1 // SPDX-License-Identifier: GPL-2.0
3 * Framework for userspace DMA-BUF allocations
5 * Copyright (C) 2011 Google, Inc.
6 * Copyright (C) 2019 Linaro Ltd.
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/nospec.h>
18 #include <linux/uaccess.h>
19 #include <linux/syscalls.h>
20 #include <linux/dma-heap.h>
21 #include <uapi/linux/dma-heap.h>
23 #define DEVNAME "dma_heap"
25 #define NUM_HEAP_MINORS 128
28 * struct dma_heap - represents a dmabuf heap in the system
29 * @name: used for debugging/device-node name
30 * @ops: ops struct for this heap
31 * @heap_devt heap device node
32 * @list list head connecting to list of heaps
33 * @heap_cdev heap char device
35 * Represents a heap of memory from which buffers can be made.
39 const struct dma_heap_ops *ops;
42 struct list_head list;
43 struct cdev heap_cdev;
46 static LIST_HEAD(heap_list);
47 static DEFINE_MUTEX(heap_list_lock);
48 static dev_t dma_heap_devt;
49 static struct class *dma_heap_class;
50 static DEFINE_XARRAY_ALLOC(dma_heap_minors);
52 static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
53 unsigned int fd_flags,
54 unsigned int heap_flags)
57 * Allocations from all heaps have to begin
58 * and end on page boundaries.
60 len = PAGE_ALIGN(len);
64 return heap->ops->allocate(heap, len, fd_flags, heap_flags);
67 static int dma_heap_open(struct inode *inode, struct file *file)
69 struct dma_heap *heap;
71 heap = xa_load(&dma_heap_minors, iminor(inode));
73 pr_err("dma_heap: minor %d unknown.\n", iminor(inode));
77 /* instance data as context */
78 file->private_data = heap;
79 nonseekable_open(inode, file);
84 static long dma_heap_ioctl_allocate(struct file *file, void *data)
86 struct dma_heap_allocation_data *heap_allocation = data;
87 struct dma_heap *heap = file->private_data;
90 if (heap_allocation->fd)
93 if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
96 if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
99 fd = dma_heap_buffer_alloc(heap, heap_allocation->len,
100 heap_allocation->fd_flags,
101 heap_allocation->heap_flags);
105 heap_allocation->fd = fd;
110 static unsigned int dma_heap_ioctl_cmds[] = {
111 DMA_HEAP_IOCTL_ALLOC,
114 static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
117 char stack_kdata[128];
118 char *kdata = stack_kdata;
120 unsigned int in_size, out_size, drv_size, ksize;
121 int nr = _IOC_NR(ucmd);
124 if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
127 nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds));
128 /* Get the kernel ioctl cmd that matches */
129 kcmd = dma_heap_ioctl_cmds[nr];
131 /* Figure out the delta between user cmd size and kernel cmd size */
132 drv_size = _IOC_SIZE(kcmd);
133 out_size = _IOC_SIZE(ucmd);
135 if ((ucmd & kcmd & IOC_IN) == 0)
137 if ((ucmd & kcmd & IOC_OUT) == 0)
139 ksize = max(max(in_size, out_size), drv_size);
141 /* If necessary, allocate buffer for ioctl argument */
142 if (ksize > sizeof(stack_kdata)) {
143 kdata = kmalloc(ksize, GFP_KERNEL);
148 if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
153 /* zero out any difference between the kernel/user structure size */
155 memset(kdata + in_size, 0, ksize - in_size);
158 case DMA_HEAP_IOCTL_ALLOC:
159 ret = dma_heap_ioctl_allocate(file, kdata);
166 if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
169 if (kdata != stack_kdata)
174 static const struct file_operations dma_heap_fops = {
175 .owner = THIS_MODULE,
176 .open = dma_heap_open,
177 .unlocked_ioctl = dma_heap_ioctl,
179 .compat_ioctl = dma_heap_ioctl,
184 * dma_heap_get_drvdata() - get per-subdriver data for the heap
185 * @heap: DMA-Heap to retrieve private data for
188 * The per-subdriver data for the heap.
190 void *dma_heap_get_drvdata(struct dma_heap *heap)
195 struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
197 struct dma_heap *heap, *h, *err_ret;
198 struct device *dev_ret;
202 if (!exp_info->name || !strcmp(exp_info->name, "")) {
203 pr_err("dma_heap: Cannot add heap without a name\n");
204 return ERR_PTR(-EINVAL);
207 if (!exp_info->ops || !exp_info->ops->allocate) {
208 pr_err("dma_heap: Cannot add heap with invalid ops struct\n");
209 return ERR_PTR(-EINVAL);
212 /* check the name is unique */
213 mutex_lock(&heap_list_lock);
214 list_for_each_entry(h, &heap_list, list) {
215 if (!strcmp(h->name, exp_info->name)) {
216 mutex_unlock(&heap_list_lock);
217 pr_err("dma_heap: Already registered heap named %s\n",
219 return ERR_PTR(-EINVAL);
222 mutex_unlock(&heap_list_lock);
224 heap = kzalloc(sizeof(*heap), GFP_KERNEL);
226 return ERR_PTR(-ENOMEM);
228 heap->name = exp_info->name;
229 heap->ops = exp_info->ops;
230 heap->priv = exp_info->priv;
232 /* Find unused minor number */
233 ret = xa_alloc(&dma_heap_minors, &minor, heap,
234 XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL);
236 pr_err("dma_heap: Unable to get minor number for heap\n");
237 err_ret = ERR_PTR(ret);
242 heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor);
244 cdev_init(&heap->heap_cdev, &dma_heap_fops);
245 ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1);
247 pr_err("dma_heap: Unable to add char device\n");
248 err_ret = ERR_PTR(ret);
252 dev_ret = device_create(dma_heap_class,
257 if (IS_ERR(dev_ret)) {
258 pr_err("dma_heap: Unable to create device\n");
259 err_ret = ERR_CAST(dev_ret);
262 /* Add heap to the list */
263 mutex_lock(&heap_list_lock);
264 list_add(&heap->list, &heap_list);
265 mutex_unlock(&heap_list_lock);
270 cdev_del(&heap->heap_cdev);
272 xa_erase(&dma_heap_minors, minor);
278 static char *dma_heap_devnode(struct device *dev, umode_t *mode)
280 return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
283 static int dma_heap_init(void)
287 ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME);
291 dma_heap_class = class_create(THIS_MODULE, DEVNAME);
292 if (IS_ERR(dma_heap_class)) {
293 unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
294 return PTR_ERR(dma_heap_class);
296 dma_heap_class->devnode = dma_heap_devnode;
300 subsys_initcall(dma_heap_init);