1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_NVRAM_H |
3 | #define _LINUX_NVRAM_H |
4 | |
5 | #include <linux/errno.h> |
6 | #include <uapi/linux/nvram.h> |
7 | |
8 | #ifdef CONFIG_PPC |
9 | #include <asm/machdep.h> |
10 | #endif |
11 | |
12 | /** |
13 | * struct nvram_ops - NVRAM functionality made available to drivers |
14 | * @read: validate checksum (if any) then load a range of bytes from NVRAM |
15 | * @write: store a range of bytes to NVRAM then update checksum (if any) |
16 | * @read_byte: load a single byte from NVRAM |
17 | * @write_byte: store a single byte to NVRAM |
18 | * @get_size: return the fixed number of bytes in the NVRAM |
19 | * |
20 | * Architectures which provide an nvram ops struct need not implement all |
21 | * of these methods. If the NVRAM hardware can be accessed only one byte |
22 | * at a time then it may be sufficient to provide .read_byte and .write_byte. |
23 | * If the NVRAM has a checksum (and it is to be checked) the .read and |
24 | * .write methods can be used to implement that efficiently. |
25 | * |
26 | * Portable drivers may use the wrapper functions defined here. |
27 | * The nvram_read() and nvram_write() functions call the .read and .write |
28 | * methods when available and fall back on the .read_byte and .write_byte |
29 | * methods otherwise. |
30 | */ |
31 | |
32 | struct nvram_ops { |
33 | ssize_t (*get_size)(void); |
34 | unsigned char (*read_byte)(int); |
35 | void (*write_byte)(unsigned char, int); |
36 | ssize_t (*read)(char *, size_t, loff_t *); |
37 | ssize_t (*write)(char *, size_t, loff_t *); |
38 | #if defined(CONFIG_X86) || defined(CONFIG_M68K) |
39 | long (*initialize)(void); |
40 | long (*set_checksum)(void); |
41 | #endif |
42 | }; |
43 | |
44 | extern const struct nvram_ops arch_nvram_ops; |
45 | |
46 | static inline ssize_t nvram_get_size(void) |
47 | { |
48 | #ifdef CONFIG_PPC |
49 | if (ppc_md.nvram_size) |
50 | return ppc_md.nvram_size(); |
51 | #else |
52 | if (arch_nvram_ops.get_size) |
53 | return arch_nvram_ops.get_size(); |
54 | #endif |
55 | return -ENODEV; |
56 | } |
57 | |
58 | static inline unsigned char nvram_read_byte(int addr) |
59 | { |
60 | #ifdef CONFIG_PPC |
61 | if (ppc_md.nvram_read_val) |
62 | return ppc_md.nvram_read_val(addr); |
63 | #else |
64 | if (arch_nvram_ops.read_byte) |
65 | return arch_nvram_ops.read_byte(addr); |
66 | #endif |
67 | return 0xFF; |
68 | } |
69 | |
70 | static inline void nvram_write_byte(unsigned char val, int addr) |
71 | { |
72 | #ifdef CONFIG_PPC |
73 | if (ppc_md.nvram_write_val) |
74 | ppc_md.nvram_write_val(addr, val); |
75 | #else |
76 | if (arch_nvram_ops.write_byte) |
77 | arch_nvram_ops.write_byte(val, addr); |
78 | #endif |
79 | } |
80 | |
81 | static inline ssize_t nvram_read_bytes(char *buf, size_t count, loff_t *ppos) |
82 | { |
83 | ssize_t nvram_size = nvram_get_size(); |
84 | loff_t i; |
85 | char *p = buf; |
86 | |
87 | if (nvram_size < 0) |
88 | return nvram_size; |
89 | for (i = *ppos; count > 0 && i < nvram_size; ++i, ++p, --count) |
90 | *p = nvram_read_byte(addr: i); |
91 | *ppos = i; |
92 | return p - buf; |
93 | } |
94 | |
95 | static inline ssize_t nvram_write_bytes(char *buf, size_t count, loff_t *ppos) |
96 | { |
97 | ssize_t nvram_size = nvram_get_size(); |
98 | loff_t i; |
99 | char *p = buf; |
100 | |
101 | if (nvram_size < 0) |
102 | return nvram_size; |
103 | for (i = *ppos; count > 0 && i < nvram_size; ++i, ++p, --count) |
104 | nvram_write_byte(val: *p, addr: i); |
105 | *ppos = i; |
106 | return p - buf; |
107 | } |
108 | |
109 | static inline ssize_t nvram_read(char *buf, size_t count, loff_t *ppos) |
110 | { |
111 | #ifdef CONFIG_PPC |
112 | if (ppc_md.nvram_read) |
113 | return ppc_md.nvram_read(buf, count, ppos); |
114 | #else |
115 | if (arch_nvram_ops.read) |
116 | return arch_nvram_ops.read(buf, count, ppos); |
117 | #endif |
118 | return nvram_read_bytes(buf, count, ppos); |
119 | } |
120 | |
121 | static inline ssize_t nvram_write(char *buf, size_t count, loff_t *ppos) |
122 | { |
123 | #ifdef CONFIG_PPC |
124 | if (ppc_md.nvram_write) |
125 | return ppc_md.nvram_write(buf, count, ppos); |
126 | #else |
127 | if (arch_nvram_ops.write) |
128 | return arch_nvram_ops.write(buf, count, ppos); |
129 | #endif |
130 | return nvram_write_bytes(buf, count, ppos); |
131 | } |
132 | |
133 | #endif /* _LINUX_NVRAM_H */ |
134 | |