Hi,
I'm having a driver, which wants to use and share some physical memory with an application.
1.) What I implemented: the mmap-implementation of my driver returns a virtual address for a physical adress known by the driver (cacheable and bufferable) to the application.
2.) The application may read / write modify the buffer.
3.) at a later moment the driver wants to be sure, that the buffer is entirely flushed before doing his work.
What function call do I have to do?
More info:
- Linux: 2.6.10
- Processor: ARM11
- driver knows physical address and the virtual address given to the application
- buffer is cachaeble and bufferable
DRIVER CODE ========================================== The mmap function without error checking: my_mmap(struct file *file, struct vm_area_struct *vma) { struct my_device *dev = file->private_data; unsigned long start = vma->vm_start; unsigned long size = vma->vm_end - vma->vm_start; vout_data *vout = video_get_drvdata(dev);
pgprot_t my_prot; my_prot= pgprot_noncached(PAGE_SHARED); if (remap_pfn_range(vma, start, vma->vm_pgoff, size, my_prot)); return 0; }
APPLICATION CODE ===================================================== the application code (pseudo code):
int fd= open(dev_name); char *buf = mmap (NULL, length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset);
dosomething_with(buf);
// following ioctl cannot be split ioctl(fd, DO_SOMETHING_FLUSH_AND_DO_SOMETHING_MORE, param);
thanks for any help
nsp