Due to the RIOT_EPOCH of 2020 this overflow will happen in year 2084. It would be scary if IoT devices are still around then.
We can save RAM and ROM. Furthermore, this overflow handling should block BACKUP power mode in order to keep track of the reference year.
A if `netdev_driver_t::confirm_send()` is provided, it provides the
new netdev API. However, detecting the API at runtime and handling
both API styles comes at a cost. This can be optimized in case only
new or only old style netdevs are in use.
To do so, this adds the pseudo modules `netdev_legacy_api` and
`netdev_new_api`. As right now no netdev actually implements the new
API, all netdevs pull in `netdev_legacy_api`. If `netdev_legacy_api` is
in used but `netdev_new_api` is not, we can safely assume at compile
time that only legacy netdevs are in use. Similar, if only
`netdev_new_api` is used, only support for the new API is needed. Only
when both are in use, run time checks are needed.
This provides two helper function to check for a netif if the
corresponding netdev implements the old or the new API. (With one
being the inverse of the other.) They are suitable for constant folding
when only new or only legacy devices are in use. Consequently, dead
branches should be eliminated by the optimizer.
The source / destination address of the SDHC transfer needs to be
word-aligned.
Use the mtd buffer to fix the alignment if `mtd_write_page` is used,
otherwise return -ENOTSUP.
`rtt_get_counter()` already waits for syncbusy before reading the time,
but we also have to do this in RTC mode (`rtc_get_time()`) to avoid
reading old values.
Thus, always wait for syncbusy to clear when accessing the COUNT register.
On SAM L21 only 8 EXTWAKE pins can wake the CPU from Backup sleep.
Handle this analogous to the RTC tamper pins on SAM D5x/E5x where
configuring them as an interrupt will also cause them to wake the
device from Deep Sleep.
The sam0 rtt busy loops for 180us every time an alarm is set or
the counter is read, this propagates and leads to timing errors
on ztimer_msec that are higher than > +-1msec.
The same goes for fe310.
This introduces KCONFIG_BOARD_CONFIG and KCONFIG_CPU_CONFIG variable for
boards and CPUs (including common directories) to add default
configuration files to be merged. The current approach, as it uses
Makefile.features, would include boards first, not allowing them to
override CPU configurations.
