Right now serial drivers process sysrq keys deep in their character
receiving code.  This means that they've already grabbed their
port->lock spinlock.  This can end up getting in the way if we've go
to do serial stuff (especially kgdb) in response to the sysrq.

Serial drivers have various hacks in them to handle this.  Looking at
'8250_port.c' you can see that the console_write() skips locking if
we're in the sysrq handler.  Looking at 'msm_serial.c' you can see
that the port lock is dropped around uart_handle_sysrq_char().

It turns out that these hacks aren't exactly perfect.  If you have
lockdep turned on and use something like the 8250_port hack you'll get
a splat that looks like:

  WARNING: possible circular locking dependency detected
  [...] is trying to acquire lock:
  ... (console_owner){-.-.}, at: console_unlock+0x2e0/0x5e4

  but task is already holding lock:
  ... (&port_lock_key){-.-.}, at: serial8250_handle_irq+0x30/0xe4

  which lock already depends on the new lock.

  the existing dependency chain (in reverse order) is:

  -> #1 (&port_lock_key){-.-.}:
         _raw_spin_lock_irqsave+0x58/0x70
         serial8250_console_write+0xa8/0x250
         univ8250_console_write+0x40/0x4c
         console_unlock+0x528/0x5e4
         register_console+0x2c4/0x3b0
         uart_add_one_port+0x350/0x478
         serial8250_register_8250_port+0x350/0x3a8
         dw8250_probe+0x67c/0x754
         platform_drv_probe+0x58/0xa4
         really_probe+0x150/0x294
         driver_probe_device+0xac/0xe8
         __driver_attach+0x98/0xd0
         bus_for_each_dev+0x84/0xc8
         driver_attach+0x2c/0x34
         bus_add_driver+0xf0/0x1ec
         driver_register+0xb4/0x100
         __platform_driver_register+0x60/0x6c
         dw8250_platform_driver_init+0x20/0x28
	 ...

  -> #0 (console_owner){-.-.}:
         lock_acquire+0x1e8/0x214
         console_unlock+0x35c/0x5e4
         vprintk_emit+0x230/0x274
         vprintk_default+0x7c/0x84
         vprintk_func+0x190/0x1bc
         printk+0x80/0xa0
         __handle_sysrq+0x104/0x21c
         handle_sysrq+0x30/0x3c
         serial8250_read_char+0x15c/0x18c
         serial8250_rx_chars+0x34/0x74
         serial8250_handle_irq+0x9c/0xe4
         dw8250_handle_irq+0x98/0xcc
         serial8250_interrupt+0x50/0xe8
         ...

  other info that might help us debug this:

   Possible unsafe locking scenario:

         CPU0                    CPU1
         ----                    ----
    lock(&port_lock_key);
                                 lock(console_owner);
                                 lock(&port_lock_key);
    lock(console_owner);

   *** DEADLOCK ***

The hack used in 'msm_serial.c' doesn't cause the above splats but it
seems a bit ugly to unlock / lock our spinlock deep in our irq
handler.

It seems like we could defer processing the sysrq until the end of the
interrupt handler right after we've unlocked the port.  With this
scheme if a whole batch of sysrq characters comes in one irq then we
won't handle them all, but that seems like it should be a fine
compromise.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit c550f01c.

Turns out the samsung tty driver is mucking around in the "unused" port
fields and this patch breaks that code :(

So we need to fix that driver up before this can be accepted.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Steve Sakoman <steve@sakoman.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add the ISO7816 ioctl and associated accessors and data structure.
Drivers can then use this common implementation to handle ISO7816
(smart cards).
Signed-off-by: NNicolas Ferre <nicolas.ferre@microchip.com>
[ludovic.desroches@microchip.com: squash and rebase, removal of gpios, checkpatch fixes]
Signed-off-by: NLudovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add a "pps_4wire" file to serial ports in sysfs in case the kernel is
configured with CONFIG_PPS_CLIENT_LDISC. Writing 1 to the file enables
the use of CTS instead of DCD for PPS signal input. This is necessary
in case a serial port is not completely wired.
Though this affects PPS processing the patch is against the serial core
as the source of the serial port PPS event dispatching has to be
modified. Furthermore it should be possible to modify the source of
serial port PPS event dispatching before changing the line discipline.
Signed-off-by: NAndreas Steinmetz <ast@domdv.de>
Signed-off-by: NSteve Sakoman <steve@sakoman.com>
Tested-by: NSteve Sakoman <steve@sakoman.com>
Tested-by: NEric Gallimore <egallimore@ucsd.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add these two hooks so that they can be overridden with driver specific
implementations.
Signed-off-by: NJisheng Zhang <Jisheng.Zhang@synaptics.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As part of bringup I ended up wanting to call an earlycon driver by a
name that was exactly 16-bytes big, specifically "qcom_geni_serial".

Unfortunately, when I tried this I found that things compiled just
fine.  They just didn't work.

Specifically the compiler felt perfectly justified in initting the
".name" field of "struct earlycon_id" with the full 16-bytes and just
skipping the '\0'.  Needless to say, that behavior didn't seem ideal,
but I guess someone must have allowed it for a reason.

One way to fix this is to shorten the name field to 15 bytes and then
add an extra byte after that nobody touches.  This should always be
initted to 0 and we're golden.

There are, of course, other ways to fix this too.  We could audit all
the users of the "name" field and make them stop at both null
termination or at 16 bytes.  We could also just make the name field
much bigger so that we're not likely to run into this.  ...but both
seem like we'll just hit the bug again.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This change adds a flag to indicate that a UART is has an external means
of synchronising its FIFO, without needing CTSRTS or XON/XOFF.

This allows us to use the throttle/unthrottle callbacks, without having
to claim other methods of flow control.
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Tested-by: NEddie James <eajames@linux.vnet.ibm.com>
Tested-by: NJoel Stanley <joel@jms.id.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 99492c39 ("earlycon: Fix __earlycon_table stride") tried to fix
__earlycon_table stride by forcing the earlycon_id struct alignment to 32
and asking the linker to 32-byte align the __earlycon_table symbol.  This
fix was based on commit 07fca0e5 ("tracing: Properly align linker
defined symbols") which tried a similar fix for the tracing subsystem.

However, this fix doesn't quite work because there is no guarantee that
gcc will place structures packed into an array format.  In fact, gcc 4.9
chooses to 64-byte align these structs by inserting additional padding
between the entries because it has no clue that they are supposed to be in
an array.  If we are unlucky, the linker will assign symbol
"__earlycon_table" to a 32-byte aligned address which does not correspond
to the 64-byte aligned contents of section "__earlycon_table".

To address this same problem, the fix to the tracing system was
subsequently re-implemented using a more robust table of pointers approach
by commits:
 3d56e331 ("tracing: Replace syscall_meta_data struct array with pointer array")
 65498646 ("tracepoints: Fix section alignment using pointer array")
 e4a9ea5e ("tracing: Replace trace_event struct array with pointer array")

Let's use this same "array of pointers to structs" approach for
EARLYCON_TABLE.

Fixes: 99492c39 ("earlycon: Fix __earlycon_table stride")
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Suggested-by: NAaron Durbin <adurbin@chromium.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Tested-by: NGuenter Roeck <groeck@chromium.org>
Reviewed-by: NGuenter Roeck <groeck@chromium.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Re-use the object-like macro EARLYCON_USED_OR_UNUSED to mark
`earlycon_acpi_spcr_enable` as maybe_unused.

Fix the following warning (treated as error in W=1)

  CC      arch/powerpc/kernel/setup-common.o
In file included from ./include/linux/serial_8250.h:14:0,
                 from arch/powerpc/kernel/setup-common.c:33:
./include/linux/serial_core.h:382:19: error: ‘earlycon_acpi_spcr_enable’ defined but not used [-Werror=unused-const-variable=]
 static const bool earlycon_acpi_spcr_enable;
                   ^~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Signed-off-by: NMathieu Malaterre <malat@debian.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

SPCR is currently only enabled or ARM64 and x86 can use SPCR to setup
an early console.

General fixes include updating Documentation & Kconfig (for x86),
updating comments, and changing parse_spcr() to acpi_parse_spcr(),
and earlycon_init_is_deferred to earlycon_acpi_spcr_enable to be
more descriptive.

On x86, many systems have a valid SPCR table but the table version is
not 2 so the table version check must be a warning.

On ARM64 when the kernel parameter earlycon is used both the early console
and console are enabled.  On x86, only the earlycon should be enabled by
by default.  Modify acpi_parse_spcr() to allow options for initializing
the early console and console separately.
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Reviewed-by: NMark Salter <msalter@redhat.com>
Tested-by: NMark Salter <msalter@redhat.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The pointed string is never modified from within uart_parse_options, so
it should be marked as const in the function prototype.
Signed-off-by: NPaul Cercueil <paul@crapouillou.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit ef838a81 ("serial: Add common rs485 device tree parsing
function") consolidated retrieval of rs485 OF properties in a common
helper function but did not #ifdef it to CONFIG_OF.  The function is
therefore included on ACPI platforms as well even though it's not used.

On the other hand ACPI platforms with rs485 do exist (e.g. Siemens
IOT2040) and they may leverage _DSD to store rs485 properties.  Likewise,
UART platform devices instantiated from an MFD should be able to specify
rs485 properties.  In fact, the tty subsystem maintainer had asked for
a "generic" function during review of commit ef838a81:
https://marc.info/?l=linux-serial&m=150143441725194&w=4

Thus, instead of constraining the helper to OF platforms, make it
platform-agnostic by converting it to device_property_*() functions
and renaming it accordingly.

In imx.c, move the invocation of uart_get_rs485_mode() from
serial_imx_probe_dt() to serial_imx_probe() so that it also gets called
for non-OF devices.

In omap-serial.c, move its invocation further up within
serial_omap_probe_rs485() so that the RTS polarity can be overridden
with the driver-specific "rs485-rts-active-high" property once we
introduce a generic "rs485-rts-active-low" property.

Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Several drivers have the same device tree parsing code. Create
a common helper function for it.

This patch bases on work done by Sascha Hauer.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no need to duplicate a flag which IRQ core takes care of.

Replace custom flag by IRQ core API that retrieves its state.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

First 16 bits in the flags field are user-visible except
UPF_NO_TXEN_TEST. To keep it clean we introduce internal quirks and move
UPF_NO_TXEN_TEST to them. Rename the constant to UPQ_NO_TXEN_TEST to
distinguish with port flags. Users are converted accordingly.

The quirks field might be extended later to hold the additional ones.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The probing of THRE irq behaviour assumes the other end will be reading
bytes out of the buffer in order to probe the port at driver init. In
some cases the other end cannot be relied upon to read these bytes, so
provide a flag for them to skip this step.

Bit 19 was chosen as the flags are a int and the top bits are taken.
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NJoel Stanley <joel@jms.id.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Don't allow modifications of port name. It's serial core's business only.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce a field to store name of uart_port that can be used to easily
identify UART port instances on a system that has more than one UART
instance. The name is of the form ttyXN(eg. ttyS0, ttyAMA0,..) where N
is number that particular UART instance.
This field will be useful when printing debug info for a particular port
or in register IRQs with unique IRQ name. Port name is populated during
uart_add_one_port().
Signed-off-by: NVignesh R <vigneshr@ti.com>
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

many embedded boards have a disconnected TTL level serial which can
generate some garbage that can lead to spurious false sysrq detects.
Signed-off-by: NJohn Crispin <john@phrozen.org>
Signed-off-by: NFelix Fietkau <nbd@nbd.name>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

__bitwise__ used to mean "yes, please enable sparse checks
unconditionally", but now that we dropped __CHECK_ENDIAN__
__bitwise is exactly the same.
There aren't many users, replace it by __bitwise everywhere.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NStefan Schmidt <stefan@osg.samsung.com>
Acked-by: NKrzysztof Kozlowski <krzk@kernel.org>
Akced-by: NLee Duncan <lduncan@suse.com>

Expose set_ldisc() function so that it can be overridden with a
platform specific implementation.
Signed-off-by: NEd Blake <ed.blake@imgtec.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

'ARM Server Base Boot Requiremets' [1] mentions SPCR (Serial Port
Console Redirection Table) [2] as a mandatory ACPI table that
specifies the configuration of serial console.

Defer initialization of DT earlycon until ACPI/DT decision is made.

Parse the ACPI SPCR table, setup earlycon if required,
enable specified console.

Thanks to Peter Hurley for explaining how this should work.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0044a/index.html
[2] https://msdn.microsoft.com/en-us/library/windows/hardware/dn639132(v=vs.85).aspxSigned-off-by: NAleksey Makarov <aleksey.makarov@linaro.org>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Tested-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: NChristopher Covington <cov@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 761ed4a9 ("tty: serial_core: convert uart_close to use
tty_port_close") created a case where a port used for a console does not
get shutdown on tty closing. Then a call to uart_tx_stopped() segfaults
because the tty is NULL. This could be fixed to restore old behavior,
but we also want to allow tty_ports to work without a tty attached. So
this change to allow a NULL tty_struct is needed either way.

Fixes: 761ed4a9 ("tty: serial_core: convert uart_close to use tty_port_close")
Reported-by: Nkernel test robot <xiaolong.ye@intel.com>
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

earlycon implementation used "unsigned long" internally, but there are systems
(ARM with LPAE) where sizeof(unsigned long) == 4 and uart is mapped beyond 4GiB
address range.

Switch to resource_size_t internally and replace obsoleted simple_strtoul() with
kstrtoull().
Signed-off-by: NAlexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Keep earlycon related symbols only when CONFIG_SERIAL_EARLYCON is
enabled and the driver is built-in.  This will be helpful to clean
up ifdefs surrounding earlycon code in serial drivers.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Exposes get_mctrl() function so that it can be overriden with platform
specific implementation.
Signed-off-by: NWan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

For serial core operations not already excluded by holding port->mutex,
use reference counting to protect deferencing the state->uart_port.

Introduce helper functions, uart_port_ref() and uart_port_deref(), to
wrap uart_port access, and helper macros, uart_port_lock() and
uart_port_unlock(), to wrap combination uart_port access with uart
port lock sections.

Port removal in uart_remove_one_port() waits for reference count to
drop to zero before detaching the uart port from struct uart_state.

For functions only reading the tx circular buffer indexes (where the
uart port lock is claimed to prevent concurrent users), a NULL uart
port is simply ignored and the operation completes normally.

For functions change the tx circular buffer indexes (where the uart
port lock is claimed to prevent concurrent users), the operation is
aborted if the uart port is NULL (ie., has been detached).
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Cleanup the early DT/earlycon separation; remove the 'addr' parameter
from of_setup_earlycon() and get the uart phys addr directly with a
new wrapper function, of_flat_dt_translate_addr(). Limit
fdt_translate_address() to file scope.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Read the optional "reg-offset", "reg-shift", "reg-io-width" and endianness
properties and initialize the respective struct uart_port field if found.

NB: These bindings are common to several drivers and the values merely
indicate the default value; the registering earlycon setup() method can
simply override the values if required.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Pass-through any options string in the 'stdout-path' property to the
earlycon "driver" setup.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use the console name embedded in the OF earlycon table by the
OF_EARLYCON_DECLARE() macro to initialize the struct console 'name'
and 'index' fields.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use a single common table of struct earlycon_id for both command line
and devicetree. Re-define OF_EARLYCON_DECLARE() macro to instance a
unique earlycon declaration (the declaration is only guaranteed to be
unique within a compilation unit; separate compilation units must still
use unique earlycon names).

The semantics of OF_EARLYCON_DECLARE() is different; it declares an
earlycon which can matched either on the command line or by devicetree.
EARLYCON_DECLARE() is semantically unchanged; it declares an earlycon
which is matched by command line only. Remove redundant instances of
EARLYCON_DECLARE().

This enables all earlycons to properly initialize struct console
with the appropriate name and index, which improves diagnostics and
enables direct earlycon-to-console handoff.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The original semantics of UPIO_MEM did not include the notion of bitness
and endianness; different drivers used UPIO_MEM to refer to their original
mmio bitness/endianness. For example, for the 8250 driver this is 8-bit LE
but for the amba-pl011 driver this is 16-bit LE. Since UPIO_* values are
userspace ABI via TIOCGSERIAL/TIOCSSERIAL ioctls, the original meaning of
UPIIO_MEM must remain as it was: the original mmio stride/width/endianness
of the driver.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Acked-by: NTimur Tabi <timur@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, 8-bit (MMIO) and 32-bit (MMIO32) register interfaces are
supported for the 8250 console, but the 16-bit (MMIO16) is not.
The 8250 UART device on my board is connected to a 16-bit bus and
my main motivation is to use earlycon with it.
(Refer to arch/arm/boot/dts/uniphier-support-card.dtsi)
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If CONFIG_SERIAL_CORE_CONSOLE=n, build warnings are generated by
uart_console() macro expansion:

drivers/tty/serial/of_serial.c: In function ‘of_serial_suspend_8250’:
drivers/tty/serial/of_serial.c:262:20: warning: unused variable ‘port’ [-Wunused-variable]
  struct uart_port *port = &port8250->port;
                    ^
drivers/tty/serial/of_serial.c: In function ‘of_serial_resume_8250’:
drivers/tty/serial/of_serial.c:272:20: warning: unused variable ‘port’ [-Wunused-variable]
  struct uart_port *port = &port8250->port;
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The compiler and the linker must agree on the alignment of
struct earlycon_id; empirical testing and commit 07fca0e5
("tracing: Properly align linker defined symbols") suggests
32-byte alignment is the LCD.
Reported-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This adds a mapsize field to struct uart_port to be used in
conjunction with mapbase. If set, it overrides whatever value
serial8250_port_size() would otherwise report.
Signed-off-by: NMans Rullgard <mans@mansr.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Earlycon matching can only be triggered if 'earlycon=...' has been
specified on the kernel command line. To workaround this limitation
requires tight coupling between arches and specific serial drivers
in order to start an earlycon. Devicetree avoids this limitation
with a link table that contains the required data to match earlycons.

Mirror this approach for earlycon match by name. Re-purpose
EARLYCON_DECLARE to generate a table entry which associates name with
setup() function. Re-purpose setup_earlycon() to scan this table for
an earlycon match, which is registered if found.

Declare one "earlycon" early_param, which calls setup_earlycon().

This design allows setup_earlycon() to be called directly with a
param string (as if 'earlycon=...' had been set on the command line).
Re-registration (either directly or by early_param) is prevented.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

UART drivers that share ttyS namespace cannot trivially compute the
ttyS index from the port->line value since the minor_start may be
offset from minor 64. Further, to do so requires a pointer to the
uart driver since there is no back pointer from uart_port to
uart_driver.

Rather than have UART drivers computing the minor value by themselves,
encapsulate within the serial core at port registration time.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Prepare to support console-defined matching; refactor the command
line parameter string processing from parse_options() into a
new core function, uart_parse_earlycon(), which decodes command line
parameters of the form:
   earlycon=<name>,io|mmio|mmio32,<addr>,<options>
   console=<name>,io|mmio|mmio32,<addr>,<options>
   earlycon=<name>,0x<addr>,<options>
   console=<name>,0x<addr>,<options>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>