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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d

 kernel/include/linux/nvram.h
..
..
@@ -2,13 +2,132 @@
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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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-/* __foo is foo without grabbing the rtc_lock - get it yourself */
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-extern unsigned char __nvram_read_byte(int i);
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-extern unsigned char nvram_read_byte(int i);
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-extern void __nvram_write_byte(unsigned char c, int i);
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-extern void nvram_write_byte(unsigned char c, int i);
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-extern int __nvram_check_checksum(void);
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-extern int nvram_check_checksum(void);
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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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+/**
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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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+
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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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+
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+extern const struct nvram_ops arch_nvram_ops;
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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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 #endif  /* _LINUX_NVRAM_H */