If the earlycon parameter is given twice, the kernel will spit out a
WARN() in register_console() because it was already registered. The
non-dt variant setup_earlycon() already handles that gracefully. The dt
variant of_setup_earlycon() doesn't. Add the check there and add the
-EALREADY handling in early_init_dt_scan_chosen_stdout().
FWIW, this doesn't happen if CONFIG_ACPI_SPCR_TABLE is set. In that case
the registration is delayed until after earlycon parameter(s) are
parsed.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220628120705.200617-1-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Regarding Exynos Auto v9 SoC, it supports uarts up to 12. However, the
maximum number of the ports has been derived from
CONFIG_SERIAL_SAMSUNG_UARTS and tightly coupled with the config for
previous Samsung SoCs such as s3c24xx and s3c64xx. To overcome this
limitation, this changes the usage of the definition to UART_NR which is
widely used from other serial drivers. This also defines the value to 12
only for ARM64 SoCs to not affect the change to previous arm32 SoCs.
Instead of enumerating all the ports as predefined arrays, this
introduces s3c24xx_serial_init_port_default that is initializing the
structure as the default value.
Reviewed-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Link: https://lore.kernel.org/r/20220629005538.60132-1-chanho61.park@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit e8ffbb71f7 ("serial: 8250: use THRE & __stop_tx also with
DMA") changed __dma_tx_complete() to enable THRI that is cleared in
__stop_tx() once THRE is asserted as UART runs out bits to transmit. It
is possible, however, that more data arrives in between in which case
serial8250_tx_dma() resumes Tx. THRI is not supposed to be on during
DMA Tx because DMA is based on completion handler, therefore THRI must
be cleared unconditionally in serial8250_tx_dma().
When Tx is about to start, another race window exists with
serial8250_handle_irq() leading to a call into __stop_tx() while the
Tx has already been resumed:
__tx_complete():
-> spin_lock(port->lock)
-> dma->tx_running = 0
-> serial8250_set_THRI()
-> spin_unlock(port->lock)
uart_start():
serial8250_handle_irq():
-> spin_lock(port->lock)
-> serial8250_tx_dma():
-> dma->tx_running = 1
-> spin_unlock(port->lock)
-> spin_lock(port->lock)
-> __stop_tx()
Close this race by checking !dma->tx_running before calling into
__stop_tx().
Fixes: e8ffbb71f7 ("serial: 8250: use THRE & __stop_tx also with DMA")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220615090651.15340-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().
ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.
Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().
[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use 32-bit reads in order to not lose higher bits of DW UART regs. This
change does not fix any known issue as the high bits are not used for
anything related to 8250 driver (dw8250_readl_ext and dw8250_writel_ext
used within the dwlib are already doing
readl/writel/ioread32be/iowrite32be anyway).
This change is necessary to enables 9th bit address mode. DW UART
reports address frames with BIT(8) of LSR.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-4-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit 31f6bd7fad ("serial: Store character timing information
to uart_port"), per frame timing information is available on uart_port.
Uart port's timeout can be derived from frame_time by multiplying with
fifosize.
Most callers of uart_poll_timeout are not made under port's lock. To be
on the safe side, make sure frame_time is only accessed once. As
fifo_size is effectively a constant, it shouldn't cause any issues.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220613113905.22962-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Disable MMIO tracing for geni serial driver to prevent excessive
logging. Any access over serial console would involve a lot of
TX and RX register accesses (and few others), so these MMIO
read/write trace events in these drivers cause a lot of unwanted
noise because of the high frequency of such operations and it is
not very useful tracing these events for such drivers.
Given we want to enable these trace events on development devices
(maybe not production devices) where performance also really matters
so that we don't regress other components by wasting CPU cycles and
memory collecting these traces, it makes more sense to disable these
traces from such drivers.
Also another reason to disable these traces would be to prevent
recursive tracing when we display the trace buffer containing
these MMIO trace events since writing onto serial console would
further record MMIO traces.
Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Serial core handles serial_rs485 sanitization.
When em485 init fails, there are two possible paths of entry:
1) uart_rs485_config (init path) that fully clears port->rs485 on
error.
2) ioctl path with a pre-existing, valid port->rs485 unto which the
kernel falls back on error and port->rs485 should therefore be
kept untouched. The temporary rs485 struct is not returned to
userspace in case of error so its flag don't matter.
...Thus SER_RS485_ENABLED clearing on error can/should be dropped.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-37-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Serial core handles serial_rs485 sanitization. Remove custom
sanitization from lpuart_config_rs485.
This change loses dev_err when SER_RS485_RX_DURING_TX is set due to
incorrect configuration. Other drivers do not do similar prinout for
full-duplex case and it should be done in serial core if it is
desirable to notify on this condition. Personally, I doesn't see it
important because the kernel gracefully downgrades to half-duplex.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-31-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In order to be add new flags more cleanly and safely, return -EINVAL
from TIOCSRS485 ioctl for the flags bits which are not among the
current legacy ones.
This might cause a regression for userspace as those non-flag bits do
not currently trigger -EINVAL. However, it would only occur if the
userspace is sending garbage bits so perhaps we'll get away with this
change.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-25-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When SER_RS485_ENABLED is not set, having any other flag/field set in
serial_rs485 struct does not have an effect different from not having
them set. Thus, make the serial_rs485 struct also match the behavior
for all flags, not just SER_RS485_ENABLED.
Some drivers do similar clearing of rs485 struct in their
rs485_config() already, but not all. This change makes the behavior
consistent across drivers.
Don't try to validate rs485 struct further when no RS485 is requested,
this silences some bogus warnings.
This change has (minor) userspace visible impact.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-24-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sanitize serial_rs485 struct before calling into rs485_setup. The
drivers provide supported_rs485 to help sanitization of the fields.
If neither of SER_RS485_RTS_ON_SEND or SER_RS485_RTS_AFTER_SEND
supported, don't pretend they can be set to sane settings but clear
them both instead. If only one of them is supported it may look
tempting to use the one driver supports to set the other, however, the
userspace does not have that information readily available so it
wouldn't be helpful.
While adjusting the documentation, remove also the claim that
TIOCGRS485 would call driver specific code. In reality, it does nothing
else than copies the stored serial_rs485 structure from uart_port to
userspace.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-23-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
