The PXA variant of the 8250 UART adds a UART enable bit which must not
be cleared. Make the earlycon support maintain this bit if it is set.
This implies some initialization of the UART, but we cannot
unconditionally set the bit as some other variants require this bit to
be clear for other functions.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In early 8250, IER is already zero so no point in writing this - twice
per line
This helped improve the SystemC model based ARC OSCI platform
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the conversion to generic early console, the passing of options from
the early 8250 console to the regular ttyS console was broken. This
resulted in the baud rate changing when switching consoles during boot.
This feature allows specifying a single console option on the kernel
command line rather than both an early console and regular serial tty
console. It would be nice to generalize this feature. However, it only
works if the correct baud rate can be probed early which is not the
case on many platforms which have non-standard UART clock rates. So for
now, this is left as an 8250 specific feature.
Reported-and-tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit d2fd6810a8 (tty/serial: convert 8250 to generic earlycon)
removed setup_early_serial8250_console, but there are still 2 callers
in:
arch/mips/mti-malta/malta-init.c
drivers/firmware/pcdp.c
Add back the function implemented as a wrapper to setup_earlycon.
Reported-by: Yinghai Lu <yinghai@kernel.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With the generic earlycon infrastructure in place, convert the 8250
early console to use it.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix the following sparse warning:
drivers/tty/serial/8250/8250_early.c:196:26: error: incompatible types in comparison expression (different type sizes)
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The earlier change to use strlcpy uncovered a bug in the options
argument length calculation causing last character to be truncated.
This makes the actual console to be configured with incorrect
baudrate when specifying the console using console=uart,... syntax.
Bug symptom seen in kernel log output:
Kernel command line: console=uart,mmio,0x90000000,115200
Early serial console at MMIO 0x90000000 (options '11520')
which then results in a invalid baud rate 11520 instead of the
expected 115200 when the console is switched to ttyS0 later
in the boot process.
Signed-off-by: Henrik Nordstrom <henrik@henriknordstrom.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The fields must be null-terminated, or next printk for %s, will cause issue.
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Allows overriding default methods serial_in/serial_out.
In such platform specific replacement it is possible to use
other regshift, biased register offset, any other manipulation
that is not covered with common default methods.
Overriding default methods may be useful for platforms which got
serial peripheral with registers represented in big endian.
In this situation and assuming that 32 bit operations / alignment
is required then it may be useful to swab words before/after
accessing the serial registers.
Signed-off-by: Noam Camus <noamc@ezchip.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Modify divisor to select the nearest baud rate divider rather than the
lowest. It minimizes baud rate errors especially on low UART clock
frequencies.
For example, if uartclk is 33000000 and baud is 115200 the ratio is
about 17.9 The current code selects 17 (5% error) but should select 18
(0.5% error).
This 5% error in baud rate leads to garbage on receiving end, while 0.5%
doesn't.
The issue showed up when using the stock 8250 driver for
Synopsys DW UART. This was on a FPGA with ~12MHz UART clock.
When we enabled early serial, we saw garbage which was narrowed down
to the rounding error.
So the bug had been latent and it only showed up with such low clock rates.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The drivers/tty/serial dir is already getting rather busy.
Relocate the 8250 related drivers to their own subdir to
reduce the clutter.
Note that sunsu.c is not included in this move -- it is
8250-like hardware, but it does not use any of the existing
infrastructure -- and does not depend on SERIAL_8250.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
