add snps IP uart support / genaralize UART

This is an amalgam of a patch by Doug Ambrisko to
generalize uart_acpi_find_device, imp moving the
ACPI table to uart_dev_ns8250.c and advice by jhb
to wor

add snps IP uart support / genaralize UART

This is an amalgam of a patch by Doug Ambrisko to
generalize uart_acpi_find_device, imp moving the
ACPI table to uart_dev_ns8250.c and advice by jhb
to work around a bug in the EPYC 3151 BIOS
(the BIOS incorrectly marks the serial ports as
disabled)

Reviewed by: imp
MFC after: 8 weeks
Differential Revision: https://reviews.freebsd.org/D16432

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sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error

sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

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Allow setting access-width for UART registers.

This is required for FDT's standard "reg-io-width" property
(similar to "reg-shift" property) found in many DTS files.

This fixes operation on Altera

Allow setting access-width for UART registers.

This is required for FDT's standard "reg-io-width" property
(similar to "reg-shift" property) found in many DTS files.

This fixes operation on Altera Arria 10 SOC Development Kit,
where standard ns8250 uart allows 4-byte access only.

Reviewed by: kan, marcel
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9785

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Allow uart(4) to use MSI interrupts on single-port PCI instances.

Do this here as puc(4) disallows single-port instances; at least
one multi-port PCIe UART chip (in this case, the ASIX MCS9922)
pres

Allow uart(4) to use MSI interrupts on single-port PCI instances.

Do this here as puc(4) disallows single-port instances; at least
one multi-port PCIe UART chip (in this case, the ASIX MCS9922)
present separate PCI configuration space (functions) for each UART.

Tested using lrzsz and a null-modem cable. The ExpressCard/34
variants containing the MCS9922 should also use MSI with this change.

Reviewed by: jhb, imp, rpokala
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D9123

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Do not reallocate driver softc for uart unnecessarily.

Do not assume that all uart drivers use uart_softc structure as is.
Some do a sensible thing and do declare their uart class and driver
properl

Do not reallocate driver softc for uart unnecessarily.

Do not assume that all uart drivers use uart_softc structure as is.
Some do a sensible thing and do declare their uart class and driver
properly and arrive into uart_bus_attach with suitably sized softc.

Submitted by: kan
Sponsored by: DARPA, AFRL

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Fix UART PPS capture mode printing

* Add breaks to prevent fallthrough and printing of multiple modes.
* Only check the mode, mask out all other bits.

Restore uart PPS signal capture polarity to its historical norm, and add an
option to invert the polarity in software. Also add an option to capture
very narrow pulses by using the hardware's MSR del

Restore uart PPS signal capture polarity to its historical norm, and add an
option to invert the polarity in software. Also add an option to capture
very narrow pulses by using the hardware's MSR delta-bit capability of
latching line state changes.

This effectively reverts the mistake I made in r286595 which was based on
empirical measurements made on hardware using TTL-level signaling, in which
the logic levels are inverted from RS-232. Thus, this re-syncs the polarity
with the requirements of RFC 2783, which is writen in terms of RS-232
signaling.

Narrow-pulse mode uses the ability of most ns8250 and similar chips to
provide a delta indication in the modem status register. The hardware is
able to notice and latch the change when the pulse width is shorter than
interrupt latency, which results in the signal no longer being asserted by
time the interrupt service code runs. When running in this mode we get
notified only that "a pulse happened" so the driver synthesizes both an
ASSERT and a CLEAR event (with the same timestamp for each). When the pulse
width is about equal to the interrupt latency the driver may intermittantly
see both edges of the pulse. To prevent generating spurious events, the
driver implements a half-second lockout period after generating an event
before it will generate another.

Differential Revision: https://reviews.freebsd.org/D4477

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Use bus_alloc_resource_any(), rather than bus_alloc_resource()
with start 0 and end ~0. This avoids confusion WRT to what the
value of length can or should be.

Style fix, no functional changes -- do the braces for switches correctly.

Correct the polarity of the PPS assert and clear events with respect to the
electrical signals on the serial port. Virtually all devices which output a
PPS signal generate a brief higher-voltage pul

Correct the polarity of the PPS assert and clear events with respect to the
electrical signals on the serial port. Virtually all devices which output a
PPS signal generate a brief higher-voltage pulse, the leading edge of which
is the on-time point.

Both DCD and CTS are active-low signals on the wire, meaning the assertion
of their status bits in the modem status register corresponds to the lower
voltage level on the wire. So when the status bit transitions to not-set,
create a PPS assert event; when the status bit transitions to set, create a
PPS clear event.

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Allow the choice of PPS signal captured by uart(4) to be runtime-configured,
eliminating the need to build a custom kernel to use the CTS signal.

The historical UART_PPS_ON_CTS kernel option is stil

Allow the choice of PPS signal captured by uart(4) to be runtime-configured,
eliminating the need to build a custom kernel to use the CTS signal.

The historical UART_PPS_ON_CTS kernel option is still honored, but now it
can be overridden at runtime using a tunable to configure all uart devices
(hw.uart.pps_mode) or specific devices (dev.uart.#.pps_mode). The per-
device config is both a tunable and a writable sysctl.

This syncs the PPS capabilities of uart(4) with the enhancements recently
recently added to ucom(4) for capturing from USB serial devices.

Relnotes: yes

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Provide the tty-layer mutex when initializing the pps api. This allows
time_pps_fetch() to be used in blocking mode.

Also, don't init the pps api for system devices (consoles) that provide a
custom

Provide the tty-layer mutex when initializing the pps api. This allows
time_pps_fetch() to be used in blocking mode.

Also, don't init the pps api for system devices (consoles) that provide a
custom attach routine. The device may actually be a keyboard or other non-
tty device. If it wants to do pps processing (unlikely) it must handle
everything for itself. (In reality, only a sun keyboard uses a custom
attach routine, and it doesn't make a good pps device.)

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- Since r253161, uart_intr() abuses FILTER_SCHEDULE_THREAD for signaling
uart_bus_attach() during its test that 20 iterations weren't sufficient
for clearing all pending interrupts, assuming this

- Since r253161, uart_intr() abuses FILTER_SCHEDULE_THREAD for signaling
uart_bus_attach() during its test that 20 iterations weren't sufficient
for clearing all pending interrupts, assuming this means that hardware
is broken and doesn't deassert interrupts. However, under pressure, 20
iterations also can be insufficient for clearing all pending interrupts,
leading to a panic as intr_event_handle() tries to schedule an interrupt
handler not registered. Solve this by introducing a flag that is set in
test mode and otherwise restores pre-r253161 behavior of uart_intr(). The
approach of additionally registering uart_intr() as handler as suggested
in PR 194979 is not taken as that in turn would abuse special pccard and
pccbb handling code of intr_event_handle(). [1]
- Const'ify uart_driver_name.
- Fix some minor style bugs.

PR: 194979 [1]
Reviewed by: marcel (earlier version)
MFC after: 3 days

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If uart interrupts are not functioning then schedule the callout to do the
polling at device attach time [1].

Add tunables 'debug.uart_force_poll' and 'debug.uart_poll_freq' to control
uart polling.

If uart interrupts are not functioning then schedule the callout to do the
polling at device attach time [1].

Add tunables 'debug.uart_force_poll' and 'debug.uart_poll_freq' to control
uart polling.

Submitted by: Aleksey Kuleshov ([email protected]) [1]

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Add support for the uart classes to set their default register shift value.
This is needed with the pl011 driver. Before this change it would default
to a shift of 0, however the hardware places the

Add support for the uart classes to set their default register shift value.
This is needed with the pl011 driver. Before this change it would default
to a shift of 0, however the hardware places the registers at 4-byte
addresses meaning the value should be 2.

This patch fixes this for the pl011 when configured using the fdt. The
other drivers have a default value of 0 to keep this a no-op.

MFC after: 1 week

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Back out r262921. I don't know what I was thinking, but it is lame.

Set the baud rate if it isn't 0 (meaning it has been specified) not
only if it is 0 (meaning that it hasn't been specified and is likely
to turn off the UART's transmitter).

Don't lock in the generic grab just to lock again in the specific grabs.
(I committed the wrong version of uart_core.c, which still had this).

Pointy hat: imp

Introduce grab and ungrab upcalls. When the kernel desires to grab the
console, it calls the grab functions. These functions should turn off
the RX interrupts, and any others that interfere. This mak

Introduce grab and ungrab upcalls. When the kernel desires to grab the
console, it calls the grab functions. These functions should turn off
the RX interrupts, and any others that interfere. This makes mountroot
prompt work again. If there's more generalized need other than
prompting, many of these routines should be expanded to do those new
things.

Should have been part of r260889, but waasn't due to command line typo.

Reviewed by: bde (with reservations)

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Allow UART_POLL_FREQ to be set as a kernel option as well as via tunable
(the code was already set up for this, just needs to be in conf/options).

Also, if reporting that polling is being used, repo

Allow UART_POLL_FREQ to be set as a kernel option as well as via tunable
(the code was already set up for this, just needs to be in conf/options).

Also, if reporting that polling is being used, report the frequency too.

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Protect against broken hardware. In this particular case, protect against
H/W not de-asserting the interrupt at all. On x86, and because of the
following conditions, this results in a hard hang with

Protect against broken hardware. In this particular case, protect against
H/W not de-asserting the interrupt at all. On x86, and because of the
following conditions, this results in a hard hang with interrupts disabled:
1. The uart(4) driver uses a spin lock to protect against concurrent
access to the H/W. Spin locks disable and restore interrupts.
2. Restoring the interrupt on x86 always writes the flags register. Even
if we're restoring the interrupt from disabled to disabled.
3. The x86 CPU has a short window in which interrupts are enabled when the
flags register is written.
4. The uart(4) driver registers a fast interrupt by default.

To catch this case, we first try to clear any pending H/W interrupts and in
particular, before setting up the interrupt. This makes sure the interrupt
is masked on the PIC. The interrupt handler now has a limit set on the
number of iterations it'll go through to clear interrupt conditions. If the
limit is hit, the handler will return FILTER_SCHEDULE_THREAD. The attach
function will check for this return code and avoid setting up the interrupt
and foce polling in that case.

Obtained from: Juniper Networks, Inc.

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Fix several typos

PR: kern/176054
Submitted by: Christoph Mallon <[email protected]>
MFC after: 3 days

Accommodate uart devices with large FIFOs (or DMA buffers which amount
to the same thing) by allocating the uart(4) rx buffer based on the
device's rxfifosz rather than using a hard-coded size of 384

Accommodate uart devices with large FIFOs (or DMA buffers which amount
to the same thing) by allocating the uart(4) rx buffer based on the
device's rxfifosz rather than using a hard-coded size of 384 bytes.

The historical 384 byte size is 3 times the largest hard-coded fifo
size in the tree, so use that ratio as a guide and allocate the buffer
as three times rxfifosz, but never smaller than the historical size.

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uart: add resume method and enable it for attachments on the most common
x86 buses

Otherwise the uart hardware could be in such a state after the resume
where IER is cleared and thus no interrupts a

uart: add resume method and enable it for attachments on the most common
x86 buses

Otherwise the uart hardware could be in such a state after the resume
where IER is cleared and thus no interrupts are generated.

This behavior is observed and tested with QEMU, so I am comitting this
change to help with my debugging.
There has been no feedback from users of serial ports on real hardware.

MFC after: 20 days

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MFC change 197721:
Fix RTS/CTS flow control, broken by the TTY overhaul. The new TTY
interface is fairly simple WRT dealing with flow control, but
needed 2 new RX buffer functions with "get-char-fro

MFC change 197721:
Fix RTS/CTS flow control, broken by the TTY overhaul. The new TTY
interface is fairly simple WRT dealing with flow control, but
needed 2 new RX buffer functions with "get-char-from-buf" separated
from "advance-buf-pointer" so that the pointer could be advanced
only when ttydisc_rint() succeeded.

Approved by: re (kib)

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