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 42 static 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 */ 52 inline 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_assert_fp_enabled - Check if FPU protection is enabled 63 * 64 * This function tells if the code is already under FPU protection or not. A 65 * function that works as an API for a set of FPU operations can use this 66 * function for checking if the caller invoked it after DC_FP_START(). For 67 * example, take a look at dcn20_fpu.c file. 68 * 69 * Similar to dc_assert_fp_enabled, but does not assert, returns status instead. 70 */ 71 inline bool dc_is_fp_enabled(void) 72 { 73 int depth; 74 75 depth = this_cpu_read(fpu_recursion_depth); 76 77 return (depth >= 1); 78 } 79 80 /** 81 * dc_fpu_begin - Enables FPU protection 82 * @function_name: A string containing the function name for debug purposes 83 * (usually __func__) 84 * 85 * @line: A line number where DC_FP_START was invoked for debug purpose 86 * (usually __LINE__) 87 * 88 * This function is responsible for managing the use of kernel_fpu_begin() with 89 * the advantage of providing an event trace for debugging. 90 * 91 * Note: Do not call this function directly; always use DC_FP_START(). 92 */ 93 void dc_fpu_begin(const char *function_name, const int line) 94 { 95 int depth; 96 97 WARN_ON_ONCE(!in_task()); 98 preempt_disable(); 99 depth = this_cpu_inc_return(fpu_recursion_depth); 100 if (depth == 1) { 101 BUG_ON(!kernel_fpu_available()); 102 kernel_fpu_begin(); 103 } 104 105 TRACE_DCN_FPU(true, function_name, line, depth); 106 } 107 108 /** 109 * dc_fpu_end - Disable FPU protection 110 * @function_name: A string containing the function name for debug purposes 111 * @line: A-line number where DC_FP_END was invoked for debug purpose 112 * 113 * This function is responsible for managing the use of kernel_fpu_end() with 114 * the advantage of providing an event trace for debugging. 115 * 116 * Note: Do not call this function directly; always use DC_FP_END(). 117 */ 118 void dc_fpu_end(const char *function_name, const int line) 119 { 120 int depth; 121 122 depth = this_cpu_dec_return(fpu_recursion_depth); 123 if (depth == 0) { 124 kernel_fpu_end(); 125 } else { 126 WARN_ON_ONCE(depth < 0); 127 } 128 129 TRACE_DCN_FPU(false, function_name, line, depth); 130 preempt_enable(); 131 } 132