diff options
Diffstat (limited to 'include/linux/nvram.h')
| -rw-r--r-- | include/linux/nvram.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/nvram.h b/include/linux/nvram.h index 79431dab87a1..bb4ea8cc6ea6 100644 --- a/include/linux/nvram.h +++ b/include/linux/nvram.h @@ -5,8 +5,30 @@ #include <linux/errno.h> #include <uapi/linux/nvram.h> +/** + * struct nvram_ops - NVRAM functionality made available to drivers + * @read: validate checksum (if any) then load a range of bytes from NVRAM + * @write: store a range of bytes to NVRAM then update checksum (if any) + * @read_byte: load a single byte from NVRAM + * @write_byte: store a single byte to NVRAM + * @get_size: return the fixed number of bytes in the NVRAM + * + * Architectures which provide an nvram ops struct need not implement all + * of these methods. If the NVRAM hardware can be accessed only one byte + * at a time then it may be sufficient to provide .read_byte and .write_byte. + * If the NVRAM has a checksum (and it is to be checked) the .read and + * .write methods can be used to implement that efficiently. + * + * Portable drivers may use the wrapper functions defined here. + * The nvram_read() and nvram_write() functions call the .read and .write + * methods when available and fall back on the .read_byte and .write_byte + * methods otherwise. + */ + struct nvram_ops { ssize_t (*get_size)(void); + unsigned char (*read_byte)(int); + void (*write_byte)(unsigned char, int); ssize_t (*read)(char *, size_t, loff_t *); ssize_t (*write)(char *, size_t, loff_t *); }; @@ -25,11 +47,21 @@ static inline ssize_t nvram_get_size(void) static inline unsigned char nvram_read_byte(int addr) { +#ifdef CONFIG_PPC +#else + if (arch_nvram_ops.read_byte) + return arch_nvram_ops.read_byte(addr); +#endif return 0xFF; } static inline void nvram_write_byte(unsigned char val, int addr) { +#ifdef CONFIG_PPC +#else + if (arch_nvram_ops.write_byte) + arch_nvram_ops.write_byte(val, addr); +#endif } static inline ssize_t nvram_read(char *buf, size_t count, loff_t *ppos) |