drivers/dma-buf/dma-heap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Framework for userspace DMA-BUF allocations
   4  *
   5  * Copyright (C) 2011 Google, Inc.
   6  * Copyright (C) 2019 Linaro Ltd.
   7  */
   8
   9 #include <linux/cdev.h>
  10 #include <linux/debugfs.h>
  11 #include <linux/device.h>
  12 #include <linux/dma-buf.h>
  13 #include <linux/err.h>
  14 #include <linux/xarray.h>
  15 #include <linux/list.h>
  16 #include <linux/slab.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/syscalls.h>
  19 #include <linux/dma-heap.h>
  20 #include <uapi/linux/dma-heap.h>
  21
  22 #define DEVNAME "dma_heap"
  23
  24 #define NUM_HEAP_MINORS 128
  25
  26 /**
  27  * struct dma_heap - represents a dmabuf heap in the system
  28  * @name:               used for debugging/device-node name
  29  * @ops:                ops struct for this heap
  30  * @heap_devt           heap device node
  31  * @list                list head connecting to list of heaps
  32  * @heap_cdev           heap char device
  33  *
  34  * Represents a heap of memory from which buffers can be made.
  35  */
  36 struct dma_heap {
  37         const char *name;
  38         const struct dma_heap_ops *ops;
  39         void *priv;
  40         dev_t heap_devt;
  41         struct list_head list;
  42         struct cdev heap_cdev;
  43 };
  44
  45 static LIST_HEAD(heap_list);
  46 static DEFINE_MUTEX(heap_list_lock);
  47 static dev_t dma_heap_devt;
  48 static struct class *dma_heap_class;
  49 static DEFINE_XARRAY_ALLOC(dma_heap_minors);
  50
  51 static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
  52                                  unsigned int fd_flags,
  53                                  unsigned int heap_flags)
  54 {
  55         /*
  56          * Allocations from all heaps have to begin
  57          * and end on page boundaries.
  58          */
  59         len = PAGE_ALIGN(len);
  60         if (!len)
  61                 return -EINVAL;
  62
  63         return heap->ops->allocate(heap, len, fd_flags, heap_flags);
  64 }
  65
  66 static int dma_heap_open(struct inode *inode, struct file *file)
  67 {
  68         struct dma_heap *heap;
  69
  70         heap = xa_load(&dma_heap_minors, iminor(inode));
  71         if (!heap) {
  72                 pr_err("dma_heap: minor %d unknown.\n", iminor(inode));
  73                 return -ENODEV;
  74         }
  75
  76         /* instance data as context */
  77         file->private_data = heap;
  78         nonseekable_open(inode, file);
  79
  80         return 0;
  81 }
  82
  83 static long dma_heap_ioctl_allocate(struct file *file, void *data)
  84 {
  85         struct dma_heap_allocation_data *heap_allocation = data;
  86         struct dma_heap *heap = file->private_data;
  87         int fd;
  88
  89         if (heap_allocation->fd)
  90                 return -EINVAL;
  91
  92         if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
  93                 return -EINVAL;
  94
  95         if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
  96                 return -EINVAL;
  97
  98         fd = dma_heap_buffer_alloc(heap, heap_allocation->len,
  99                                    heap_allocation->fd_flags,
 100                                    heap_allocation->heap_flags);
 101         if (fd < 0)
 102                 return fd;
 103
 104         heap_allocation->fd = fd;
 105
 106         return 0;
 107 }
 108
 109 static unsigned int dma_heap_ioctl_cmds[] = {
 110         DMA_HEAP_IOCTL_ALLOC,
 111 };
 112
 113 static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
 114                            unsigned long arg)
 115 {
 116         char stack_kdata[128];
 117         char *kdata = stack_kdata;
 118         unsigned int kcmd;
 119         unsigned int in_size, out_size, drv_size, ksize;
 120         int nr = _IOC_NR(ucmd);
 121         int ret = 0;
 122
 123         if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
 124                 return -EINVAL;
 125
 126         /* Get the kernel ioctl cmd that matches */
 127         kcmd = dma_heap_ioctl_cmds[nr];
 128
 129         /* Figure out the delta between user cmd size and kernel cmd size */
 130         drv_size = _IOC_SIZE(kcmd);
 131         out_size = _IOC_SIZE(ucmd);
 132         in_size = out_size;
 133         if ((ucmd & kcmd & IOC_IN) == 0)
 134                 in_size = 0;
 135         if ((ucmd & kcmd & IOC_OUT) == 0)
 136                 out_size = 0;
 137         ksize = max(max(in_size, out_size), drv_size);
 138
 139         /* If necessary, allocate buffer for ioctl argument */
 140         if (ksize > sizeof(stack_kdata)) {
 141                 kdata = kmalloc(ksize, GFP_KERNEL);
 142                 if (!kdata)
 143                         return -ENOMEM;
 144         }
 145
 146         if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
 147                 ret = -EFAULT;
 148                 goto err;
 149         }
 150
 151         /* zero out any difference between the kernel/user structure size */
 152         if (ksize > in_size)
 153                 memset(kdata + in_size, 0, ksize - in_size);
 154
 155         switch (kcmd) {
 156         case DMA_HEAP_IOCTL_ALLOC:
 157                 ret = dma_heap_ioctl_allocate(file, kdata);
 158                 break;
 159         default:
 160                 ret = -ENOTTY;
 161                 goto err;
 162         }
 163
 164         if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
 165                 ret = -EFAULT;
 166 err:
 167         if (kdata != stack_kdata)
 168                 kfree(kdata);
 169         return ret;
 170 }
 171
 172 static const struct file_operations dma_heap_fops = {
 173         .owner          = THIS_MODULE,
 174         .open           = dma_heap_open,
 175         .unlocked_ioctl = dma_heap_ioctl,
 176 #ifdef CONFIG_COMPAT
 177         .compat_ioctl   = dma_heap_ioctl,
 178 #endif
 179 };
 180
 181 /**
 182  * dma_heap_get_drvdata() - get per-subdriver data for the heap
 183  * @heap: DMA-Heap to retrieve private data for
 184  *
 185  * Returns:
 186  * The per-subdriver data for the heap.
 187  */
 188 void *dma_heap_get_drvdata(struct dma_heap *heap)
 189 {
 190         return heap->priv;
 191 }
 192
 193 struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 194 {
 195         struct dma_heap *heap, *h, *err_ret;
 196         struct device *dev_ret;
 197         unsigned int minor;
 198         int ret;
 199
 200         if (!exp_info->name || !strcmp(exp_info->name, "")) {
 201                 pr_err("dma_heap: Cannot add heap without a name\n");
 202                 return ERR_PTR(-EINVAL);
 203         }
 204
 205         if (!exp_info->ops || !exp_info->ops->allocate) {
 206                 pr_err("dma_heap: Cannot add heap with invalid ops struct\n");
 207                 return ERR_PTR(-EINVAL);
 208         }
 209
 210         /* check the name is unique */
 211         mutex_lock(&heap_list_lock);
 212         list_for_each_entry(h, &heap_list, list) {
 213                 if (!strcmp(h->name, exp_info->name)) {
 214                         mutex_unlock(&heap_list_lock);
 215                         pr_err("dma_heap: Already registered heap named %s\n",
 216                                exp_info->name);
 217                         return ERR_PTR(-EINVAL);
 218                 }
 219         }
 220         mutex_unlock(&heap_list_lock);
 221
 222         heap = kzalloc(sizeof(*heap), GFP_KERNEL);
 223         if (!heap)
 224                 return ERR_PTR(-ENOMEM);
 225
 226         heap->name = exp_info->name;
 227         heap->ops = exp_info->ops;
 228         heap->priv = exp_info->priv;
 229
 230         /* Find unused minor number */
 231         ret = xa_alloc(&dma_heap_minors, &minor, heap,
 232                        XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL);
 233         if (ret < 0) {
 234                 pr_err("dma_heap: Unable to get minor number for heap\n");
 235                 err_ret = ERR_PTR(ret);
 236                 goto err0;
 237         }
 238
 239         /* Create device */
 240         heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor);
 241
 242         cdev_init(&heap->heap_cdev, &dma_heap_fops);
 243         ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1);
 244         if (ret < 0) {
 245                 pr_err("dma_heap: Unable to add char device\n");
 246                 err_ret = ERR_PTR(ret);
 247                 goto err1;
 248         }
 249
 250         dev_ret = device_create(dma_heap_class,
 251                                 NULL,
 252                                 heap->heap_devt,
 253                                 NULL,
 254                                 heap->name);
 255         if (IS_ERR(dev_ret)) {
 256                 pr_err("dma_heap: Unable to create device\n");
 257                 err_ret = ERR_CAST(dev_ret);
 258                 goto err2;
 259         }
 260         /* Add heap to the list */
 261         mutex_lock(&heap_list_lock);
 262         list_add(&heap->list, &heap_list);
 263         mutex_unlock(&heap_list_lock);
 264
 265         return heap;
 266
 267 err2:
 268         cdev_del(&heap->heap_cdev);
 269 err1:
 270         xa_erase(&dma_heap_minors, minor);
 271 err0:
 272         kfree(heap);
 273         return err_ret;
 274 }
 275
 276 static char *dma_heap_devnode(struct device *dev, umode_t *mode)
 277 {
 278         return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
 279 }
 280
 281 static int dma_heap_init(void)
 282 {
 283         int ret;
 284
 285         ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME);
 286         if (ret)
 287                 return ret;
 288
 289         dma_heap_class = class_create(THIS_MODULE, DEVNAME);
 290         if (IS_ERR(dma_heap_class)) {
 291                 unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
 292                 return PTR_ERR(dma_heap_class);
 293         }
 294         dma_heap_class->devnode = dma_heap_devnode;
 295
 296         return 0;
 297 }
 298 subsys_initcall(dma_heap_init);