/* SPDX-License-Identifier: GPL-2.0-only */

  /*
   * Persistent Storage - pstore.h
   *
   * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   *
   * This code is the generic layer to export data records from platform
   * level persistent storage via a file system.

   */
  #ifndef _LINUX_PSTORE_H
  #define _LINUX_PSTORE_H

  #include <linux/compiler.h>
  #include <linux/errno.h>

  #include <linux/kmsg_dump.h>

  #include <linux/mutex.h>

  #include <linux/semaphore.h>

  #include <linux/time.h>
  #include <linux/types.h>

  struct module;

  /*
   * pstore record types (see fs/pstore/platform.c for pstore_type_names[])
   * These values may be written to storage (see EFI vars backend), so
   * they are kind of an ABI. Be careful changing the mappings.
   */

  enum pstore_type_id {

  	/* Frontend storage types */

  	PSTORE_TYPE_DMESG	= 0,
  	PSTORE_TYPE_MCE		= 1,

  	PSTORE_TYPE_CONSOLE	= 2,

  	PSTORE_TYPE_FTRACE	= 3,

  
  	/* PPC64-specific partition types */

  	PSTORE_TYPE_PPC_RTAS	= 4,

  	PSTORE_TYPE_PPC_OF	= 5,

  	PSTORE_TYPE_PPC_COMMON	= 6,

  	PSTORE_TYPE_PMSG	= 7,

  	PSTORE_TYPE_PPC_OPAL	= 8,

  
  	/* End of the list */
  	PSTORE_TYPE_MAX

  };

  const char *pstore_type_to_name(enum pstore_type_id type);
  enum pstore_type_id pstore_name_to_type(const char *name);

  struct pstore_info;
  /**
   * struct pstore_record - details of a pstore record entry
   * @psi:	pstore backend driver information
   * @type:	pstore record type
   * @id:		per-type unique identifier for record
   * @time:	timestamp of the record

   * @buf:	pointer to record contents
   * @size:	size of @buf
   * @ecc_notice_size:
   *		ECC information for @buf

   *
   * Valid for PSTORE_TYPE_DMESG @type:
   *
   * @count:	Oops count since boot
   * @reason:	kdump reason for notification
   * @part:	position in a multipart record
   * @compressed:	whether the buffer is compressed
   *

   */
  struct pstore_record {
  	struct pstore_info	*psi;
  	enum pstore_type_id	type;
  	u64			id;

  	struct timespec64	time;

  	char			*buf;
  	ssize_t			size;
  	ssize_t			ecc_notice_size;

  
  	int			count;
  	enum kmsg_dump_reason	reason;
  	unsigned int		part;
  	bool			compressed;

  };

  /**
   * struct pstore_info - backend pstore driver structure
   *

   * @owner:	module which is responsible for this backend driver

   * @name:	name of the backend driver
   *

   * @buf_lock:	semaphore to serialize access to @buf

   * @buf:	preallocated crash dump buffer

   * @bufsize:	size of @buf available for crash dump bytes (must match
   *		smallest number of bytes available for writing to a
   *		backend entry, since compressed bytes don't take kindly
   *		to being truncated)

   *
   * @read_mutex:	serializes @open, @read, @close, and @erase callbacks
   * @flags:	bitfield of frontends the backend can accept writes for

   * @max_reason:	Used when PSTORE_FLAGS_DMESG is set. Contains the
   *		kmsg_dump_reason enum value. KMSG_DUMP_UNDEF means
   *		"use existing kmsg_dump() filtering, based on the
   *		printk.always_kmsg_dump boot param" (which is either
   *		KMSG_DUMP_OOPS when false, or KMSG_DUMP_MAX when
   *		true); see printk.always_kmsg_dump for more details.

   * @data:	backend-private pointer passed back during callbacks
   *
   * Callbacks:
   *
   * @open:
   *	Notify backend that pstore is starting a full read of backend
   *	records. Followed by one or more @read calls, and a final @close.
   *
   *	@psi:	in: pointer to the struct pstore_info for the backend
   *
   *	Returns 0 on success, and non-zero on error.
   *
   * @close:
   *	Notify backend that pstore has finished a full read of backend
   *	records. Always preceded by an @open call and one or more @read
   *	calls.
   *
   *	@psi:	in: pointer to the struct pstore_info for the backend
   *
   *	Returns 0 on success, and non-zero on error. (Though pstore will
   *	ignore the error.)
   *
   * @read:
   *	Read next available backend record. Called after a successful
   *	@open.
   *

   *	@record:
   *		pointer to record to populate. @buf should be allocated
   *		by the backend and filled. At least @type and @id should
   *		be populated, since these are used when creating pstorefs
   *		file names.

   *
   *	Returns record size on success, zero when no more records are
   *	available, or negative on error.
   *
   * @write:

   *	A newly generated record needs to be written to backend storage.

   *

   *	@record:

   *		pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
   *		@buf will be pointing to the preallocated @psi.buf, since
   *		memory allocation may be broken during an Oops. Regardless,
   *		@buf must be proccesed or copied before returning. The
   *		backend is also expected to write @id with something that

   *		can help identify this record to a future @erase callback.
   *		The @time field will be prepopulated with the current time,
   *		when available. The @size field will have the size of data
   *		in @buf.

   *
   *	Returns 0 on success, and non-zero on error.
   *

   * @write_user:

   *	Perform a frontend write to a backend record, using a specified

   *	buffer that is coming directly from userspace, instead of the
   *	@record @buf.
   *
   *	@record:	pointer to record metadata.
   *	@buf:		pointer to userspace contents to write to backend

   *
   *	Returns 0 on success, and non-zero on error.
   *
   * @erase:
   *	Delete a record from backend storage.  Different backends

   *	identify records differently, so entire original record is
   *	passed back to assist in identification of what the backend
   *	should remove from storage.

   *

   *	@record:	pointer to record metadata.

   *
   *	Returns 0 on success, and non-zero on error.
   *
   */

  struct pstore_info {
  	struct module	*owner;

  	const char	*name;

  	struct semaphore buf_lock;

  	char		*buf;
  	size_t		bufsize;

  
  	struct mutex	read_mutex;

  	int		flags;

  	int		max_reason;

  	void		*data;

  	int		(*open)(struct pstore_info *psi);
  	int		(*close)(struct pstore_info *psi);

  	ssize_t		(*read)(struct pstore_record *record);

  	int		(*write)(struct pstore_record *record);

  	int		(*write_user)(struct pstore_record *record,
  				      const char __user *buf);

  	int		(*erase)(struct pstore_record *record);

  };

  /* Supported frontends */

  #define PSTORE_FLAGS_DMESG	BIT(0)
  #define PSTORE_FLAGS_CONSOLE	BIT(1)
  #define PSTORE_FLAGS_FTRACE	BIT(2)
  #define PSTORE_FLAGS_PMSG	BIT(3)

  extern int pstore_register(struct pstore_info *);

  extern void pstore_unregister(struct pstore_info *);

  struct pstore_ftrace_record {
  	unsigned long ip;
  	unsigned long parent_ip;
  	u64 ts;
  };
  
  /*
   * ftrace related stuff: Both backends and frontends need these so expose
   * them here.
   */
  
  #if NR_CPUS <= 2 && defined(CONFIG_ARM_THUMB)
  #define PSTORE_CPU_IN_IP 0x1
  #elif NR_CPUS <= 4 && defined(CONFIG_ARM)
  #define PSTORE_CPU_IN_IP 0x3
  #endif
  
  #define TS_CPU_SHIFT 8
  #define TS_CPU_MASK (BIT(TS_CPU_SHIFT) - 1)
  
  /*
   * If CPU number can be stored in IP, store it there, otherwise store it in
   * the time stamp. This means more timestamp resolution is available when
   * the CPU can be stored in the IP.
   */
  #ifdef PSTORE_CPU_IN_IP
  static inline void
  pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
  {
  	rec->ip |= cpu;
  }
  
  static inline unsigned int
  pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
  {
  	return rec->ip & PSTORE_CPU_IN_IP;
  }
  
  static inline u64
  pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
  {
  	return rec->ts;
  }
  
  static inline void
  pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
  {
  	rec->ts = val;
  }
  #else
  static inline void
  pstore_ftrace_encode_cpu(struct pstore_ftrace_record *rec, unsigned int cpu)
  {
  	rec->ts &= ~(TS_CPU_MASK);
  	rec->ts |= cpu;
  }
  
  static inline unsigned int
  pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec)
  {
  	return rec->ts & TS_CPU_MASK;
  }
  
  static inline u64
  pstore_ftrace_read_timestamp(struct pstore_ftrace_record *rec)
  {
  	return rec->ts >> TS_CPU_SHIFT;
  }
  
  static inline void
  pstore_ftrace_write_timestamp(struct pstore_ftrace_record *rec, u64 val)
  {
  	rec->ts = (rec->ts & TS_CPU_MASK) | (val << TS_CPU_SHIFT);
  }
  #endif

  #endif /*_LINUX_PSTORE_H*/