Commit | Line | Data |
---|---|---|
30650239 AP |
1 | /* |
2 | * A udbg backend which logs messages and reads input from in memory | |
3 | * buffers. | |
4 | * | |
5 | * The console output can be read from memcons_output which is a | |
6 | * circular buffer whose next write position is stored in memcons.output_pos. | |
7 | * | |
8 | * Input may be passed by writing into the memcons_input buffer when it is | |
9 | * empty. The input buffer is empty when both input_pos == input_start and | |
10 | * *input_start == '\0'. | |
11 | * | |
12 | * Copyright (C) 2003-2005 Anton Blanchard and Milton Miller, IBM Corp | |
13 | * Copyright (C) 2013 Alistair Popple, IBM Corp | |
14 | * | |
15 | * This program is free software; you can redistribute it and/or | |
16 | * modify it under the terms of the GNU General Public License | |
17 | * as published by the Free Software Foundation; either version | |
18 | * 2 of the License, or (at your option) any later version. | |
19 | */ | |
20 | ||
30650239 AP |
21 | #include <linux/kernel.h> |
22 | #include <asm/barrier.h> | |
23 | #include <asm/page.h> | |
24 | #include <asm/processor.h> | |
25 | #include <asm/udbg.h> | |
26 | ||
27 | struct memcons { | |
28 | char *output_start; | |
29 | char *output_pos; | |
30 | char *output_end; | |
31 | char *input_start; | |
32 | char *input_pos; | |
33 | char *input_end; | |
34 | }; | |
35 | ||
36 | static char memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE]; | |
37 | static char memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE]; | |
38 | ||
39 | struct memcons memcons = { | |
40 | .output_start = memcons_output, | |
41 | .output_pos = memcons_output, | |
42 | .output_end = &memcons_output[CONFIG_PPC_MEMCONS_OUTPUT_SIZE], | |
43 | .input_start = memcons_input, | |
44 | .input_pos = memcons_input, | |
45 | .input_end = &memcons_input[CONFIG_PPC_MEMCONS_INPUT_SIZE], | |
46 | }; | |
47 | ||
48 | void memcons_putc(char c) | |
49 | { | |
50 | char *new_output_pos; | |
51 | ||
52 | *memcons.output_pos = c; | |
53 | wmb(); | |
54 | new_output_pos = memcons.output_pos + 1; | |
55 | if (new_output_pos >= memcons.output_end) | |
56 | new_output_pos = memcons.output_start; | |
57 | ||
58 | memcons.output_pos = new_output_pos; | |
59 | } | |
60 | ||
61 | int memcons_getc_poll(void) | |
62 | { | |
63 | char c; | |
64 | char *new_input_pos; | |
65 | ||
66 | if (*memcons.input_pos) { | |
67 | c = *memcons.input_pos; | |
68 | ||
69 | new_input_pos = memcons.input_pos + 1; | |
70 | if (new_input_pos >= memcons.input_end) | |
71 | new_input_pos = memcons.input_start; | |
72 | else if (*new_input_pos == '\0') | |
73 | new_input_pos = memcons.input_start; | |
74 | ||
75 | *memcons.input_pos = '\0'; | |
76 | wmb(); | |
77 | memcons.input_pos = new_input_pos; | |
78 | return c; | |
79 | } | |
80 | ||
81 | return -1; | |
82 | } | |
83 | ||
84 | int memcons_getc(void) | |
85 | { | |
86 | int c; | |
87 | ||
88 | while (1) { | |
89 | c = memcons_getc_poll(); | |
90 | if (c == -1) | |
91 | cpu_relax(); | |
92 | else | |
93 | break; | |
94 | } | |
95 | ||
96 | return c; | |
97 | } | |
98 | ||
99 | void udbg_init_memcons(void) | |
100 | { | |
101 | udbg_putc = memcons_putc; | |
102 | udbg_getc = memcons_getc; | |
103 | udbg_getc_poll = memcons_getc_poll; | |
104 | } |