This patch fixes the broken serial log when changing the clock source
of uart device. Before disabling the original clock source, this patch
enables the new clock source to protect the clock off state for a split second.
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This makes the ath79 bootconsole behave the same way as the generic 8250
bootconsole.

Also waiting for TEMT (transmit buffer is empty) instead of just THRE
(transmit buffer is not full) ensures that all characters have been
transmitted before the real serial driver starts reconfiguring the serial
controller (which would sometimes result in garbage being transmitted.)
This change does not cause a visible performance loss.

In addition, this seems to fix a hang observed in certain configurations on
many AR7xxx/AR9xxx SoCs during autoconfig of the real serial driver.

A more complete follow-up patch will disable 8250 autoconfig for ath79
altogether (the serial controller is detected as a 16550A, which is not
fully compatible with the ath79 serial, and the autoconfig may lead to
undefined behavior on ath79.)

Cc: <stable@vger.kernel.org>
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The msm_find_best_baud() function is written with the assumption
that the port->uartclk rate is fixed to a particular rate at boot
time, but now this driver changes that clk rate at runtime when
the baud is changed.

The way the hardware works is that an input clk rate comes from
the clk controller into the uart hw block. That rate is typically
1843200 or 3686400 Hz. That rate can then be divided by an
internal divider in the hw block to achieve a particular baud on
the serial wire. msm_find_best_baud() is looking for that divider
value.

A few things are wrong with the way the code is written. First,
it assumes that the maximum baud that the uart can support if the
clk rate is fixed at boot is 460800, which would correspond to an
input clk rate of 230400 * 16 == 3686400 Hz.  Except some devices
have a boot rate of 1843200 Hz or max baud of 115200, so
achieving 230400 on those devices doesn't work at all because we
don't increase the clk rate unless max baud is 460800.

Second, we can't achieve bauds higher than 460800 that require
anything besides a divisor of 1, because we always call
msm_find_best_baud() with a fixed port->uartclk rate that will
eventually be changed after we calculate the divisor. So if we
need to get a baud of 500000, we'll just multiply that by 16 and
hope that the clk can give us 500000 * 16 == 8000000 Hz, which it
typically can't do. To really achieve 500000 baud, we need to get
an input clk rate of 24000000 Hz and then divide that by 3 inside
the uart hardware.

Finally, we return success for bauds even when we can't actually
achieve them. This means that when the user asks for 500000 baud,
we actually get 921600 right now, but the user doesn't know that.

Fix all of this by searching through the divisor and clk rate
space with a combination of clk_round_rate() and baud
calculations, keeping track of the best clk rate and divisor we
find if we can't get an exact match. Typically we can get an
exact match with a divisor of 1, but sometimes we need to keep
track and try more frequencies. On my msm8916 device, this
results in all standard bauds in baud_table being supported
except for 1800, 576000, 1152000, and 4000000.

Fixes: 850b37a7 ("tty: serial: msm: Remove 115.2 Kbps maximum baud rate limitation")
Cc: "Ivan T. Ivanov" <iivanov.xz@gmail.com>
Cc: Matthew McClintock <mmcclint@codeaurora.org>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Andy Gross <andy.gross@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Cristian Prundeanu <cprundea@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Enable reporting of DSR events (which is named DTR in the registers
because Freescale uses the names as seem from a DCE).
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

According to tty_ioctl(4) (from man-pages 4.04) the rng member only
counts 0->1 transitions. For the other signals (DSR, CD, CTS) both edges
are supposed to be counted.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure that events that are not handled in the irq function don't
trigger an interrupt.

When the serial port is operated in DTE mode, the events for DCD and RI
events are enabled after a system reset by default.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This gives the irq core a chance to disable the serial interrupt in case
an event isn't cleared in the handler.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When in DTE mode, the bit USR2_RIIN is active low. So invert the logic
accordingly.

Fixes: 90ebc483 ("serial: imx: repair and complete handshaking")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add __init attribute on a function that is only called from other __init
functions and that is not inlined, at least with gcc version 4.8.4 on an
x86 machine with allyesconfig.  Currently, the function is put in the
.text.unlikely segment.  Declaring it as __init will cause it to be put in
the .init.text and to disappear after initialization.

The result of objdump -x on the function before the change is as follows:

000000000000014c l     F .text.unlikely 0000000000000a2e init_r_port

And after the change it is as follows:

0000000000000000 l     F .init.text	0000000000000a29 init_r_port

Done with the help of Coccinelle.  The semantic patch checks for local
static non-init functions that are called from an __init function and are
not called from any other function.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Alphascale ASM9260 uart IP has some common registers with
Freescale STMP37XX. This patch provide changes which
allow to reuse mxs-auart.c code for ASM9260.
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

SC16is7xx has feature for auto hardware flow control using RTS/CTS,
so we don't need "uart_handle_cts_change" to invoke "start_tx/stop_tx"
for flow control.

In addition, for software CTS, interrupt "SC16IS7XX_IIR_CTSRTS_SRC"
just report the nCTS change of state from active(low) to inactive(high),
driver don't know when the state of nCTS change from incactive to active,
so can't resume the transmission when a peer device is again ready and
re-assert nRTS signal.
Signed-off-by: Wills Wang <wills.wang@live.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Some RS-232 to RS-485 transceivers require Rx to be disabled on Tx to
avoid echo of Tx data into the Rx buffer. Specifically, the XR3160E
RS-232/RS-485/RS-422 transceiver behaves this way.

This commit disables Rx on active Tx when SER_RS485_ENABLED is active and
SER_RS485_RX_DURING_TX is disabled.

Note that this is a change in behavior of the driver. Until now
SER_RS485_RX_DURING_TX was enabled unconditionally even when disabled in
the TIOCSRS485 ioctl serial_rs485 flags field.

Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Enabling support for the UART on Marvell EBU SoCs only make sense when
compiling for Marvell EBU SoCs, unless compile-testing.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The Kconfig currently controlling compilation of this code is:

drivers/tty/serial/Kconfig:config SERIAL_MVEBU_UART
drivers/tty/serial/Kconfig:     bool "Marvell EBU serial port support"

...meaning that it currently is not being built as a module by anyone.

Lets remove the modular code that is essentially orphaned, so that
when reading the driver there is no doubt it is builtin-only.

We explicitly disallow a driver unbind, since that doesn't have a
sensible use case anyway, and it allows us to drop the ".remove"
code for non-modular drivers.

Since the code wasn't using module_init to begin with, the init ordering
remains unchanged with this commit.

Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.

We also delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.

Cc: Wilson Ding <dingwei@marvell.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

No need to set .owner here. The core will do it.

Generated by: scripts/coccinelle/api/platform_no_drv_owner.cocci

CC: Wilson Ding <dingwei@marvell.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Split off the bulk of the existing meson_serial_console_write()
implementation into meson_serial_port_write() for implementing
meson_serial_early_console_write().

Use "meson" as the earlycon driver name, courtesy of Nicolas.
Signed-off-by: Nicolas Saenz Julienne <nicolassaenzj@gmail.com>
Acked-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The issue with setting up a fixed clock rate at probe is that it would
overwrite the console rate set by the bootloader for its console device.
This would result in serial out corruption or missing log when we system
is booted with earlycon. This is not a issue if we boot system without
earlycon.

This setup is at least not required with the mainline driver, this code
used to be required because the clk_enable() call would fail if
clk_set_rate() wasn't called first.

Originally the issue was noticed on DB410c which is based on APQ8016
chipset.

Without this patch the console log with earlycon would look like:
...
[    0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=64, nr_cpu_ids=1
[    0.000000] NR_IRQS:64 nr_irqs:64 0
����+HH��0.699378] console [ttyMSM0] enabled
[    0.699378] console [ttyMSM0] enabled
[    0.702003] bootconsole [uart0] disabled
[    0.702003] bootconsole [uart0] disabled
...

with this patch I can see all the skipped lines on the console
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Andy Gross <andy.gross@linaro.org>
Tested-by: Pramod Gurav <gpramod@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

noctty was removed as a parameter by commit 11e1d4aa
("tty: Consolidate noctty check in tty_open()").
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

TTY_NUMBER() has been unused since v2.5.71; removed by
"[PATCH] callout removal: callout is gone".
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For tty operations which may expect uart port to have been removed
but still have other necessary work to accomplish, check for NULL
uart port; specifically uart_close(), uart_hangup() and sub-functions
(uart_shutdown() and uart_port_shutdown()).
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg 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: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

uart_remove_one_port() may race with every serial core operation
requiring a valid dereference of state->uart_port. In particular,
uart_remove_one_port() may unlink the uart port concurrently with
any serial core operation that may dereference same.

Ensure safe dereference for those operations that already claim
the port->mutex, and extend that guarantee for trivial cases,
such as the ioctl handlers. Introduce the uart_port_check() helper
which asserts port->mutex is held (only when lockdep is on).

For ioctls, return -EIO as if the port has been hung up (since it has).
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Prepare uart_poll_init() to safely dereference uart port; expand the
port mutex section to guarantee uart port remains valid until
uart_poll_init() completes.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Purposefully break out-of-tree driver compiles using kernel
ASYNC_* bits which have been superceded by TTY_PORT* flags and
their respective helper functions.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ASYNC*_SHARE_IRQ is no longer used; remove.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace ASYNC_INITIALIZED bit in the tty_port::flags field with
TTY_PORT_INITIALIZED bit in the tty_port::iflags field. Introduce helpers
tty_port_set_initialized() and tty_port_initialized() to abstract
atomic bit ops.

Note: the transforms for test_and_set_bit() and test_and_clear_bit()
are unnecessary as the state transitions are already mutually exclusive;
the tty lock prevents concurrent open/close/hangup.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace ASYNC_SUSPENDED bit in the tty_port::flags field with
TTY_PORT_SUSPENDED bit in the tty_port::iflags field. Introduce helpers
tty_port_set_suspended() and tty_port_suspended() to abstract
atomic bit ops.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace ASYNC_CHECK_CD bit in the tty_port::flags field with
TTY_PORT_CHECK_CD bit in the tty_port::iflags field. Introduce helpers
tty_port_set_check_carrier() and tty_port_check_carrier() to abstract
the atomic bit ops.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace ASYNC_NORMAL_ACTIVE bit in the tty_port::flags field with
TTY_PORT_ACTIVE bit in the tty_port::iflags field. Introduce helpers
tty_port_set_active() and tty_port_active() to abstract atomic bit ops.

Extract state changes from port lock sections, as this usage is
broken and confused; the state transitions are protected by the
tty lock (which mutually excludes parallel open/close/hangup),
and no user tests the active state while holding the port lock.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace ASYNC_CTS_FLOW bit in the tty_port::flags field with
TTY_PORT_CTS_FLOW bit in the tty_port::iflags field. Add
tty_port_set_cts_flow() helper to abstract the atomic bit ops.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Prepare for relocating kernel private state bits out of tty_port::flags
field; tty_port::flags field is not atomic and can become corrupted
by concurrent updates. It also suffers from the complication of sharing
in a userspace-visible field which must be masked.

Define new tty_port::iflags field and new, substitute bit definitions
for the former ASYNC_* flags.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Abstract TTY_THROTTLED bit tests with tty_throttled().
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Abstract TTY_IO_ERROR status test treewide with tty_io_error().
NB: tty->flags uses atomic bit ops; replace non-atomic bit test
with test_bit().
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Version 2 of the Server Base System Architecture (SBSAv2) describes UART
hardware registers as 32 bits wide, giving no guidance on access sizes. The
SBSA UART driver previously assumed partial-length 16 and 8 bit accesses would
work. But the SBSAv2 UART hardware on the Qualcomm Technologies QDF2432 only
supports full-length 32 bit register accesses, so use those exclusively. This
is compatible with SBSAv3, which explicitly requires UART hardware support 32
(and 16 and sometimes 8) bit accesses.

Tested on Juno, Midway, QDF2432, Seattle, and X-Gene 1.
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 1cf6e8fc ("tty/serial: at91: fix RTS line management when
hardware handshake is enabled") actually allowed to enable hardware
handshaking.
Before, the CRTSCTS flags was silently ignored.

As the DMA controller can't drive RTS (as explain in the commit message).
Ensure that hardware flow control stays disabled when DMA is used and FIFOs
are not available.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Fixes: 1cf6e8fc ("tty/serial: at91: fix RTS line management when hardware handshake is enabled")
Cc: stable <stable@vger.kernel.org> # v4.0+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Dmitry reported, that the current cleanup code in n_gsm can trigger a
warning:
WARNING: CPU: 2 PID: 24238 at drivers/tty/n_gsm.c:2048 gsm_cleanup_mux+0x166/0x6b0()
...
Call Trace:
...
 [<ffffffff81247ab9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:490
 [<ffffffff828d0456>] gsm_cleanup_mux+0x166/0x6b0 drivers/tty/n_gsm.c:2048
 [<ffffffff828d4d87>] gsmld_open+0x5b7/0x7a0 drivers/tty/n_gsm.c:2386
 [<ffffffff828b9078>] tty_ldisc_open.isra.2+0x78/0xd0 drivers/tty/tty_ldisc.c:447
 [<ffffffff828b973a>] tty_set_ldisc+0x1ca/0xa70 drivers/tty/tty_ldisc.c:567
 [<     inline     >] tiocsetd drivers/tty/tty_io.c:2650
 [<ffffffff828a14ea>] tty_ioctl+0xb2a/0x2140 drivers/tty/tty_io.c:2883
...

But this is a legal path when open fails to find a space in the
gsm_mux array and tries to clean up. So make it a standard test
instead of a warning.
Reported-by: "Dmitry Vyukov" <dvyukov@google.com>
Cc: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/CACT4Y+bHQbAB68VFi7Romcs-Z9ZW3kQRvcq+BvHH1oa5NcAdLA@mail.gmail.com
Fixes: 5a640967 ("tty/n_gsm.c: fix a memory leak in gsmld_open()")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since commit 21947ba6 ("serial: 8250_pci: replace switch-case by
formula"), the 8250 driver crashes in the byt_set_termios() function
with a divide error. This is caused by the fact that a baud rate of 0 (B0)
is not handled properly. Fix it by falling back to B9600 in this case.
Signed-off-by: David Müller <d.mueller@elsoft.ch>
Fixes: 21947ba6 ("serial: 8250_pci: replace switch-case by formula")
Cc: stable@vger.kernel.org
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>