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Confirm that ptimer_src_freq is not zero before using it in arithmetic operations. This check will avoid accidental division by zero. JIRA NVGPU-4925 Change-Id: I44cb895e00d64303f4a6bc0ab1f4e3018a33fa6a Signed-off-by: tkudav <tkudav@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2294654 Reviewed-by: Automatic_Commit_Validation_User Reviewed-by: Vaibhav Kachore <vkachore@nvidia.com> Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com> Tested-by: mobile promotions <svcmobile_promotions@nvidia.com> GVS: Gerrit_Virtual_Submit
121 lines
4.2 KiB
C
121 lines
4.2 KiB
C
/*
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* Copyright (c) 2017-2020, NVIDIA CORPORATION. All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#ifndef NVGPU_PTIMER_H
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#define NVGPU_PTIMER_H
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/**
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* @file
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*
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* Declares structs, defines and APIs exposed by ptimer unit.
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*/
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#include <nvgpu/types.h>
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#include <nvgpu/static_analysis.h>
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struct gk20a;
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struct nvgpu_cpu_time_correlation_sample {
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u64 cpu_timestamp;
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u64 gpu_timestamp;
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};
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/**
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* PTIMER_REF_FREQ_HZ corresponds to a period of 32 nanoseconds.
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* 32 ns is the resolution of ptimer.
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*/
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#define PTIMER_REF_FREQ_HZ 31250000U
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/**
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* @brief Computes the ptimer scaling factor
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*
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* @param ptimer_src_freq [in] source frequency to ptimer
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*
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* 1. The ptimer has a resolution of 32 ns and so requires a reference frequency
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* of:
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* ~~~~~~~~~~~~~~~~~~~~~
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* 1 / 32ns = 31.25 MHz
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* ~~~~~~~~~~~~~~~~~~~~~
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*
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* 2. If the source frequency to ptimer is different than the above reference
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* frequency, we need to get the scaling factor as:
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* Scale_factor = ptimer_ref_freq / ptimer_src_freq
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* 3. The scale_factor is multiplied by 10, so that we get an additional digit
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* decimal precision.
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*
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* 4. For example,
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* - On Maxwell, the ptimer source frequency is 19.2 MHz.
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* scaling_factor_10x = (31250000 * 10)/ 19200000 = 16
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* - On Volta, ptimer_source frequency = 31250000 Hz = ptimer_ref_frequency.
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* scaling_factor_10x = 10
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* @return Scale factor between ptimer reference and source frequency with
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* one digit decimal precision.
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*/
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static inline u32 ptimer_scalingfactor10x(u32 ptimer_src_freq)
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{
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nvgpu_assert(ptimer_src_freq != 0U);
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return nvgpu_safe_cast_u64_to_u32((U64(PTIMER_REF_FREQ_HZ) * U64(10))
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/ U64(ptimer_src_freq));
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}
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/**
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* @brief Scales back the ptimer based timeout value as per the scale factor
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*
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* @param timeout [in] Time value captured using ptimer reference clock
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* @param scale10x [in] The scale factor multiplied by 10 to be used for
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* scaling the ptimer based timeout value.
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*
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* 1. When the ptimer source frequency is not same as expected ptimer reference
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* frequency, we need to scale the ptimer based time value. The scaled value
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* is calculated as follows:
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* Scaled valued = timeout / scale_factor.
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* 2. To retain 1 digit decimal precision, the above equation is calculated
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* after multiplication by 10.
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*
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* @return Scaled \a timeout value as per \a scale10x
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*/
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static inline u32 scale_ptimer(u32 timeout , u32 scale10x)
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{
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nvgpu_assert(scale10x != 0U);
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if ((nvgpu_safe_mult_u32(timeout, 10U) % scale10x) >= (scale10x/2U)) {
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return ((timeout * 10U) / scale10x) + 1U;
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} else {
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return (timeout * 10U) / scale10x;
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}
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}
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#ifdef CONFIG_NVGPU_IOCTL_NON_FUSA
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int nvgpu_get_timestamps_zipper(struct gk20a *g,
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u32 source_id, u32 count,
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struct nvgpu_cpu_time_correlation_sample *samples);
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#endif /* CONFIG_NVGPU_IOCTL_NON_FUSA */
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#endif
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