ld emits relocations for weak undefined symbols. We want to safely skip
them.

This lets us decide where the stack live, and place it at the best
possible spot for it to grow towards the image.

This is the first step towards having a heap in l0dables.

Commit 82b5b21f intoduced
card10_reset().  This patch refactors the pmic module to also make use
of this new implementation.

Signed-off-by: Rahix <rahix@rahix.de>

Other existing API calls also use raw `int` for descriptors
so I think we should use it for file-functions as well.

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

This patch is a workaround for #54.  A lockup is detected if more than
4096 attempts to write to the USB FIFO fail.  If this condition is
detected, CDC-ACM is disabled until the next reboot.

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>

Signed-off-by: Rahix <rahix@rahix.de>