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5 Commits

Author SHA1 Message Date
Linus Walleij
2c50a570e9 ARM: 9004/1: debug: Split waituart to CTS and TXRDY 
This patch was triggered by a remark from Russell that
introducing a call to the waituart (needed to fix debug prints
on the Qualcomm platforms) was dangerous because in some cases
this will involve waiting for a modem CTS (clear to send)
signal, and debug messages would maybe not work on platforms
with no modem connected to the UART port: they will just
hang waiting for the modem to assert CTS and this might never
happen.

Looking through all UART debug drivers implementing the waituart
macro I discovered that all users except two actually use this
macro to check if the UART is ready for TX, let's call this
TXRDY.

Only two debug UART drivers actually check for CTS:
- arch/arm/include/debug/8250.S
- arch/arm/include/debug/tegra.S

The former is very significant since the 8250 is possibly
the most common UART on the planet.

We have the following problem: the semantics of waituart are
ambiguous making it dangerous to introduce the macro to debug
code fixing debug prints for Qualcomm. To start to pry this
problem apart, this patch does the following:

- Convert all debug UART drivers to define two macros:

  - waituartcts with the clear semantic to wait for CTS
    to be asserted

  - waituarttxrdy with the clear semantic to wait for the TX
    capability of the UART to be ready

- When doing this take care to assign the right function to
  each drivers macro, so they now do exactly the above.

- Update the three sites in the kernel invoking the waituart
  macro to call waituartcts/waituarttxrdy in sequence, so that
  the functional impact on the kernel should be zero.

After this we can start to change the code sites using this
code to do the right thing.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
 2020-09-15 14:35:27 +01:00
Thomas Gleixner
a636cd6c42 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 4 
Based on 1 normalized pattern(s):

  licensed under gplv2 or later

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 118 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154040.961286471@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2019-05-21 11:28:40 +02:00
Guo Zeng
01ea63d993 ARM: sirf: add two debug ports for CSRatlas7 SoC 
this patch adds UART0 and UART1 as LLUART port, as the new Atlas7
registers layout are different, it also refines some names of old
hard-coded MARCOs and uses CONFIG_DEBUG_UART_PHYS/DEBUG_UART_VIRT
to define different base addresses for multiple ports.

Signed-off-by: Guo Zeng <Guo.Zeng@csr.com>
Signed-off-by: Zhiwu Song <Zhiwu.Song@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
 2015-01-20 19:42:56 +08:00
Barry Song
07dde66c29 ARM: sirf: drop Marco low-level debug port 
Marco will not be supported any more. it has been replaced by CSR
Atlas7.

Signed-off-by: Barry Song <Baohua.Song@csr.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
 2015-01-14 20:54:50 +08:00
Arnd Bergmann
67bdb28718 ARM: sirf: move debug-macro.S to include/debug/sirf.S 
The new style ll_debug implementation for multiplatform requires the
platform glue to be in include/debug, so let's move it there to
separate the debugging logic from the platform code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Barry Song <Baohua.Song@csr.com>
 2013-03-25 12:29:40 +01:00