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