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