1// SPDX-License-Identifier: MIT
  2/*
  3 * Copyright 2021 Advanced Micro Devices, Inc.
  4 *
  5 * Permission is hereby granted, free of charge, to any person obtaining a
  6 * copy of this software and associated documentation files (the "Software"),
  7 * to deal in the Software without restriction, including without limitation
  8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  9 * and/or sell copies of the Software, and to permit persons to whom the
 10 * Software is furnished to do so, subject to the following conditions:
 11 *
 12 * The above copyright notice and this permission notice shall be included in
 13 * all copies or substantial portions of the Software.
 14 *
 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 18 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 19 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 20 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 21 * OTHER DEALINGS IN THE SOFTWARE.
 22 *
 23 * Authors: AMD
 24 *
 25 */
 26
 27#include "dc_trace.h"
 28
 29#include <linux/fpu.h>
 30
 31/**
 32 * DOC: DC FPU manipulation overview
 33 *
 34 * DC core uses FPU operations in multiple parts of the code, which requires a
 35 * more specialized way to manage these areas' entrance. To fulfill this
 36 * requirement, we created some wrapper functions that encapsulate
 37 * kernel_fpu_begin/end to better fit our need in the display component. In
 38 * summary, in this file, you can find functions related to FPU operation
 39 * management.
 40 */
 41
 42static DEFINE_PER_CPU(int, fpu_recursion_depth);
 43
 44/**
 45 * dc_assert_fp_enabled - Check if FPU protection is enabled
 46 *
 47 * This function tells if the code is already under FPU protection or not. A
 48 * function that works as an API for a set of FPU operations can use this
 49 * function for checking if the caller invoked it after DC_FP_START(). For
 50 * example, take a look at dcn20_fpu.c file.
 51 */
 52inline void dc_assert_fp_enabled(void)
 53{
 54	int depth;
 55
 56	depth = __this_cpu_read(fpu_recursion_depth);
 57
 58	ASSERT(depth >= 1);
 59}
 60
 61/**
 62 * dc_fpu_begin - Enables FPU protection
 63 * @function_name: A string containing the function name for debug purposes
 64 *   (usually __func__)
 65 *
 66 * @line: A line number where DC_FP_START was invoked for debug purpose
 67 *   (usually __LINE__)
 68 *
 69 * This function is responsible for managing the use of kernel_fpu_begin() with
 70 * the advantage of providing an event trace for debugging.
 71 *
 72 * Note: Do not call this function directly; always use DC_FP_START().
 73 */
 74void dc_fpu_begin(const char *function_name, const int line)
 75{
 76	int depth;
 77
 78	WARN_ON_ONCE(!in_task());
 79	preempt_disable();
 80	depth = __this_cpu_inc_return(fpu_recursion_depth);
 81	if (depth == 1) {
 82		BUG_ON(!kernel_fpu_available());
 83		kernel_fpu_begin();
 84	}
 85
 86	TRACE_DCN_FPU(true, function_name, line, depth);
 87}
 88
 89/**
 90 * dc_fpu_end - Disable FPU protection
 91 * @function_name: A string containing the function name for debug purposes
 92 * @line: A-line number where DC_FP_END was invoked for debug purpose
 93 *
 94 * This function is responsible for managing the use of kernel_fpu_end() with
 95 * the advantage of providing an event trace for debugging.
 96 *
 97 * Note: Do not call this function directly; always use DC_FP_END().
 98 */
 99void dc_fpu_end(const char *function_name, const int line)
100{
101	int depth;
102
103	depth = __this_cpu_dec_return(fpu_recursion_depth);
104	if (depth == 0) {
105		kernel_fpu_end();
106	} else {
107		WARN_ON_ONCE(depth < 0);
108	}
109
110	TRACE_DCN_FPU(false, function_name, line, depth);
111	preempt_enable();
112}