If the counter overflows during a __delay operation, we will exit the
loop prematurely. For example, calling __delay(0x100) with the counter
at 0xffffff00 gives us a target of 0x0. The unsigned comparison in the
while loop will likely be false on the first iteration (if the counter
is now anything other than 0) and we will return early.

This patch fixes the problem by comparing deltas in the loop rather than
absolute values.

Cc: Jon Masters <jcm@redhat.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NJonas Bonn <jonas@southpole.se>

The openrisc implementation of __const_udelay casts the result of a
32-bit multiplication to 64 bits and passes the top 32 bits to __delay.
Since there are no casts on the arguments, this results in a __delay of
zero, regardless of the xloops parameter.

This patch fixes the problem by casting xloops to (unsigned long long),
ensuring that the multiplication is not truncated.

Cc: Jon Masters <jcm@redhat.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NJonas Bonn <jonas@southpole.se>

Signed-off-by: NJonas Bonn <jonas@southpole.se>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>