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thanks amit!
got it now
:-)
inside the your_read() function coded
in the driver , you would have allocated memory , static or otherwise using
kmalloc and friends ... you would use this memory to copy whatever is read
from the device to the buffer,
and this buffer which is residing in the
kernel as part of your code is the second arg to
copy_to_user.
cheers,
Amith
Dhanashri Bhate wrote:
okay, let me in detail tell you whatever my understanding is:
register_chrdev:
register_chrdev(major, name, fops) - here we specify that this is my device-driver name, the major number for it and fops pointer. (that is the device related functions to read/write.open/close the device).
so whenever kernel sees any device read/write request, it will look for the driver with matching major number and that is how it will select which function to call.
what i want to know is in the drivers read method , we will read data from the device memory and copy it to the buffer in user area. using function copy_to_user( user-buf-pointer, device-data-ptr, count)
where do i get the "device-data-ptr" from?
i'm very sorry if my question is too silly!!
thanks for ur reply!
-----Original Message-----
From: karthick.sundararajan@xxxxxxxxx
[mailto:karthick.sundararajan@xxxxxxxxx]
Sent: Thursday, February 17, 2005 11:06 AM
To: kernelnewbies@xxxxxxxxxxxx; Dhanashri Bhate
Subject: RE: Basic question about device driver
Hi Dhanshri,
Can you be a bit more specific about the question: I am not able to
understand if you are asking about how register_chrdev works
or just the
usage of register_chrdev.
Rgds,
Karthick S.
-----Original Message-----
From: kernelnewbies-bounce@xxxxxxxxxxxx
[mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of
Dhanashri Bhate
Sent: Thursday, February 17, 2005 10:42
To: kernelnewbies@xxxxxxxxxxxx
Subject: Basic question about device driver
hi,
i know unix fairly well and good at C, but new to the linux
environment.
I'm studying device driver development(kernel space). i'm refering the
linux device driver book by allessandro rubini. which is
quite good...
but still i'm having some problems in thoroghly understanding
the basic
concepts!
someone pls answer this: how exactly a device address comes to the
driver? ( which will be used by copy-to-user/copy-from-user)
Thanks,
Dhanshri
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