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 #if defined(CONFIG_X86)
30 #include <asm/fpu/api.h>
31 #elif defined(CONFIG_PPC64)
32 #include <asm/switch_to.h>
33 #include <asm/cputable.h>
34 #elif defined(CONFIG_ARM64)
35 #include <asm/neon.h>
36 #elif defined(CONFIG_LOONGARCH)
37 #include <asm/fpu.h>
38 #endif
39 
40 /**
41  * DOC: DC FPU manipulation overview
42  *
43  * DC core uses FPU operations in multiple parts of the code, which requires a
44  * more specialized way to manage these areas' entrance. To fulfill this
45  * requirement, we created some wrapper functions that encapsulate
46  * kernel_fpu_begin/end to better fit our need in the display component. In
47  * summary, in this file, you can find functions related to FPU operation
48  * management.
49  */
50 
51 static DEFINE_PER_CPU(int, fpu_recursion_depth);
52 
53 /**
54  * dc_assert_fp_enabled - Check if FPU protection is enabled
55  *
56  * This function tells if the code is already under FPU protection or not. A
57  * function that works as an API for a set of FPU operations can use this
58  * function for checking if the caller invoked it after DC_FP_START(). For
59  * example, take a look at dcn20_fpu.c file.
60  */
61 inline void dc_assert_fp_enabled(void)
62 {
63 	int *pcpu, depth = 0;
64 
65 	pcpu = get_cpu_ptr(&fpu_recursion_depth);
66 	depth = *pcpu;
67 	put_cpu_ptr(&fpu_recursion_depth);
68 
69 	ASSERT(depth >= 1);
70 }
71 
72 /**
73  * dc_fpu_begin - Enables FPU protection
74  * @function_name: A string containing the function name for debug purposes
75  *   (usually __func__)
76  *
77  * @line: A line number where DC_FP_START was invoked for debug purpose
78  *   (usually __LINE__)
79  *
80  * This function is responsible for managing the use of kernel_fpu_begin() with
81  * the advantage of providing an event trace for debugging.
82  *
83  * Note: Do not call this function directly; always use DC_FP_START().
84  */
85 void dc_fpu_begin(const char *function_name, const int line)
86 {
87 	int *pcpu;
88 
89 	pcpu = get_cpu_ptr(&fpu_recursion_depth);
90 	*pcpu += 1;
91 
92 	if (*pcpu == 1) {
93 #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
94 		migrate_disable();
95 		kernel_fpu_begin();
96 #elif defined(CONFIG_PPC64)
97 		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
98 			preempt_disable();
99 			enable_kernel_vsx();
100 		} else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
101 			preempt_disable();
102 			enable_kernel_altivec();
103 		} else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
104 			preempt_disable();
105 			enable_kernel_fp();
106 		}
107 #elif defined(CONFIG_ARM64)
108 		kernel_neon_begin();
109 #endif
110 	}
111 
112 	TRACE_DCN_FPU(true, function_name, line, *pcpu);
113 	put_cpu_ptr(&fpu_recursion_depth);
114 }
115 
116 /**
117  * dc_fpu_end - Disable FPU protection
118  * @function_name: A string containing the function name for debug purposes
119  * @line: A-line number where DC_FP_END was invoked for debug purpose
120  *
121  * This function is responsible for managing the use of kernel_fpu_end() with
122  * the advantage of providing an event trace for debugging.
123  *
124  * Note: Do not call this function directly; always use DC_FP_END().
125  */
126 void dc_fpu_end(const char *function_name, const int line)
127 {
128 	int *pcpu;
129 
130 	pcpu = get_cpu_ptr(&fpu_recursion_depth);
131 	*pcpu -= 1;
132 	if (*pcpu <= 0) {
133 #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
134 		kernel_fpu_end();
135 		migrate_enable();
136 #elif defined(CONFIG_PPC64)
137 		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
138 			disable_kernel_vsx();
139 			preempt_enable();
140 		} else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
141 			disable_kernel_altivec();
142 			preempt_enable();
143 		} else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
144 			disable_kernel_fp();
145 			preempt_enable();
146 		}
147 #elif defined(CONFIG_ARM64)
148 		kernel_neon_end();
149 #endif
150 	}
151 
152 	TRACE_DCN_FPU(false, function_name, line, *pcpu);
153 	put_cpu_ptr(&fpu_recursion_depth);
154 }
155