When the kernel command line parameter, no_console_suspend, is used,
the console should continue to output console messages during and
after system suspend. For a serial console, the serial core ensures
that the device is not shutdown when no_console_suspend is specified.
However, the default operation of the pnp bus will disable and suspend
the device and no further output occurs.

When registering the 8250 port, if the serial device is a console
set the PNP_CONSOLE capability, which prevents device power-off
if consoles are not suspending.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In early 8250, IER is already zero so no point in writing this - twice
per line

This helped improve the SystemC model based ARC OSCI platform

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Some of FSL SoCs like T1040 has new version of UART controller which
can support 64byte FiFo.
To enable 64 byte support, following needs to be done:
-FCR[EN64] needs to be programmed to 1 to enable it.
-Also, when FCR[EN64]==1, RTL bits to be used as below
to define various Receive Trigger Levels:
        -FCR[RTL] = 00  1 byte
        -FCR[RTL] = 01  16 bytes
        -FCR[RTL] = 10  32 bytes
        -FCR[RTL] = 11  56 bytes
-tx_loadsz is set to 63-bytes instead of 64-bytes to implement
 workaround of errata A-008006 which states that tx_loadsz should
 be configured less than Maximum supported fifo bytes
Signed-off-by: NVijay Rai <vijay.rai@freescale.com>
Signed-off-by: NPriyanka Jain <Priyanka.Jain@freescale.com>
Signed-off-by: NPoonam Aggrwal <poonam.aggrwal@freescale.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>

Enable APM X-Gene SoC serial port functionality when using ACPI table to
initialize serial port.
Signed-off-by: NFeng Kan <fkan@apm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no need to terminate transfer in the __dma_rx_complete() since it's
called at the end of transfer. Special case when serial timeout occurs is
handled separately where we have to terminate transfer.
Signed-off-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>

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>

WCH384 4S board is a PCI-E card with 4 DB9 COM ports detected as
Serial controller: Device 1c00:3470 (rev 10) (prog-if 05 [16850])
Signed-off-by: NSergej Pupykin <ml@sergej.pp.ru>
Acked-by: NZany Yan <sirlight@cox.net>
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>

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 everywhere under
drivers/tty/.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Attempting to use SysRq via the 8250 serial port with spin lock
debugging on on a uniprocessor system results in the following splat:

 SysRq :
 BUG: spinlock trylock failure on UP on CPU#0, swapper/0
  lock: serial8250_ports+0x0/0x8c0, .magic: dead4ead, .owner: swapper/0, .owner_cpu: 0
 CPU: 0 PID: 0 Comm: swapper Not tainted 3.18.0-rc4+ #37
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
  ffffffff8245ba00 ffffffff81628b28 ffffffff812c8d27 ffffffff81628b48
  ffffffff8106812e ffffffff8245ba00 ffffffff814e22ed ffffffff81628b68
  ffffffff810681a6 0000000000000000 0000000000000000 ffffffff81628b88
 Call Trace:
  <IRQ>  [<ffffffff812c8d27>] dump_stack+0x19/0x1b
  [<ffffffff8106812e>] spin_dump+0x7e/0xd0
  [<ffffffff810681a6>] spin_bug+0x26/0x30
  [<ffffffff8106843c>] do_raw_spin_trylock+0x4c/0x60
  [<ffffffff812cdb1d>] _raw_spin_trylock+0x1d/0x60
  [<ffffffff812336d8>] serial8250_console_write+0x68/0x190
  [<ffffffff811eb0b0>] ? sprintf+0x40/0x50
  [<ffffffff8106ab5e>] call_console_drivers.constprop.11+0x9e/0xf0
  [<ffffffff8106b276>] console_unlock+0x3e6/0x490
  [<ffffffff8106b595>] vprintk_emit+0x275/0x530
  [<ffffffff812c869a>] printk+0x4d/0x4f
  [<ffffffff8121e612>] __handle_sysrq+0x62/0x1b0
  [<ffffffff8121e5b5>] ? __handle_sysrq+0x5/0x1b0
  [<ffffffff8121ebc6>] handle_sysrq+0x26/0x30
  [<ffffffff81233157>] serial8250_rx_chars+0x1d7/0x250
  [<ffffffff812338bb>] serial8250_handle_irq+0x7b/0x90
  [<ffffffff812338f3>] serial8250_default_handle_irq+0x23/0x30
  [<ffffffff812318b3>] serial8250_interrupt+0x63/0xe0
  [<ffffffff8106d80e>] handle_irq_event_percpu+0x4e/0x200
  [<ffffffff8106da01>] handle_irq_event+0x41/0x70
  [<ffffffff810701ee>] ? handle_edge_irq+0x1e/0x110
  [<ffffffff8107026e>] handle_edge_irq+0x9e/0x110
  [<ffffffff810041c2>] handle_irq+0x22/0x40
  [<ffffffff812d096e>] do_IRQ+0x4e/0xf0
  [<ffffffff812cf4ed>] common_interrupt+0x6d/0x6d
  <EOI>  [<ffffffff8100acbf>] ? default_idle+0x1f/0xd0
  [<ffffffff8100acbd>] ? default_idle+0x1d/0xd0
  [<ffffffff8100b61f>] arch_cpu_idle+0xf/0x20
  [<ffffffff8105c1db>] cpu_startup_entry+0x25b/0x360
  [<ffffffff812c726e>] rest_init+0xbe/0xd0
  [<ffffffff816a4dcb>] start_kernel+0x339/0x346
  [<ffffffff816a4495>] x86_64_start_reservations+0x2a/0x2c
  [<ffffffff816a4589>] x86_64_start_kernel+0xf2/0xf6
 HELP : loglevel(0-9) reboot(b) crash(c) show-all-locks(d) te...

Before ebade5e8 ("serial: 8250: Clean up the locking for -rt")
this was handled by not even attempting to try the lock if port->sysrq,
since it is known to be taken by the interrupt handler; see
https://bugzilla.kernel.org/show_bug.cgi?id=6716#c1.  Restore that
behavior.
Signed-off-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The original driver fixed the io address with 0xe000+idx*8,
but real io address assigned from BIOS is dynamically from
read PCI configure space 0x24, 0x20, 0x1c.

The Fintek F81504/F81508/F81512 maybe malfunction without
this patch and malfunction surely when more then 1 PCI card.
Signed-off-by: NPeter Hung <hpeter+linux_kernel@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Although the existing code appears to work on most hardware, the
hardware designers tell us that 8-bit access to the registers is not
guaranteed to be reliable.  Also the OCTEON simulation environments
prohibit 8-bit accesses.

For these reasons, we use __raw_readq/__raw_writeq for OCTEON.  This
code is protected with #ifdef CONFIG_64BIT so it still builds under
configurations lacking readq/writeq.

We can get rid of the #ifdef __BIG_ENDIAN, as under 64-bit accesses,
OCTEON is byte order invariant.
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Signed-off-by: NAleksey Makarov <aleksey.makarov@auriga.com>
Signed-off-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>

In serial8250_rx_chars(), max_count is set to 256. Due to the
post-decrement operator used in the while() condition, the maximum
number of iterations actually 257. This is not a problem, but it is
mildly surprising if you're debugging. Use pre-decrement instead.
Signed-off-by: NFrans Klaver <frans.klaver@xsens.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In the serial8250_tx_dma() the tx_err flag is set in case of error. Thus, there
is no need to repeat this in __dma_tx_complete().
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Since we have the same check inside the function we may drop it away in
__dma_tx_complete().
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no more users for this functions. All the 8250 drivers are
using the rs485 handler on serial_core instead.
Reviewed-by: NAlan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In order to remove the handler for rs485 ioctls on serial_8250, all the
drivers must use the implementation on serial_core.
Reviewed-by: NAlan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Initialize recently added rs485 fields on serial_core
Reviewed-by: NAlan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

fixed a sparse warning in 8250_core.c :
	incorrect type in assignment (different address spaces)

the warning was because an unsigned char pointer was being assigned to
a pointer of unsigned char __iomem type .
Signed-off-by: NSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

WCH382 is a PCI-E card with 1 LPT and 2 DB9 COM ports detected as
Serial controller: Device 1c00:3250 (rev 10) (prog-if 05 [16850])
Signed-off-by: NSergej Pupykin <ml@sergej.pp.ru>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Switching to the N_PPS line discipline may require enabling
modem status interrupts; conversely switching from N_PPS may
require disabling modem status interrupts.

Affected drivers:
8250
amba-pl010
atmel

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Three UART drivers (8250, atmel & amba-pl010) directly call their
enable_ms() method; the uart port lock must be acquired before
any h/w programming.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

UART drivers which enable modem status interrupts when switching
to N_PPS line discipline need to determine if modem status
interrupts should be disabled when switching from N_PPS.
Specifically, the set_ldisc() notification needs to evaluate
UART_ENABLE_MS() which requires termios->c_cflag.

Convert in-tree UART drivers to new interface.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Get index of serial line from device tree using function of_alias_get_id().
If no alias is found, the 8250 core takes care of incrementing the line number.
Signed-off-by: NJulien CHAUVEAU <julien.chauveau@neo-technologies.fr>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Check the return value of ioremap_nocache to make sure we got a
valid mapping.
Signed-off-by: NAaron Sierra <asierra@xes-inc.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Several init/setup functions passed the PCI BAR resource start address
to ioremap_nocache() via an unsigned long. This caused address truncation
for a 32-bit device mapped above 4 GiB (i.e. the CPU interacts with the
device via a translated address), which resulted in a kernel panic.

This patch replaces all of the instances of intermediate variable use
with pci_ioremap_bar() to ensure the full resource_size_t start address
is used and that ioremap_nocache() is still called.

The kernel panic (Exar XR17V358 PCIe device on a Freescale P2020 SBC):

Machine check in kernel mode.
Caused by (from MCSR=10008): Bus - Read Data Bus Error
Oops: Machine check, sig: 7 [#1]
SMP NR_CPUS=2 X-ES P2020
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.14.15-xes_r2-00002-g560e401 #978
task: bf850000 ti: bffee000 task.ti: bf84c000
NIP: 80318e10 LR: 80319ecc CTR: 80318dfc
REGS: bffeff10 TRAP: 0204   Not tainted  (3.14.15-xes_r2-00002-g560e401)
MSR: 00021000 <CE,ME>  CR: 20adbe42  XER: 00000000
DEAR: c1058001 ESR: 00000000
GPR00: 00000000 bf84db30 bf850000 80cb4af8 00000001 00000000 80000007 80000000
GPR08: bf837c9c c1058001 00000001 00000000 80000007 00000000 80002a10 00000000
GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 80cb0000 80c72dc4
GPR24: 80cb4900 fffffffe 00029000 00000001 bf8c11e8 ffffffea 80c72ce4 80cb4af8
NIP [80318e10] mem_serial_in+0x14/0x28
LR [80319ecc] serial8250_config_port+0x160/0xe38
Call Trace:
[bf84db30] [80319d94] serial8250_config_port+0x28/0xe38 (unreliable)
[bf84db60] [80315e3c] uart_add_one_port+0x148/0x3a4
[bf84dbf0] [8031bf40] serial8250_register_8250_port+0x2dc/0x3c8
[bf84dc20] [8032111c] pciserial_init_ports+0xd4/0x1c0
[bf84dd50] [803212f8] pciserial_init_one+0xf0/0x224
[bf84dd90] [802d8ff4] local_pci_probe+0x34/0x8c
[bf84dda0] [802d92c8] pci_device_probe+0x84/0xa0
[bf84ddc0] [80329ee0] driver_probe_device+0xac/0x26c
[bf84dde0] [8032a15c] __driver_attach+0xbc/0xc0
[bf84de00] [80328388] bus_for_each_dev+0x90/0xcc
[bf84de30] [80329cd0] driver_attach+0x24/0x34
[bf84de40] [80328e28] bus_add_driver+0x104/0x1fc
[bf84de60] [8032a8c8] driver_register+0x70/0x138
[bf84de70] [802d93c0] __pci_register_driver+0x48/0x58
[bf84de80] [8077e0e4] serial_pci_driver_init+0x24/0x34
[bf84de90] [80002228] do_one_initcall+0x34/0x1b0
[bf84df00] [80764294] kernel_init_freeable+0x138/0x1e8
[bf84df30] [80002a24] kernel_init+0x14/0x108
[bf84df40] [8000ef94] ret_from_kernel_thread+0x5c/0x64
Instruction dump:
800800c4 7d290214 39290001 7c0004ac 7ca049ae 7c0004ac 4e800020 88030035
81230008 7c840030 7d292214 7c0004ac <88690000> 0c030000 4c00012c 5463063e
---[ end trace e3c16443b5d573c6 ]---
Signed-off-by: NAaron Sierra <asierra@xes-inc.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

In mtk8250_set_termios function, calculating quot value can not be zero,
otherwise, using DIV_ROUND_CLOSEST(port->uartclk, quot * baud) will fail due to
divisor is zero.
Signed-off-by: NEddie Huang <eddie.huang@mediatek.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add the config symbol for Mediatek MT7620 SoC to the SERIAL_8250_RT288X
dependencies.
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The Ralink RT2880 SoC and its successors have an internal 8250 core. This core
needs the same quirks applied as the AMD AU1xxx uart. In addition to these
quirks, the ports memory region is only 0x100 unlike the AU1xxx which has a
size of 0x1000.
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

devm_kzalloc() already warns if allocation fails; remove duplicate
message.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

setup_serial_console() is obsolete and has been superseded by
early_serial_setup() which is called at the end of the function.

The IA64 arch does not call this function; only the m68k arch setup
calls this function.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The calculation of value quot for highspeed register set to three
was wrong. This patch fixes the calculation so that the serial port
for baudrates bigger then 576000 baud is working correctly.
Signed-off-by: NMatthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The dma pointer under struct uart_8250_port is currently left
unassigned for non-ACPI platforms. It should be pointing to the dma
member in struct dw8250_data like how it was done for ACPI, so the core
8250 code will try to request for DMA when registering the port

If DMA is not enabled in device tree, request DMA will fail and the
driver will fall back to PIO
Signed-off-by: NRay Jui <rjui@broadcom.com>
Reviewed-by: NJD (Jiandong) Zheng <jdzheng@broadcom.com>
Reviewed-by: NScott Branden <sbranden@broadcom.com>
Tested-by: NScott Branden <sbranden@broadcom.com>
Reviewed-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
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>