Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and
include/asm-x86_64/serial.h. the serial8250_ports need to be probed late in
serial initializing stage. the console_init=>serial8250_console_init=>
register_console=>serial8250_console_setup will return -ENDEV, and console
ttyS0 can not be enabled at that time. need to wait till uart_add_one_port in
drivers/serial/serial_core.c to call register_console to get console ttyS0.
that is too late.
Make early_uart to use early_param, so uart console can be used earlier. Make
it to be bootconsole with CON_BOOT flag, so can use console handover feature.
and it will switch to corresponding normal serial console automatically.
new command line will be:
console=uart8250,io,0x3f8,9600n8
console=uart8250,mmio,0xff5e0000,115200n8
or
earlycon=uart8250,io,0x3f8,9600n8
earlycon=uart8250,mmio,0xff5e0000,115200n8
it will print in very early stage:
Early serial console at I/O port 0x3f8 (options '9600n8')
console [uart0] enabled
later for console it will print:
console handover: boot [uart0] -> real [ttyS0]
Signed-off-by: <yinghai.lu@sun.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After a suspend/resume cycle, the UART may have been reset into
low-speed mode -- either because it's actually been reset, or because
the firmware pokes at the old-style divisor registers. If we detected it
as a NS16550A SuperIO chip in the first place and set baud_base to
921600, then we should do so again in the resume path.
This patch adds that code to serial8250_resume_port(), and also makes
serial8250_resume() actually call serial8250_resume_port() for each port
instead of just calling uart_resume_port() directly. And thus fixes
serial port operation after suspend/resume.
It also fixes a bogus comment where we write the EXCR2 register with a
comment saying /* EXCR1 */
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove some obviously old interrupt disable/enable code that has been
commented out.
Signed-off-by: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add support for the integrated serial ports of the MIPS RM9122 processor
and its relatives.
The patch also does some whitespace cleanup.
[akpm@linux-foundation.org: cleanups]
Signed-off-by: Thomas Koeller <thomas.koeller@baslerweb.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Serial driver patch for the PMC-Sierra MSP71xx devices.
There are three different fixes:
1 Fix for DesignWare APB THRE errata: In brief, this is a non-standard
16550 in that the THRE interrupt will not re-assert itself simply by
disabling and re-enabling the THRI bit in the IER, it is only re-enabled
if a character is actually sent out.
It appears that the "8250-uart-backup-timer.patch" in the "mm" tree
also fixes it so we have dropped our initial workaround. This patch now
needs to be applied on top of that "mm" patch.
2 Fix for Busy Detect on LCR write: The DesignWare APB UART has a feature
which causes a new Busy Detect interrupt to be generated if it's busy
when the LCR is written. This fix saves the value of the LCR and
rewrites it after clearing the interrupt.
3 Workaround for interrupt/data concurrency issue: The SoC needs to
ensure that writes that can cause interrupts to be cleared reach the UART
before returning from the ISR. This fix reads a non-destructive register
on the UART so the read transaction completion ensures the previously
queued write transaction has also completed.
Signed-off-by: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 40b36daa introduced possibility that serial8250_backup_timeout() ->
serial8250_handle_port() locks port.lock without disabling irqs, thus
allowing deadlock against interrupt handler (port.lock is acquired in
serial8250_interrupt()).
Spotted by lockdep.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I encountered the following kernel panic. The cause of this problem was
NULL pointer access in check_modem_status() in 8250.c. I confirmed this
problem is fixed by the attached patch, but I don't know this is the
correct fix.
sadc[4378]: NaT consumption 2216203124768 [1]
Modules linked in: binfmt_misc dm_mirror dm_mod thermal processor fan
container button sg e100 eepro100 mii ehci_hcd ohci_hcd
Pid: 4378, CPU 0, comm: sadc
psr : 00001210085a2010 ifs : 8000000000000289 ip : [<a000000100482071>]
Not tainted
ip is at check_modem_status+0xf1/0x360
Call Trace:
[<a000000100013940>] show_stack+0x40/0xa0
[<a0000001000145a0>] show_regs+0x840/0x880
[<a0000001000368e0>] die+0x1c0/0x2c0
[<a000000100036a30>] die_if_kernel+0x50/0x80
[<a000000100037c40>] ia64_fault+0x11e0/0x1300
[<a00000010000bdc0>] ia64_leave_kernel+0x0/0x280
[<a000000100482070>] check_modem_status+0xf0/0x360
[<a000000100482300>] serial8250_get_mctrl+0x20/0xa0
[<a000000100478170>] uart_read_proc+0x250/0x860
[<a0000001001c16d0>] proc_file_read+0x1d0/0x4c0
[<a0000001001394b0>] vfs_read+0x1b0/0x300
[<a000000100139cd0>] sys_read+0x70/0xe0
[<a00000010000bc20>] ia64_ret_from_syscall+0x0/0x20
[<a000000000010620>] __kernel_syscall_via_break+0x0/0x20
Fix the possible NULL pointer access in check_modem_status() in 8250.c. The
check_modem_status() would access 'info' member of uart_port structure, but it
is not initialized before uart_open() is called. The check_modem_status() can
be called through /proc/tty/driver/serial before uart_open() is called.
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Taku Izumi <izumi2005@soft.fujitsu.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The patch below works around a minor bug found in the UART of the remote
management card used in many HP ia64 and parisc servers (aka the Diva
UARTs). The problem is that the UART does not reassert the THRE interrupt
if it has been previously cleared and the IIR THRI bit is re-enabled. This
can produce a very annoying failure mode when used as a serial console,
allowing a boot/reboot to hang indefinitely until an RX interrupt kicks it
into working again (ie. an unattended reboot could stall).
To solve this problem, a backup timer is introduced that runs alongside the
standard interrupt driven mechanism. This timer wakes up periodically,
checks for a hang condition and gets characters moving again. This backup
mechanism is only enabled if the UART is detected as having this problem,
so systems without these UARTs will have no additional overhead.
This version of the patch incorporates previous comments from Pavel and
removes races in the bug detection code. The test is now done before the
irq linking to prevent races with interrupt handler clearing the THRE
interrupt. Short delays and syncs are also added to ensure the device is
able to update register state before the result is tested.
Aristeu says:
this was tested on the following HP machines and solved the problem:
rx2600, rx2620, rx1600 and rx1620s.
hpa says:
I have seen this same bug in soft UART IP from "a major vendor."
Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Acked-by: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Get the Perle quad-modem PCI card (PCI-RAS4) detected by serial driver. It
may also get the PCI-RAS8 running, but can't guarantee as I didn't had one for
testing.
Signed-off-by: Thomas Hoehn <thomas.hoehn@avocent.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
o MODPOST generates warning for i386 if compiled with CONFIG_RELOCATABLE=y
and serial console support is enabled.
o Serial console setup function, serial8250_console_setup(), is a non __init
function and it calls functions which are of type __init().
(uart_parse_options() and uart_set_options()). Assuming, setup will
be called during init time, changing serial8250_console_setup() to __init.
o Adding one more pattern to modpost whitelist. Console drivers might
have *_console structures containing references to setup functions which
can be of __init type. Don't generate warnings for those.
WARNING: vmlinux - Section mismatch: reference to .init.text: from .data between 'serial8250_console' (at offset 0xc05a33d8) and 'serial8250_reg'
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
This is the grungy swap all the occurrences in the right places patch that
goes with the updates. At this point we have the same functionality as
before (except that sgttyb() returns speeds not zero) and are ready to
begin turning new stuff on providing nobody reports lots of bugs
If you are a tty driver author converting an out of tree driver the only
impact should be termios->ktermios name changes for the speed/property
setting functions from your upper layers.
If you are implementing your own TCGETS function before then your driver
was broken already and its about to get a whole lot more painful for you so
please fix it 8)
Also fill in c_ispeed/ospeed on init for most devices, although the current
code will do this for you anyway but I'd like eventually to lose that extra
paranoia
[akpm@osdl.org: bluetooth fix]
[mp3@de.ibm.com: sclp fix]
[mp3@de.ibm.com: warning fix for tty3270]
[hugh@veritas.com: fix tty_ioctl powerpc build]
[jdike@addtoit.com: uml: fix ->set_termios declaration]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Martin Peschke <mp3@de.ibm.com>
Acked-by: Peter Oberparleiter <oberpar@de.ibm.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Serial is _slow_ sometimes. So slow, that the NMI watchdog kicks in.
NMI Watchdog detected LOCKUP on CPU2CPU 2
Modules linked in: loop usb_storage md5 ipv6 parport_pc lp parport autofs4 i2c_dev i2c_core rfcomm l2cap bluetooth sunrpc pcdPid: 3138, comm: gpm Not tainted 2.6.11-1.1290_FC4smp
RIP: 0010:[<ffffffff80273b8a>] <ffffffff80273b8a>{serial_in+106}
RSP: 0018:ffff81003afc3d50 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000005 RDI: ffffffff804dcd60
RBP: 00000000000024fc R08: 000000000000000a R09: 0000000000000033
R10: ffff81001beb7c20 R11: 0000000000000020 R12: ffffffff804dcd60
R13: ffffffff804ade76 R14: 000000000000002b R15: 000000000000002c
FS: 00002aaaaaac4920(0000) GS:ffffffff804fca00(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00002aaaaabcb000 CR3: 000000003c0d0000 CR4: 00000000000006e0
Process gpm (pid: 3138, threadinfo ffff81003afc2000, task ffff81003eb63780)
Stack: ffffffff80275f2e 0000000000000000 ffffffff80448380 0000000000007d6b
000000000000002c fffffffffffffbbf 0000000000000292 0000000000008000
ffffffff80138e8c 0000000000007d97
Call Trace:<ffffffff80275f2e>{serial8250_console_write+270} <ffffffff80138e8c>{__call_console_drivers+76}
<ffffffff8013914b>{release_console_sem+315} <ffffffff80260325>{con_open+149}
<ffffffff80254e99>{tty_open+537} <ffffffff80192713>{chrdev_open+387}
<ffffffff80188824>{dentry_open+260} <ffffffff80188994>{filp_open+68}
<ffffffff80187b73>{get_unused_fd+227} <ffffffff80188a6c>{sys_open+76}
<ffffffff8010ebc6>{tracesys+209}
Code: 0f b6 c0 c3 66 90 41 57 49 89 f7 41 56 41 be 00 01 00 00 41
console shuts up ...
I initially did the patch below a year ago for the Fedora kernel, and have
been keeping it up to date since. I recently got the same thing happening
on a vanilla kernel, so figured it was time to repost this.
Signed-off-by: Dave Jones <davej@redhat.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The patch below is necessary for 115200 baud on an OMAP1510 internal UART.
It's been in the linux-omap tree for some time and with it applied to a
vanilla Linus git tree the serial console on the Amstrad Delta (which is
OMAP1510 based and whose initial bootloader runs at 115200) works fine (it
doesn't without it).
Signed-off-by: Jonathan McDowell <noodles@earth.li>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
8250.c and serial_txx9.c port suspend/resume handler still have this obsolete
argument documented...
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
I think register ranges obviously need to be claimed/released for all UARTs
including those with UPIO_MEM32 and UPIO_TSI iotype.
Also, serial8250_request_rsa_resources() returns false positives with
UPIO_MEM32, UPIO_AU, and UPIO_TSI iotype -- I don't think this makes any sense.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
(le32_to_cpu(x) >> 8) & 0xff is a very odd way to spell (x >> 16) & 0xff,
even if that code is hit only on ppc. The value is host-endian - we've
got it from readl(), after all...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Fix http://bugzilla.kernel.org/show_bug.cgi?id=6716
Doing a sysrq over a serial line into an SMP machine presently deadlocks.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The following patch gets rid of CONFIG_TSI108_BRIDGE. I add UPIO_TSI to
handle IIR and IER register in serial_in and serial_out.
(1) the reason to rewrite serial_in:
TSI108 rev Z1 version ERRATA. Reading the UART's Interrupt
Identification Register (IIR) clears the Transmit Holding Register
Empty (THRE) and Transmit buffer Empty (TEMP) interrupts even if they
are not enabled in the Interrupt Enable Register (IER). This leads to
loss of the interrupts. Interrupts are not cleared when reading UART
registers as 32-bit word.
(2) the reason to rewrite serial_out:
Check for UART_IER_UUE bit in the autoconfig routine. This section
of autoconfig is excluded for Tsi108/109 because bits 7 and 6 are
reserved for internal use. They are R/W bits. In addition to
incorrect identification, changing these bits (from 00) will make
Tsi108/109 UART non-functional.
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
x86 SMP breaks as a result of the previous change, we have no real
option other than to add locking to the 8250 console write function.
If an oops is in progress, try to acquire the lock. If we fail to
do so, continue anyway.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
A bug report from Gerd Hoffmann has highlighted that unconditionally
enabling the transmit interrupt at the end of console writes is very
bad.
In Gerd's case, it causes the test for buggy UARTs to give false
positives, incorrectly identifying ports as buggy when they are not.
Moreover, if we unconditionally enable the interrupt, and the port
is sharing it's interrupt with other ports, there is the very real
possibility that we'll cause an interrupt storm. (Not all ports use
OUT2 as an interrupt mask.)
Hence, revert part of f91a3715db and
all of f5968b37b3 until a better solution
can be found.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Alchemy SoC uart have got a non-standard divisor register that needs some
special handling.
This patch adds divisor read/write functions with test and special
handling for Alchemy internal uart.
Signed-off-by: Jon Anders Haugum <jonah@omegav.ntnu.no>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
I've noticed that the 8250/Au1x00 driver (drivers/serial/8250_au1x00.c)
doesn't claim UART memory ranges and uses wrong (KSEG1-based) UART
addresses instead of the physical ones.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Fix a lot of typos. Eyeballed by jmc@ in OpenBSD.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Glen Turner reported that writing LFCR rather than the more
traditional CRLF causes issues with some terminals.
Since this aflicts many serial drivers, extract the common code
to a library function (uart_console_write) and arrange for each
driver to supply a "putchar" function.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
early_serial_setup() must not be called after console initialisation.
Add a comment prior to the function explicitly stating this.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
On some embedded PowerPC (MPC834x) systems an extra byte would some
times be required to flush data out of the fifo.
serial8250_console_write() was updating the IER in hardware without
also updating the copy in uart_8250_port. This causes issues functions
like serial8250_start_tx() and __stop_tx() to misbehave.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The functionality UPF_BOOT_ONLYMCA provided has been replaced by
the 8250_mca module, which only registers MCA ports if MCA is
present.
UPF_AUTOPROBE has no functional effect - in fact, it's never
tested. Only ibmasm set the flag.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch resolves most of the problems with an SMP serial console race
with output via the tty path. At the end of the serial console print we
force enable the tx int in case we clobbered the tx interrupt status
racing between the console and tty output. That way the extra tx
interrupt causes the transmit path to restart not hang.
It also makes the serial console printk use the FIFO. This is neccessary
because some remote management devices fake serial console with FIFO and
are confused into sending one packet per character over ethernet when we
stall rather than filling the FIFO.
In order to preserve existing reliability semantics the function waits
for the serial queue to completely empty before returning.
Both of these problems were identified by a Red Hat partner.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Commit 7493a314cb changed the ordering
of the registration of the platform device driver vs the 8250 drivers
internal initialisation. This led to the probe function being called
before the driver had finished its internal initialisation, causing
mayhem. Revert the ordering change.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Do not use platform_device_register_simple() as it is going away.
Also set up driver's owner to create link driver->module in sysfs.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Turn several drivers/serial/ semaphores-used-as-mutex into mutexes
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.
This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.
When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.
For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).
Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.
The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.
I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.
Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real. That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.
Description:
tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification]. It
does now also return the number of chars inserted
There are also
tty_buffer_request_room(tty, len)
which asks for a buffer block of the length requested and returns the space
found. This improves efficiency with hardware that knows how much to
transfer.
and tty_insert_flip_string_flags(tty, str, flags, len)
to insert a string of characters and flags
For a smart interface the usual code is
len = tty_request_buffer_room(tty, amount_hardware_says);
tty_insert_flip_string(tty, buffer_from_card, len);
More description!
At the moment tty buffers are attached directly to the tty. This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)
I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers. This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.
So far so good. Lots of drivers reference tty->flip.*. Several of them also
call directly and unsafely into function pointers it provides. This will all
break. Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.
At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say
int tty_buffer_request_room(tty, size)
Try and ensure at least size bytes are available, returns actual room (may be
zero). At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative. (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space. The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.
int tty_insert_flip_char(tty, ch, flag)
As before insert a character if there is room. Now returns 1 for success, 0
for failure.
int tty_insert_flip_string(tty, str, len)
Insert a block of non error characters. Returns the number inserted.
int tty_prepare_flip_string(tty, strptr, len)
Adjust the buffer to allow len characters to be added. Returns a buffer
pointer in strptr and the length available. This allows for hardware that
needs to use functions like insl or mencpy_fromio.
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Also add a nr_uarts module option to the 8250 code to override
this, up to a maximum of CONFIG_SERIAL_8250_NR_UARTS
This should appease people who complain about a proliferation
of /dev/ttyS & /sysfs nodes whilst at the same time allowing
a single kernel image to support the rarer occasions of
lots of devices.
Signed-off-by: Dave Jones <davej@redhat.com>
All call sites for serial8250_handle_port() acquired the port spinlock
and released it afterwards. This is a needless duplication of code.
Move the spinlocking inside serial8250_handle_port().
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Reading the MSR register on 8250-compatible UARTs results in any
modem status interrupts being cleared. To avoid missing any
status changes, arrange for get_mctrl() to read the current
status via check_modem_status(), which will process any pending
state changes for us.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch marks a few serial data structures const, moving them to
.rodata where they won't false-share cachelines with things that get
written to.
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
xscale-type UARTs have an extra bit (UUE) in the IER register that has
to be written as 1 to enable the UART. At the end of autoconfig() in
drivers/serial/8250.c, the IER register is unconditionally written as
zero, which turns off the UART, and makes any subsequent printch() hang
the box.
Since other 8250-type UARTs don't have this enable bit and are thus
always 'enabled' in this sense, it can't hurt to enable xscale-type
serial ports all the time as well. The attached patch changes the
autoconfig() exit path to see if the port has an UUE enable bit, and if
yes, to write UUE=1 instead of just putting a zero into IER, using the
same test as is used at the beginning of serial8250_console_write().
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This allows us to eliminate the casts in the drivers, and eventually
remove the use of the device_driver function pointer methods for
platform device drivers.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Large console spews from IRQ or local_irq_disable() sections can cause the NMI
watchdog to go off.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The offsets of the registers are in a different place, and
some parts cannot handle a full set of modem control signals.
Signed-off-by: Pantelis Antoniou <pantelis@embeddedalley.ocm>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Convert everyone who uses platform_bus_type to include
linux/platform_device.h.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
