serial: lpuart: Avoid division by zero when requested baudrate is ...

With serdev device support added there's now a corner case where:

 1. There is a DT node for a serdev device on one of the UARTs
 2. There is no driver that binds against serdev device's compatibility
    string

with 1 and 2 being true it is possible to end up in a situation where
a particualr UART has not been initalized to any baudrate when
clock_notifier_call_chain() gets called. This effectively translates
to

	set_baudrate(uart, 0);

which for LPUART driver result in a division by zero.

To avoid this problem, convert lpuart_serial_setbaudrate() to treat
zero baudrate as a request to disable the UART. While we are at it add
a BUG_ON() to lpuart_setbrg() to simplify finding any future bugs.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

serial: i.MX: Add i.MX8 support ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

serial/lpuart: Do not enable UART FIFO ...

Using FIFO in LPUART results in subtle serial input draining issues
which are quite difficult to reproduce and troubleshoot. Since the
change offered only moderate performance gain revert the code to
operate in no-FIFO mode to avoid FIFO-related problems alltogether.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: i.MX: Add i.MX7 base architecture support ...

Signed-off-by Juergen Borleis <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'for-next/vybrid'

i.MX: Add DEBUG_LL hooks for VF610 ...

Add code to support DEBUG_LL functionality on VF610/Vybrid platform.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

serial: i.MX uart: Allow DTE mode in lowlevel code ...

Some consoles must be configured for DTE mode. Allow to set this
in lowlevel code.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add i.MX50 support ...

Signed-off-by: Alexander Kurz <akurz@blala.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

serial: imx: Support DTE mode ...

Based on Kernel commit 20ff2fe60a: serial: imx: add support for DTE mode

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'for-next/vincell'

ARM: i.MX: make early UART functions independent of DEBUG_LL ...

We have functions to setup the i.MX uart for early use, but these all
depend on DEBUG_LL. Move them to imx-uart.h to make them usable for
the regular PBL console.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

i.MX: serial: Add baud rate calculation convenience functions ...

Add two functions to calculate values for UBMR and UBIR
registers. This way both early serial initalization code and
serial_imx.c can use them and not duplicate the code.

Singed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

i.MX: serial: Add constants for UART clock divisor ...

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

i.MX: Move UART definitions into a separate file ...

Move UART definitions into a separate file to avoid redefinition in
<mach/debug_ll.h> and magical constants in low level UART
initialization code.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>