Document power-domains, operating-points-v2 and interconnects to allow
making performance state votes for certain clock frequencies of the UART
DM controller. The interconnect path to DRAM is needed when UART DM is
used together with a DMA engine.
Voting for these shared resources is necessary to guarantee performance
with power management enabled. Otherwise these resources might run at
minimal performance state which is not sufficient for certain UART
baud rates.
Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231128-serial-msm-dvfs-v1-1-4f290d20a4be@kernkonzept.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Refer ARM DDI 0487I.a ID081822, D17.3.8, DBGDTRTX_EL0,
"If TXfull is set to 1, set DTRRX and DTRTX to UNKNOWN"
Thus one should always check for TXfull condition before hvc can be
used as an early console. This is similar to what is being done
today in hvc_dcc_console_init() and hvc_dcc_init().
The count 0x4000000 has been obtained from uboot (v2024.01-rc3)
drivers/serial/arm_dcc.c "TIMEOUT_COUNT".
It reads the dcc status and waits for 0x4000000 times for the TX Fifo
to be available before returning an error. Thus, it will prevent DCC
to be used as early console.
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Link: https://lore.kernel.org/r/20231205123534.3376883-1-ayan.kumar.halder@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When using the serial port as RS485 port, the tx statemachine is used to
control the RTS pin to drive the RS485 transceiver TX_EN pin. When the
TTY port is closed in the middle of a transmission (for instance during
userland application crash), imx_uart_shutdown disables the interface
and disables the Transmission Complete interrupt. afer that,
imx_uart_stop_tx bails on an incomplete transmission, to be retriggered
by the TC interrupt. This interrupt is disabled and therefore the tx
statemachine never transitions out of SEND. The statemachine is in
deadlock now, and the TX_EN remains low, making the interface useless.
imx_uart_stop_tx now checks for incomplete transmission AND whether TC
interrupts are enabled before bailing to be retriggered. This makes sure
the state machine handling is reached, and is properly set to
WAIT_AFTER_SEND.
Fixes: cb1a609236 ("serial: imx: implement rts delaying for rs485")
Signed-off-by: Paul Geurts <paul_geurts@live.nl>
Tested-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Tested-by: Eberhard Stoll <eberhard.stoll@gmx.de>
Link: https://lore.kernel.org/r/AM0PR09MB26758F651BC1B742EB45775995B8A@AM0PR09MB2675.eurprd09.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Designware UART has an optional feature to enable Fractional Baud Rate
Divisor (DLF) through the FRACTIONAL_BAUD_DIVISOR_EN configuration
parameter, and it is not dependent on ADDITIONAL_FEATURES.
dw8250_setup_port() checks DLF to determine dlf_size only when UART
Component Version (UCV) is non-zero. As mentioned above DLF and UCV are
independent features. Move the logic corresponding to DLF size
calculation ahead of the UCV check to prevent early return. Otherwise,
dlf_size will be zero and driver will not be able to use the
controller's fractional baud rate divisor (DLF) feature.
Signed-off-by: Vamshi Gajjela <vamshigajjela@google.com>
Link: https://lore.kernel.org/r/20231126160420.2442330-1-vamshigajjela@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This means:
* move outbuf to the end of struct hvc_struct and convert from pointer
to flexible array (the structure is smaller now)
* use struct_size() at the allocation site
* align outbuf in the struct instead of ALIGN() at kzalloc()
And apart from the above, use u8 instead of char (which are the same
thanks to -funsigned-char). The former is now preferred over the latter.
It makes the code easier to understand.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20231121092258.9334-12-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_write_message() has only one user: quotas. In particular, there the
use depends on CONFIG_PRINT_QUOTA_WARNING. And that is deprecated and
marked as BROKEN already too.
So make tty_write_message() dependent on that very config option. This
action in fact drops tty_write_message() from the vmlinux binary. Good
riddance.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Jan Kara <jack@suse.com>
Acked-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231121092258.9334-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Let's move tty and serdev controller to be children of the serial core port
device. This way the runtime PM usage count of a child device propagates
to the serial hardware device.
The tty and serdev devices are associated with a specific serial port of
a serial hardware controller device, and we now have serial core hierarchy
of controllers and ports.
The tty device moves happily with just a change of the parent device and
update of device_find_child() handling. The serdev device init needs some
changes to separate the serial hardware controller device from the parent
device.
With this change the tty devices move under sysfs similar to this x86_64
qemu example of a diff of "find /sys -name ttyS*":
/sys/class/tty/ttyS0
/sys/class/tty/ttyS3
/sys/class/tty/ttyS1
-/sys/devices/pnp0/00:04/tty/ttyS0
-/sys/devices/platform/serial8250/tty/ttyS2
-/sys/devices/platform/serial8250/tty/ttyS3
-/sys/devices/platform/serial8250/tty/ttyS1
+/sys/devices/pnp0/00:04/00:04:0/00:04:0.0/tty/ttyS0
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.3/tty/ttyS3
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.1/tty/ttyS1
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.2/tty/ttyS2
If a serdev device is used instead of a tty, it moves in a similar way.
Suggested-by: Johan Hovold <johan@kernel.org>
Cc: Maximilian Luz <luzmaximilian@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20231113080758.30346-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This way we can do:
`echo _reisub > /proc/sysrq-trigger`
Instead of:
`for i in r e i s u b; do echo "$i" > /proc/sysrq-trigger; done;`
This can be very useful when trying to execute sysrq combo remotely
or from userspace. When sending keys in multiple separate writes,
userspace (eg. bash or ssh) can be killed before whole combo is completed.
Therefore putting all keys in single write is more robust approach.
Signed-off-by: Tomas Mudrunka <tomas.mudrunka@gmail.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231120111451.527952-1-tomas.mudrunka@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty/vt currently uses memdup_user() and vmemdup_array_user() to copy
userspace arrays.
Whereas there is no danger of overflowing, the call to vmemdup_user()
currently utilizes array_size() to calculate the array size
nevertheless. This is not useful because array_size() would return
SIZE_MAX and pass it to vmemdup_user() in case of (the impossible)
overflow.
string.h from the core-API now provides the wrappers memdup_array_user()
and vmemdup_array_user() to copy userspace arrays in a standardized
manner. Additionally, they also perform generic overflow-checks.
Use these wrappers to make it more obvious and readable that arrays are
being copied.
As we are at it, remove two unnecessary empty lines.
Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Link: https://lore.kernel.org/r/20231103111207.74621-2-pstanner@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With this current driver regmap implementation, it is hard to make sense
of the register addresses displayed using the regmap debugfs interface,
because they do not correspond to the actual register addresses documented
in the datasheet. For example, register 1 is displayed as registers 04 thru
07:
$ cat /sys/kernel/debug/regmap/spi0.0/registers
04: 10 -> Port 0, register offset 1
05: 10 -> Port 1, register offset 1
06: 00 -> Port 2, register offset 1 -> invalid
07: 00 -> port 3, register offset 1 -> invalid
...
The reason is that bits 0 and 1 of the register address correspond to the
channel (port) bits, so the register address itself starts at bit 2, and we
must 'mentally' shift each register address by 2 bits to get its real
address/offset.
Also, only channels 0 and 1 are supported by the chip, so channel mask
combinations of 10b and 11b are invalid, and the display of these
registers is useless.
This patch adds a separate regmap configuration for each port, similar to
what is done in the max310x driver, so that register addresses displayed
match the register addresses in the chip datasheet. Also, each port now has
its own debugfs entry.
Example with new regmap implementation:
$ cat /sys/kernel/debug/regmap/spi0.0-port0/registers
1: 10
2: 01
3: 00
...
$ cat /sys/kernel/debug/regmap/spi0.0-port1/registers
1: 10
2: 01
3: 00
As an added bonus, this also simplifies some operations (read/write/modify)
because it is no longer necessary to manually shift register addresses.
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231030211447.974779-1-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
