Strategies for accessing driver data from file operations!?
Daniel Hilst Selli
danielhilst at gmail.com
Tue Aug 12 09:47:20 EDT 2014
I was writing an spi driver, and taking a look into spidev.c, I see the the author
allocates a linked list to hold driver data instances. From open it iterates over
the list comparing two dev_t fields, one from current element on list other from
struct inode * parameter, here is the lines:
static int spidev_open(struct inode *inode, struct file *filp)
{
struct spidev_data *spidev;
int status = -ENXIO;
mutex_lock(&device_list_lock);
list_for_each_entry(spidev, &device_list, device_entry) {
if (spidev->devt == inode->i_rdev) {
status = 0;
break;
}
}
...
Now it set the filp->private data to its driver data, and on read and write file
operations he knows how to access is driver data,
I was looking for a simpler strategy, on my module I would have same devices on
distinct spi busses and chipselects, but it wouldn't go greater than 9 devices.
I need to access spi_device struct pointer for the right device from read and
write file operations.
Isn't there any path from struct file *filp to struct device *devp created
with device_create? I can't see it, but if is possible I can set device private
data from my probe function.
Cheers,
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