Reading from the DCC grabs a character from the buffer and
clears the status bit. Since this is a context-changing
operation, instructions following the character read that rely on
the status bit being accurate need to be synchronized with an
ISB.
In this case, the status bit check needs to execute after the
character read otherwise we run the risk of reading the character
and checking the status bit before the read can clear the status
bit in the first place. When this happens, the user will see the
same character they typed twice, instead of once.
Add an ISB after the read and the write, so that the status check
is synchronized with the read/write operations.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This reverts commit 361162459f.
It causes an infinite loop when booting Linux under Xen, as so:
[ 2.382984] console [hvc0] enabled
[ 2.382984] console [hvc0] enabled
[ 2.382984] console [hvc0] enabled
...
as reported by Konrad Rzeszutek Wilk. And Rusty reports the same for
lguest. He goes on to say:
"This is not a concurrency problem: the issue seems to be that
calling register_console() twice on the same struct console is a bad
idea."
and Greg says he'll fix it up properly at some point later. Revert for now.
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: Rusty Russell <rusty@ozlabs.org>
Requested-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Miche Baker-Harvey <miche@google.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix building following build error:
drivers/tty/hvc/hvc_opal.c:244:12: error: 'THIS_MODULE' undeclared here (not in a function)
Signed-off-by: Michael Neuling <mikey@neuling.org>
[ New file from powerpc tree not following the new rules from the
module.h split, both of which were merged today. - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
Revert "tracing: Include module.h in define_trace.h"
irq: don't put module.h into irq.h for tracking irqgen modules.
bluetooth: macroize two small inlines to avoid module.h
ip_vs.h: fix implicit use of module_get/module_put from module.h
nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
include: replace linux/module.h with "struct module" wherever possible
include: convert various register fcns to macros to avoid include chaining
crypto.h: remove unused crypto_tfm_alg_modname() inline
uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
pm_runtime.h: explicitly requires notifier.h
linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
miscdevice.h: fix up implicit use of lists and types
stop_machine.h: fix implicit use of smp.h for smp_processor_id
of: fix implicit use of errno.h in include/linux/of.h
of_platform.h: delete needless include <linux/module.h>
acpi: remove module.h include from platform/aclinux.h
miscdevice.h: delete unnecessary inclusion of module.h
device_cgroup.h: delete needless include <linux/module.h>
net: sch_generic remove redundant use of <linux/module.h>
net: inet_timewait_sock doesnt need <linux/module.h>
...
Fix up trivial conflicts (other header files, and removal of the ab3550 mfd driver) in
- drivers/media/dvb/frontends/dibx000_common.c
- drivers/media/video/{mt9m111.c,ov6650.c}
- drivers/mfd/ab3550-core.c
- include/linux/dmaengine.h
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (106 commits)
powerpc/p3060qds: Add support for P3060QDS board
powerpc/83xx: Add shutdown request support to MCU handling on MPC8349 MITX
powerpc/85xx: Make kexec to interate over online cpus
powerpc/fsl_booke: Fix comment in head_fsl_booke.S
powerpc/85xx: issue 15 EOI after core reset for FSL CoreNet devices
powerpc/8xxx: Fix interrupt handling in MPC8xxx GPIO driver
powerpc/85xx: Add 'fsl,pq3-gpio' compatiable for GPIO driver
powerpc/86xx: Correct Gianfar support for GE boards
powerpc/cpm: Clear muram before it is in use.
drivers/virt: add ioctl for 32-bit compat on 64-bit to fsl-hv-manager
powerpc/fsl_msi: add support for "msi-address-64" property
powerpc/85xx: Setup secondary cores PIR with hard SMP id
powerpc/fsl-booke: Fix settlbcam for 64-bit
powerpc/85xx: Adding DCSR node to dtsi device trees
powerpc/85xx: clean up FPGA device tree nodes for Freecsale QorIQ boards
powerpc/85xx: fix PHYS_64BIT selection for P1022DS
powerpc/fsl-booke: Fix setup_initial_memory_limit to not blindly map
powerpc: respect mem= setting for early memory limit setup
powerpc: Update corenet64_smp_defconfig
powerpc: Update mpc85xx/corenet 32-bit defconfigs
...
Fix up trivial conflicts in:
- arch/powerpc/configs/40x/hcu4_defconfig
removed stale file, edited elsewhere
- arch/powerpc/include/asm/udbg.h, arch/powerpc/kernel/udbg.c:
added opal and gelic drivers vs added ePAPR driver
- drivers/tty/serial/8250.c
moved UPIO_TSI to powerpc vs removed UPIO_DWAPB support
We are cleaning up the issue that means module.h is omnipresent.
These tty users are the people who implictly are relying on that.
Fix up the real users to call out the include that they really need.
In the case of jsm_driver.c file, it had moduleparam.h but that
isn't enough and it needs the full module.h
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
printk only works for "registered consoles." Currently, the hvc_console
code calls register_console() from hvc_instantiate(), but that's only
used in the early console case. In hvc_alloc(), register_console() was
not called.
Add a call to register_console() in hvc_alloc(), set up the index in
the hvc_console, and set up the necessary vtermnos[] and cons_op[]
entries so that printk functions work.
Signed-off-by: Miche Baker-Harvey <miche@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).
So now this flag is a NOOP and can be removed.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This adds a udbg and an hvc console backend for supporting a console
using the OPAL console interfaces.
On OPAL v1 we have hvc0 mapped to whatever console the system was
configured for (network or hvsi serial port) via the service
processor.
On OPAL v2 we have hvcN mapped to the Nth console provided by OPAL
which generally corresponds to:
hvc0 : network console (raw protocol)
hvc1 : serial port S1 (hvsi)
hvc2 : serial port S2 (hvsi)
Note: At this point, early debug console only works with OPAL v1
and shouldn't be enabled in a normal kernel.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The Power platform requires the partner info buffer to be page aligned
otherwise it will fail the partner info hcall with H_PARAMETER. Switch
from using kmalloc to allocate this buffer to __get_free_page to ensure
page alignment.
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Let's use the newly added helper to avoid stalls in drivers which are
not yet ported to tty_port helpers.
Those which are broken (call tty_wait_until_sent with irqs disabled)
are left untouched. They are in a deeper trouble than we are trying to
solve here. This includes amiserial, 68328serial, 68360serial and
crisv10.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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>
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>
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>
Embed the struct hvsi_header in the various packet definitions
rather than open coding it multiple times. Will help provide
stronger type checking.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This moves various HVSI protocol definitions from the hvsi.c
driver to a header file that can be used later on by a udbg
implementation
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (47 commits)
doc: CONFIG_UNEVICTABLE_LRU doesn't exist anymore
Update cpuset info & webiste for cgroups
dcdbas: force SMI to happen when expected
arch/arm/Kconfig: remove one to many l's in the word.
asm-generic/user.h: Fix spelling in comment
drm: fix printk typo 'sracth'
Remove one to many n's in a word
Documentation/filesystems/romfs.txt: fixing link to genromfs
drivers:scsi Change printk typo initate -> initiate
serial, pch uart: Remove duplicate inclusion of linux/pci.h header
fs/eventpoll.c: fix spelling
mm: Fix out-of-date comments which refers non-existent functions
drm: Fix printk typo 'failled'
coh901318.c: Change initate to initiate.
mbox-db5500.c Change initate to initiate.
edac: correct i82975x error-info reported
edac: correct i82975x mci initialisation
edac: correct commented info
fs: update comments to point correct document
target: remove duplicate include of target/target_core_device.h from drivers/target/target_core_hba.c
...
Trivial conflict in fs/eventpoll.c (spelling vs addition)
* 'stable/hvc-console' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen/hvc: Disable probe_irq_on/off from poking the hvc-console IRQ line.
* 'stable/gntalloc.v6' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
xen: gntdev: fix build warning
xen/p2m/m2p/gnttab: do not add failed grant maps to m2p override
xen-gntdev: Add cast to pointer
xen-gntdev: Fix incorrect use of zero handle
xen: change xen/[gntdev/gntalloc] to default m
xen-gntdev: prevent using UNMAP_NOTIFY_CLEAR_BYTE on read-only mappings
xen-gntdev: Avoid double-mapping memory
xen-gntdev: Avoid unmapping ranges twice
xen-gntdev: Use map->vma for checking map validity
xen-gntdev: Fix unmap notify on PV domains
xen-gntdev: Fix memory leak when mmap fails
xen/gntalloc,gntdev: Add unmap notify ioctl
xen-gntalloc: Userspace grant allocation driver
xen-gntdev: Support mapping in HVM domains
xen-gntdev: Add reference counting to maps
xen-gntdev: Use find_vma rather than iterating our vma list manually
xen-gntdev: Change page limit to be global instead of per-open
* 'stable/balloon' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: (24 commits)
xen-gntdev: Use ballooned pages for grant mappings
xen-balloon: Add interface to retrieve ballooned pages
xen-balloon: Move core balloon functionality out of module
xen/balloon: Remove pr_info's and don't alter retry_count
xen/balloon: Protect against CPU exhaust by event/x process
xen/balloon: Migration from mod_timer() to schedule_delayed_work()
xen/balloon: Removal of driver_pages
This fixes a particular nasty racing problem found when using
Xen hypervisor with the console (hvc) output being routed to the
serial port and the serial port receiving data when
probe_irq_off(probe_irq_on) is running.
Specifically the bug manifests itself with:
[ 4.470693] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 4.470693] IP: [<ffffffff810a8c65>] handle_IRQ_event+0xe/0xc9
..snip..
[ 4.470693] Call Trace:
[ 4.470693] <IRQ>
[ 4.470693] [<ffffffff810aa645>] handle_percpu_irq+0x3c/0x69
[ 4.470693] [<ffffffff8123cda7>] __xen_evtchn_do_upcall+0xfd/0x195
[ 4.470693] [<ffffffff810308cf>] ? xen_restore_fl_direct_end+0x0/0x1
[ 4.470693] [<ffffffff8123d873>] xen_evtchn_do_upcall+0x32/0x47
[ 4.470693] [<ffffffff81034dfe>] xen_do_hypervisor_callback+0x1e/0x30
[ 4.470693] <EOI>
[ 4.470693] [<ffffffff8100922a>] ? hypercall_page+0x22a/0x1000
[ 4.470693] [<ffffffff8100922a>] ? hypercall_page+0x22a/0x1000
[ 4.470693] [<ffffffff810301c5>] ? xen_force_evtchn_callback+0xd/0xf
[ 4.470693] [<ffffffff810308e2>] ? check_events+0x12/0x20
[ 4.470693] [<ffffffff81030889>] ? xen_irq_enable_direct_end+0x0/0x7
[ 4.470693] [<ffffffff810ab0a0>] ? probe_irq_on+0x8f/0x1d7
[ 4.470693] [<ffffffff812b105e>] ? serial8250_config_port+0x7b7/0x9e6
[ 4.470693] [<ffffffff812ad66c>] ? uart_add_one_port+0x11b/0x305
The bug is trigged by three actors working together:
A). serial_8250_config_port calling
probe_irq_off(probe_irq_on())
wherein all of the IRQ handlers are being started and shut off.
The functions utilize the sleep functions so the minimum time
they are run is 120 msec.
B). Xen hypervisor receiving on the serial line any character and
setting the bits in the event channel - during this 120 msec timeframe.
C). The hvc API makes a call to 'request_irq' (and hence setting desc->action
to a valid value), much much later - when user space opens
/dev/console (hvc_open). To make the console usable during bootup,
the Xen HVC implementation sets the IRQ chip (and correspondingly
the event channel) much earlier. The IRQ chip handler that is used
is the handle_percpu_irq (aaca49642b)
Back to the issue. When A) is being called it ends up calling the
xen_percpu_chip's chip->startup twice and chip->shutdown once. Those
are set to the default_startup and mask_irq (events.c) respectivly.
If (and this seems to depend on what serial concentrator you use), B)
gets data from the serial port it sets in the event channel a pending bit.
When A) calls chip->startup(), the masking of the pending bit, and
unmasking of the event channel mask, and also setting of the upcall_pending
flag is done (since there is data present on the event channel).
If before the 120 msec has elapsed, any IRQ handler (Xen IRQ has one
IRQ handler, which checks the event channels bitmap to figure which one
to call) is called we end up calling the handle_percpu_irq. The
handle_percpu_irq calls desc->action (which is NULL) and we blow up.
Caveats: I could only reproduce this on 2.6.32 pvops. I am not sure
why this is not showing up on 2.6.38 kernel.
The probe_irq_on/off has code to disable poking specific IRQ lines. This is
done by using the set_irq_noprobe() and then we do not have to
worry about the handle_percpu_irq being called before the IRQ action
handler has been installed.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The HVCS driver, for those who don't know, is a driver for the "server" side
of the IBM virtual terminal mechanism allowing Linux partitions to act as
terminal servers under IBM PowerVM hypervisor. It's almost never used on
the field at the moment.
However, it's part of our configs, and in its current incarnation, will
allocate the tty driver & major (with 64 minors) and create a kernel thread
whether it's used or not, ie, whether the hypervisor did put a virtual
terminal server device node in the partition or not (or whether running on
a pseries machine or not even).
This in turns causes modern distro's udev's to start trying to open all
those 64 minors at boot, which, since they aren't linked to anything,
causes the driver to spew errors in the kernel log for each of them.
Not nice.
This moves all that initialization to a function which is now only called
the first time a terminal server virtual IO device is actually probed
(that is almost never).
There's still a _LOT_ of cleanup that can be done in this driver, some
simple (almost all printk's statements in there shall either just be
removed or in some case turned into better written & more informative
messages, including using the dev_* variants etc...). This is left as
an exercise for whoever actually cares about that driver.
One could also try to be smart and dispose of all the tty related
resources when the last instance of the VIO server device
is removed (Hotplug anybody ?).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The Kconfig options for the drivers/tty/ files still were hanging around
in the "big" drivers/char/Kconfig file, so move them to the proper
location under drivers/tty and drivers/tty/hvc/
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Doing tiocmget was such fun we should do tiocmset as well for the same
reasons
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
We don't actually need this and it causes problems for internal use of
this functionality. Currently there is a single use of the FILE * pointer.
That is the serial core which uses it to check tty_hung_up_p. However if
that is true then IO_ERROR is also already set so the check may be removed.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This converts the existing bfin_jtag_comm TTY driver to the HVC layer so
that the common HVC code can worry about all of the TTY/polling crap and
leave the Blackfin code to worry about the Blackfin bits.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The inline assembly differences for v6 vs. v7 in the hvc_dcc
driver are purely optimizations. On a v7 processor, an mrc with
the pc sets the condition codes to the 28-31 bits of the register
being read. It just so happens that the TX/RX full bits the DCC
driver is testing for are high enough in the register to be put
into the condition codes. On a v6 processor, this "feature" isn't
implemented and thus we have to do the usual read, mask, test
operations to check for TX/RX full.
Since we already test the RX/TX full bits before calling
__dcc_getchar() and __dcc_putchar() we don't actually need to do
anything special for v7 over v6. The only difference is in
hvc_dcc_get_chars(). We would test RX full, poll RX full, and
then read a character from the buffer, whereas now we will test
RX full, read a character from the buffer, and then test RX full
again for the second iteration of the loop. It doesn't seem
possible for the buffer to go from full to empty between testing
the RX full and reading a character. Therefore, replace the v7
versions with the v6 versions and everything works the same.
Acked-by: Tony Lindgren <tony@atomide.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Daniel Walker <dwalker@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Casting and anding with 0xff is unnecessary in
hvc_dcc_put_chars() since buf is already a char[].
__dcc_get_char() can't return an int less than 0 since it only
returns a char. Simplify the if statement in hvc_dcc_get_chars()
to take this into account.
Cc: Daniel Walker <dwalker@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Without marking the asm __dcc_getstatus() volatile my compiler
decides it can cache the value of __ret in a register and then
check the value of it continually in hvc_dcc_put_chars() (I had
to replace get_wait/put_wait with 1 and fixup the branch
otherwise my disassembler barfed on __dcc_(get|put)char).
00000000 <hvc_dcc_put_chars>:
0: ee103e11 mrc 14, 0, r3, cr0, cr1, {0}
4: e3a0c000 mov ip, #0 ; 0x0
8: e2033202 and r3, r3, #536870912 ; 0x20000000
c: ea000006 b 2c <hvc_dcc_put_chars+0x2c>
10: e3530000 cmp r3, #0 ; 0x0
14: 1afffffd bne 10 <hvc_dcc_put_chars+0x10>
18: e7d1000c ldrb r0, [r1, ip]
1c: ee10fe11 mrc 14, 0, pc, cr0, cr1, {0}
20: 2afffffd bcs 1c <hvc_dcc_put_chars+0x1c>
24: ee000e15 mcr 14, 0, r0, cr0, cr5, {0}
28: e28cc001 add ip, ip, #1 ; 0x1
2c: e15c0002 cmp ip, r2
30: bafffff6 blt 10 <hvc_dcc_put_chars+0x10>
34: e1a00002 mov r0, r2
38: e12fff1e bx lr
As you can see, the value of the mrc is checked against
DCC_STATUS_TX (bit 29) and then stored in r3 for later use.
Marking the asm volatile produces the following:
00000000 <hvc_dcc_put_chars>:
0: e3a03000 mov r3, #0 ; 0x0
4: ea000007 b 28 <hvc_dcc_put_chars+0x28>
8: ee100e11 mrc 14, 0, r0, cr0, cr1, {0}
c: e3100202 tst r0, #536870912 ; 0x20000000
10: 1afffffc bne 8 <hvc_dcc_put_chars+0x8>
14: e7d10003 ldrb r0, [r1, r3]
18: ee10fe11 mrc 14, 0, pc, cr0, cr1, {0}
1c: 2afffffd bcs 18 <hvc_dcc_put_chars+0x18>
20: ee000e15 mcr 14, 0, r0, cr0, cr5, {0}
24: e2833001 add r3, r3, #1 ; 0x1
28: e1530002 cmp r3, r2
2c: bafffff5 blt 8 <hvc_dcc_put_chars+0x8>
30: e1a00002 mov r0, r2
34: e12fff1e bx lr
which looks better and actually works. Mark all the inline
assembly in this file as volatile since we don't want the
compiler to optimize away these statements or move them around
in any way.
Acked-by: Tony Lindgren <tony@atomide.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Daniel Walker <dwalker@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Commit 728674a7e4 moved virtio_console.c
to drivers/tty/hvc/ under the perception of this being an hvc driver.
It was such once, but these days it has generic communication
capabilities as well, so move it to drivers/char/.
In the future, the hvc part from this file can be split off and moved
under drivers/tty/hvc/.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
As requested by Arnd Bergmann, the hvc drivers are now
moved to the drivers/tty/hvc/ directory. The virtio_console.c driver
was also moved, as it required the hvc_console.h file to be able to be
built, and it really is a hvc driver.
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
