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 #ifdef notyet
43 static DEFINE_PER_CPU(int, fpu_recursion_depth);
44 #else
45 static int fpu_recursion_depth;
46
47 #define __this_cpu_read(x) atomic_read(&x)
48 #define __this_cpu_inc_return(x) atomic_inc_return(&x)
49 #define __this_cpu_dec_return(x) atomic_dec_return(&x)
50 #endif
51
52 /**
53 * dc_assert_fp_enabled - Check if FPU protection is enabled
54 *
55 * This function tells if the code is already under FPU protection or not. A
56 * function that works as an API for a set of FPU operations can use this
57 * function for checking if the caller invoked it after DC_FP_START(). For
58 * example, take a look at dcn20_fpu.c file.
59 */
dc_assert_fp_enabled(void)60 void dc_assert_fp_enabled(void)
61 {
62 int depth;
63
64 depth = __this_cpu_read(fpu_recursion_depth);
65
66 ASSERT(depth >= 1);
67 }
68
69 /**
70 * dc_fpu_begin - Enables FPU protection
71 * @function_name: A string containing the function name for debug purposes
72 * (usually __func__)
73 *
74 * @line: A line number where DC_FP_START was invoked for debug purpose
75 * (usually __LINE__)
76 *
77 * This function is responsible for managing the use of kernel_fpu_begin() with
78 * the advantage of providing an event trace for debugging.
79 *
80 * Note: Do not call this function directly; always use DC_FP_START().
81 */
dc_fpu_begin(const char * function_name,const int line)82 void dc_fpu_begin(const char *function_name, const int line)
83 {
84 int depth;
85
86 WARN_ON_ONCE(!in_task());
87 preempt_disable();
88 depth = __this_cpu_inc_return(fpu_recursion_depth);
89 if (depth == 1) {
90 BUG_ON(!kernel_fpu_available());
91 kernel_fpu_begin();
92 }
93
94 TRACE_DCN_FPU(true, function_name, line, depth);
95 }
96
97 /**
98 * dc_fpu_end - Disable FPU protection
99 * @function_name: A string containing the function name for debug purposes
100 * @line: A-line number where DC_FP_END was invoked for debug purpose
101 *
102 * This function is responsible for managing the use of kernel_fpu_end() with
103 * the advantage of providing an event trace for debugging.
104 *
105 * Note: Do not call this function directly; always use DC_FP_END().
106 */
dc_fpu_end(const char * function_name,const int line)107 void dc_fpu_end(const char *function_name, const int line)
108 {
109 int depth;
110
111 depth = __this_cpu_dec_return(fpu_recursion_depth);
112 if (depth == 0) {
113 kernel_fpu_end();
114 } else {
115 WARN_ON_ONCE(depth < 0);
116 }
117
118 TRACE_DCN_FPU(false, function_name, line, depth);
119 preempt_enable();
120 }
121