Here is the "big" set of tty and serial driver updates for 7.3-rc1. Not
really all that much happened this development cycle for this subsystem,
changes in here are:
- removal of the ipwireless driver as it's no longer used or needed
- new 8250_mxpcie driver added
- qcom serial driver updates and additions
- vt mode validation addition
- lots of other small serial driver updates and additions
All of these have been in linux-next for weeks with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-----BEGIN PGP SIGNATURE-----
iG0EABECAC0WIQT0tgzFv3jCIUoxPcsxR9QN2y37KQUCao2mTw8cZ3JlZ0Brcm9h
aC5jb20ACgkQMUfUDdst+yk34ACdFfyDYJ0n1JcdskTxdNMBSPRkj7UAoJtMC/2y
jxCfyfkM18YIuwZD6CvO
=MlfE
-----END PGP SIGNATURE-----
Merge tag 'tty-7.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull TTY / serial driver updates from Greg KH:
"Here is the "big" set of tty and serial driver updates for 7.3-rc1.
Not really all that much happened this development cycle for this
subsystem, changes in here are:
- removal of the ipwireless driver as it's no longer used or needed
- new 8250_mxpcie driver added
- qcom serial driver updates and additions
- vt mode validation addition
- lots of other small serial driver updates and additions
All of these have been in linux-next for weeks with no reported issues"
* tag 'tty-7.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (97 commits)
serial: imx: serialize imx_uart_ports[] lifetime
tty: clear cdev pointer after cdev_add() failure
tty: skip cdev_del() when no cdev is registered
serial: core: clear freed pointers on uart_register_driver() failure
serial: core: do fallible allocations before the console can be registered
serial: 8250_mxpcie: implement rx_trig_bytes callbacks via MUEx50 RTL
serial: 8250_mxpcie: introduce per-port private data structure
serial: 8250: allow UART drivers to override rx_trig_bytes handling
serial: 8250_mxpcie: add break support for RS485 using MUEx50 features
serial: 8250: allow low-level drivers to override break control
serial: 8250_mxpcie: support serial interface mode switching
serial: 8250_mxpcie: speed up TX using memory-mapped FIFO window
serial: 8250_mxpcie: speed up RX using memory-mapped FIFO window
serial: 8250_mxpcie: add custom handle_irq callback
serial: 8250_mxpcie: offload XON/XOFF flow control to MUEx50 hardware
serial: 8250_mxpcie: enable automatic RTS/CTS flow control
serial: 8250_mxpcie: enable enhanced mode and program FIFO trigger levels
serial: 8250: add Moxa MUEx50 UART port type
serial: 8250: split Moxa PCIe serial board support out of 8250_pci
serial: qcom-geni: Use geni_se_set_perf_level() for baud rate perf level
...
imx_uart_probe() publishes its devm-allocated port in imx_uart_ports[]
before uart_add_one_port() because console setup uses the table. The entry
is not cleared when adding the port fails or after removal, leaving a
dangling pointer.
A sibling probe can register the shared console through that stale entry.
This was reproduced under KASAN on QEMU mcimx6ul-evk by unbinding a
sibling UART, unbinding the console UART and rebinding the sibling.
Keep the entry valid through uart_remove_one_port(), then clear it. Protect
port addition and removal together with their table updates so sibling
operations cannot interleave. Reject an occupied slot rather than
clobbering an active port during a duplicate-line probe.
Fixes: dbff4e9ea2 ("IMX UART: remove statically initialized tables")
Fixes: 9f322ad064 ("imx: serial: handle initialisation failure correctly")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://lore.kernel.org/all/20260719162850.043B41F000E9@smtp.kernel.org
Link: https://lore.kernel.org/all/20260719222501.CB4CB1F000E9@smtp.kernel.org
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260731181844.11330-6-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
uart_register_driver() leaves drv->state pointing to freed memory when
tty_alloc_driver() fails. If tty_register_driver() fails, drv->tty_driver
also retains a pointer after its reference is dropped.
Drivers that use drv->state as an "already registered" flag can then skip
registration on the next probe and pass the freed state to
uart_add_one_port().
This issue was found with failslab on QEMU's raspi1ap board by
failing registration and binding the PL011 port again.
Clear both pointers on their failure paths, as uart_unregister_driver()
already does.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Fixes: 9e845abfc8 ("serial: fix NULL pointer dereference")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Link: https://patch.msgid.link/20260731181844.11330-3-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial_core_add_one_port() allocates uport->tty_groups after
uart_configure_port(), which may register the console. If the allocation
fails, the driver unwinds the port while its console remains registered.
The earlier uport->name allocation has a related failure path that leaves
state->uart_port linked to a port being freed.
Failslab reproduced a NULL dereference in PL011 console output and a KASAN
use-after-free in i.MX console output after failed binds.
Allocate the name and tty_groups before linking the port and configuring
it. Reserve space for the optional driver attribute group because
config_port() may populate uport->attr_group during configuration.
Fixes: 266dcff03e ("Serial: allow port drivers to have a default attribute group")
Fixes: f7048b1590 ("tty: serial_core: Add name field to uart_port struct")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260719070454.D6FA21F000E9@smtp.kernel.org/
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Link: https://patch.msgid.link/20260731181844.11330-2-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The MUEx50 UART exposes a programmable RX trigger level via the RTL
register.
Implement uart_port RX trigger set/get callbacks for the mxpcie driver
and wire them up to the generic rx_trig_bytes sysfs interface. Store the
configured trigger level in the per-port private data.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-15-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Introduce a private per-port data structure for the mxpcie driver and
replace the shared flexible array of registered lines with an array of
per-port objects.
This prepares the driver for storing per-port state needed by subsequent
features.
No functional change intended.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-14-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The rx_trig_bytes sysfs attribute currently relies on 8250-internal
helper functions and assumes a fixed mapping between trigger levels and
FIFO behavior.
Some UARTs provide hardware-specific RX trigger mechanisms that do not
fit this model. Add optional uart_port callbacks for setting and getting
the RX trigger level, and use them when provided, while preserving the
existing 8250 helpers as the default fallback.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-13-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On MUEx50, break signaling under RS485 requires a driver-specific
sequence and cannot be handled correctly by the generic 8250 break
implementation alone.
Implement a mxpcie break_ctl callback that performs MUEx50-specific
break handling when RS485 is enabled and fall back to the default 8250
break handling for other modes.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-12-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some UARTs require driver-specific handling for break signaling, which
cannot be expressed by the generic 8250 break implementation alone.
Add an optional uart_port break_ctl callback and route
serial8250_break_ctl() through it when provided. Rename the existing
8250 implementation to serial8250_do_break_ctl() and export it so
low-level drivers can reuse the default 8250 behavior when appropriate.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-11-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Moxa PCIe multiport serial boards support switching the serial interface
mode between RS232, RS422, RS485-2W, and RS485-4W via on-board control
registers.
Implement an rs485_config() callback and map TIOCSRS485 requests to the
corresponding hardware modes using serial_rs485 flags:
- RS232 = (no flags set)
- RS422 = SER_RS485_ENABLED | SER_RS485_MODE_RS422
- RS485_2W (half-duplex) = SER_RS485_ENABLED
- RS485_4W (full-duplex) = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX
This allows users to reconfigure the serial mode at runtime via ioctl().
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-10-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The MUEx50 UART provides a memory-mapped TX FIFO data window along with
a TX FIFO level counter.
Fill the TX FIFO in bulk via the MMIO FIFO window based on available
FIFO space, using uart_port_tx_limited() for the common serial-core TX
handling.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-9-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The MUEx50 UART provides a memory-mapped RX FIFO data window along with
an RX FIFO byte counter.
When no break or error conditions are present, read received data in
bulk via the MMIO FIFO window and push it to the tty layer in one
operation. Fall back to the generic 8250 RX path for break and error
handling.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-8-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add a mxpcie-specific handle_irq() implementation for Moxa PCIe serial
ports.
This keeps the interrupt handling self-contained in the driver and
provides a hook point for MUEx50-specific RX/TX paths added in subsequent
patches. The handler processes RX, updates modem status, and handles TX
when THRE is asserted.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-7-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The MUEx50 UART can handle in-band software flow control (XON/XOFF)
directly in hardware.
Program the on-chip XON/XOFF characters from termios settings and enable
the corresponding MUEx50 flow control modes when IXON or IXOFF is
requested. Provide throttle and unthrottle callbacks so RX can be
stopped and resumed cleanly.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-6-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The MUEx50 UART supports automatic RTS/CTS flow control via the enhanced
feature register.
Implement a mxpcie-specific set_termios() callback that enables MUEx50
auto-RTS/auto-CTS when CRTSCTS is requested and disables it otherwise.
Keep the 8250 port status flags in sync with the hardware configuration.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-5-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The MUEx50 UART provides an enhanced register set and programmable FIFO
trigger levels for RX, TX, and flow control.
Enable enhanced mode during port startup and program the MUEx50 FIFO
trigger registers according to the configured port settings. Clear the
programmed state again during shutdown to restore the default UART
configuration.
The TX FIFO write pointer and read pointer are driven by different
clocks. Clear the FIFOs repeatedly during startup so both pointers are
reset before programming the trigger levels.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-4-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add a new 8250 port type for the Moxa MUEx50 UART and describe its basic
FIFO size and trigger characteristics in the 8250 port configuration
table.
The 8250_mxpcie driver sets UPF_FIXED_TYPE and uses PORT_MUEX50 so that
the generic 8250 core applies the correct defaults.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Link: https://patch.msgid.link/20260731074820.735619-3-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Moxa PCIe multiport serial boards are currently handled as part of
8250_pci.c. In preparation for adding Moxa-specific UART features and
optimizations, move the Moxa PCIe implementation into a dedicated
driver.
This introduces drivers/tty/serial/8250/8250_mxpcie.c and wires it up
via Kconfig and Makefile, while preserving the existing probe flow and
device IDs.
This change was suggested during earlier reviews by Andy Shevchenko [1][2].
No functional change intended.
Link: https://lore.kernel.org/all/ZmQovC6TbDpTb3c8@surfacebook.localdomain/ [1]
Link: https://lore.kernel.org/all/CAHp75VeDsVt0GQYUFxLM+obfmqXBPa3hM3YMsFbc26uzWZG-SQ@mail.gmail.com/ [2]
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://patch.msgid.link/20260731074820.735619-2-crescentcy.hsieh@moxa.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver implements its own helper to select the performance level
corresponding to a requested baud rate. The helper duplicates
functionality already provided by geni_se_set_perf_level() in the GENI
core.
Replace the local implementation with the common helper and remove the
associated duplicate definitions and code. This consolidates
performance-level management in the GENI framework and reduces driver
specific code.
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260801-reuse_common_geni_framework_helpers-v2-3-13753256ef71@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To manage GENI serial engine resources during runtime power
management, drivers currently need to call functions for ICC, clock,
and SE resource operations in both suspend and resume paths, resulting
in code duplication across drivers.
The new geni_se_resources_activate() and geni_se_resources_deactivate()
helper APIs addresses this issue by providing a streamlined method to
enable or disable all resources based, thereby eliminating redundancy
across drivers.
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260801-reuse_common_geni_framework_helpers-v2-2-13753256ef71@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The UART driver maintains local helpers for resource and power-domain
initialisation that duplicate functionality already provided by the common
GENI framework.
Replace the driver-specific implementations with geni_se_resources_init()
and geni_se_domain_attach(), and use the power-domain list stored in
struct geni_se. This reduces code duplication and centralises GENI resource
management without functional changes.
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260801-reuse_common_geni_framework_helpers-v2-1-13753256ef71@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pl011_console_write_atomic() runs from nbcon atomic context, where
sleeping is not allowed. It calls clk_enable(), which takes the common-clk
enable_lock. Under PREEMPT_RT that is a sleeping lock:
clk_enable_lock() first tries spin_trylock_irqsave(), but on contention
falls back to spin_lock_irqsave(). Therefore, an atomic-context printk on
an RT kernel with a clk-backed pl011 can trip:
BUG: sleeping function called from invalid context at spinlock_rt.c:48
__might_resched from rt_spin_lock
rt_spin_lock from clk_enable_lock
clk_enable_lock from clk_enable
clk_enable from pl011_console_write_atomic
... from vprintk_emit
This was found and reproduced on PREEMPT_RT. Arm32 and arm64 DT SoCs are
affected; arm64 SBSA/ACPI has no clk, so clk_enable(NULL) short-circuits
before the lock. In addition, write_atomic() may be invoked from NMI
context and is documented to avoid locking. Removing clk_enable() from
the callback also avoids a potentially unsafe NMI acquisition of the
common-clock enable_lock.
An nbcon atomic-capable console must be printable from any context, so
the clock cannot be gated between writes. Enable the clock while the
console is available for output: use clk_prepare_enable() in
pl011_console_setup(), release it via clk_disable_unprepare() in the
console .exit() callback, and drop the per-write clk_enable()/clk_disable()
pairs from write_atomic() and write_thread().
When printk suspends consoles, drop the reference after
uart_suspend_port() stops console access and restore it before
uart_resume_port() -- but only if suspend actually marked the port
suspended (a wake-capable tty stays running and must keep its clock), and
keep it when console_suspend_enabled is false so no_console_suspend works.
The active power cost of keeping the clock enabled is platform-dependent:
none where the UART clock is a fixed always-on oscillator, real where it
is a gateable clock branch, which then cannot be gated (nor possibly can
its parent clocks) while the console is available for output. When serial
core actually suspends the port, the reference is released so the clock
provider can gate the clock tree.
Fixes: 2eb2608618 ("serial: amba-pl011: Implement nbcon console")
Suggested-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/all/8733xeaxix.fsf@jogness.linutronix.de/
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Link: https://patch.msgid.link/20260724213348.77418-3-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pl011_console_setup() calls clk_prepare() on the UART clock, but the
console provides no matching teardown, so the clock is never unprepared
when the console is unregistered -- via the sysfs "console" attribute or
a driver unbind. Each re-registration prepares the clock again, leaking
one prepare reference per cycle.
Even where preparing the clock has no hardware effect, the stale
reference leaves the clock framework's prepare count unbalanced. For
providers with prepare/unprepare operations or runtime-PM integration,
it may also retain resources after the console is unregistered.
Add a console .exit() callback that clk_unprepare()s the clock,
balancing the clk_prepare() in pl011_console_setup().
Fixes: 4b4851c65d ("clk: amba-pl011: convert to clk_prepare()/clk_unprepare()")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Link: https://patch.msgid.link/20260724213348.77418-2-kmehltretter@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Genio board DTs provide serial aliases for all enabled UARTs, but
the MTK 8250 driver still registered every port with the default line
number. If uart0 deferred and another UART probed first, the 8250 core
could still assign ttyS0 to the wrong port despite the DT aliases.
Read the serial alias during OF probe and seed uart.port.line before
registering the port so the 8250 core reserves the requested ttyS slot.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://patch.msgid.link/20260727-ccaione-genio-serial-aliases-v2-2-0f2ae41a8e89@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dmaengine_terminate_all() does not wait for a running callback, so the TX
callback can still touch the TX buffer after it is freed. The RX poll
timer reads the RX buffers without the port lock.
Switch to dmaengine_terminate_sync() and delete the RX timer before
freeing the buffers.
Fixes: ead76f329f ("ARM: 6763/1: pl011: add optional RX DMA to PL011 v2")
Cc: stable <stable@kernel.org>
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260731085915.326775-4-fanwu01@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The RS485 trigger hrtimers are embedded in the devm-managed port and can
fire after it is freed. The IRQ handler can arm a timer, so free the IRQ
first and then cancel both timers.
Complete the RS485 stop without arming a timer, and cancel the timers
in remove() for the suspend-then-unbind path, where shutdown is not
called.
This issue was found by an in-house static analysis tool.
Fixes: 2c1fd53af2 ("serial: amba-pl011: Fix RTS handling in RS485 mode")
Cc: stable <stable@kernel.org>
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260731085915.326775-3-fanwu01@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The RS485 stop hrtimer is used both to drain the transmitter and to wait
out delay_rts_after_send. The callback cannot tell the two apart, so it
restarts the post-send delay on every expiry and the timer never stops.
Add a WAIT_AFTER_SEND_DELAY state so its expiry ends the stop sequence
instead of restarting the delay.
Fixes: 2c1fd53af2 ("serial: amba-pl011: Fix RTS handling in RS485 mode")
Cc: stable <stable@kernel.org>
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260731085915.326775-2-fanwu01@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout
interrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT
(0x0c) but LSR.DR is clear. A character timeout is only cleared by
reading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is
set, so nothing ever clears the condition. The interrupt is
level-triggered and re-fires immediately, so on a single-core ARM926
the resulting interrupt storm livelocks the CPU.
It is reproducible when userspace repeatedly opens the front-panel port
(ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and
the handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping
the soft-lockup detector in serial8250_handle_irq_locked().
LPC32xx has no dedicated 8250 glue driver, it's driven by the generic
8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up
in of_platform_serial_setup() the same way fsl8250_handle_irq is
installed. The handler follows dw8250_handle_irq(): on an RX timeout
with an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR
read to clear the condition, then calls serial8250_handle_irq_locked().
No real received data is ever discarded, and it is a no-op on healthy
UARTs which never report a timeout with DR clear.
This is the same class of bug already worked around in other 8250 drivers;
see commit 424d79183a ("serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt")
which reports the identical iir=0xcc/lsr=0x60. See also
UART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271.
Cc: stable <stable@kernel.org>
Assisted-by: Claude:Opus4.8
Signed-off-by: Ryan Wilbur <rwilbur633@gmail.com>
Link: https://patch.msgid.link/20260730193920.28954-1-rwilbur633@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The GENI main sequencer handles console TX while the secondary sequencer
handles FIFO RX. Before nbcon, the legacy console writer disabled both
interrupt domains while it performed a long polled M-side transfer. This
left the small S-side FIFO unserviced, allowing console input to overrun
and be lost.
The nbcon conversion replaces IRQ masking with the UART port lock, but a
threaded console write still prevents the RX handler from draining the
FIFO. Keep S-side RX enabled independently of M-side TX and drain it
while refilling each bounded console command. This preserves interactive
input during console output.
Atomic output masks only M-side TX state, leaving FIFO RX handling
independent. The threaded writer can also detect a SysRq character while
it drains RX, so defer delivery until device_unlock() drops the UART port
lock, as the existing IRQ path does with uart_unlock_and_check_sysrq().
Assisted-by: OpenCode:GPT-5.5
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
Link: https://patch.msgid.link/20260729-qcom-geni-nbcon-v1-2-3053b96465ed@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The legacy GENI console writer serializes every message around a
synchronous polled M-side transfer. It blocks printk callers for UART
wire time and cannot provide atomic output while normal console output is
active.
Convert the console to nbcon threaded and atomic writers. Use the UART
port lock as the device lock and bound threaded M-side commands so
urgent diagnostics can take over atomic output. The threaded writer is
batching the output in 32-source-byte commands, a value chosen to
balance the command setup overhead with atomic-handoff latency.
Atomic output can cancel an active normal TX command. Use irq_work to
resume queued TTY output afterward, honor flow control, and prevent the
deferred restart from accessing the port during shutdown or removal.
Assisted-by: OpenCode:GPT-5.5
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
Link: https://patch.msgid.link/20260729-qcom-geni-nbcon-v1-1-3053b96465ed@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver currently relies on qcom_geni_serial_pm() through the
uart_ops.pm callback to manage runtime PM references. However, the
callback has a void return type, so failures from
pm_runtime_resume_and_get() cannot be propagated to the caller.
As a result, startup() may continue and access hardware even when the
runtime PM resume operation failed, leading to register accesses while
the device is not powered.
Move runtime PM acquisition to qcom_geni_serial_startup() and release it
to qcom_geni_serial_shutdown(). Since startup() can return an error, PM
resume failures are now detected and propagated before any hardware
initialization is performed. The startup/shutdown pair also provides a
natural place to balance runtime PM references for normal port usage.
During probe, uart_add_one_port() may configure the port before any user
opens the TTY, meaning startup() has not yet been called. To keep the
hardware powered during port registration, acquire a runtime PM
reference with pm_runtime_resume_and_get() before uart_add_one_port()
and release it with pm_runtime_put() afterwards.
By moving runtime PM handling out of uart_ops.pm, resume failures are no
longer silently ignored and all hardware accesses are guaranteed to
occur while the device is powered.
Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260720-remove_uart_change_state-v2-1-30153ce4333b@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This driver doesn't really need to split the registration of the GPIO
chip into stages, as platform_device_info already provides fields for
the firmware node, parent device and the software node. Use
platform_device_register_full() and simplify the code. This also
addresses the problem with incorrect reference count of the assigned
firmware node.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260728-exar-pdev-reg-full-v1-1-7a96e77309e1@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Coccinelle warns about missing clk_put on the error path after clk_get,
but the error path returns with an ERR_PTR where clk_put must not be
called. Restructure into a single if block so the logic is clear to
silence false positive coccinelle warning.
Commit 580d952e44 ("tty: serial: bcm63xx: fix missing clk_put() in
bcm63xx_uart") previously tried to fix this same warning by adding a
clk_put, which was reverted because it was wrong.
Prevent anyone from making the same mistake again.
Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Link: https://patch.msgid.link/604886147edb67c3ed85b192eb3f7a4a6dd0f0ac.1784788388.git.xiaopei01@kylinos.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The minimum baud rate supported by this driver is 0, so even for the B0
case, uart_get_baud_rate() will return 9600, not zero. This check is no
longer necessary since commit 16ae2a877b ("serial: Fix crash if the
minimum rate of the device is > 9600 baud") so remove it.
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://patch.msgid.link/20260720193411.3517484-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The minimum baud rate supported by this driver is 0, so even for the B0
case, uart_get_baud_rate() will return 9600, not zero. This check is no
longer necessary since commit 16ae2a877b ("serial: Fix crash if the
minimum rate of the device is > 9600 baud") so remove it.
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://patch.msgid.link/20260720195147.3630241-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 3d9e6f556e.
The 8250 driver no longer depends on @oops_in_progress and
will no longer violate the port->lock locking constraints.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://patch.msgid.link/20260729120439.281252-3-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Implement the necessary callbacks to switch the 8250 console driver
to perform as an nbcon console.
Add implementations for the nbcon console callbacks:
->write_atomic()
->write_thread()
->device_lock()
->device_unlock()
and add CON_NBCON to the initial @flags.
All hardware access in the callbacks is within unsafe sections.
The ->write_atomic() and ->write_thread() callbacks allow safe
handover/takeover per byte and add a preceding newline if they
take over from another context mid-line.
For the ->write_atomic() callback, a new irq_work is used to defer
modem control since it may be called from a context that does not
allow waking up tasks. During suspend/resume the irq_work is not
used as this has been shown to cause suspend problems for some
hardware. Upon resume, any pending modem control is performed.
Note: A new __serial8250_clear_IER() is introduced for direct
clearing of UART_IER during console writing (which will not be
holding the port lock for atomic printing or KDB/KGDB). This
allows restoring a lockdep check to serial8250_clear_IER() in
a follow-up commit.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20260729120439.281252-2-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The inclusion of <linux/kconfig.h> in commit 7ab80d1e72 ("serial: 8250:
fix compile error with hub6_match_port() when compiled as a module") is
unneeded as it's guaranteed by the build starting from commit 2a11c8ea20
("kconfig: Introduce IS_ENABLED(), IS_BUILTIN() and IS_MODULE()").
Remove it here.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260721144847.3728422-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The inclusion of <linux/kconfig.h> in commit f18643843b ("serial:
max310x: fix compile errors if CONFIG_SPI_MASTER is disabled") is
unneeded as it's guaranteed by the build starting from the commit
2a11c8ea20 ("kconfig: Introduce IS_ENABLED(), IS_BUILTIN() and
IS_MODULE()"). Remove it here.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260721144420.3727708-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When transmit flushing a qcom-geni UART during an ongoing TX DMA, the
UART gets stuck infinitely repeating corrupted TX DMA frames.
The DMA-mode uart_ops does not provide a flush_buffer callback, so an
in-flight transfer can complete after serial core has reset the transmit
kfifo, underflowing its length and resubmitting page-sized transfers
indefinitely. Add one that stops the transfer and clears tx_remaining
and tx_queued.
The stop path was also broken: it unmapped the buffer while the serial
engine could still read it, and never reset the TX DMA state machine.
Cancel the main sequencer command first, then reset the state machine
and wait for it before unmapping. Drop the early return so a pending
mapping is also cleaned up when the main command is inactive.
The bug can be triggered from userspace with a large write immediately
followed by TCOFLUSH. A following tcdrain will hang forever. The bug was
reproduced and this fix was validated on Arduino Uno Q (QRB2210)
using /dev/ttyHS1.
Assisted-by: Claude:claude-5-opus Codex:gpt-5
Signed-off-by: Jan Sebastian Götte <linux@jaseg.de>
Fixes: 2aaa43c707 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Cc: stable <stable@kernel.org>
Reviewed-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
Link: https://patch.msgid.link/20260729174105.21838-2-git@jaseg.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial8250_release_dma() terminates RX DMA and releases the channel, but
leaves rx_running set. If the port is closed while an RX transfer is
active, the stale state remains while rxchan is NULL until the channel is
requested again on the next open.
The DesignWare BUSY workaround added by commit a7b9ce39fb
("serial: 8250_dw: Ensure BUSY is deasserted") calls
serial8250_rx_dma_flush() from the LCR write path during startup. This
happens before serial8250_request_dma() obtains a new RX channel. On
reopen, the stale rx_running state therefore makes the flush path pass a
NULL channel to dmaengine_pause(), causing a kernel Oops.
Clear rx_running after terminating RX DMA, matching the TX cleanup. Also
make the flush helper return if the DMA object or RX channel is not
available so startup and teardown paths cannot pass a NULL channel to the
DMAengine API.
Fixes: 0fcb7901f9 ("tty: serial: 8250_dma: keep own book keeping about RX transfers")
Cc: stable <stable@kernel.org>
Signed-off-by: Cunhao Lu <1579567540@qq.com>
Link: https://patch.msgid.link/tencent_9EE2945F4C933B4D810C73C2D7485E000F06@qq.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sc16is7xx_handle_tx() currently requests the THRI enable only after it has
filled the TX FIFO. The request is asynchronous because the IER update is
performed later by reg_work.
The SC16IS7xx generates a THRI interrupt when the TX FIFO crosses its
trigger level. If the FIFO drains past that level before reg_work enables
THRI, the chip does not generate a new interrupt. Characters remain queued
indefinitely even though the hardware FIFO is empty.
This was observed on an SC16IS752 while both UART channels were active.
During the stall the software TX buffer remained non-empty while TXLVL
reported 64 bytes free, LSR reported THR and transmitter empty, IER had
THRI enabled, and IIR reported no interrupt pending.
Enable THRI synchronously before filling the FIFO so the threshold crossing
cannot be missed.
Fixes: cc4c1d05eb ("sc16is7xx: Properly resume TX after stop")
Cc: stable <stable@kernel.org>
Signed-off-by: Luca Fresi <luca.fresi@bithiatec.com>
Link: https://patch.msgid.link/20260721222404.204746-1-luca.fresi@bithiatec.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit d338ab1d90.
uart_console() only indicates that the port is selected as the console.
It does not mean that the console has already been registered or has
printed the buffered messages.
On platforms where an initial 8250 port is replaced when the real UART
device is registered, clearing CON_PRINTBUFFER causes the console to
start at the end of the printk ring buffer. Without earlycon, all
messages logged before UART registration are therefore lost.
Fixes: d338ab1d90 ("serial: 8250: Clear CON_PRINTBUFFER on port re-registration")
Reported-by: Mark Brown <broonie@kernel.org>
Reported-by: Anirudh Srinivasan <asrinivasan@oss.tenstorrent.com>
Link: https://lore.kernel.org/all/20260522101042.21976-1-fushuai.wang@linux.dev/
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20260724093151.53216-1-fushuai.wang@linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It's strongly recommended for GPIO drivers to always implement the
.get_direction() callback - even when the direction is tracked in
software. The GPIO core emits a warning when the callback is missing
and a user reads the direction of a line, e.g. via
/sys/kernel/debug/gpio.
Fixes: dfeae619d7 ("serial: sc16is7xx")
Cc: stable <stable@kernel.org>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260716210813.2582826-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
