317178b88f
The system tick count is a 64 bit quantity that gets updated from
interrupt context, meaning that it's dangerously non-atomic and has to
be locked. The core kernel clock code did this right.
But the value was also exposed to the rest of the universe as a global
variable, and virtually nothing else was doing this correctly. Even
in the timer ISRs themselves, the interrupts may be themselves
preempted (most of our architectures support nested interrupts) by
code that wants to set timeouts and inspect system uptime.
Define a z_tick_{get,set}() API, eliminate the old variable, and make
sure everyone uses the right mechanism.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
40 lines
702 B
C
40 lines
702 B
C
/*
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* Copyright (c) 2017 Synopsys, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief Time Stamp API for ARCv2
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*
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* Provide 64-bit time stamp API
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*/
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#include <kernel.h>
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#include <toolchain.h>
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#include <kernel_structs.h>
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/*
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* @brief Read 64-bit timestamp value
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*
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* This function returns a 64-bit bit time stamp value that is clocked
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* at the same frequency as the CPU.
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*
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* @return 64-bit time stamp value
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*/
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u64_t _tsc_read(void)
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{
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unsigned int key;
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u64_t t;
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u32_t count;
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key = irq_lock();
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t = (u64_t)z_tick_get();
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count = _arc_v2_aux_reg_read(_ARC_V2_TMR0_COUNT);
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irq_unlock(key);
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t *= (u64_t)sys_clock_hw_cycles_per_tick();
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t += (u64_t)count;
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return t;
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}
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