stable inclusion
from stable-v5.10.94
commit f0653cd4da669cbcddd81f8edd9f542805252691
bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f0653cd4da669cbcddd81f8edd9f542805252691

--------------------------------

[ Upstream commit 028e0838 ]

The UCR4_OREN should be disabled before disabling the uart receiver in
.stop_rx() instead of in the .shutdown().

Otherwise, if we have the overrun error during the receiver disable
process, the overrun interrupt will keep trigging until we disable the
OREN interrupt in the .shutdown(), because the ORE status can only be
cleared when read the rx FIFO or reset the controller.  Although the
called time between the receiver disable and OREN disable in .shutdown()
is very short, there is still the risk of endless interrupt during this
short period of time. So here change to disable OREN before the receiver
been disabled in .stop_rx().
Signed-off-by: NFugang Duan <fugang.duan@nxp.com>
Signed-off-by: NSherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20211125020349.4980-1-sherry.sun@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

stable inclusion
from stable-5.10.80
commit 068dfa570d8c36da0f1493d97695a04e8e84d8bd
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=068dfa570d8c36da0f1493d97695a04e8e84d8bd

--------------------------------

[ Upstream commit 6d0d1b5a ]

If the device used as a serial console gets detached/attached at runtime,
register_console() will try to call imx_uart_setup_console(), but this
is not possible since it is marked as __init.

For instance

  # cat /sys/devices/virtual/tty/console/active
  tty1 ttymxc0
  # echo -n N > /sys/devices/virtual/tty/console/subsystem/ttymxc0/console
  # echo -n Y > /sys/devices/virtual/tty/console/subsystem/ttymxc0/console

[   73.166649] 8<--- cut here ---
[   73.167005] Unable to handle kernel paging request at virtual address c154d928
[   73.167601] pgd = 55433e84
[   73.167875] [c154d928] *pgd=8141941e(bad)
[   73.168304] Internal error: Oops: 8000000d [#1] SMP ARM
[   73.168429] Modules linked in:
[   73.168522] CPU: 0 PID: 536 Comm: sh Not tainted 5.15.0-rc6-00056-g3968ddcf #3
[   73.168675] Hardware name: Freescale i.MX6 Ultralite (Device Tree)
[   73.168791] PC is at imx_uart_console_setup+0x0/0x238
[   73.168927] LR is at try_enable_new_console+0x98/0x124
[   73.169056] pc : [<c154d928>]    lr : [<c0196f44>]    psr: a0000013
[   73.169178] sp : c2ef5e70  ip : 00000000  fp : 00000000
[   73.169281] r10: 00000000  r9 : c02cf970  r8 : 00000000
[   73.169389] r7 : 00000001  r6 : 00000001  r5 : c1760164  r4 : c1e0fb08
[   73.169512] r3 : c154d928  r2 : 00000000  r1 : efffcbd1  r0 : c1760164
[   73.169641] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[   73.169782] Control: 10c5387d  Table: 8345406a  DAC: 00000051
[   73.169895] Register r0 information: non-slab/vmalloc memory
[   73.170032] Register r1 information: non-slab/vmalloc memory
[   73.170158] Register r2 information: NULL pointer
[   73.170273] Register r3 information: non-slab/vmalloc memory
[   73.170397] Register r4 information: non-slab/vmalloc memory
[   73.170521] Register r5 information: non-slab/vmalloc memory
[   73.170647] Register r6 information: non-paged memory
[   73.170771] Register r7 information: non-paged memory
[   73.170892] Register r8 information: NULL pointer
[   73.171009] Register r9 information: non-slab/vmalloc memory
[   73.171142] Register r10 information: NULL pointer
[   73.171259] Register r11 information: NULL pointer
[   73.171375] Register r12 information: NULL pointer
[   73.171494] Process sh (pid: 536, stack limit = 0xcd1ba82f)
[   73.171621] Stack: (0xc2ef5e70 to 0xc2ef6000)
[   73.171731] 5e60:                                     ???????? ???????? ???????? ????????
[   73.171899] 5e80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172059] 5ea0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172217] 5ec0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172377] 5ee0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172537] 5f00: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172698] 5f20: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.172856] 5f40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173016] 5f60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173177] 5f80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173336] 5fa0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173496] 5fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173654] 5fe0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.173826] [<c0196f44>] (try_enable_new_console) from [<c01984a8>] (register_console+0x10c/0x2ec)
[   73.174053] [<c01984a8>] (register_console) from [<c06e2c90>] (console_store+0x14c/0x168)
[   73.174262] [<c06e2c90>] (console_store) from [<c0383718>] (kernfs_fop_write_iter+0x110/0x1cc)
[   73.174470] [<c0383718>] (kernfs_fop_write_iter) from [<c02cf5f4>] (vfs_write+0x31c/0x548)
[   73.174679] [<c02cf5f4>] (vfs_write) from [<c02cf970>] (ksys_write+0x60/0xec)
[   73.174863] [<c02cf970>] (ksys_write) from [<c0100080>] (ret_fast_syscall+0x0/0x1c)
[   73.175052] Exception stack(0xc2ef5fa8 to 0xc2ef5ff0)
[   73.175167] 5fa0:                   ???????? ???????? ???????? ???????? ???????? ????????
[   73.175327] 5fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
[   73.175486] 5fe0: ???????? ???????? ???????? ????????
[   73.175608] Code: 00000000 00000000 00000000 00000000 (00000000)
[   73.175744] ---[ end trace 9b75121265109bf1 ]---

A similar issue could be triggered by unbinding/binding the serial
console device [*].

Drop __init so that imx_uart_setup_console() can be safely called at
runtime.

[*] https://lore.kernel.org/all/20181114174940.7865-3-stefan@agner.ch/

Fixes: a3cb39d2 ("serial: core: Allow detach and attach serial device for console")
Reviewed-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NFrancesco Dolcini <francesco.dolcini@toradex.com>
Link: https://lore.kernel.org/r/20211020192643.476895-2-francesco.dolcini@toradex.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

mainline inclusion
from mainline-v5.121-rc1
commit aef1b6a2
category: bugfix
bugzilla: 108552 https://gitee.com/openeuler/kernel/issues/I4DDEL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=aef1b6a27970607721a618a0b990716ca8dbbf9

-------------------------------------------------

As described in Documentation, poll_init() is called by kgdb to initialize
hardware which supports both poll_put_char() and poll_get_char().

It's necessary to enable TXEN bit, otherwise, it will cause hardware fault
and kernel panic when calling imx_poll_put_char().

Generally, if use /dev/ttymxc0 as kgdb console as well as system
console, ttymxc0 is initialized early by system console which does enable
TXEN bit.But when use /dev/ttymxc1 as kgbd console, ttymxc1 is only
initialized by imx_poll_init() cannot enable the TXEN bit, which will
cause kernel panic.
Signed-off-by: NMingrui Ren <jiladahe1997@gmail.com>
Link: https://lore.kernel.org/r/20201202072543.151-1-972931182@qq.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLu Jialin <lujialin4@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

For below code, there has chance to cause deadlock in SMP system:
Thread 1:
clk_enable_lock();
pr_info("debug message");
clk_enable_unlock();

Thread 2:
imx_uart_console_write()
	clk_enable()
		clk_enable_lock();

Thread 1:
Acuired clk enable_lock -> printk -> console_trylock_spinning
Thread 2:
console_unlock() -> imx_uart_console_write -> clk_disable -> Acquite clk enable_lock

So the patch is to keep console port clocks always on like
other console drivers.

Fixes: 1cf93e0d ("serial: imx: remove the uart_console() check")
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NFugang Duan <fugang.duan@nxp.com>
Link: https://lore.kernel.org/r/20201111025136.29818-1-fugang.duan@nxp.com
Cc: stable <stable@vger.kernel.org>
[fix up build warning - gregkh]
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Enabling the lock dependency validator has revealed
that the way spinlocks are used in the IMX serial
port could result in a deadlock.

Specifically, imx_uart_int() acquires a spinlock
without disabling the interrupts, meaning that another
interrupt could come along and try to acquire the same
spinlock, potentially causing the two to wait for each
other indefinitely.

Use spin_lock_irqsave() instead to disable interrupts
upon acquisition of the spinlock.

Fixes: c974991d ("tty:serial:imx: use spin_lock instead of spin_lock_irqsave in isr")
Reviewed-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NSam Nobs <samuel.nobs@taitradio.com>
Link: https://lore.kernel.org/r/1604955006-9363-1-git-send-email-samuel.nobs@taitradio.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The IPG clock is disabled at the end of imx_uart_shutdown(); we really
don't want to run any IRQ handlers after this point.

At least on i.MX8MN, the UART will happily continue to generate interrupts
even with its clocks disabled, but in this state, all register writes are
ignored (which will cause the shadow registers to differ from the actual
register values, resulting in all kinds of weirdness).

In a transfer without DMA, this could lead to the following sequence of
events:

- The UART finishes its transmission while imx_uart_shutdown() is run,
  triggering the TXDC interrupt (we can trigger this fairly reliably by
  writing a single byte to the TTY and closing it right away)
- imx_uart_shutdown() finishes, disabling the UART clocks
- imx_uart_int() -> imx_uart_transmit_buffer() -> imx_uart_stop_tx()

imx_uart_stop_tx() should now clear UCR4_TCEN to disable the TXDC
interrupt, but this register write is ineffective. This results in an
interrupt storm.

To disable all interrupts in the same place, and to avoid setting UCR4
twice, clearing UCR4_OREN is moved below del_timer_sync() as well; this
should be harmless.
Signed-off-by: NMatthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200925082412.12960-1-matthias.schiffer@ew.tq-group.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When calculate "ucr1" UCR1_TRDYEN is duplicate.
Signed-off-by: NYe Bin <yebin10@huawei.com>
Reviewed-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200903062401.692442-1-yebin10@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support for building i.MX serial driver as module.

The changes of the patch:
- imx console driver can be built as module.
- move out earlycon code to separated driver like imx_earlycon.c,
  and imx earlycon driver only support build-in.
Signed-off-by: NFugang Duan <fugang.duan@nxp.com>
Link: https://lore.kernel.org/r/20200724070815.11445-2-fugang.duan@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch imitates 6e0a5de2 ("serial: 8250: Use hrtimers for
rs485 delays") in replacing the previously used classic timers
with hrtimers. The old way provided a too coarse resolution on
systems with configs of less than 1000 HZ.

Use of hrtimers addresses this and can be easily extended to
support microsecond resolution in future when support
for this arrives upstream.
Signed-off-by: NAhmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20200714093012.21621-3-uwe@kleine-koenig.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This adds support for delays between assertion of RTS (which is supposed
to enable the rs485 transmitter) and sending as well as between the last
send char and deassertionof RTS.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200714093012.21621-2-uwe@kleine-koenig.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 8f065ace.

There has been a quick fix against uninitialised lock revealed by
the commit f743061a ("serial: core: Initialise spin lock before use
in uart_configure_port()"). Since we have now better fix in serial core,
this may be safely reverted.

Fixes: 8f065ace ("serial: imx: Initialize lock for non-registered console")
Depends-on: f743061a ("serial: core: Initialise spin lock before use in uart_configure_port()")
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200711135346.71171-4-andriy.shevchenko@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The AGTIM flag must be cleared explicitly, otherwise the IRQ handler
will be called in an endless loop.

Fortunately, this issue currently doesn't affect mainline kernels in
practice, as the the RX FIFO trigger level is set to 1 in UFCR. When
setting the trigger level to a higher number, the issue is trivially
reproducible by any RX without DMA that doesn't fill the FIFO up to the
configured level.
Signed-off-by: NMatthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200528154747.14201-1-matthias.schiffer@ew.tq-group.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The commit a3cb39d2
("serial: core: Allow detach and attach serial device for console")
changed a bit logic behind lock initialization since for most of the console
driver it's supposed to have lock already initialized even if console is not
enabled. However, it's not the case for Freescale IMX console.

Initialize lock explicitly in the ->probe().

Note, there is still an open question should or shouldn't not this driver
register console properly.

Fixes: a3cb39d2 ("serial: core: Allow detach and attach serial device for console")
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200525105952.13744-1-andriy.shevchenko@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We're about to amend uart_get_rs485_mode() to support a GPIO pin for
rs485 bus termination.  Retrieving the GPIO descriptor may fail, so
allow uart_get_rs485_mode() to return an errno and change all callers
to check for failure.

The GPIO descriptor is going to be stored in struct uart_port.  Pass
that struct to uart_get_rs485_mode() in lieu of a struct device and
struct serial_rs485, both of which are directly accessible from struct
uart_port.

A few drivers call uart_get_rs485_mode() before setting the struct
device pointer in struct uart_port.  Shuffle those calls around where
necessary.

[Heiko Stuebner did the ar933x_uart.c portion, hence his Signed-off-by.]
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/271e814af4b0db3bffbbb74abf2b46b75add4516.1589285873.git.lukas@wunner.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

RX irq is required, so add return value check for platform_get_irq().
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1589180996-618-1-git-send-email-Anson.Huang@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The peripheral has support for inverting its input and/or output
signals.  This is useful if the hardware flips polarity of the
peripheral's signal, such as swapped +/- pins on an RS-422 transceiver,
or an inverting level shifter.  Add support for these control registers
via the device tree binding.

As part of this change, make the writes of the various registers more
uniform by moving the UCR3 block up near the other registers' blocks,
since the INVT bit must be set before enabling the peripheral.
Signed-off-by: NGeorge Hilliard <ghilliard@kopismobile.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200226222319.18383-3-ghilliard@kopismobile.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There has oops as below happen on i.MX8MP EVK platform that has
6G bytes DDR memory.

when (xmit->tail < xmit->head) && (xmit->head == 0),
it setups one sg entry with sg->length is zero:
	sg_set_buf(sgl + 1, xmit->buf, xmit->head);

if xmit->buf is allocated from >4G address space, and SDMA only
support <4G address space, then dma_map_sg() will call swiotlb_map()
to do bounce buffer copying and mapping.

But swiotlb_map() don't allow sg entry's length is zero, otherwise
report BUG_ON().

So the patch is to correct the tx DMA scatter list.

Oops:
[  287.675715] kernel BUG at kernel/dma/swiotlb.c:497!
[  287.680592] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[  287.686075] Modules linked in:
[  287.689133] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.3-00016-g3fdc4e0-dirty #10
[  287.696872] Hardware name: FSL i.MX8MP EVK (DT)
[  287.701402] pstate: 80000085 (Nzcv daIf -PAN -UAO)
[  287.706199] pc : swiotlb_tbl_map_single+0x1fc/0x310
[  287.711076] lr : swiotlb_map+0x60/0x148
[  287.714909] sp : ffff800010003c00
[  287.718221] x29: ffff800010003c00 x28: 0000000000000000
[  287.723533] x27: 0000000000000040 x26: ffff800011ae0000
[  287.728844] x25: ffff800011ae09f8 x24: 0000000000000000
[  287.734155] x23: 00000001b7af9000 x22: 0000000000000000
[  287.739465] x21: ffff000176409c10 x20: 00000000001f7ffe
[  287.744776] x19: ffff000176409c10 x18: 000000000000002e
[  287.750087] x17: 0000000000000000 x16: 0000000000000000
[  287.755397] x15: 0000000000000000 x14: 0000000000000000
[  287.760707] x13: ffff00017f334000 x12: 0000000000000001
[  287.766018] x11: 00000000001fffff x10: 0000000000000000
[  287.771328] x9 : 0000000000000003 x8 : 0000000000000000
[  287.776638] x7 : 0000000000000000 x6 : 0000000000000000
[  287.781949] x5 : 0000000000200000 x4 : 0000000000000000
[  287.787259] x3 : 0000000000000001 x2 : 00000001b7af9000
[  287.792570] x1 : 00000000fbfff000 x0 : 0000000000000000
[  287.797881] Call trace:
[  287.800328]  swiotlb_tbl_map_single+0x1fc/0x310
[  287.804859]  swiotlb_map+0x60/0x148
[  287.808347]  dma_direct_map_page+0xf0/0x130
[  287.812530]  dma_direct_map_sg+0x78/0xe0
[  287.816453]  imx_uart_dma_tx+0x134/0x2f8
[  287.820374]  imx_uart_dma_tx_callback+0xd8/0x168
[  287.824992]  vchan_complete+0x194/0x200
[  287.828828]  tasklet_action_common.isra.0+0x154/0x1a0
[  287.833879]  tasklet_action+0x24/0x30
[  287.837540]  __do_softirq+0x120/0x23c
[  287.841202]  irq_exit+0xb8/0xd8
[  287.844343]  __handle_domain_irq+0x64/0xb8
[  287.848438]  gic_handle_irq+0x5c/0x148
[  287.852185]  el1_irq+0xb8/0x180
[  287.855327]  cpuidle_enter_state+0x84/0x360
[  287.859508]  cpuidle_enter+0x34/0x48
[  287.863083]  call_cpuidle+0x18/0x38
[  287.866571]  do_idle+0x1e0/0x280
[  287.869798]  cpu_startup_entry+0x20/0x40
[  287.873721]  rest_init+0xd4/0xe0
[  287.876949]  arch_call_rest_init+0xc/0x14
[  287.880958]  start_kernel+0x420/0x44c
[  287.884622] Code: 9124c021 9417aff8 a94363f7 17ffffd5 (d4210000)
[  287.890718] ---[ end trace 5bc44c4ab6b009ce ]---
[  287.895334] Kernel panic - not syncing: Fatal exception in interrupt
[  287.901686] SMP: stopping secondary CPUs
[  288.905607] SMP: failed to stop secondary CPUs 0-1
[  288.910395] Kernel Offset: disabled
[  288.913882] CPU features: 0x0002,2000200c
[  288.917888] Memory Limit: none
[  288.920944] ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
Reported-by: NEagle Zhou <eagle.zhou@nxp.com>
Tested-by: NEagle Zhou <eagle.zhou@nxp.com>
Signed-off-by: NFugang Duan <fugang.duan@nxp.com>
Cc: stable <stable@vger.kernel.org>
Fixes: 7942f857 ("serial: imx: TX DMA: clean up sg initialization")
Reviewed-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/1581401761-6378-1-git-send-email-fugang.duan@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The main irq handler function starts by first masking disabled
interrupts in the status register values to ensure to only handle
enabled interrupts. This is important as when the RX path in the
hardware is disabled reading the RX fifo results in an external abort.

This checking must be done under the port lock, otherwise the following
can happen:

     CPU1                            | CPU2
                                     |
     irq triggers as there are chars |
     in the RX fifo                  |
				     | grab port lock
     imx_uart_int finds RRDY enabled |
     and calls imx_uart_rxint which  |
     has to wait for port lock       |
                                     | disable RX (e.g. because we're
                                     | using RS485 with !RX_DURING_TX)
                                     |
                                     | release port lock
     read from RX fifo with RX       |
     disabled => exception           |

So take the port lock only once in imx_uart_int() instead of in the
functions called from there.
Reported-by: NAndre Renaud <arenaud@designa-electronics.com>
Cc: stable@vger.kernel.org
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200121071702.20150-1-u.kleine-koenig@pengutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The SUPPORT_SYSRQ ifdeffery is not nice as:
- May create misunderstanding about sizeof(struct uart_port) between
  different objects
- Prevents moving functions from serial_core.h
- Reduces readability (well, it's ifdeffery - it's hard to follow)

In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added.
Initialise it in driver's probe and remove ifdeffery.

Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: NDmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-20-dima@arista.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The dmaengine_prep_slave_sg needs to use sg count returned
by dma_map_sg, not use sport->dma_tx_nents, because the return
value of dma_map_sg is not always same with "nents".

Fixes: b4cdc8f6 ("serial: imx: add DMA support for imx6q")
Signed-off-by: NPeng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/1573108875-26530-1-git-send-email-peng.fan@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

All i.MX SoCs except i.MX1 have ONLY one necessary IRQ, use
platform_get_irq_optional() to get second/third IRQ which are
optional to avoid below error message during probe:

[    0.726219] imx-uart 30860000.serial: IRQ index 1 not found
[    0.731329] imx-uart 30860000.serial: IRQ index 2 not found

Fixes: 7723f4c5 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1570614559-11900-1-git-send-email-Anson.Huang@nxp.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Using only 4 DMA periods for UART RX is very few if we have a high
frequency of small transfers - like in our case using Bluetooth with
many small packets via UART - causing many dma transfers but in each
only filling a fraction of a single buffer. Such a case may lead to
the situation that DMA RX transfer is triggered but no free buffer is
available. When this happens dma channel ist stopped - with the patch
"dmaengine: imx-sdma: fix dma freezes" temporarily only - with the
possible consequences that:
with disabled hw flow control:
  If enough data is incoming on UART port the RX FIFO runs over and
  characters will be lost. What then happens depends on upper layer.

with enabled hw flow control:
  If enough data is incoming on UART port the RX FIFO reaches a level
  where CTS is deasserted and remote device sending the data stops.
  If it fails to stop timely the i.MX' RX FIFO may run over and data
  get lost. Otherwise it's internal TX buffer may getting filled to
  a point where it runs over and data is again lost. It depends on
  the remote device how this case is handled and if it is recoverable.

Obviously we want to avoid having no free buffers available. So we
decrease the size of the buffers and increase their number and the
total buffer size.
Signed-off-by: NPhilipp Puschmann <philipp.puschmann@emlix.com>
Reviewed-by: NLucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190923135916.1212-1-philipp.puschmann@emlix.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This should help to avoid unnecessary gaps in transmission while
adding little overhead due to low default Tx threshold level (2
bytes).
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-6-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_set_termios(): avoid writing baud rate divider registers when the
values to be written are the same as current. Any writing seems to
restart transmission/receiving logic in the hardware, that leads to
data breakage even when rate doesn't in fact change. E.g., user
switches RTS/CTS handshake and suddenly gets broken bytes.
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-5-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_set_termios(): disabling individual interrupt requests in UART for
duration of the routine is pointless. Get rid of it.
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-4-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_set_termios(): stopping receiver and transmitter does harm when
something that doesn't touch transmission format/rate changes, such as
RTS/CTS handshake.

OTOH, it does no good on baud rate or format change, as
synchronization on upper-level protocols is still required to do it
right.

Therefore, just stop doing it.
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-3-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_set_termios(): remove busy-waiting "drain Tx FIFO" loop. Worse
yet, it was potentially unbounded wait due to RTS/CTS (hardware)
handshake.

Let user space ensure draining is done before termios change, if
draining is needed in the first place.
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1567017475-11919-2-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Called in only one place, for RS232, it only obscures things, as it
doesn't go well with 2 similar named functions,
imx_uart_rts_inactive() and imx_uart_rts_active(), that both are
RS485-specific.
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1564167161-3972-4-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_uart_set_mctrl() happened to set UCR2_CTSC bit whenever TIOCM_RTS
was set, no matter if RTS/CTS handshake is enabled or not. Now fixed by
turning handshake on only when CRTSCTS bit for the port is set.
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1564167161-3972-3-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Don't let receiver hardware automatically control RTS output if it
was requested to be inactive.

To ensure this, set_termios() shouldn't set UCR2_CTSC bit if UCR2_CTS
(=TIOCM_RTS) is cleared. Added corresponding check in imx_uart_rts_auto()
to fix this.
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1564167161-3972-2-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_set_termios() cleared RTS on every call, now fixed.
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1561558293-7683-5-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Avoid repeating the same code for rs485 twice.

Make it obvious we clear CRTSCTS bit in termios->c_cflag whenever
sport->have_rtscts is false.

Make it obvious we clear UCR2_IRTS whenever CRTSCTS is set.
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Link: https://lore.kernel.org/r/1561558293-7683-4-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Set common bits in a separate statement to make initialization
explicit and not repeat the common part.
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Tested-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Reviewed-by: NUwe Kleine-Knig <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/1561558293-7683-3-git-send-email-sorganov@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

imx_uart_set_termios() called imx_uart_rts_active(), or
imx_uart_rts_inactive() before taking port->port.lock.

As a consequence, sport->port.mctrl that these functions modify
could have been changed without holding port->port.lock.

Moved locking of port->port.lock above the calls to fix the issue.
Signed-off-by: NSergey Organov <sorganov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

dev_info() is more appropriate for printing messages inside drivers, so
switch to dev_info().
Signed-off-by: NFabio Estevam <festevam@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Each time the DMA engine signals a transaction error the driver prints
a message at error level. Getting transaction errors is pretty much
expected on baudrate mismatches and the correspoding error counters
are increased in this case properly. Remove the error message which
is possibly repeated at a very high rate which can lock up the whole
system.
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: NFabio Estevam <festevam@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The ipg clock only needs to be unprepared in case preparing
per clock fails. The ipg clock has already disabled at the point.

Fixes: 1cf93e0d ("serial: imx: remove the uart_console() check")
Signed-off-by: NStefan Agner <stefan@agner.ch>
Reviewed-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Back in 2015 when irda was dropped from the driver imx1 was broken. This
change reintroduces the support for the third interrupt of the UART.

Fixes: afe9cbb1 ("serial: imx: drop support for IRDA")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: NLeonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

On some i.MX SoCs' low power mode, such as i.MX7D's LPSR(low power
state retention), UART iomux settings will be lost, need to add
pinctrl sleep/default mode switch during suspend/resume to make
sure UART iomux settings are correct after resume.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In noirq suspend/resume stage with no_console_suspend enabled,
imx_uart_console_write() may be called to print out log_buf
message by printk(), so there will be race condition between
imx_uart_console_write() and imx_uart_save/restore_context(),
need to add lock to protect the registers save/restore operations.
Signed-off-by: NAnson Huang <Anson.Huang@nxp.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>