9 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
d2912cb15b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:55 +02:00
Linus Torvalds
8fac2f96ab Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM updates from Russell King:
 "Low priority fixes and updates for ARM:

   - add some missing includes

   - efficiency improvements in system call entry code when tracing is
     enabled

   - ensure ARMv6+ is always built as EABI

   - export save_stack_trace_tsk()

   - fix fatal signal handling during mm fault

   - build translation table base address register from scratch

   - appropriately align the .data section to a word boundary where we
     rely on that data being word aligned"

* 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8691/1: Export save_stack_trace_tsk()
  ARM: 8692/1: mm: abort uaccess retries upon fatal signal
  ARM: 8690/1: lpae: build TTB control register value from scratch in v7_ttb_setup
  ARM: align .data section
  ARM: always enable AEABI for ARMv6+
  ARM: avoid saving and restoring registers unnecessarily
  ARM: move PC value into r9
  ARM: obtain thread info structure later
  ARM: use aliases for registers in entry-common
  ARM: 8689/1: scu: add missing errno include
  ARM: 8688/1: pm: add missing types include
2017-09-12 06:10:44 -07:00
Russell King
1abd350237 ARM: align .data section
Robert Jarzmik reports that his PXA25x system fails to boot with 4.12,
failing at __flush_whole_cache in arch/arm/mm/proc-xscale.S:215:

   0xc0019e20 <+0>:     ldr     r1, [pc, #788]
   0xc0019e24 <+4>:     ldr     r0, [r1]	<== here

with r1 containing 0xc06f82cd, which is the address of "clean_addr".
Examination of the System.map shows:

c06f22c8 D user_pmd_table
c06f22cc d __warned.19178
c06f22cd d clean_addr

indicating that a .data.unlikely section has appeared just before the
.data section from proc-xscale.S.  According to objdump -h, it appears
that our assembly files default their .data alignment to 2**0, which
is bad news if the preceding .data section size is not power-of-2
aligned at link time.

Add the appropriate .align directives to all assembly files in arch/arm
that are missing them where we require an appropriate alignment.

Reported-by: Robert Jarzmik <robert.jarzmik@free.fr>
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2017-08-14 16:22:55 +01:00
Tony Lindgren
51ef70037e ARM: debug: Use generic 8250 debug_ll for am3517 and am335x
We want to use generic 8250 debug_ll code to get DEBUG_UNCOMPRESS
working and to simplify the code. The old debug_ll code is no longer
needed and the machine ID based detection is no longer used.

Note that for most part there's no need to keep DEBUG_LL enabled.
We now have CONFIG_SERIAL_EARLYCON working very early as long as
the kernel cmdline has "earlycon" in it and the board specific dts
file has chosen configured with with the port using stdout-path.

Cc: Hoeun Ryu <hoeun.ryu@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2017-07-17 00:53:42 -07:00
Tony Lindgren
2d1f7d2e24 ARM: debug: Use generic 8250 debug_ll for ti81xx
We want to use generic 8250 debug_ll code to get DEBUG_UNCOMPRESS
working and to simplify the code. The old debug_ll code is no longer
needed and the machine ID based detection is no longer used.

Note that for most part there's no need to keep DEBUG_LL enabled.
We now have CONFIG_SERIAL_EARLYCON working very early as long as
the kernel cmdline has "earlycon" in it and the board specific dts
file has chosen configured with with the port using stdout-path.

Cc: Hoeun Ryu <hoeun.ryu@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2017-07-17 00:51:46 -07:00
Tony Lindgren
fc23beb8a5 ARM: debug: Use generic 8250 debug_ll for omap3/4/5
We want to use generic 8250 debug_ll code to get DEBUG_UNCOMPRESS
working and to simplify the code. The old debug_ll code is no longer
needed and the machine ID based detection is no longer used.

Note that for most part there's no need to keep DEBUG_LL enabled.
We now have CONFIG_SERIAL_EARLYCON working very early as long as
the kernel cmdline has "earlycon" in it and the board specific dts
file has chosen configured with with the port using stdout-path.

Cc: Hoeun Ryu <hoeun.ryu@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2017-07-17 00:49:08 -07:00
Tony Lindgren
d2b310b023 ARM: debug: Use generic 8250 debug_ll for omap2 and omap3/4/5 common uarts
We want to use generic 8250 debug_ll code to get DEBUG_UNCOMPRESS
working and to simplify the code. The old debug_ll code is no longer
needed and the machine ID based detection is no longer used.

Note that for most part there's no need to keep DEBUG_LL enabled.
We now have CONFIG_SERIAL_EARLYCON working very early as long as
the kernel cmdline has "earlycon" in it and the board specific dts
file has chosen configured with with the port using stdout-path.

Cc: Hoeun Ryu <hoeun.ryu@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2017-07-17 00:35:39 -07:00
Tony Lindgren
808b7e0746 ARM: OMAP2+: Add multiplatform debug_ll support
Add multiplatform debug_ll support by stripping away
the custom hacks to detect the port from debug-macro.S.

Note that this now requires the specific debug_ll port to
be selected in the .config.

The old debug-macro.S will be removed a bit later
once we are sure things work properly with multiplatform
enabled.

Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
2013-01-11 11:24:19 -08:00