Extend struct todr_chip_handle with a todr_quality member. This allows us
to assign a quality to RTC implementation and pick the "best" RTC if a
system has multiple RTCs (or multiple interfaces to an RTC). This allows
us to prefer a battery-backed I2C RTC over an RTC that is part of the SoC
which is only running of the SoC is powered. It also allows us to
work around issues with firmware RTC interfaces that may lie to us or
even crash the system.

This change makes sure the todr_quality member of the struct is always
initialized. In most cases the quality will be set to zero; further
adjustments of the quality for specific subsystems/architectures will follow.

ok cheloha@, patrick@

constify struct cfattach

Remove unused header files and make some cosmetic changes.

ok patrick@

Remove unused function pointers from `todr_handle'.

from miod@

Don't clear OSF flag when we attach such that we can reject the RTC clock
time if the flag is set. Instead clear the flag when we set the time.
This way we don't use the clock time if the oscillator has been interrupted.
This happens for example when the battery is dead.

ok sthen@

Change the identification string to "nxp,pcf8523" as this is what is stored
in the FDT.

Attempt to clear the OS flag when we attach.

Driver for the NXP PCF8523 Real Time Clock.

constify struct cfattach

Remove unused header files and make some cosmetic changes.

ok patrick@

Remove unused function pointers from `todr_handle'.

from miod@

Don't clear OSF flag when we attach such that we can reject the RTC clock
time if the flag is set. Instead clear the flag when we set the time.
This way we don't use the clock time if the oscillator has been interrupted.
This happens for example when the battery is dead.

ok sthen@

Change the identification string to "nxp,pcf8523" as this is what is stored
in the FDT.

Attempt to clear the OS flag when we attach.

Driver for the NXP PCF8523 Real Time Clock.

Remove unused header files and make some cosmetic changes.

ok patrick@

Remove unused function pointers from `todr_handle'.

from miod@

Don't clear OSF flag when we attach such that we can reject the RTC clock
time if the flag is set. Instead clear the flag when we set the time.
This way we don't use the clock time if the oscillator has been interrupted.
This happens for example when the battery is dead.

ok sthen@

Change the identification string to "nxp,pcf8523" as this is what is stored
in the FDT.

Attempt to clear the OS flag when we attach.

Driver for the NXP PCF8523 Real Time Clock.

Remove unused function pointers from `todr_handle'.

from miod@

Don't clear OSF flag when we attach such that we can reject the RTC clock
time if the flag is set. Instead clear the flag when we set the time.
This way we don't use the clock time if the oscillator has been interrupted.
This happens for example when the battery is dead.

ok sthen@

Change the identification string to "nxp,pcf8523" as this is what is stored
in the FDT.

Attempt to clear the OS flag when we attach.

Driver for the NXP PCF8523 Real Time Clock.

Don't clear OSF flag when we attach such that we can reject the RTC clock
time if the flag is set. Instead clear the flag when we set the time.
This way we don't use the clock time if the oscillator has been interrupted.
This happens for example when the battery is dead.

ok sthen@

Change the identification string to "nxp,pcf8523" as this is what is stored
in the FDT.

Attempt to clear the OS flag when we attach.

Driver for the NXP PCF8523 Real Time Clock.

Change the identification string to "nxp,pcf8523" as this is what is stored
in the FDT.

Attempt to clear the OS flag when we attach.

Driver for the NXP PCF8523 Real Time Clock.