134 lines
3.5 KiB
C
134 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_NVRAM_H
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#define _LINUX_NVRAM_H
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#include <linux/errno.h>
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#include <uapi/linux/nvram.h>
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#ifdef CONFIG_PPC
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#include <asm/machdep.h>
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#endif
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/**
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* struct nvram_ops - NVRAM functionality made available to drivers
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* @read: validate checksum (if any) then load a range of bytes from NVRAM
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* @write: store a range of bytes to NVRAM then update checksum (if any)
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* @read_byte: load a single byte from NVRAM
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* @write_byte: store a single byte to NVRAM
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* @get_size: return the fixed number of bytes in the NVRAM
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*
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* Architectures which provide an nvram ops struct need not implement all
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* of these methods. If the NVRAM hardware can be accessed only one byte
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* at a time then it may be sufficient to provide .read_byte and .write_byte.
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* If the NVRAM has a checksum (and it is to be checked) the .read and
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* .write methods can be used to implement that efficiently.
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*
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* Portable drivers may use the wrapper functions defined here.
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* The nvram_read() and nvram_write() functions call the .read and .write
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* methods when available and fall back on the .read_byte and .write_byte
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* methods otherwise.
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*/
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struct nvram_ops {
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ssize_t (*get_size)(void);
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unsigned char (*read_byte)(int);
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void (*write_byte)(unsigned char, int);
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ssize_t (*read)(char *, size_t, loff_t *);
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ssize_t (*write)(char *, size_t, loff_t *);
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#if defined(CONFIG_X86) || defined(CONFIG_M68K)
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long (*initialize)(void);
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long (*set_checksum)(void);
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#endif
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};
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extern const struct nvram_ops arch_nvram_ops;
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static inline ssize_t nvram_get_size(void)
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{
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#ifdef CONFIG_PPC
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if (ppc_md.nvram_size)
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return ppc_md.nvram_size();
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#else
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if (arch_nvram_ops.get_size)
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return arch_nvram_ops.get_size();
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#endif
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return -ENODEV;
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}
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static inline unsigned char nvram_read_byte(int addr)
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{
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#ifdef CONFIG_PPC
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if (ppc_md.nvram_read_val)
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return ppc_md.nvram_read_val(addr);
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#else
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if (arch_nvram_ops.read_byte)
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return arch_nvram_ops.read_byte(addr);
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#endif
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return 0xFF;
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}
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static inline void nvram_write_byte(unsigned char val, int addr)
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{
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#ifdef CONFIG_PPC
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if (ppc_md.nvram_write_val)
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ppc_md.nvram_write_val(addr, val);
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#else
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if (arch_nvram_ops.write_byte)
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arch_nvram_ops.write_byte(val, addr);
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#endif
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}
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static inline ssize_t nvram_read_bytes(char *buf, size_t count, loff_t *ppos)
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{
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ssize_t nvram_size = nvram_get_size();
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loff_t i;
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char *p = buf;
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if (nvram_size < 0)
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return nvram_size;
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for (i = *ppos; count > 0 && i < nvram_size; ++i, ++p, --count)
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*p = nvram_read_byte(i);
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*ppos = i;
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return p - buf;
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}
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static inline ssize_t nvram_write_bytes(char *buf, size_t count, loff_t *ppos)
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{
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ssize_t nvram_size = nvram_get_size();
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loff_t i;
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char *p = buf;
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if (nvram_size < 0)
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return nvram_size;
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for (i = *ppos; count > 0 && i < nvram_size; ++i, ++p, --count)
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nvram_write_byte(*p, i);
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*ppos = i;
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return p - buf;
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}
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static inline ssize_t nvram_read(char *buf, size_t count, loff_t *ppos)
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{
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#ifdef CONFIG_PPC
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if (ppc_md.nvram_read)
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return ppc_md.nvram_read(buf, count, ppos);
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#else
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if (arch_nvram_ops.read)
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return arch_nvram_ops.read(buf, count, ppos);
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#endif
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return nvram_read_bytes(buf, count, ppos);
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}
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static inline ssize_t nvram_write(char *buf, size_t count, loff_t *ppos)
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{
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#ifdef CONFIG_PPC
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if (ppc_md.nvram_write)
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return ppc_md.nvram_write(buf, count, ppos);
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#else
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if (arch_nvram_ops.write)
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return arch_nvram_ops.write(buf, count, ppos);
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#endif
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return nvram_write_bytes(buf, count, ppos);
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}
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#endif /* _LINUX_NVRAM_H */
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