Commit d006199e72a9 ("serial: sh-sci: Regtype probing doesn't need to be
fatal.") made sci_init_single() return when sci_probe_regmap() succeeds,
although it should return when sci_probe_regmap() fails. This causes
systems using the serial sh-sci driver to crash during boot.
Fix the problem by using the right return condition.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
of_alias_get_id() is broken and being reverted. Remove the reference
to it and replace with a single incrementing id number.
There is no risk of regression here on the imx driver since the imx
change to use of_alias_get_id() is commit 22698aa2, "serial/imx: add
device tree probe support" which is new for v3.1, and it won't get
used unless CONFIG_OF is enabled and the board is booted using a
device tree. A single incrementing integer is sufficient for now.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
It adds device tree probe support for imx tty/serial driver.
Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
Signed-off-by: Jason Liu <jason.hui@linaro.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
The patch removes all the uses of cpu_is_mx1(). Instead, it uses
the .id_table of platform_driver to distinguish the uart device type,
IMX1_UART and IMX21_UART. The IMX21_UART type runs on all i.mx
except i.mx1.
A couple of !cpu_is_mx1 logic gets turned into is_imx21_uart,
as the codes wrapped there are really IMX21 type uart specific.
It also removes macro MX1_UCR3_REF25 and MX1_UCR3_REF30 which are
not used anywhere.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (26 commits)
amba pl011: workaround for uart registers lockup
n_gsm: fix the wrong FCS handling
pch_uart: add missing comment about OKI ML7223
pch_uart: Add MSI support
tty: fix "IRQ45: nobody cared"
PTI feature to allow user to name and mark masterchannel request.
0 for o PTI Makefile bug.
tty: serial: samsung.c remove legacy PM code.
SERIAL: SC26xx: Fix link error.
serial: mrst_max3110: initialize waitqueue earlier
mrst_max3110: Change max missing message priority.
tty: s5pv210: Add delay loop on fifo reset function for UART
tty/serial: Fix XSCALE serial ports, e.g. ce4100
serial: bfin_5xx: fix off-by-one with resource size
drivers/tty: use printk_ratelimited() instead of printk_ratelimit()
tty: n_gsm: Added refcount usage to gsm_mux and gsm_dlci structs
tty: n_gsm: Add raw-ip support
tty: n_gsm: expose gsmtty device nodes at ldisc open time
pch_phub: Fix register miss-setting issue
serial: 8250, increase PASS_LIMIT
...
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (99 commits)
drivers/virt: add missing linux/interrupt.h to fsl_hypervisor.c
powerpc/85xx: fix mpic configuration in CAMP mode
powerpc: Copy back TIF flags on return from softirq stack
powerpc/64: Make server perfmon only built on ppc64 server devices
powerpc/pseries: Fix hvc_vio.c build due to recent changes
powerpc: Exporting boot_cpuid_phys
powerpc: Add CFAR to oops output
hvc_console: Add kdb support
powerpc/pseries: Fix hvterm_raw_get_chars to accept < 16 chars, fixing xmon
powerpc/irq: Quieten irq mapping printks
powerpc: Enable lockup and hung task detectors in pseries and ppc64 defeconfigs
powerpc: Add mpt2sas driver to pseries and ppc64 defconfig
powerpc: Disable IRQs off tracer in ppc64 defconfig
powerpc: Sync pseries and ppc64 defconfigs
powerpc/pseries/hvconsole: Fix dropped console output
hvc_console: Improve tty/console put_chars handling
powerpc/kdump: Fix timeout in crash_kexec_wait_realmode
powerpc/mm: Fix output of total_ram.
powerpc/cpufreq: Add cpufreq driver for Momentum Maple boards
powerpc: Correct annotations of pmu registration functions
...
Fix up trivial Kconfig/Makefile conflicts in arch/powerpc, drivers, and
drivers/cpufreq
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits)
fs: Merge split strings
treewide: fix potentially dangerous trailing ';' in #defined values/expressions
uwb: Fix misspelling of neighbourhood in comment
net, netfilter: Remove redundant goto in ebt_ulog_packet
trivial: don't touch files that are removed in the staging tree
lib/vsprintf: replace link to Draft by final RFC number
doc: Kconfig: `to be' -> `be'
doc: Kconfig: Typo: square -> squared
doc: Konfig: Documentation/power/{pm => apm-acpi}.txt
drivers/net: static should be at beginning of declaration
drivers/media: static should be at beginning of declaration
drivers/i2c: static should be at beginning of declaration
XTENSA: static should be at beginning of declaration
SH: static should be at beginning of declaration
MIPS: static should be at beginning of declaration
ARM: static should be at beginning of declaration
rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check
Update my e-mail address
PCIe ASPM: forcedly -> forcibly
gma500: push through device driver tree
...
Fix up trivial conflicts:
- arch/arm/mach-ep93xx/dma-m2p.c (deleted)
- drivers/gpio/gpio-ep93xx.c (renamed and context nearby)
- drivers/net/r8169.c (just context changes)
* 'next/cleanup' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc: (133 commits)
ARM: EXYNOS4: Change devname for FIMD clkdev
ARM: S3C64XX: Cleanup mach/regs-fb.h from mach-s3c64xx
ARM: S5PV210: Cleanup mach/regs-fb.h from mach-s5pv210
ARM: S5PC100: Cleanup mach/regs-fb.h from mach-s5pc100
ARM: S3C24XX: Use generic s3c_set_platdata for devices
ARM: S3C64XX: Use generic s3c_set_platdata for OneNAND
ARM: SAMSUNG: Use generic s3c_set_platdata for NAND
ARM: SAMSUNG: Use generic s3c_set_platdata for USB OHCI
ARM: SAMSUNG: Use generic s3c_set_platdata for HWMON
ARM: SAMSUNG: Use generic s3c_set_platdata for FB
ARM: SAMSUNG: Use generic s3c_set_platdata for TS
ARM: S3C64XX: Add PWM backlight support on SMDK6410
ARM: S5P64X0: Add PWM backlight support on SMDK6450
ARM: S5P64X0: Add PWM backlight support on SMDK6440
ARM: S5PC100: Add PWM backlight support on SMDKC100
ARM: S5PV210: Add PWM backlight support on SMDKV210
ARM: EXYNOS4: Add PWM backlight support on SMDKC210
ARM: EXYNOS4: Add PWM backlight support on SMDKV310
ARM: SAMSUNG: Create a common infrastructure for PWM backlight support
clocksource: convert 32-bit down counting clocksource on S5PV210/S5P64X0
...
Fix up trivial conflict in arch/arm/mach-imx/mach-scb9328.c
* 'devicetree/next' of git://git.secretlab.ca/git/linux-2.6:
dt: include linux/errno.h in linux/of_address.h
of/address: Add of_find_matching_node_by_address helper
dt: remove extra xsysace platform_driver registration
tty/serial: Add devicetree support for nVidia Tegra serial ports
dt: add empty of_property_read_u32[_array] for non-dt
dt: bindings: move SEC node under new crypto/
dt: add helper function to read u32 arrays
tty/serial: change of_serial to use new of_property_read_u32() api
dt: add 'const' for of_property_read_string parameter **out_string
dt: add helper functions to read u32 and string property values
tty: of_serial: support for 32 bit accesses
dt: document the of_serial bindings
dt/platform: allow device name to be overridden
drivers/amba: create devices from device tree
dt: add of_platform_populate() for creating device from the device tree
dt: Add default match table for bus ids
Uart port is registered as a console during the driver's probe.
So explict registration of console with console_initcall is
removed.
Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
[kgene.kim@samsung.com: removed changes of s3c2400 and s3c24a0]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
For some reason I didn't notice the failure in my test builds,
probably lacking caffeine or something...
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Add poll_get_char and poll_put_char for kdb. Enable kdb at boot with:
kgdboc=hvc0
or at runtime with:
echo hvc0 > /sys/module/kgdboc/parameters/kgdboc
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
commit 4d2bb3f500 (powerpc/pseries: Re-implement HVSI as part of
hvc_vio) changed udbg_getc to be based on hvterm_raw_get_chars.
Unfortunately hvterm_raw_get_chars returns -EAGAIN if you ask
for anything less than 16 characters. As a result xmon no longer
accepts input and prints a stream of junk to the screen.
The recent change highlights a problem that xmon on pseries VIO
has had all along, that it can drop input characters. The issue
is the hypervisor call does not take a count argument and can
return up to 16 characters.
This patch adds a per vterm buffer that we copy input data into
and give it out as requested.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently, the hvc_console_print() function drops console output if the
hvc backend's put_chars() returns 0. This patch changes this behavior
to allow a retry through returning -EAGAIN.
This change also affects the hvc_push() function. Both functions are
changed to handle -EAGAIN and to retry the put_chars() operation.
If a hvc backend returns -EAGAIN, the retry handling differs:
- hvc_console_print() spins to write the complete console output.
- hvc_push() behaves the same way as for returning 0.
Now hvc backends can indirectly control the way how console output is
handled through the hvc console layer.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
On Tue, 28 Jun 2011, Ben Dooks wrote:
> On Tue, Jun 28, 2011 at 11:22:57PM +0200, Arnd Bergmann wrote:
>
> > On a related note, what about mach-s3c2400? It seems to be even more
> > incomplete.
>
> Probably the same fate awaits that. It is so old that there's little
> incentive to do anything with it.
So out it goes as well.
The PORT_S3C2400 definition in include/linux/serial_core.h is left there
to prevent a reuse of the same number for another port type.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Commit bcae8aeb32 "[ARM] S3C24A0: Initial architecture support files"
brought in a bunch of files while explicitly leaving out the corresponding
Kconfig entry, stating that the series is not complete.
More than 2.5 years later, the support for this has not seen any progress.
This is therefore dead code. If someone wants to revive this code, it is
always possible to retrieve it from the Git repository.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
This workaround aims to break the deadlock situation
which raises during continuous transfer of data for long
duration over uart with hardware flow control. It is
observed that CTS interrupt cannot be cleared in uart
interrupt register (ICR). Hence further transfer over
uart gets blocked.
It is seen that during such deadlock condition ICR
don't get cleared even on multiple write. This leads
pass_counter to decrease and finally reach zero. This
can be taken as trigger point to run this UART_BT_WA.
Workaround backups the register configuration, does soft
reset of UART using BIT-0 of PRCC_K_SOFTRST_SET/CLEAR
registers and restores the registers.
This patch also provides support for uart init and exit
function calls if present.
Signed-off-by: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
FCS could be GSM0_SOF, so will break state machine...
[This byte isn't quoted in any way so a SOF here doesn't imply an error
occurred.]
Signed-off-by: Alek Du <alek.du@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org> [3.0]
[Trivial but best backported once its in 3.1rc I think]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
In s3c24xx_serial_console_setup function, if the uart port that is
being setup as a console has not been initialized, an error can be
returned instead of using uart port 0 as the default console port.
The uart port that was intended to be used as a console could be
initialized at a later point during boot and then registered as a
console. This will avoid using uart port 0 as a unintended console
port.
Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
* 'at91/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-2.6-arm-soc:
AT91: Change nand buswidth logic to match hardware default configuration
at91: Use "pclk" as con_id on at91cap9 and at91rm9200
at91: fix udc, ehci and mmc clock device name for cap9/9g45/9rl
atmel_serial: fix internal port num
at91: fix at91_set_serial_console: use platform device id
Unthrottling the TTY during close ends up enabling interrupts
on a device not on the active list, which will never have the
interrupts cleared. Doctor, it hurts when I do this.
>>> On 6/2/2011 at 01:56 AM, in message <20110601145608.3e586e16@bob.linux.org.uk>, Alan Cox <alan@linux.intel.com> wrote:
> On Wed, 01 Jun 2011 10:34:07 +1200
> "andrew mcgregor" <andrew.mcgregor@alliedtelesis.co.nz> wrote:
> > The LKML message
> > http://kerneltrap.org/mailarchive/linux-kernel/2010/2/25/4541847 from
> > February doesn't seem to have been resolved since. We struck the
> > issue, and the patch below (against 2.6.32) fixes it. Should I
> > supply a patch against 3.0.0rc?
>
> I think that would be sensible. I don't actually see how you hit it as
> the IRQ ought to be masked by then but it's certainly wrong for n_tty
> to be calling into check_unthrottle at that point.
>
> So yes please send a patch with a suitable Signed-off-by: line to
> linux-serial and cc GregKH <greg@kroah.com> as well.
>
> Alan
Signed-off-by: Andrew McGregor <andrew.mcgregor@alliedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch "modernize" tty/serial/samsung.c to use non-legacy code for
suspend/resume.
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: KyungMin Park <kyungmin.park@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Kconfig allows enabling console support for the SC26xx driver even when
it's configured as a module resulting in a:
ERROR: "uart_console_device" [drivers/tty/serial/sc26xx.ko] undefined!
modpost error since the driver was merged in
eea63e0e8a [SC26XX: New serial driver for
SC2681 uarts] in 2.6.25. Fixed by only allowing console support to be
enabled if the driver is builtin.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: stable <stable@kernel.org>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The driver went to initialize its waitqueue at the start of the main processing
thread. However, it is possible that this thread is not scheduled on a CPU
before the write function is called which leads to a following error:
BUG: spinlock bad magic on CPU#1, swapper/1
lock: f5f3ebdc, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
Pid: 1, comm: swapper Not tainted 3.0.0-rc2+ #67
Call Trace:
[<c1289663>] spin_bug+0xa3/0xf0
[<c12897ad>] do_raw_spin_lock+0x7d/0x150
[<c1490006>] ? init_idle+0x8d/0x20c
[<c14963de>] _raw_spin_lock_irqsave+0x4e/0x60
[<c102f2bb>] ? __wake_up+0x1b/0x50
[<c102f2bb>] __wake_up+0x1b/0x50
[<c12d03bc>] ? uart_console_write+0x4c/0x60
[<c12d36c0>] ? serial_m3110_enable_ms+0x10/0x10
[<c12d3715>] serial_m3110_con_write+0x55/0x60
[<c1041575>] __call_console_drivers+0x75/0x90
[<c10415d9>] _call_console_drivers+0x49/0x80
[<c1041baa>] console_unlock+0xca/0x1f0
[<c10420ef>] vprintk+0x18f/0x4f0
[<c10787cb>] ? trace_hardirqs_on+0xb/0x10
[<c14928a3>] printk+0x18/0x1a
[<c1042730>] register_console+0x2e0/0x350
[<c12d098e>] uart_add_one_port+0x33e/0x3d0
[<c10787cb>] ? trace_hardirqs_on+0xb/0x10
[<c103e10b>] ? try_to_wake_up+0x18b/0x250
[<c1485ba6>] serial_m3110_probe+0x1c2/0x1df
[<c12d3d20>] ? serial_m3110_suspend+0x40/0x40
[<c1303db7>] spi_drv_probe+0x17/0x20
...
We fix this by initializing the waitqueue before the main thread is created.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Change print message to notice instead of error to clean up
non critcal messages showing on startup. The MAX3111 not being present
is a normal path for end user systems.
Signed-off-by: William Douglas <william.douglas@intel.com>
[rebased on 3.0, switched to dev_dbg()]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch addes delay loop on fifo reset function for UART.
On high speed freq, it needs delay function when fifo reset.
If not, system will hang by this uart reset problem when resuming
from suspend mode.
Signed-off-by: Jongpill Lee <boyko.lee@samsung.com>
Signed-off-by: Jaecheol Lee <jc.lee@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Commit 4539c24fe4 "tty/serial: Add
explicit PORT_TEGRA type" introduced separate flags describing the need
for IER bits UUE and RTOIE. Both bits are required for the XSCALE port
type. While that patch updated uart_config[] as required, the auto-probing
code wasn't updated to set the RTOIE flag when an XSCALE port type was
detected. This caused such ports to stop working. This patch rectifies
that.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: stable <stable@kernel.org> [3.0]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This doesn't cause any real bugs, but it should still be fixed.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Since the printk_ratelimit() shouldn't be used anymore (see comment in
include/linux/printk.h), replace it with printk_ratelimited().
Signed-off-by: Manuel Zerpies <manuel.f.zerpies@ww.stud.uni-erlangen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The gsm_mux is created/destroyed when ldisc is
opened/closed but clients of the MUX channel devices (gsmttyN)
may access this structure as long as the TTYs are open.
For the open, the ldisc open is guaranteed to preceed the TTY open,
but the close has no such guaranteed ordering. As a result,
the gsm_mux can be freed in the ldisc close before being accessed
by one of the TTY clients. This can happen if the ldisc is removed
while there are open, active MUX channels.
A similar situation exists for DLCI-0, it is basically a resource
shared by MUX and DLCI , and should not be freed while they can
be accessed
To avoid this, gsm_mux and dlcis now have a reference counter
ldisc open takes a reference on the mux and all the dlcis
gsmtty_open takes a reference on the mux, dlci0 and its specific
dlci. Dropping the last reference initiates the actual free.
Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch adds the ability to open a network data connection over a mux
virtual tty channel. This is for modems that support data connections
with raw IP frames instead of PPP. On high speed data connections this
eliminates a significant amount of PPP overhead. To use this interface,
the application must first tell the modem to open a network connection on
a virtual tty. Once that has been accomplished, the app will issue an
IOCTL on that virtual tty to create the network interface. The IOCTL will
return the index of the interface created.
The two IOCTL commands are:
ioctl( fd, GSMIOC_ENABLE_NET );
ioctl( fd, GSMIOC_DISABLE_NET );
Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The n_gsm driver being an ldisc, does not provide a convenient method
e.g. udev to create the tty device nodes automatically when the ldisc
is opened.
The TTY device nodes are now created via calls to tty_register_device
from the ldisc open.
Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
A mix of think & mismerge on my side caused a problem where both the
new hvsi_lib and the old hvsi driver gets compiled and try to define
symbols with the same name.
This fixes it by renaming the hvsi_lib exported symbols.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Some platforms e.g. TI Davinci require 32-bit accesses to the UARTs.
The of_serial driver currently registers all UARTs as UPIO_MEM. Add a
new attribute "reg-io-width" to allow the port to be registered with
different IO width requirements.
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
On pseries machines, consoles are provided by the hypervisor using
a low level get_chars/put_chars type interface. However, this is
really just a transport to the service processor which implements
them either as "raw" console (networked consoles, HMC, ...) or as
"hvsi" serial ports.
The later is a simple packet protocol on top of the raw character
interface that is supposed to convey additional "serial port" style
semantics. In practice however, all it does is provide a way to
read the CD line and set/clear our DTR line, that's it.
We currently implement the "raw" protocol as an hvc console backend
(/dev/hvcN) and the "hvsi" protocol using a separate tty driver
(/dev/hvsi0).
However this is quite impractical. The arbitrary difference between
the two type of devices has been a major source of user (and distro)
confusion. Additionally, there's an additional mini -hvsi implementation
in the pseries platform code for our low level debug console and early
boot kernel messages, which means code duplication, though that low
level variant is impractical as it's incapable of doing the initial
protocol negociation to establish the link to the FSP.
This essentially replaces the dedicated hvsi driver and the platform
udbg code completely by extending the existing hvc_vio backend used
in "raw" mode so that:
- It now supports HVSI as well
- We add support for hvc backend providing tiocm{get,set}
- It also provides a udbg interface for early debug and boot console
This is overall less code, though this will only be obvious once we
remove the old "hvsi" driver, which is still available for now. When
the old driver is enabled, the new code still kicks in for the low
level udbg console, replacing the old mini implementation in the platform
code, it just doesn't provide the higher level "hvc" interface.
In addition to producing generally simler code, this has several benefits
over our current situation:
- The user/distro only has to deal with /dev/hvcN for the hypervisor
console, avoiding all sort of confusion that has plagued us in the past
- The tty, kernel and low level debug console all use the same code
base which supports the full protocol establishment process, thus the
console is now available much earlier than it used to be with the
old HVSI driver. The kernel console works much earlier and udbg is
available much earlier too. Hackers can enable a hard coded very-early
debug console as well that works with HVSI (previously that was only
supported for the "raw" mode).
I've tried to keep the same semantics as hvsi relative to how I react
to things like CD changes, with some subtle differences though:
- I clear DTR on close if HUPCL is set
- Current hvsi triggers a hangup if it detects a up->down transition
on CD (you can still open a console with CD down). My new implementation
triggers a hangup if the link to the FSP is severed, and severs it upon
detecting a up->down transition on CD.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Rafael J. Wysocki