• David Gibson's avatar
    serial: define FIXED_PORT flag for serial_core · abb4a239
    David Gibson authored
    At present, the serial core always allows setserial in userspace to change the
    port address, irq and base clock of any serial port.  That makes sense for
    legacy ISA ports, but not for (say) embedded ns16550 compatible serial ports
    at peculiar addresses.  In these cases, the kernel code configuring the ports
    must know exactly where they are, and their clocking arrangements (which can
    be unusual on embedded boards).  It doesn't make sense for userspace to change
    these settings.
    
    Therefore, this patch defines a UPF_FIXED_PORT flag for the uart_port
    structure.  If this flag is set when the serial port is configured, any
    attempts to alter the port's type, io address, irq or base clock with
    setserial are ignored.
    
    In addition this patch uses the new flag for on-chip serial ports probed in
    arch/powerpc/kernel/legacy_serial.c, and for other hard-wired serial ports
    probed by drivers/serial/of_serial.c.
    Signed-off-by: default avatarDavid Gibson <dwg@au1.ibm.com>
    Cc: Russell King <rmk@arm.linux.org.uk>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    abb4a239
serial_core.c 58.2 KB