Hello,
I am working on kernel modules on an i.MX537 ARM platform where we use
GPIO pins to control various
external chips, LEDs etc.
For accessing these ports I use ioremap_nocache(). But I only want to
use single bits of these big 32 ports,
and some other kernel modules should reuse the other free pins of that
port.
Therefore I am afraid about the shared simultaneously registers access
between:
- 2 kernel modules (user contex)
- interrupt context (IRQF_NODELAY) and simultaneously from the user
context (ioctl() etc.) in the kernel module
What is the right way to access these registers for e.g setting a single
bit of such a register to avoid read/modify/write problems ?
Do I have to use some locking / atomic operations ?
Can someone recommend a kernel driver for studying where such shared
registers access is used / handled?
Best regards,
Matthias
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