kernel/linux.git/drivers/clocksource/arm_global_timer.c, branch v6.12.80

clocksource/driver/arm_global_timer: Remove unnecessary ‘0’ values from err

2024-07-12T14:07:05+00:00

The 'err' variable is initialized whatever the code path, it is pointless to initialize it when it is declared. Signed-off-by: Li kunyu Link: https://lore.kernel.org/r/20240705052159.22235-1-kunyu@nfschina.com Signed-off-by: Daniel Lezcano

clocksource/drivers/arm_global_timer: Simplify prescaler register access

2024-02-26T09:07:25+00:00

Use GENMASK() to define the prescaler mask and make the whole driver use the mask (together with helpers such as FIELD_{GET,PREP,FIT}) instead of needing an additional shift and max value constant. Signed-off-by: Martin Blumenstingl Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240225151336.2728533-4-martin.blumenstingl@googlemail.com

clocksource/drivers/arm_global_timer: Guard against division by zero

2024-02-26T09:07:25+00:00

The result of the division of new_rate by gt_target_rate can be zero (if new_rate is smaller than gt_target_rate). Using that result as divisor without checking can result in a division by zero error. Guard against this by checking for a zero value earlier. While here, also change the psv variable to an unsigned long to make sure we don't overflow the datatype as all other types involved are also unsiged long. Signed-off-by: Martin Blumenstingl Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240225151336.2728533-3-martin.blumenstingl@googlemail.com

clocksource/drivers/arm_global_timer: Make gt_target_rate unsigned long

2024-02-26T09:07:25+00:00

Change the data type of gt_target_rate to unsigned long as this is what we get back from clk_get_rate(). Signed-off-by: Martin Blumenstingl Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240225151336.2728533-2-martin.blumenstingl@googlemail.com

clocksource: arm_global_timer: fix non-kernel-doc comment

2024-02-21T08:56:06+00:00

Use a common C comment "/*" instead of a kernel-doc marker "/**" to prevent kernel-doc warnings: arm_global_timer.c:92: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst * To ensure that updates to comparator value register do not set the arm_global_timer.c:92: warning: missing initial short description on line: * To ensure that updates to comparator value register do not set the Signed-off-by: Randy Dunlap Cc: Patrice Chotard Cc: linux-arm-kernel@lists.infradead.org Cc: Daniel Lezcano Cc: Thomas Gleixner Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240115053641.29129-1-rdunlap@infradead.org

clocksource/drivers/arm_global_timer: Remove stray tab

2024-02-18T23:48:54+00:00

Remove a stray tab in global_timer_of_register() which is different from the coding style in the rest of the driver. Signed-off-by: Martin Blumenstingl Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240218174138.1942418-3-martin.blumenstingl@googlemail.com

clocksource/drivers/arm_global_timer: Fix maximum prescaler value

2024-02-18T23:48:54+00:00

The prescaler in the "Global Timer Control Register bit assignments" is documented to use bits [15:8], which means that the maximum prescaler register value is 0xff. Fixes: 171b45a4a70e ("clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes") Signed-off-by: Martin Blumenstingl Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20240218174138.1942418-2-martin.blumenstingl@googlemail.com

clocksource/drivers/arm_global_timer: Remove duplicated argument in arm_global_timer

2021-06-16T15:33:04+00:00

Fix the following coccicheck warning: drivers/clocksource/arm_global_timer.c:107:4-23: duplicated argument to & or | Signed-off-by: Wan Jiabing Reviewed-by: Patrice Chotard Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20210615115440.8881-1-wanjiabing@vivo.com

clocksource/drivers/arm_global_timer: Make symbol 'gt_clk_rate_change_nb' static

2021-06-16T15:33:04+00:00

The sparse tool complains as follows: drivers/clocksource/arm_global_timer.c:54:23: warning: symbol 'gt_clk_rate_change_nb' was not declared. Should it be static? This symbol is not used outside of arm_global_timer.c, so mark it static. Reported-by: Hulk Robot Signed-off-by: Zou Wei Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/1623490046-37972-1-git-send-email-zou_wei@huawei.com

clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes

2021-06-16T15:33:04+00:00

This patch adds rate change notification support for the parent clock; should that clock change, then we try to adjust the our prescaler in order to compensate (i.e. we adjust to still get the same timer frequency). This is loosely based on what it's done in timer-cadence-ttc. timer-sun51, mips-gic-timer and smp_twd.c also seem to look at their parent clock rate and to perform some kind of adjustment whenever needed. In this particular case we have only one single counter and prescaler for all clocksource, clockevent and timer_delay, and we just update it for all (i.e. we don't let it go and call clockevents_update_freq() to notify to the kernel that our rate has changed). Note that, there is apparently no other way to fixup things, because once we call register_current_timer_delay(), specifying the timer rate, it seems that that rate is not supposed to change ever. In order for this mechanism to work, we have to make assumptions about how much the initial clock is supposed to eventually decrease from the initial one, and set our initial prescaler to a value that we can eventually decrease enough to compensate. We provide an option in KConfig for this. In case we end up in a situation in which we are not able to compensate the parent clock change, we fail returning NOTIFY_BAD. This fixes a real-world problem with Zynq arch not being able to use this driver and CPU_FREQ at the same time (because ARM global timer is fed by the CPU clock, which may keep changing when CPU_FREQ is enabled). Signed-off-by: Andrea Merello Cc: Patrice Chotard Cc: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: Michal Simek Cc: Sören Brinkmann Reviewed-by: Patrice Chotard Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20210406130045.15491-2-andrea.merello@gmail.com