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x86/hpet: Add function to select a /dev/hpet channel 

If CONFIG_HPET=y is enabled the x86 specific HPET code should reserve at
least one channel for the /dev/hpet character device, so that not all
channels are absorbed for per CPU clockevent devices.

Create a function to assign HPET_MODE_DEVICE so the rework of the
clockevents allocation code can utilize the mode information instead of
reducing the number of evaluated channels by #ifdef hackery.

The function is not yet used, but provided as a separate patch for ease of
review. It will be used when the rework of the clockevent selection takes
place.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/20190623132436.002758910@linutronix.de
This commit is contained in:
Thomas Gleixner 2019-06-23 15:24:01 +02:00
parent 9e16e4933e
commit af5a1dadf3
1 changed files with 17 additions and 0 deletions
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17
arch/x86/kernel/hpet.c
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@ -228,8 +228,25 @@ static void __init hpet_reserve_platform_timers(void)
hpet_alloc(&hd);
}
static void __init hpet_select_device_channel(void)
{
int i;
for (i = 0; i < hpet_base.nr_channels; i++) {
struct hpet_channel *hc = hpet_base.channels + i;
/* Associate the first unused channel to /dev/hpet */
if (hc->mode == HPET_MODE_UNUSED) {
hc->mode = HPET_MODE_DEVICE;
return;
}
}
}
#else
static inline void hpet_reserve_platform_timers(void) { }
static inline void hpet_select_device_channel(void) {}
#endif
/* Common HPET functions */