Commit Graph

23 Commits

Author SHA1 Message Date
Ian Lepore
fdfbb3f5b1 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
Ian Lepore
196d3019a8 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
Ian Lepore
b59236cece 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.)
2015-08-08 20:11:47 +00:00
Marius Strobl
86fb540033 - 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
2015-07-24 17:01:16 +00:00
Andrew Turner
405ada37fb 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
2015-04-11 17:16:23 +00:00
Andriy Gapon
5b23b1b9e7 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
2013-02-02 11:38:26 +00:00
Peter Grehan
332cda07c0 Complete polled-mode operation by using a callout if the device will be
used in polled-mode. The callout invokes uart_intr, which rearms the timeout.
Implemented for bhyve, but generically useful for e.g. embedded bringup
when the interrupt controller hasn't been setup, or if it's not deemed
worthy to wire an interrupt line from a serial port.

Submitted by:	neel
Reviewed by:	marcel
Obtained from:	NetApp
MFC after:	3 weeks
2012-04-12 18:46:48 +00:00
Marcel Moolenaar
0acb3c4aac 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.

MFC after:	1 week
2009-10-02 22:30:44 +00:00
Marcel Moolenaar
f8100ce2a7 Don't expose the uart_ops structure directly, but instead have
it obtained through the uart_class structure. This allows us
to declare the uart_class structure as weak and as such allows
us to reference it even when it's not compiled-in.
It also allows is to get the uart_ops structure by name, which
makes it possible to implement the dt tag handling in uart_getenv().
The side-effect of all this is that we're using the uart_class
structure more consistently which means that we now also have
access to the size of the bus space block needed by the hardware
when we map the bus space, eliminating any hardcoding.
2007-04-02 22:00:22 +00:00
Marcel Moolenaar
a31f91a061 Implement the ipend() method of the serdev I/F. 2006-04-28 18:29:23 +00:00
Marcel Moolenaar
8d1289fe6d Eliminate the sc_hasfifo flag from the softc. It was only used by
the NS8250 class driver. The UART has FIFOs if sc_rxfifosz>1, so
test for that instead.
While here properly initialize sc_rxfifosz and sc_txfifosz in the
case the UART doesn't have FIFOs.
2006-04-02 21:45:54 +00:00
Marcel Moolenaar
8af03381d8 Add support for scc(4). 2006-03-30 18:37:03 +00:00
Marcel Moolenaar
ea54941449 Replace our local UART_SIGMASK_* with the global SER_MASK_*. 2006-02-24 05:40:17 +00:00
Marcel Moolenaar
2d5118050a MFp4:
Stop using our local UART_IPEND_* and instead use the global SER_INT_*
as defined in <sys/serial.h>.
2006-02-24 02:42:26 +00:00
Warner Losh
098ca2bda9 Start each of the license/copyright comments with /*-, minor shuffle of lines 2005-01-06 01:43:34 +00:00
Marcel Moolenaar
54e2bcc7ad Add UART_IOCTL_BAUD to allow us to query the hardware about the
current baudrate setting. Use this ioctl() when we don't know the
baudrate of the sysdev (as represented by a 0 value). When the
ioctl() fails, e.g. when the backend hasn't implemented it or the
hardware doesn't provide the means to determine its current baudrate
setting, we invalidate the baudrate setting by setting it to -1.
None of the backends currently implement the new ioctl().
2004-11-14 23:12:14 +00:00
Poul-Henning Kamp
79a8d927d3 Use generic tty code instead of (comparatively little) local copies. 2004-10-12 08:22:31 +00:00
Poul-Henning Kamp
28710806cb Use the new serial port definitions for modemsignals. 2004-06-24 10:07:28 +00:00
Poul-Henning Kamp
89c9c53da0 Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.
2004-06-16 09:47:26 +00:00
Marcel Moolenaar
875f70dba4 Revert the introduction of iobase in struct uart_bas. Both the SAB82532
and the Z8530 drivers used the I/O address as a quick and dirty way to
determine which channel they operated on, but formalizing this by
introducing iobase is not a solution. How for example would a driver
know which channel it controls for a multi-channel UART that only has a
single I/O range?

Instead, add an explicit field, called chan, to struct uart_bas that
holds the channel within a device, or 0 otherwise. The chan field is
initialized both by the system device probing (i.e. a system console)
or it is passed down to uart_bus_probe() by any of the bus front-ends.
As such, it impacts all platforms and bus drivers and makes it a rather
large commit.

Remove the use of iobase in uart_cpu_eqres() for pc98. It is expected
that platforms have the capability to compare tag and handle pairs for
equality; as to determine whether two pairs access the same device or
not. The use of iobase for pc98 makes it impossible to formalize this
and turn it into a real newbus function later. This commit reverts
uart_cpu_eqres() for pc98 to an unimplemented function. It has to be
reimplemented using only the tag and handle fields in struct uart_bas.

Rewrite the SAB82532 and Z8530 drivers to use the chan field in struct
uart_bas. Remove the IS_CHANNEL_A and IS_CHANNEL_B macros. We don't
need to abstract anything anymore.

Discussed with: nyan
Tested on: i386, ia64, sparc64
2003-09-26 05:14:56 +00:00
Marcel Moolenaar
06287620b4 Add locking to the hardware drivers. I intended to figure out more
precisely where locking would be needed before adding it, but it
seems uart(4) draws slightly too much attention to have it without
locking for too long.
The lock added is a spinlock that protects access to the underlying
hardware. As a first and obvious stab at this, each method of the
hardware interface grabs the lock. Roughly speaking this serializes
the methods. Exceptions are the probe, attach and detach methods.
2003-09-17 01:41:21 +00:00
Marcel Moolenaar
8194412b89 Add support for using uart(4) for pulse capturing for the Pulse Per
Second (PPS) timing interface. The support is non-optional and by
default uses the DCD line signal as the pulse input. A compile-time
option (UART_PPS_ON_CTS) can be used to have uart(4) use the CTS line
signal.

Include <sys/timepps.h> in uart_bus.h to avoid having to add the
inclusion of that header in all source files.

Reviewed by: phk
2003-09-11 23:06:42 +00:00
Marcel Moolenaar
27d5dc189c 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