blob: 8f5848aa144fec35a2de2ea68558c27dc3083669 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Framework for userspace DMA-BUF allocations
*
* Copyright (C) 2011 Google, Inc.
* Copyright (C) 2019 Linaro Ltd.
*/
#include <linux/cdev.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/dma-buf.h>
#include <linux/err.h>
#include <linux/xarray.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
#include <linux/dma-heap.h>
#include <uapi/linux/dma-heap.h>
#define DEVNAME "dma_heap"
#define NUM_HEAP_MINORS 128
/**
* struct dma_heap - represents a dmabuf heap in the system
* @name: used for debugging/device-node name
* @ops: ops struct for this heap
* @heap_devt heap device node
* @list list head connecting to list of heaps
* @heap_cdev heap char device
*
* Represents a heap of memory from which buffers can be made.
*/
struct dma_heap {
const char *name;
const struct dma_heap_ops *ops;
void *priv;
dev_t heap_devt;
struct list_head list;
struct cdev heap_cdev;
};
static LIST_HEAD(heap_list);
static DEFINE_MUTEX(heap_list_lock);
static dev_t dma_heap_devt;
static struct class *dma_heap_class;
static DEFINE_XARRAY_ALLOC(dma_heap_minors);
static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
unsigned int fd_flags,
unsigned int heap_flags)
{
struct dma_buf *dmabuf;
int fd;
/*
* Allocations from all heaps have to begin
* and end on page boundaries.
*/
len = PAGE_ALIGN(len);
if (!len)
return -EINVAL;
dmabuf = heap->ops->allocate(heap, len, fd_flags, heap_flags);
if (IS_ERR(dmabuf))
return PTR_ERR(dmabuf);
fd = dma_buf_fd(dmabuf, fd_flags);
if (fd < 0) {
dma_buf_put(dmabuf);
/* just return, as put will call release and that will free */
}
return fd;
}
static int dma_heap_open(struct inode *inode, struct file *file)
{
struct dma_heap *heap;
heap = xa_load(&dma_heap_minors, iminor(inode));
if (!heap) {
pr_err("dma_heap: minor %d unknown.\n", iminor(inode));
return -ENODEV;
}
/* instance data as context */
file->private_data = heap;
nonseekable_open(inode, file);
return 0;
}
static long dma_heap_ioctl_allocate(struct file *file, void *data)
{
struct dma_heap_allocation_data *heap_allocation = data;
struct dma_heap *heap = file->private_data;
int fd;
if (heap_allocation->fd)
return -EINVAL;
if (heap_allocation->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
return -EINVAL;
if (heap_allocation->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
return -EINVAL;
fd = dma_heap_buffer_alloc(heap, heap_allocation->len,
heap_allocation->fd_flags,
heap_allocation->heap_flags);
if (fd < 0)
return fd;
heap_allocation->fd = fd;
return 0;
}
static unsigned int dma_heap_ioctl_cmds[] = {
DMA_HEAP_IOCTL_ALLOC,
};
static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
unsigned long arg)
{
char stack_kdata[128];
char *kdata = stack_kdata;
unsigned int kcmd;
unsigned int in_size, out_size, drv_size, ksize;
int nr = _IOC_NR(ucmd);
int ret = 0;
if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
return -EINVAL;
nr = array_index_nospec(nr, ARRAY_SIZE(dma_heap_ioctl_cmds));
/* Get the kernel ioctl cmd that matches */
kcmd = dma_heap_ioctl_cmds[nr];
/* Figure out the delta between user cmd size and kernel cmd size */
drv_size = _IOC_SIZE(kcmd);
out_size = _IOC_SIZE(ucmd);
in_size = out_size;
if ((ucmd & kcmd & IOC_IN) == 0)
in_size = 0;
if ((ucmd & kcmd & IOC_OUT) == 0)
out_size = 0;
ksize = max(max(in_size, out_size), drv_size);
/* If necessary, allocate buffer for ioctl argument */
if (ksize > sizeof(stack_kdata)) {
kdata = kmalloc(ksize, GFP_KERNEL);
if (!kdata)
return -ENOMEM;
}
if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
ret = -EFAULT;
goto err;
}
/* zero out any difference between the kernel/user structure size */
if (ksize > in_size)
memset(kdata + in_size, 0, ksize - in_size);
switch (kcmd) {
case DMA_HEAP_IOCTL_ALLOC:
ret = dma_heap_ioctl_allocate(file, kdata);
break;
default:
ret = -ENOTTY;
goto err;
}
if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
ret = -EFAULT;
err:
if (kdata != stack_kdata)
kfree(kdata);
return ret;
}
static const struct file_operations dma_heap_fops = {
.owner = THIS_MODULE,
.open = dma_heap_open,
.unlocked_ioctl = dma_heap_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = dma_heap_ioctl,
#endif
};
/**
* dma_heap_get_drvdata() - get per-subdriver data for the heap
* @heap: DMA-Heap to retrieve private data for
*
* Returns:
* The per-subdriver data for the heap.
*/
void *dma_heap_get_drvdata(struct dma_heap *heap)
{
return heap->priv;
}
/**
* dma_heap_get_name() - get heap name
* @heap: DMA-Heap to retrieve private data for
*
* Returns:
* The char* for the heap name.
*/
const char *dma_heap_get_name(struct dma_heap *heap)
{
return heap->name;
}
struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
{
struct dma_heap *heap, *h, *err_ret;
struct device *dev_ret;
unsigned int minor;
int ret;
if (!exp_info->name || !strcmp(exp_info->name, "")) {
pr_err("dma_heap: Cannot add heap without a name\n");
return ERR_PTR(-EINVAL);
}
if (!exp_info->ops || !exp_info->ops->allocate) {
pr_err("dma_heap: Cannot add heap with invalid ops struct\n");
return ERR_PTR(-EINVAL);
}
/* check the name is unique */
mutex_lock(&heap_list_lock);
list_for_each_entry(h, &heap_list, list) {
if (!strcmp(h->name, exp_info->name)) {
mutex_unlock(&heap_list_lock);
pr_err("dma_heap: Already registered heap named %s\n",
exp_info->name);
return ERR_PTR(-EINVAL);
}
}
mutex_unlock(&heap_list_lock);
heap = kzalloc(sizeof(*heap), GFP_KERNEL);
if (!heap)
return ERR_PTR(-ENOMEM);
heap->name = exp_info->name;
heap->ops = exp_info->ops;
heap->priv = exp_info->priv;
/* Find unused minor number */
ret = xa_alloc(&dma_heap_minors, &minor, heap,
XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL);
if (ret < 0) {
pr_err("dma_heap: Unable to get minor number for heap\n");
err_ret = ERR_PTR(ret);
goto err0;
}
/* Create device */
heap->heap_devt = MKDEV(MAJOR(dma_heap_devt), minor);
cdev_init(&heap->heap_cdev, &dma_heap_fops);
ret = cdev_add(&heap->heap_cdev, heap->heap_devt, 1);
if (ret < 0) {
pr_err("dma_heap: Unable to add char device\n");
err_ret = ERR_PTR(ret);
goto err1;
}
dev_ret = device_create(dma_heap_class,
NULL,
heap->heap_devt,
NULL,
heap->name);
if (IS_ERR(dev_ret)) {
pr_err("dma_heap: Unable to create device\n");
err_ret = ERR_CAST(dev_ret);
goto err2;
}
/* Add heap to the list */
mutex_lock(&heap_list_lock);
list_add(&heap->list, &heap_list);
mutex_unlock(&heap_list_lock);
return heap;
err2:
cdev_del(&heap->heap_cdev);
err1:
xa_erase(&dma_heap_minors, minor);
err0:
kfree(heap);
return err_ret;
}
static char *dma_heap_devnode(struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "dma_heap/%s", dev_name(dev));
}
static int dma_heap_init(void)
{
int ret;
ret = alloc_chrdev_region(&dma_heap_devt, 0, NUM_HEAP_MINORS, DEVNAME);
if (ret)
return ret;
dma_heap_class = class_create(THIS_MODULE, DEVNAME);
if (IS_ERR(dma_heap_class)) {
unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
return PTR_ERR(dma_heap_class);
}
dma_heap_class->devnode = dma_heap_devnode;
return 0;
}
subsys_initcall(dma_heap_init);