72  * This is used to create a struct drm_sysfs_class pointer that can then be used
  73  * in calls to drm_sysfs_device_add().
  74  *
  75  * Note, the pointer created here is to be destroyed when finished by making a
  76  * call to drm_sysfs_destroy().
  77  */
  78 struct drm_sysfs_class *drm_sysfs_create(struct module *owner, char *name)
  79 {
  80         struct drm_sysfs_class *cs;
  81         int retval;
  82
  83         cs = kmalloc(sizeof(*cs), GFP_KERNEL);
  84         if (!cs) {
  85                 retval = -ENOMEM;
  86                 goto error;
  87         }
  88         memset(cs, 0x00, sizeof(*cs));
  89
  90         cs->class.name = name;
  91         cs->class.class_release = drm_sysfs_class_release;
  92         cs->class.release = release_simple_dev;
  93
  94         cs->attr.attr.name = "dev";
  95         cs->attr.attr.mode = S_IRUGO;
  96         cs->attr.attr.owner = owner;
  97         cs->attr.show = show_dev;
  98         cs->attr.store = NULL;
  99
 100         retval = class_register(&cs->class);
 101         if (retval)
 102                 goto error;
 103         class_create_file(&cs->class, &class_attr_version);
 104
 105         return cs;
 106
 107       error:
 108         kfree(cs);
 109         return ERR_PTR(retval);
 110 }
 111
 112 /**
 113  * drm_sysfs_destroy - destroys a struct drm_sysfs_class structure
 114  * @cs: pointer to the struct drm_sysfs_class that is to be destroyed
 115  *
 116  * Note, the pointer to be destroyed must have been created with a call to
 117  * drm_sysfs_create().
 118  */
 119 void drm_sysfs_destroy(struct drm_sysfs_class *cs)
 120 {
 121         if ((cs == NULL) || (IS_ERR(cs)))
 122                 return;
 123
 124         class_unregister(&cs->class);
 125 }
 126
 127 /**
 128  * drm_sysfs_device_add - adds a class device to sysfs for a character driver
 129  * @cs: pointer to the struct drm_sysfs_class that this device should be registered to.
 130  * @dev: the dev_t for the device to be added.
 131  * @device: a pointer to a struct device that is assiociated with this class device.
 132  * @fmt: string for the class device's name
 133  *
 134  * A struct class_device will be created in sysfs, registered to the specified
 135  * class.  A "dev" file will be created, showing the dev_t for the device.  The
 136  * pointer to the struct class_device will be returned from the call.  Any further
 137  * sysfs files that might be required can be created using this pointer.
 138  * Note: the struct drm_sysfs_class passed to this function must have previously been
 139  * created with a call to drm_sysfs_create().
 140  */
 141 struct class_device *drm_sysfs_device_add(struct drm_sysfs_class *cs, dev_t dev,
 142                                           struct device *device,
 143                                           const char *fmt, ...)
 144 {
 145         va_list args;
 146         struct simple_dev *s_dev = NULL;
 147         int retval;
 148
 149         if ((cs == NULL) || (IS_ERR(cs))) {
 150                 retval = -ENODEV;
 151                 goto error;
 152         }
 153
 154         s_dev = kmalloc(sizeof(*s_dev), GFP_KERNEL);
 155         if (!s_dev) {
 156                 retval = -ENOMEM;
 157                 goto error;
 158         }
 159         memset(s_dev, 0x00, sizeof(*s_dev));
 160
 161         s_dev->dev = dev;
 162         s_dev->class_dev.dev = device;
 163         s_dev->class_dev.class = &cs->class;
 164
 165         va_start(args, fmt);
 166         vsnprintf(s_dev->class_dev.class_id, BUS_ID_SIZE, fmt, args);
 167         va_end(args);
 168         retval = class_device_register(&s_dev->class_dev);
 169         if (retval)
 170                 goto error;
 171
 172         class_device_create_file(&s_dev->class_dev, &cs->attr);
 173
 174         spin_lock(&simple_dev_list_lock);
 175         list_add(&s_dev->node, &simple_dev_list);
 176         spin_unlock(&simple_dev_list_lock);
 177
 178         return &s_dev->class_dev;
 179
 180       error:
 181         kfree(s_dev);
 182         return ERR_PTR(retval);
 183 }
 184
 185 /**
 186  * drm_sysfs_device_remove - removes a class device that was created with drm_sysfs_device_add()
 187  * @dev: the dev_t of the device that was previously registered.
 188  *
 189  * This call unregisters and cleans up a class device that was created with a
 190  * call to drm_sysfs_device_add()
 191  */
 192 void drm_sysfs_device_remove(dev_t dev)
 193 {
 194         struct simple_dev *s_dev = NULL;
 195         int found = 0;
 196
 197         spin_lock(&simple_dev_list_lock);
 198         list_for_each_entry(s_dev, &simple_dev_list, node) {
 199                 if (s_dev->dev == dev) {
 200                         found = 1;
 201                         break;
 202                 }
 203         }
 204         if (found) {
 205                 list_del(&s_dev->node);
 206                 spin_unlock(&simple_dev_list_lock);
 207                 class_device_unregister(&s_dev->class_dev);
 208         } else {
 209                 spin_unlock(&simple_dev_list_lock);
 210         }
 211 }