does not reliably prevent the triggering of interrupts for all supported
configurations. Thus, the FIFO size probe could cause an interrupt,
which could lead to an interrupt storm in the shared interrupt case.
To prevent this, change ns8250_bus_probe() to use the overflow bit in
the line status register instead of the RX ready bit in the interrupt
identification register to detect whether the FIFO has filled up.
This allows us to clear all bits in the interrupt enable register during
the probe, which should prevent interrupts reliably.
Additionally, the detected FIFO size may be a bit more accurate, because
the overflow bit is only set when the FIFO did actually fill up, while
interrupts would trigger a bit early.
Reviewed and tested on a lot of hardware by: marcel
not as a pending interrupt status, but as a matter of status quo.
Consequently, when there's no data to be transmitted the condition
is not cleared and uart_intr() is stuck in an infinite loop trying
to clear the UART_IPEND_TXIDLE status.
The z8530_bus_ipend() function is changed to return idle only once
after having sent any data.
The root cause for this problem is that we cannot use the interrupt
status bits of the SCC itself. The register that holds the interrupt
status can only be accessed by channel A and holds the status for
both channels. Using the interrupt status register would complicate
the driver because we need to synchronize access to the SCC between
the channels.
Elementary testing: marius
"... uart_cpu_sparc64.c currently only looks at /options if ttyX is
the selected console. However, there's one case where it should
additionally look at /chosen. If "keyboard" is the selected input-
device and "screen" the output-device (both via /options) but the
keyboard is unplugged, OF automatically switches to ttya for the
console. It even prints a line telling so on "screen". Solaris
respects this behaviour and uses ttya as the console in this case
and people probably expect FreeBSD to do the same (it's also very
handy to temporarily switch consoles)..."
Submitted by: Marius Strobl <marius@alchemy.franken.de>
Has no doubt the change is correct: marcel
of UARTs. We already did this in uart_cpu_getdev().
While here, also check the compat name for "su" or "su16550".
Both changes submitted by: Marius Strobl <marius@alchemy.franken.de>
Does not doubt the correctness of the second change: marcel
to select a serial console and debug port (resp). On ia64 these replace
the use of hints completely and take precedence over hints on alpha,
amd64 and i386. On sparc64 these variables are not yet recognised.
The reasons for introducing these variables are:
1. Hints have side-effects. They reserve the unit number for use by
isa or acpi devices and therefore cannot be used to select a pci
device. Also, the use of a unit number to select a device prior
to bus enumeration is nonsense. The new variables have no side-
effects and are not based on unit numbers.
2. Hints don't have the expression power to allow the sysadmin to
select UARTs that are not legacy PC devices and need the support
of compile-time constants to give the sysadmin some level of
flexibility.
The hw.uart.console and hw.uart.dbgport variables specify a list of
attributes. An attribute is a tag-value pair, seperated by a colon.
Attributes are seperated by a comma. Where possible, tags are the
same as those in /etc/remote (only br and pa in practice). Details
can be found in the manpage (not part of this commit).
Not tested on: amd64, pc98
Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.
Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.
Add missing D_TTY flags to various drivers.
Complete asserts that dev_t's passed to ttyread(), ttywrite(),
ttypoll() and ttykqwrite() have (d_flags & D_TTY) and a struct tty
pointer.
Make ttyread(), ttywrite(), ttypoll() and ttykqwrite() the default
cdevsw methods for D_TTY drivers and remove the explicit initializations
in various drivers cdevsw structures.
this problem put these lines back in. While they should be
unnecessary, they appear to be sometimes necessary.
Reviewed in concept: dfr
Approved by: re (scottl@)
to the pci attachment. Cardbus is a derived class of pci so all pci
drivers are automatically available for matching against cardbus devices.
Reviewed by: imp
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
an UART interface could get stuck when a new interrupt condition
arose while servicing a previous interrupt. Since an interrupt was
already pending, no new interrupt would be triggered.
Avoid infinite recursion by flushing the Rx FIFO and marking an
overrun condition when we could not move the data from the Rx
FIFO to the receive buffer in toto. Failure to flush the Rx FIFO
would leave the Rx ready condition pending.
Note that the SAB 82532 already did this due to the nature of the
chip.
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.
We simply use the detected FIFO size to determine whether we have
a post 16550 UART or not. The support lacks proper serialization of
hardware access for now.
the "compatible" property too in the ns8250 case. This gets the serial
console to work on Blade 100s, where the device name is just "serial".
Reviewed by: marcel
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
is not a size of 1. Since we already know there is a FIFO, we can
safely assume that it is at least 16 bytes. Note that all this is
mostly academic anyway. We don't use the size of the Rx FIFO
currently. If we add support for hardware flow control, we only
care about Rx FIFO sizes larger than 16.
from the SAB82532 and the Z8530 hardware drivers by introducing
uart_cpu_busaddr(). The assumption is not true on pc98 where
bus_space_handle_t is a pointer to a structure.
The uart_cpu_busaddr() function will return the bus address
corresponding the tag and handle given to it by the BAS.
WARNING: the intend of the function is STRICTLY to allow hardware
drivers to determine which logical channel they control and is NOT
to be used for actual I/O. It is therefore EXPLICITLY allowed that
uart_cpu_busaddr() returns only the lower 8 bits of the address
and garbage in all other bits. No mistakes...
(ns8250 copied and s/ns8250/i8251/g), but there for linkage purposes.
Real code to follow, once I get past some boot issues on my pc98 boxes
with recent current.
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.
