On 07/08/2025 17:02, Marc Zyngier wrote:
> Add a new driver for the MMIO side of the ARM architected timer.
> Most of it has been lifted from the existing arch timer code,
> massaged, and finally rewritten.
>
> It supports both DT and ACPI as firmware descriptions.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> MAINTAINERS | 1 +
> drivers/clocksource/arm_arch_timer_mmio.c | 420 ++++++++++++++++++++++
> 2 files changed, 421 insertions(+)
> create mode 100644 drivers/clocksource/arm_arch_timer_mmio.c
>
[...]
> +static void arch_timer_mmio_setup(struct arch_timer *at, int irq)
> +{
> + at->evt = (struct clock_event_device) {
> + .features = (CLOCK_EVT_FEAT_ONESHOT |
> + CLOCK_EVT_FEAT_DYNIRQ),
> + .name = "arch_mem_timer",
> + .rating = 400,
> + .cpumask = cpu_possible_mask,
> + .irq = irq,
> + .set_next_event = arch_timer_mmio_set_next_event,
> + .set_state_oneshot_stopped = arch_timer_mmio_shutdown,
> + .set_state_shutdown = arch_timer_mmio_shutdown,
> + };
> +
> + at->evt.set_state_shutdown(&at->evt);
> +
> + clockevents_config_and_register(&at->evt, at->rate, 0xf, CLOCKSOURCE_MASK(56));
This doesn't work on 32 bit - clockevents_config_and_register()'s final
argument is an unsigned long, and a 56 bit mask doesn't fit. This
triggers a compiler warning:
drivers/clocksource/arm_arch_timer_mmio.c: In function
'arch_timer_mmio_setup':
./include/linux/bits.h:47:9: error: conversion from 'long long unsigned
int' to 'long unsigned int' changes value from '72057594037927935' to
'4294967295' [-Werror=overflow]
47 | ((t)(GENMASK_INPUT_CHECK(h, l) + \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
48 | (type_max(t) << (l) & \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
49 | type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h)))))
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/bits.h:52:33: note: in expansion of macro 'GENMASK_TYPE'
52 | #define GENMASK_ULL(h, l) GENMASK_TYPE(unsigned long
long, h, l)
| ^~~~~~~~~~~~
./include/linux/clocksource.h:153:32: note: in expansion of macro
'GENMASK_ULL'
153 | #define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
| ^~~~~~~~~~~
drivers/clocksource/arm_arch_timer_mmio.c:255:66: note: in expansion of
macro 'CLOCKSOURCE_MASK'
255 | clockevents_config_and_register(&at->evt, at->rate,
0xf, CLOCKSOURCE_MASK(56));
|
^~~~~~~~~~~~~~~~
Possible this should really be min(CLOCKSOURCE_MASK(56), ULONG_MAX)? But
I'm not familiar enough with this code. Most likely it's dead code on a
32 bit platform.
Thanks,
Steve
