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The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.\"
.\" Copyright (c) 2003 Marcel Moolenaar
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
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
2016-01-12 18:42:00 +00:00
.Dd December 9, 2015
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.Dt UART 4
.Os
.Sh NAME
.Nm uart
.Nd driver for Universal Asynchronous Receiver/Transmitter (UART) devices
.Sh SYNOPSIS
.Cd "device uart"
.Pp
.Cd "device puc"
.Cd "device uart"
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
.Pp
.Cd "device scc"
.Cd "device uart"
document device hints including new ones to control rx fifo trigger MFC after: 2 weeks
2008-03-12 19:09:58 +00:00
.Pp
In
.Pa /boot/device.hints :
.Cd hint.uart.0.disabled="1"
.Cd hint.uart.0.baud="38400"
.Cd hint.uart.0.port="0x3f8"
.Cd hint.uart.0.flags="0x10"
.Pp
With
.Ar flags
encoded as:
.Bl -tag -compact -width 0x000000
.It 0x00010
device is potential system console
.It 0x00080
use this port for remote kernel debugging
.It 0x00100
set RX FIFO trigger level to ``low'' (NS8250 only)
.It 0x00200
set RX FIFO trigger level to ``medium low'' (NS8250 only)
.It 0x00400
set RX FIFO trigger level to ``medium high'' (default, NS8250 only)
.It 0x00800
set RX FIFO trigger level to ``high'' (NS8250 only)
.El
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.\"
.Sh DESCRIPTION
The
.Nm
device driver provides support for various classes of UARTs implementing the
EIA RS-232C (CCITT V.24) serial communications interface.
Spelling fixes.
2004-06-21 17:42:49 +00:00
Each such interface is controlled by a separate and independent instance of
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
the
.Nm
driver.
The primary support for devices that contain multiple serial interfaces or
that contain other functionality besides one or more serial interfaces is
provided by the
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
.Xr puc 4 ,
or
.Xr scc 4
device drivers.
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
However, the serial interfaces of those devices that are managed by the
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
.Xr puc 4 ,
or
.Xr scc 4
driver are each independently controlled by the
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.Nm
driver.
As such, the
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
.Xr puc 4 ,
or
.Xr scc 4
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
driver provides umbrella functionality for the
.Nm
driver and hides the complexities that are inherent when elementary components
are packaged together.
.Pp
The
.Nm
driver has a modular design to allow it to be used on differing hardware and
for various purposes.
In the following sections the components are discussed in detail.
Options are described in the section that covers the component to which each
option applies.
.\"
.Ss CORE COMPONENT
At the heart of the
.Nm
Mdoc Review: * Remove extraneous .Pp in SYNOPSIS * Remove hard sentence break * Add the AUTHORS section
2003-09-06 23:46:29 +00:00
driver is the core component.
It contains the bus attachments and the low-level interrupt handler.
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.\"
.Ss HARDWARE DRIVERS
The core component and the kernel interfaces talk to the hardware through the
hardware interface.
This interface serves as an abstraction of the hardware and allows varying
UARTs to be used for serial communications.
.\"
.Ss SYSTEM DEVICES
System devices are UARTs that have a special purpose by way of hardware
design or software setup.
For example, Sun UltraSparc machines use UARTs as their keyboard interface.
Such an UART cannot be used for general purpose communications.
Likewise, when the kernel is configured for a serial console, the
corresponding UART will in turn be a system device so that the kernel can
output boot messages early on in the boot process.
.\"
.Ss KERNEL INTERFACES
The last but not least of the components is the kernel interface.
This component ultimately determines how the UART is made visible to the
kernel in particular and to users in general.
The default kernel interface is the TTY interface.
This allows the UART to be used for terminals, modems and serial line IP
applications.
System devices, with the notable exception of serial consoles, generally
have specialized kernel interfaces.
.\"
Add a HARDWARE section, required for autogeneration of the release notes. MFC after: 3 days
2006-02-07 03:27:06 +00:00
.Sh HARDWARE
The
.Nm
driver supports the following classes of UARTs:
.Pp
.Bl -bullet -compact
.It
NS8250: standard hardware based on the 8250, 16450, 16550, 16650, 16750 or
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
the 16950 UARTs.
Add a HARDWARE section, required for autogeneration of the release notes. MFC after: 3 days
2006-02-07 03:27:06 +00:00
.It
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
SCC: serial communications controllers supported by the
.Xr scc 4
device driver.
Add a HARDWARE section, required for autogeneration of the release notes. MFC after: 3 days
2006-02-07 03:27:06 +00:00
.El
.\"
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
2015-08-10 20:08:09 +00:00
.Sh Pulse Per Second (PPS) Timing Interface
The
.Nm
driver can capture PPS timing information as defined in RFC 2783.
The API, accessed via
ioctl(8) -> ioctl(2) MFC after: 1 month Sponsored by: The FreeBSD Foundation
2016-02-29 17:37:35 +00:00
.Xr ioctl 2 ,
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
2015-08-10 20:08:09 +00:00
is available on the tty device.
To use the PPS capture feature with
.Xr ntpd 8 ,
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
2016-01-12 18:42:00 +00:00
symlink the tty callout device
.Va /dev/cuau?
to
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
2015-08-10 20:08:09 +00:00
.Va /dev/pps0.
.Pp
The
.Va hw.uart.pps_mode
tunable configures the PPS capture mode for all uart devices;
it can be set in
.Xr loader.conf 5 .
The
.Va dev.uart.0.pps_mode
sysctl configures the PPS capture mode for a specific uart device;
it can be set in
.Xr loader.conf 5
or
.Xr sysctl.conf 5 .
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
2016-01-12 18:42:00 +00:00
.Pp
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
2015-08-10 20:08:09 +00:00
The following capture modes are available:
.Bl -tag -compact -offset "mmmm" -width "mmmm"
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
2016-01-12 18:42:00 +00:00
.It 0x00
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
2015-08-10 20:08:09 +00:00
Capture disabled.
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
2016-01-12 18:42:00 +00:00
.It 0x01
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
2015-08-10 20:08:09 +00:00
Capture pulses on the CTS line.
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
2016-01-12 18:42:00 +00:00
.It 0x02
Capture pulses on the DCD line.
.El
.Pp
Fix minor problems caught by mandoc -Tlint.
2016-03-31 15:16:22 +00:00
The following values may be ORed with the capture mode to configure
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
2016-01-12 18:42:00 +00:00
capture processing options:
.Bl -tag -compact -offset "mmmm" -width "mmmm"
.It 0x10
Invert the pulse (RS-232 logic low = ASSERT, high = CLEAR).
.It 0x20
Attempt to capture narrow pulses.
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
2015-08-10 20:08:09 +00:00
.El
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
2016-01-12 18:42:00 +00:00
.Pp
Add the narrow pulse option when the incoming PPS pulse width is small
enough to prevent reliable capture in normal mode.
In narrow mode the driver uses the hardware's ability to latch a line
state change; not all hardware has this capability.
The hardware latch provides a reliable indication that a pulse occurred,
but prevents distinguishing between the CLEAR and ASSERT edges of the pulse.
For each detected pulse, the driver synthesizes both an ASSERT and a CLEAR
event, using the same timestamp for each.
To prevent spurious events when the hardware is intermittently able to
see both edges of a pulse, the driver will not generate a new pair of
events within a half second of the prior pair.
Both normal and narrow pulse modes work with
.Xr ntpd 8 .
.Pp
Add the invert option when the connection to the uart device uses TTL
level signals, or when the PPS source emits inverted pulses.
RFC 2783 defines an ASSERT event as a higher-voltage line level, and a CLEAR
event as a lower-voltage line level, in the context of the RS-232 protocol.
The modem control signals on a TTL-level connection are typically
inverted from the RS-232 levels.
For example, carrier presence is indicated by a high signal on an RS-232
DCD line, and by a low signal on a TTL DCD line.
This is due to the use of inverting line driver buffers to convert between
TTL and RS-232 line levels in most hardware designs.
Generally speaking, a connection to a DB-9 style connector is an RS-232
level signal at up to 12 volts.
A connection to header pins or an edge-connector on an embedded board
is typically a TTL signal at 3.3 or 5 volts.
document the tty files that uart(4) provides like sio(4) and pty(4) both do.. This copies only part of the FILES section from sio(4).... We might want to make tty(4) document the files provided, and have each of these document the characters that it uses... Pointed out by: Yasholomew Yashinski MFC after: 3 days
2006-03-30 02:27:25 +00:00
.Sh FILES
Markup fixes.
2006-09-18 15:24:20 +00:00
.Bl -tag -width ".Pa /dev/ttyu?.init" -compact
document the tty files that uart(4) provides like sio(4) and pty(4) both do.. This copies only part of the FILES section from sio(4).... We might want to make tty(4) document the files provided, and have each of these document the characters that it uses... Pointed out by: Yasholomew Yashinski MFC after: 3 days
2006-03-30 02:27:25 +00:00
.It Pa /dev/ttyu?
for callin ports
.It Pa /dev/ttyu?.init
.It Pa /dev/ttyu?.lock
corresponding callin initial-state and lock-state devices
.Pp
.It Pa /dev/cuau?
for callout ports
.It Pa /dev/cuau?.init
.It Pa /dev/cuau?.lock
corresponding callout initial-state and lock-state devices
.El
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.Sh SEE ALSO
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
.Xr puc 4 ,
.Xr scc 4
The uart(4) driver is an universal driver for various UART hardware. It improves on sio(4) in the following areas: o Fully newbusified to allow for memory mapped I/O. This is a must for ia64 and sparc64, o Machine dependent code to take full advantage of machine and firm- ware specific ways to define serial consoles and/or debug ports. o Hardware abstraction layer to allow the driver to be used with various UARTs, such as the well-known ns8250 family of UARTs, the Siemens sab82532 or the Zilog Z8530. This is especially important for pc98 and sparc64 where it's common to have different UARTs, o The notion of system devices to unkludge low-level consoles and remote gdb ports and provides the mechanics necessary to support the keyboard on sparc64 (which is UART based). o The notion of a kernel interface so that a UART can be tied to something other than the well-known TTY interface. This is needed on sparc64 to present the user with a device and ioctl handling suitable for a keyboard, but also allows us to cleanly hide an UART when used as a debug port. Following is a list of features and bugs/flaws specific to the ns8250 family of UARTs as compared to their support in sio(4): o The uart(4) driver determines the FIFO size and automaticly takes advantages of larger FIFOs and/or additional features. Note that since I don't have sufficient access to 16[679]5x UARTs, hardware flow control has not been enabled. This is almost trivial to do, provided one can test. The downside of this is that broken UARTs are more likely to not work correctly with uart(4). The need for tunables or knobs may be large enough to warrant their creation. o The uart(4) driver does not share the same bumpy history as sio(4) and will therefore not provide the necessary hooks, tweaks, quirks or work-arounds to deal with once common hardware. To that extend, uart(4) supports a subset of the UARTs that sio(4) supports. The question before us is whether the subset is sufficient for current hardware. o There is no support for multiport UARTs in uart(4). The decision behind this is that uart(4) deals with one EIA RS232-C interface. Packaging of multiple interfaces in a single chip or on a single expansion board is beyond the scope of uart(4) and is now mostly left for puc(4) to deal with. Lack of hardware made it impossible to actually implement such a dependency other than is present for the dual channel SAB82532 and Z8350 SCCs. The current list of missing features is: o No configuration capabilities. A set of tunables and sysctls is being worked out. There are likely not going to be any or much compile-time knobs. Such configuration does not fit well with current hardware. o No support for the PPS API. This is partly dependent on the ability to configure uart(4) and partly dependent on having sufficient information to implement it properly. As usual, the manpage is present but lacks the attention the software has gotten.
2003-09-06 23:13:47 +00:00
.\"
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 5.2 .
Mdoc Review: * Remove extraneous .Pp in SYNOPSIS * Remove hard sentence break * Add the AUTHORS section
2003-09-06 23:46:29 +00:00
.Sh AUTHORS
o Add scc(4) to the build. o Add the scc(4) manpage to the build. o Update the uart(4) manpage to account for scc(4). o Update the uart(4) module build to include support for scc(4).
2006-03-30 18:39:24 +00:00
The
.Nm
device driver and this manual page were written by
use .Mt to mark up email addresses consistently (final part) PR: 191174 Submitted by: Franco Fichtner <franco at lastsummer.de>
2014-06-26 21:46:14 +00:00
.An Marcel Moolenaar Aq Mt marcel@xcllnt.net .
Reference in New Issue Copy Permalink