We can now use generic wakeirq handling and remove the custom handling
for the wake-up interrupts.
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NTony Lindgren <tony@atomide.com>

The currently in-use port->startup and port->shutdown are "okay". The
startup part for instance does the tiny omap extra part and invokes
serial8250_do_startup() for the remaining pieces. The workflow in
serial8250_do_startup() is okay except for the part where UART_RX is
read without a check if there is something to read. I tried to
workaround it in commit 0aa525d1 ("tty: serial: 8250_core: read only
RX if there is something in the FIFO") but then reverted it later in
commit ca8bb4ae ("serial: 8250: Revert "tty: serial: 8250_core: read
only RX if there is something in the FIFO"").

This is the second attempt to get it to work on older OMAPs without
breaking other chips this time
Peter Hurley suggested to pull in the few needed lines from
serial8250_do_startup() and drop everything else that is not required
including making it simpler like using just request_irq() instead the
chain handler like it is doing now.
So lets try that.

Fixes: ca8bb4ae ("serial: 8250: Revert "tty: serial: 8250_core:
       read only RX if there is something in the FIFO"")
Tested-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The currently in-use port->startup and port->shutdown are "okay". The
startup part for instance does the tiny omap extra part and invokes
serial8250_do_startup() for the remaining pieces. The workflow in
serial8250_do_startup() is okay except for the part where UART_RX is
read without a check if there is something to read. I tried to
workaround it in commit 0aa525d1 ("tty: serial: 8250_core: read only
RX if there is something in the FIFO") but then reverted it later in
commit ca8bb4ae ("serial: 8250: Revert "tty: serial: 8250_core: read
only RX if there is something in the FIFO"").

This is the second attempt to get it to work on older OMAPs without
breaking other chips this time
Peter Hurley suggested to pull in the few needed lines from
serial8250_do_startup() and drop everything else that is not required
including making it simpler like using just request_irq() instead the
chain handler like it is doing now.
So lets try that.

Fixes: ca8bb4ae ("serial: 8250: Revert "tty: serial: 8250_core:
       read only RX if there is something in the FIFO"")
Tested-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The rx_running flag should show if DMA is currently active. However
there is a window between when the flag is set/cleared and when
the DMA is started/stopped. Because the flag is queried from both
hard and soft irq contexts, the driver can make incorrect
decisions and do things like start a DMA transfer using a buffer
that is already setup to be used for a DMA transfer.

This patch adds a spinlock to synchronize the rx_running flag and
close the above mentioned window.
Signed-off-by: NJohn Ogness <john.ogness@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The serial_core.h file have been included in header file
serial_8250.h. so remove the "#include <serial_core.h>" in
some 8250 serial drivers, because they have included the header file
serial_8250.h.
Signed-off-by: NWang Long <long.wanglong@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 88838d3112702 ("serial: omap_8250: Fix RTS handling") fixed
RTS pin control when in autoRTS mode.

New support added in "serial: core: Rework hw-assisted flow control support"
enables a much simpler approach; rather than masking out autoRTS
whenever writing the EFR register, use the UPSTAT_* mode to determine if
autoRTS should be enabled when raising RTS (in omap8250_set_mctrl()).
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

hw-assisted flow control support was added to the serial core
in v3.8 with commits,
dba05832 ("SERIAL: core: add hardware assisted h/w flow control support")
2cbacafd ("SERIAL: core: add hardware assisted s/w flow control support")
9aba8d5b ("SERIAL: core: add throttle/unthrottle callbacks for hardware
                assisted flow control")
Since then, additional requirements for serial core support have arisen.
Specifically,
1. Separate tx and rx flow control settings for UARTs which only support
   tx flow control (ie., autoCTS).
2. Disable sw-assisted CTS flow control in autoCTS mode
3. Support for RTS flow control by serial core and userspace in autoRTS mode

Distinguish mode from capability; introduce UPSTAT_AUTORTS, UPSTAT_AUTOCTS
and UPSTAT_AUTOXOFF which, when set by the uart driver, enable serial core
support for hw-assisted rx, hw-assisted tx and hw-assisted in-band/IXOFF
rx flow control, respectively. [Note: hw-assisted in-band/IXON tx flow
control does not require serial core support/intervention and can be
enabled by the uart driver when required.]

These modes must be set/reset in the driver's set_termios() method, based
on termios settings, and thus can be safely queried in any context in which
one of the port lock, port mutex or termios rwsem are held. Set these modes
in the 2 in-tree drivers, omap-serial and 8250_omap, which currently
use UPF_HARD_FLOW/UPF_SOFT_FLOW support.

Retain UPF_HARD_FLOW and UPF_SOFT_FLOW as capabilities; re-define
UPF_HARD_FLOW as both UPF_AUTO_RTS and UPF_AUTO_CTS to allow for distinct
and separate rx and tx flow control capabilities.

Disable sw-assisted CTS flow control when UPSTAT_AUTOCTS is enabled.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This platform_driver does not need to set an owner, it will be populated by the
driver core.
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Because the OMAP3 UART ignores MCR[1] (RTS) in autoRTS mode, autoRTS
mode must not be enabled unless RTS is set (or port->mctrl & TIOCM_RTS,
which is equivalent).

Fixes premature raising of RTS in omap_8250_set_termios() -- RTS was
raised even before UART mode was selected.
Fixes raise of RTS after port has been shutdown; omap_8250_pm() re-enabled
RTS after omap_8250_shutdown().

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The OMAP3 UART ignores MCR[1] (ie., UART_MCR_RTS) when in autoRTS
mode (UPF_HARD_FLOW + CRTSCTS). This makes it impossible for either
the serial core or userspace to manually flow control the sender.

Disable autoRTS mode when RTS is lowered and restore the previous
mode when RTS is raised.

Note that the OMAP3 UART provides no mechanism for switching from
autoRTS mode without corrupting incoming data; to access the
necessary register, the line control settings must be set to 8-e-2
and thus any data received during that time will be interpreted with
those settings. This corruption has been observed in practice.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch invokes add_preferred_console() with ttyS based on ttyO
arguments if the user didn't specify it on its own. This ensures that
the user will see the kernel booting on his serial console in case he
forgot to update the command line.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The 8250_omap serial driver is a new user of CONFIG_PM_RUNTIME.

However, after commit b2b49ccb (PM: Kconfig: Set PM_RUNTIME if
PM_SLEEP is selected) PM_RUNTIME is always set if PM is set, so
#ifdef blocks depending on CONFIG_PM_RUNTIME may now be changed to
depend on CONFIG_PM.

Replace CONFIG_PM_RUNTIME with CONFIG_PM in 8250_omap.c.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Dan Carpenter reported:
|drivers/tty/serial/8250/8250_omap.c:1025 omap8250_probe()
|warn: unsigned 'up.port.line' is never less than zero.
|1025          if (up.port.line < 0) {

I (wrongly) assumed that line is an int and compiler didn't complain nor
did sparse. Since of_alias_get_id() and pdev->id can get negative I
check for the error via ret variable.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch adds the required pieces to 8250-OMAP UART driver for DMA
support. The TX burst size is set to 1 so we can send an arbitrary
amount of bytes.

The RX burst is currently set to 48 which means we receive an DMA
interrupt every 48 bytes and have to reprogram everything. Less bytes in
the RX-FIFO mean that no DMA transfer will happen and the UART will send a
RX-timeout _or_ RDI event at which point the FIFO will be manually purged.
There is a workaround for TX-DMA on AM33xx where we put the first byte
into the FIFO to kick start the DMA process. Haven't seen this problem on
OMAP36xx (beagle board xm) or DRA7xx.

On AM375x there is "Usage Note 2.7: UART: Cannot Acknowledge Idle
Requests in Smartidle Mode When Configured for DMA Operations" in the
errata document. This problem persists even after disabling DMA in the
UART and will be addressed in the HWMOD.

v10:
	- delay update_registers() from set_termios() until TX-DMA is
	  done. It has been reported / proved that invoking
	  update_registers() while TX-DMA is in progress may stall the
	  DMA operation and it won't finish.
	- use the new omap DMA-TX-RX hooks and DMA only interrupt
	  routine.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We have (or will have) custom DMA callbacks in the omap driver due to
the different behaviour in the RX and TX case. To make this work
we need a few changes in the IRQ handler to invoke the rx_handler again
after the "manual" mode or retry the tx_handler again before falling
back to the manual mode.

Heikki didn't want to see the extra hacks in the generic / default irq
handler and Peter wasn't too happy about an OMAP-only IRQ handler. The
way I planned it is to use this extra IRQ routine only in DMA case. If
Peter dislike this approach then I hope Heikki doesn't block changes in
the default IRQ handler :)
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The omap needs a DMA request pending right away. If it is
enqueued once the bytes are in the FIFO then nothing will happen
and the FIFO will be later purged via RX-timeout interrupt.
This patch enqueues RX-DMA request on completion but not if it
was aborted on error. The first enqueue will happen in the driver
in startup.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch provides mostly a copy of serial8250_tx_dma() +
__dma_tx_complete() with the following extensions:

- DMA bug
  At least on AM335x the following problem exists: Even if the TX FIFO is
  empty and a TX transfer is programmed (and started) the UART does not
  trigger the DMA transfer.
  After $TRESHOLD number of bytes have been written to the FIFO manually the
  UART reevaluates the whole situation and decides that now there is enough
  room in the FIFO and so the transfer begins.
  This problem has not been seen on DRA7 or beagle board xm (OMAP3). I am not
  sure if this is UART-IP core specific or DMA engine.

  The workaround is to use a threshold of one byte, program the DMA
  transfer minus one byte and then to put the first byte into the FIFO to
  kick start the transfer.

- support for runtime PM
  RPM is enabled on start_tx(). We can't disable RPM on DMA complete callback
  because there is still data in the FIFO which is being sent. We have to wait
  until the FIFO is empty before we disable it.
  For this to happen we fake a TX sent error and enable THRI. Once the
  FIFO is empty we receive an interrupt and since the TTY-buffer is still
  empty we "put RPM" via __stop_tx(). Should it been filed then in the
  start_tx() path we should program the DMA transfer and remove the error
  flag and the THRI bit.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch provides a 8250-core based UART driver for the internal OMAP
UART. The long term goal is to provide the same functionality as the
current OMAP uart driver and DMA support.
I tried to merge omap-serial code together with the 8250-core code.
There should should be hardly a noticable difference. The trigger levels
are different compared to omap-serial:
- omap serial
  TX: Interrupt comes after TX FIFO has room for 16 bytes.
      TX of 4096 bytes in one go results in 256 interrupts

  RX: Interrupt comes after there is on byte in the FIFO.
      RX of 4096 bytes results in 4096 interrupts.

- this driver
  TX: Interrupt comes once the TX FIFO is empty.
      TX of 4096 bytes results in 65 interrupts. That means there will
      be gaps on the line while the driver reloads the FIFO.

  RX: Interrupt comes once there are 48 bytes in the FIFO or less over
      "longer" time frame. We have
          1 / 11520 * 10^3 * 16 => 1.38… ms
      1.38ms to react and purge the FIFO on 115200,8N1. Since the other
      driver fired after each byte it had ~5.47ms time to react. This
      _may_ cause problems if one relies on no missing bytes and has no
      flow control. On the other hand we get only 85 interrupts for the
      same amount of data.

It has been only tested as console UART on am335x-evm, dra7-evm and
beagle bone. I also did some longer raw-transfers to meassure the load.

The device name is ttyS based instead of ttyO. If a ttyO based node name
is required please ask udev for it. If both driver are activated (this
and omap-serial) then this serial driver will take control over the
device due to the link order

v9…v10:
	- Tony noticed that omap3 won't show anything after waking up
	  from core off. In v9 I reworked the register restore and set
	  IER to 0 by accident. This went unnoticed because start_tx
	  usually sets ier (either due to DMA bug or due to TX-complete
	  IRQ).
	- dropped EFR and SLEEP from capabilities. We do have both but
	  nobody should touch it. We already handle SLEEP ourself.
	- make the private copy of the registers (like EFR) u8 instead
	  u32
	- drop MDR1 & DL[ML] reset in restore registers. Does not look
	  required it is set to the required value later.
	- update MDR1 & SCR only if changed.
	- set MDR1 as the last thing. The errata says that we should
	  setup everything before MDR1 set.
	- avoid div by 0 in omap_8250_get_divisor() if baud rate gets
	  very large (Frans Klaver fixed the same thing omap-serial)
	- drop "is in early stage" from Kconfig.
v8…v9:
	- less on a file seems to hang the am335x after a while. I
	  believe I introduce this bug a while ago since I can reproduce
	  this prior to v8. Fixed by redoing the omap8250_restore_regs()
v7…v8:
	- redo the register write. There is now one function for that
	  which is used from set_termios() and runtime-resume.
	- drop PORT_OMAP_16750 and move the setup to the omap file. We
	  have our own set termios function anyway (Heikki Krogerus)
	- use MEM instead of MEM32. TRM of AM/DM37x says that 32bit
	  access on THR might result in data abort. We only need 32bit
	  access in the errata function which is before we use 8250's
	  read function so it doesn't matter.
v4…v7:
	- change trigger levels after some tests with raw transfers.
v3…v4:
	- drop RS485 support
	- wire up ->throttle / ->unthrottle
v2…v3:
	- wire up startup & shutdown for wakeup-irq handling.
	- RS485 handling (well the core does).

v1…v2:
	- added runtime PM. Could somebody could please double check
	  this?
	- added omap_8250_set_termios()
Reviewed-by: NTony Lindgren <tony@atomide.com>
Tested-by: NTony Lindgren <tony@atomide.com>
Tested-by: NFrans Klaver <frans.klaver@xsens.com>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>