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 struct dma_buf *dmabuf; 56 int fd; 57 58 /* 59 * Allocations from all heaps have to begin 60 * and end on page boundaries. 61 */ 62 len = PAGE_ALIGN(len); 63 if (!len) 64 return -EINVAL; 65 66 dmabuf = heap->ops->allocate(heap, len, fd_flags, heap_flags); 67 if (IS_ERR(dmabuf)) 68 return PTR_ERR(dmabuf); 69 70 fd = dma_buf_fd(dmabuf, fd_flags); 71 if (fd < 0) { 72 dma_buf_put(dmabuf); 73 /* just return, as put will call release and that will free */ 74 } 75 return fd; 76 } 77 78 static int dma_heap_open(struct inode *inode, struct file *file) 79 { 80 struct dma_heap *heap; 81 82 heap = xa_load(&dma_heap_minors, iminor(inode)); 83 if (!heap) { 84 pr_err("dma_heap: minor %d unknown.\n", iminor(inode)); 85 return -ENODEV; 86 } 87 88 /* instance data as context */ 89 file->private_data = heap; 90 nonseekable_open(inode, file); 91 92 return 0; 93 } 94 95 static long dma_heap_ioctl_allocate(struct file *file, void *data) 96 { 97 struct dma_heap_allocation_data *heap_allocation = data; 98 struct dma_heap *heap = file->private_data; 99 int fd; 100 101 if (heap_allocation->fd) 102 return -EINVAL; 103 104 if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS) 105 return -EINVAL; 106 107 if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS) 108 return -EINVAL; 109 110 fd = dma_heap_buffer_alloc(heap, heap_allocation->len, 111 heap_allocation->fd_flags, 112 heap_allocation->heap_flags); 113 if (fd < 0) 114 return fd; 115 116 heap_allocation->fd = fd; 117 118 return 0; 119 } 120 121 static unsigned int dma_heap_ioctl_cmds[] = { 122 DMA_HEAP_IOCTL_ALLOC, 123 }; 124 125 static long dma_heap_ioctl(struct file *file, unsigned int ucmd, 126 unsigned long arg) 127 { 128 char stack_kdata[128]; 129 char *kdata = stack_kdata; 130 unsigned int kcmd; 131 unsigned int in_size, out_size, drv_size, ksize; 132 int nr = _IOC_NR(ucmd); 133 int ret = 0; 134 135 if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds)) 136 return -EINVAL; 137 138 /* Get the kernel ioctl cmd that matches */ 139 kcmd = dma_heap_ioctl_cmds[nr]; 140 141 /* Figure out the delta between user cmd size and kernel cmd size */ 142 drv_size = _IOC_SIZE(kcmd); 143 out_size = _IOC_SIZE(ucmd); 144 in_size = out_size; 145 if ((ucmd & kcmd & IOC_IN) == 0) 146 in_size = 0; 147 if ((ucmd & kcmd & IOC_OUT) == 0) 148 out_size = 0; 149 ksize = max(max(in_size, out_size), drv_size); 150 151 /* If necessary, allocate buffer for ioctl argument */ 152 if (ksize > sizeof(stack_kdata)) { 153 kdata = kmalloc(ksize, GFP_KERNEL); 154 if (!kdata) 155 return -ENOMEM; 156 } 157 158 if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) { 159 ret = -EFAULT; 160 goto err; 161 } 162 163 /* zero out any difference between the kernel/user structure size */ 164 if (ksize > in_size) 165 memset(kdata + in_size, 0, ksize - in_size); 166 167 switch (kcmd) { 168 case DMA_HEAP_IOCTL_ALLOC: 169 ret = dma_heap_ioctl_allocate(file, kdata); 170 break; 171 default: 172 ret = -ENOTTY; 173 goto err; 174 } 175 176 if (copy_to_user((void __user *)arg, kdata, out_size) != 0) 177 ret = -EFAULT; 178 err: 179 if (kdata != stack_kdata) 180 kfree(kdata); 181 return ret; 182 } 183 184 static const struct file_operations dma_heap_fops = { 185 .owner = THIS_MODULE, 186 .open = dma_heap_open, 187 .unlocked_ioctl = dma_heap_ioctl, 188 #ifdef CONFIG_COMPAT 189 .compat_ioctl = dma_heap_ioctl, 190 #endif 191 }; 192 193 /** 194 * dma_heap_get_drvdata() - get per-subdriver data for the heap 195 * @heap: DMA-Heap to retrieve private data for 196 * 197 * Returns: 198 * The per-subdriver data for the heap. 199 */ 200 void *dma_heap_get_drvdata(struct dma_heap *heap) 201 { 202 return heap->priv; 203 } 204 205 /** 206 * dma_heap_get_name() - get heap name 207 * @heap: DMA-Heap to retrieve private data for 208 * 209 * Returns: 210 * The char* for the heap name. 211 */ 212 const char *dma_heap_get_name(struct dma_heap *heap) 213 { 214 return heap->name; 215 } 216 217 struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) 218 { 219 struct dma_heap *heap, *h, *err_ret; 220 struct device *dev_ret; 221 unsigned int minor; 222 int ret; 223 224 if (!exp_info->name || !strcmp(exp_info->name, "")) { 225 pr_err("dma_heap: Cannot add heap without a name\n"); 226 return ERR_PTR(-EINVAL); 227 } 228 229 if (!exp_info->ops || !exp_info->ops->allocate) { 230 pr_err("dma_heap: Cannot add heap with invalid ops struct\n"); 231 return ERR_PTR(-EINVAL); 232 } 233 234 /* check the name is unique */ 235 mutex_lock(&heap_list_lock); 236 list_for_each_entry(h, &heap_list, list) { 237 if (!strcmp(h->name, exp_info->name)) { 238 mutex_unlock(&heap_list_lock); 239 pr_err("dma_heap: Already registered heap named %s\n", 240 exp_info->name); 241 return ERR_PTR(-EINVAL); 242 } 243 } 244 mutex_unlock(&heap_list_lock); 245 246 heap = kzalloc(sizeof(*heap), GFP_KERNEL); 247 if (!heap) 248 return ERR_PTR(-ENOMEM); 249 250 heap->name = exp_info->name; 251 heap->ops = exp_info->ops; 252 heap->priv = exp_info->priv; 253 254 /* Find unused minor number */ 255 ret = xa_alloc(&dma_heap_minors, &minor, heap, 256 XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL); 257 if (ret < 0) { 258 pr_err("dma_heap: Unable to get minor number for heap\n"); 259 err_ret = ERR_PTR(ret); 260 goto err0; 261 } 262 263 /* Create device */ 264 heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor); 265 266 cdev_init(&heap->heap_cdev, &dma_heap_fops); 267 ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1); 268 if (ret < 0) { 269 pr_err("dma_heap: Unable to add char device\n"); 270 err_ret = ERR_PTR(ret); 271 goto err1; 272 } 273 274 dev_ret = device_create(dma_heap_class, 275 NULL, 276 heap->heap_devt, 277 NULL, 278 heap->name); 279 if (IS_ERR(dev_ret)) { 280 pr_err("dma_heap: Unable to create device\n"); 281 err_ret = ERR_CAST(dev_ret); 282 goto err2; 283 } 284 /* Add heap to the list */ 285 mutex_lock(&heap_list_lock); 286 list_add(&heap->list, &heap_list); 287 mutex_unlock(&heap_list_lock); 288 289 return heap; 290 291 err2: 292 cdev_del(&heap->heap_cdev); 293 err1: 294 xa_erase(&dma_heap_minors, minor); 295 err0: 296 kfree(heap); 297 return err_ret; 298 } 299 300 static char *dma_heap_devnode(struct device *dev, umode_t *mode) 301 { 302 return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev)); 303 } 304 305 static int dma_heap_init(void) 306 { 307 int ret; 308 309 ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME); 310 if (ret) 311 return ret; 312 313 dma_heap_class = class_create(THIS_MODULE, DEVNAME); 314 if (IS_ERR(dma_heap_class)) { 315 unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS); 316 return PTR_ERR(dma_heap_class); 317 } 318 dma_heap_class->devnode = dma_heap_devnode; 319 320 return 0; 321 } 322 subsys_initcall(dma_heap_init); 323