Software RS485 emultaion is to be added in the following commit.
serial8250_start_tx() will need to refer serial8250_stop_rx().
Move serial8250_stop_rx() in front of serial8250_start_tx() in order
to avoid function forward declaration.
Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After masking all interrupts, wait for the irq handler to complete
before continuing shutdown.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The defunct low_latency input steering executed flush_to_ldisc()
directly from interrupt context so dropping the port lock was
necessary to avoid deadlock. That steering was removed by
commit a9c3f68f3c
Author: Peter Hurley <peter@hurleysoftware.com>
Date: Sat Feb 22 07:31:21 2014 -0500
tty: Fix low_latency BUG
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When max_count is reached, the rx loop exits. However, UART_LSR has
already been read so those char flags are lost, and subsequent rx
status will be for the wrong byte until the rx fifo drains.
Reported-by: George Spelvin <linux@horizon.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Factor the read/process one char inner loop to a separate helper
function serial8250_read_char(). No functional change.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, 8-bit (MMIO) and 32-bit (MMIO32) register interfaces are
supported for the 8250 console, but the 16-bit (MMIO16) is not.
The 8250 UART device on my board is connected to a 16-bit bus and
my main motivation is to use earlycon with it.
(Refer to arch/arm/boot/dts/uniphier-support-card.dtsi)
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We want the tty fixes and reverts in here as well so that people can
properly test and use it.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This adds an entry to the uart_config table for PORT_RT2880
enabling rx/tx FIFOs. The UART is actually a Palmchip BK-3103
which is found in several devices from Alchemy/RMI, Ralink, and
Sigma Designs.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move h/w reinit of serial console restore-from-suspend into
standalone helper function.
No functional change.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When the UART clock is set slightly under 1.8432MHz, the 8250 driver
core doesn't permit the 115200 baud rate since it calculates the maximum
frequency to pass to uart_get_baud_rate by simply dividing the uart
clock by 16 which yields a value slightly under 115200, even though the
frequency is close enough for the UART to operate reliably.
Therefore add some tolerance in the calculation of the maximum baud
rate. 1% tolerance allows for marginally slower uart clk than nominal
without introducing transmission errors.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
[pjh: Forward-port & refactor original patch; change tolerance to 1%]
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some SoCs, including Ralink/Mediatek and Alchemy Au1xxx, have a
16550-like UART with a non-standard register layout. These are
supported by a simple mapping table in 8250_port.c Rather than
list every SoC type using this access mode in the ifdefs there,
allow selecting the SERIAL_8250_RT288X Kconfig option with any
system and default it to y for the known cases needing it. The
help text is reworded accordingly.
This change simplifies adding support for other SoCs also using
the same UART.
The name of the option is a little misleading, but not knowing
the true origin of this UART, it is as good a choice as any.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The following race conditions can happen when a serial port is used
as console.
Case1: CPU_B is used to detect an interrupt from a serial port,
but it can have interrupts disabled during the waiting time.
Case2: CPU_B clears UART_IER just after CPU_A sets UART_IER and then
a serial port may not make an interrupt.
Case3: CPU_A sets UART_IER just after CPU_B clears UART_IER.
This is an unexpected behavior for serial8250_console_write().
CPU_A [autoconfig_irq] | CPU_B [serial8250_console_write]
----------------------------|---------------------------------------
|
probe_irq_on() | spin_lock_irqsave(&port->lock,)
serial_outp(,UART_IER,0x0f) | serial_out(,UART_IER,0)
udelay(20); | uart_console_write()
probe_irq_off() |
| spin_unlock_irqrestore(&port->lock,)
Case1 and 2 can make autoconfig_irq() failed.
In these cases, the console doesn't work in interrupt mode and
"input overrun" (which can make operation mistakes) can happen
on some systems. Especially in the Case1, It is known that the
problem happens with high rate every boot once it occurs
because the boot sequence is always almost same.
port mutex makes sure that the autoconfig operation is exclusive of
any other concurrent HW access except by the console operation.
console lock is required in autoconfig_irq().
Signed-off-by: Taichi Kageyama <t-kageyama@cp.jp.nec.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CIR type serial ports aren't real serial ports.
This is just a way to prevent legacy 8250 serial
driver from probing and eventually binding some
resources.
Since in current state such ports aren't providing
any real functionality and it is not possible
to change their type via setserial/ioctl(TIOCSSERIAL)
(due to UPF_FIXED_PORT flag set on them)
it is simpler and cleaner to not register them at all
with serial core.
Print a short message in this case so it is known
to user what has happened.
This way checks for PORT_8250_CIR in serial port
callbacks can be removed too, since they won't
ever be called.
Signed-off-by: Maciej Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The split of the 8250 driver into a 8250_base/8250.ko resulted in a
lack of a license for the 8250_base.ko module. This caused the module
to fail to load and the kernel to be tainted. Add the appropriate
MODULE_LICENSE to 8250_port.c, which is always compiled into
8250_base.ko
Signed-off-by: Jonathan McDowell <noodles@earth.li>
Reported-by: Mikael Pettersson <mikpelinux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The XR17V35X UART needs the ECB bit set in its XR_EFR
register to enable access to IER [7:5], ISR [5:4], FCR[5:4],
MCR[7:5], and MSR [7:0].
Also reset the IER register to mask interrupts after access
to all bits of this register has been enabled.
This makes my 8-port XR17V35X working with the in-kernel
serial driver.
Cc: Joe Schultz <jschultz@xes-inc.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
An already-active sender can swamp the interrupt handler with
"too much work" if the rx interrupts are enabled when the fifo is
disabled and operating in single-byte mode.
Defer rx and line status interrupt enable until after the fifos
are enabled in set_termios(), but at least initialize the shadow
IER value with the interrupts which will be enabled.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
