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serial: define FIXED_PORT flag for serial_core

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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: David Gibson <dwg@au1.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Gibson
2007-05-06 14:48:49 -07:00
committed by Linus Torvalds
parent bd71c182d5
commit abb4a23907
4 changed files with 18 additions and 11 deletions
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3
arch/powerpc/kernel/legacy_serial.c
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@ -115,7 +115,8 @@ static int __init add_legacy_soc_port(struct device_node *np,
{
u64 addr;
const u32 *addrp;
upf_t flags = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST | UPF_SHARE_IRQ;
upf_t flags = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST | UPF_SHARE_IRQ
| UPF_FIXED_PORT;
struct device_node *tsi = of_get_parent(np);
/* We only support ports that have a clock frequency properly