u-boot.git/drivers/serial, branch v2021.10

global: Convert simple_strtoul() with decimal to dectoul()

2021-08-02T17:32:14+00:00

It is a pain to have to specify the value 10 in each call. Add a new
dectoul() function and update the code to use it.

Signed-off-by: Simon Glass

serial: a37xx: Do not call get_ref_clk() in _debug_uart_init()

2021-07-31T07:59:59+00:00

Static inline function _debug_uart_init() should avoid calling external
(non-inline) functions. Therefore do not call get_ref_clk() in
_debug_uart_init() and reimplement its functionality without external
function calls.

Signed-off-by: Pali Rohár 
Reviewed-by: Stefan Roese

serial: a37xx: Use CONFIG_BAUDRATE for initializing early debug UART

2021-07-31T07:59:59+00:00

CONFIG_BAUDRATE should be used for setting the baudrate for the early debug
UART. This replaces current hardcoded 115200 value.

Signed-off-by: Pali Rohár 
Reviewed-by: Marek Behun 
Reviewed-by: Stefan Roese

serial: pl011: Enable DEBUG_UART_PL011 in SPL

2021-07-24T12:57:53+00:00

Commit b81406db51a6 ("arm: serial: Add debug UART capability to the
pl01x driver") add supports to use pl01x as a debug UART. However,
due to CONFIG_IS_ENABLED macro requires CONFIG_SPL_* prefix, the
_debug_uart_init() would not choose TYPE_PL011 in SPL build. This
patch fixes the bug by judging CONFIG_DEBUG_UART_PL011 explicitly.

Signed-off-by: Chen Baozi 
Reviewed-by: Simon Glass

serial: pl011: Resend the character if FIFO is full in debug uart

2021-07-23T22:53:46+00:00

pl01x_putc() might return -EAGAIN if there was no space in FIFO. In that
case, high-level caller should wait until there is space and resend the
character.

Signed-off-by: Chen Baozi 
Reviewed-by: Stefan Roese 
Reviewed-by: Simon Glass

serial: serial_msm: Delay initialization to let pins stabilize

2021-07-23T22:53:46+00:00

For some reason, the DragonBoard 410c aborts autoboot immediately if
U-Boot is started without LK. It looks like it picks up a single broken
character via serial and therefore believes a key was pressed to abort
autoboot.

After some debugging, it seems like adding some delay after pinctrl
setup but before UART initialization fixes the issue. It's also worth
mentioning that unlike when booting from LK, the pinctrl setup is
actually necessary when booting U-Boot without LK since UART is broken
if the pinctrl line is removed.

I suspect that reconfiguring the pins might take some time to stabilize
and if the UART controller is enabled too quickly it will pick up some
random noise. Adding a few milliseconds of delay fixes the issue and
shouldn't have any other negative side effects.

3ms seems to be the minimum delay required in my tests, use 5ms instead
just to be sure.

Signed-off-by: Stephan Gerhold

arm: mvebu: armada-3720: remove unused config option

2021-07-15T08:53:05+00:00

The config option CONFIG_DEBUG_UART_CLOCK is not used by Armada 3720's
serial driver (it wasn't even before the recent update of that driver).

Even if it was used, the value was incorrect (the frequency of the clock
is 25 MHz, not 25.8048 MHz).

Remove it from config files and set the default value to 0.

Signed-off-by: Marek Behún 
Cc: Stefan Roese 
Cc: Pali Rohár 
Reviewed-by: Pali Rohár 
Reviewed-by: Stefan Roese

serial: a37xx: Switch to XTAL clock when booting Linux kernel

2021-07-08T14:40:52+00:00

Unfortunately the UART driver in current Linux for Armada 3700 expects
UART's parent clock to be XTAL and calculats baudrate divisor according
to XTAL clock. Therefore we must switch back to XTAL clock before
booting kernel.

Implement .remove method for this driver with DM_FLAG_OS_PREPARE flag
set.

If current baudrate is unsuitable for XTAL clock then we do not change
anything. This can only happen if the user either configured unsupported
settings or knows what they are doing and has kernel patches which allow
usage of non-XTAL parent clock.

Signed-off-by: Pali Rohár 
Reviewed-by: Marek Behún 
Reviewed-by: Stefan Roese

serial: a37xx: Use TBG as parent clock

2021-07-08T14:40:52+00:00

Using TBG clock as parent clock for UART allows us using higher
baudrates than 230400.

Turris MOX with external FT232RL USB-UART works fine up to 3 MBaud
(which is maximum for this USB-UART controller), while EspressoBIN with
integrated pl2303 USB-UART also works fine up to 6 MBaud.

Slower baudrates with TBG as a parent clock can be achieved by
increasing TBG dividers and oversampling divider. When using the slowest
TBG clock, minimal working baudrate is 300.

Signed-off-by: Pali Rohár 
Signed-off-by: Marek Behún 
Reviewed-by: Stefan Roese

serial: a37xx: Fix parent clock rate value and divider calculation

2021-07-08T14:40:52+00:00

UART parent clock is by default the platform's xtal clock, which is
25 MHz.

The value defined in the driver, though, is 25.8048 MHz. This is a hack
for the suboptimal divisor calculation
  Divisor = UART clock / (16 * baudrate)
which does not use rounding division, resulting in a suboptimal value
for divisor if the correct parent clock rate was used.

Change the code for divisor calculation to round to closest value, i.e.
  Divisor = Round(UART clock / (16 * baudrate))
and change the parent clock rate value to that returned by
get_ref_clk().

This makes A3720 UART stable at standard UART baudrates between 1800 and
230400.

Signed-off-by: Pali Rohár 
Reviewed-by: Marek Behún 
Reviewed-by: Stefan Roese