linux-toradex.git/drivers/clocksource/dw_apb_timer_of.c, branch v5.11-rc2

clocksource/drivers/dw_apb_timer_of: Add error handling if no clock available

2020-12-05T18:33:55+00:00

commit ("b0fc70ce1f02 arm64: berlin: Select DW_APB_TIMER_OF") added the
support for the dw_apb_timer into the arm64 defconfig. However, for some
platforms like the Intel Stratix10 and Agilex, the clock manager doesn't
get loaded until after the timer driver get loaded. Thus, the driver hits
the panic "No clock nor clock-frequency property for" because it cannot
properly get the clock.

This patch adds the error handling needed for the timer driver so that
the kernel can continue booting instead of just hitting the panic.

Signed-off-by: Dinh Nguyen 
Signed-off-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/20201205105223.208604-1-dinguyen@kernel.org

clocksource: dw_apb_timer_of: Fix missing clockevent timers

2020-05-22T22:02:59+00:00

Commit 100214889973 ("clocksource: dw_apb_timer_of: use
clocksource_of_init") replaced a publicly available driver
initialization method with one called by the timer_probe() method
available after CLKSRC_OF. In current implementation it traverses
all the timers available in the system and calls their initialization
methods if corresponding devices were either in dtb or in acpi. But
if before the commit any number of available timers would be installed
as clockevent and clocksource devices, after that there would be at most
two. The rest are just ignored since default case branch doesn't do
anything. I don't see a reason of such behaviour, neither the commit
message explains it. Moreover this might be wrong if on some platforms
these timers might be used for different purpose, as virtually CPU-local
clockevent timers and as an independent broadcast timer. So in order
to keep the compatibility with the platforms where the order of the
timers detection has some meaning, lets add the secondly discovered
timer to be of clocksource/sched_clock type, while the very first and
the others would provide the clockevents service.

Fixes: 100214889973 ("clocksource: dw_apb_timer_of: use clocksource_of_init")
Signed-off-by: Serge Semin 
Cc: Alexey Malahov 
Cc: Thomas Bogendoerfer 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Alessandro Zummo 
Cc: Alexandre Belloni 
Cc: Arnd Bergmann 
Cc: Rob Herring 
Cc: linux-mips@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/20200521204818.25436-7-Sergey.Semin@baikalelectronics.ru

clocksource: dw_apb_timer: Affiliate of-based timer with any CPU

2020-05-22T22:02:50+00:00

Currently any DW APB Timer device detected in OF is bound to CPU #0.
Doing so is redundant since DW APB Timer isn't CPU-local timer, but as
having APB interface is normally accessible from any CPU in the system. By
artificially affiliating the DW timer to the very first CPU we may and in
our case will make the clockevent subsystem to decline the more performant
real CPU-local timers selection in favor of in fact non-local and
accessible over a slow bus - DW APB Timers.

Let's not affiliate the of-detected DW APB Timers to any CPU. By doing so
the clockevent framework would prefer to select the real CPU-local timer
instead of DW APB one. Otherwise if there is no other than DW APB device
for clockevents tracking then it will be selected.

Signed-off-by: Serge Semin 
Cc: Alexey Malahov 
Cc: Thomas Bogendoerfer 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Alessandro Zummo 
Cc: Alexandre Belloni 
Cc: Arnd Bergmann 
Cc: Rob Herring 
Cc: linux-mips@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Daniel Lezcano 
Link: https://lore.kernel.org/r/20200521204818.25436-6-Sergey.Semin@baikalelectronics.ru

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234

2019-06-19T15:09:07+00:00

Based on 1 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
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not see http www gnu org
  licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 503 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Alexios Zavras 
Reviewed-by: Allison Randal 
Reviewed-by: Enrico Weigelt 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman

clocksource/drivers/dw_apb: Add reset control

2018-10-07T12:16:35+00:00

Add code to retrieve the reset property from the dw-apb timers and if
the property is available, the safe operation is to assert the timer
into reset, and followed by a deassert of the timer reset (brings the
timer out of reset).

This patch is needed for systems where the bootloader has left the timer
not used in reset.

 - Trivial conflict with commit a74bd1ad7a:
    "Convert to using %pOFn instead of device_node.name"

Reported-by: Marek Vasut 
Signed-off-by: Dinh Nguyen 
Signed-off-by: Daniel Lezcano

clocksource: Convert to using %pOFn instead of device_node.name

2018-10-03T12:36:52+00:00

In preparation to remove the node name pointer from struct device_node,
convert printf users to use the %pOFn format specifier.

Cc: Daniel Lezcano 
Cc: Thomas Gleixner 
Cc: Michal Simek 
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Rob Herring 
Signed-off-by: Daniel Lezcano

clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE

2017-06-14T09:58:45+00:00

The CLOCKSOURCE_OF_DECLARE macro is used widely for the timers to declare the
clocksource at early stage. However, this macro is also used to initialize
the clockevent if any, or the clockevent only.

It was originally suggested to declare another macro to initialize a
clockevent, so in order to separate the two entities even they belong to the
same IP. This was not accepted because of the impact on the DT where splitting
a clocksource/clockevent definition does not make sense as it is a Linux
concept not a hardware description.

On the other side, the clocksource has not interrupt declared while the
clockevent has, so it is easy from the driver to know if the description is
for a clockevent or a clocksource, IOW it could be implemented at the driver
level.

So instead of dealing with a named clocksource macro, let's use a more generic
one: TIMER_OF_DECLARE.

The patch has not functional changes.

Signed-off-by: Daniel Lezcano 
Acked-by: Heiko Stuebner 
Acked-by: Neil Armstrong 
Acked-by: Arnd Bergmann 
Acked-by: Matthias Brugger 
Reviewed-by: Linus Walleij

clocksources: Switch back to the clksrc table

2016-06-28T08:19:35+00:00

All the clocksource drivers's init function are now converted to return
an error code. CLOCKSOURCE_OF_DECLARE is no longer used as well as the
clksrc-of table.

Let's convert back the names:
 - CLOCKSOURCE_OF_DECLARE_RET => CLOCKSOURCE_OF_DECLARE
 - clksrc-of-ret              => clksrc-of

Signed-off-by: Daniel Lezcano 

For exynos_mct and samsung_pwm_timer:
Acked-by: Krzysztof Kozlowski 

For arch/arc:
Acked-by: Vineet Gupta 

For mediatek driver:
Acked-by: Matthias Brugger 

For the Rockchip-part
Acked-by: Heiko Stuebner 

For STi :
Acked-by: Patrice Chotard 

For the mps2-timer.c and versatile.c changes:
Acked-by: Liviu Dudau 

For the OXNAS part :
Acked-by: Neil Armstrong 

For LPC32xx driver:
Acked-by: Sylvain Lemieux 

For Broadcom Kona timer change:
Acked-by: Ray Jui 

For Sun4i and Sun5i:
Acked-by: Chen-Yu Tsai 

For Meson6:
Acked-by: Carlo Caione 

For Keystone:
Acked-by: Santosh Shilimkar 

For NPS:
Acked-by: Noam Camus 

For bcm2835:
Acked-by: Eric Anholt

clocksource/drivers/dw_apb_timer: Convert init function to return error

2016-06-28T08:19:19+00:00

The init functions do not return any error. They behave as the following:

 - panic, thus leading to a kernel crash while another timer may work and
   make the system boot up correctly

 or

 - print an error and let the caller unaware if the state of the system

Change that by converting the init functions to return an error conforming
to the CLOCKSOURCE_OF_RET prototype.

Proper error handling (rollback, errno value) will be changed later case
by case, thus this change just return back an error or success in the init
function.

Signed-off-by: Daniel Lezcano

clocksource/drivers/dw_apb_timer_of: Implement ARM delay timer

2015-12-15T08:42:00+00:00

Implement an ARM delay timer to be used for udelay(). This allows us to
skip the delay loop calibration at boot on Marvell BG2, BG2Q, BG2CD
platforms. And after this patch, udelay() will be unaffected by CPU
frequency changes.

Note: Although in case there are several possible delay timers, we may
not select the "best" delay timer. Take one Marvell Berlin platform for
example: we have arch timer and dw-apb timer. The arch timer freq is
25MHZ while the dw-apb timer freq is 100MHZ, current selection would
choose the dw-apb timer. But the dw apb timer is on the APB bus while
arch timer sits in CPU, the cost of accessing the apb timer is higher
than the arch timer. We could introduce "rating" concept to delay
timer, but this approach "brings a lot of complexity and workarounds
in the code for a small benefit" as pointed out by Daniel.

Later, Arnd pointed out "However, we could argue that this actually
doesn't matter at all, because the entire point of the ndelay()/
udelay()/mdelay() functions is to waste CPU cycles doing not much at
all, so we can just as well waste them reading the timer register
than spinning on the CPU reading the arch timer more often.", so we
just simply register the dw apb base delay timer.

Signed-off-by: Jisheng Zhang 
Signed-off-by: Daniel Lezcano