include/linux/regmap.h

#ifndef __LINUX_REGMAP_H
#define __LINUX_REGMAP_H

/*
 * Register map access API
 *
 * Copyright 2011 Wolfson Microelectronics plc
 *
 * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/device.h>
#include <linux/list.h>
#include <linux/module.h>

struct i2c_client;
struct spi_device;

/**
 * Default value for a register.  We use an array of structs rather
 * than a simple array as many modern devices have very sparse
 * register maps.
 *
 * @reg: Register address.
 * @def: Register default value.
 */
struct reg_default {
	unsigned int reg;
	unsigned int def;
};

/**
 * Configuration for the register map of a device.
 *
 * @reg_bits: Number of bits in a register address, mandatory.
 * @val_bits: Number of bits in a register value, mandatory.
 *
 * @writeable_reg: Optional callback returning true if the register
 *                 can be written to.
 * @readable_reg: Optional callback returning true if the register
 *                can be read from.
 * @volatile_reg: Optional callback returning true if the register
 *                value can't be cached.
 * @precious_reg: Optional callback returning true if the rgister
 *                should not be read outside of a call from the driver
 *                (eg, a clear on read interrupt status register).
 *
 * @max_register: Optional, specifies the maximum valid register index.
 * @reg_defaults: Power on reset values for registers (for use with
 *                register cache support).
 * @num_reg_defaults: Number of elements in reg_defaults.
 */
struct regmap_config {
	int reg_bits;
	int val_bits;

	bool (*writeable_reg)(struct device *dev, unsigned int reg);
	bool (*readable_reg)(struct device *dev, unsigned int reg);
	bool (*volatile_reg)(struct device *dev, unsigned int reg);
	bool (*precious_reg)(struct device *dev, unsigned int reg);

	unsigned int max_register;
	struct reg_default *reg_defaults;
	int num_reg_defaults;
};

typedef int (*regmap_hw_write)(struct device *dev, const void *data,
			       size_t count);
typedef int (*regmap_hw_gather_write)(struct device *dev,
				      const void *reg, size_t reg_len,
				      const void *val, size_t val_len);
typedef int (*regmap_hw_read)(struct device *dev,
			      const void *reg_buf, size_t reg_size,
			      void *val_buf, size_t val_size);

/**
 * Description of a hardware bus for the register map infrastructure.
 *
 * @list: Internal use.
 * @type: Bus type, used to identify bus to be used for a device.
 * @write: Write operation.
 * @gather_write: Write operation with split register/value, return -ENOTSUPP
 *                if not implemented  on a given device.
 * @read: Read operation.  Data is returned in the buffer used to transmit
 *         data.
 * @owner: Module with the bus implementation, used to pin the implementation
 *         in memory.
 * @read_flag_mask: Mask to be set in the top byte of the register when doing
 *                  a read.
 */
struct regmap_bus {
	struct list_head list;
	struct bus_type *type;
	regmap_hw_write write;
	regmap_hw_gather_write gather_write;
	regmap_hw_read read;
	struct module *owner;
	u8 read_flag_mask;
};

struct regmap *regmap_init(struct device *dev,
			   const struct regmap_bus *bus,
			   const struct regmap_config *config);
struct regmap *regmap_init_i2c(struct i2c_client *i2c,
			       const struct regmap_config *config);
struct regmap *regmap_init_spi(struct spi_device *dev,
			       const struct regmap_config *config);

void regmap_exit(struct regmap *map);
int regmap_write(struct regmap *map, unsigned int reg, unsigned int val);
int regmap_raw_write(struct regmap *map, unsigned int reg,
		     const void *val, size_t val_len);
int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);
int regmap_raw_read(struct regmap *map, unsigned int reg,
		    void *val, size_t val_len);
int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
		     size_t val_count);
int regmap_update_bits(struct regmap *map, unsigned int reg,
		       unsigned int mask, unsigned int val);

#endif