This patch adds support for LZO compression when storing the register cache. For a typical device whose register map would normally occupy 25kB or 50kB by using the LZO compression technique, one can get down to ~5-7kB. There might be a performance penalty associated with each individual read/write due to decompressing/compressing the underlying cache, however that should not be noticeable. These memory benefits depend on whether the target architecture can get rid of the memory occupied by the original register defaults cache which is marked as __devinitconst. Nevertheless there will be some memory gain even if the target architecture can't get rid of the original register map, this should be around ~30-32kB instead of 50kB. Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
144 lines
4.7 KiB
C
144 lines
4.7 KiB
C
#ifndef __LINUX_REGMAP_H
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#define __LINUX_REGMAP_H
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/*
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* Register map access API
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*
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* Copyright 2011 Wolfson Microelectronics plc
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*
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* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/device.h>
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#include <linux/list.h>
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#include <linux/module.h>
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struct i2c_client;
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struct spi_device;
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/* An enum of all the supported cache types */
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enum regcache_type {
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REGCACHE_NONE,
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REGCACHE_INDEXED,
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REGCACHE_RBTREE,
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REGCACHE_LZO
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};
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/**
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* Default value for a register. We use an array of structs rather
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* than a simple array as many modern devices have very sparse
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* register maps.
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*
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* @reg: Register address.
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* @def: Register default value.
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*/
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struct reg_default {
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unsigned int reg;
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unsigned int def;
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};
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/**
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* Configuration for the register map of a device.
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*
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* @reg_bits: Number of bits in a register address, mandatory.
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* @val_bits: Number of bits in a register value, mandatory.
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*
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* @writeable_reg: Optional callback returning true if the register
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* can be written to.
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* @readable_reg: Optional callback returning true if the register
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* can be read from.
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* @volatile_reg: Optional callback returning true if the register
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* value can't be cached.
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* @precious_reg: Optional callback returning true if the rgister
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* should not be read outside of a call from the driver
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* (eg, a clear on read interrupt status register).
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*
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* @max_register: Optional, specifies the maximum valid register index.
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* @reg_defaults: Power on reset values for registers (for use with
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* register cache support).
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* @num_reg_defaults: Number of elements in reg_defaults.
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*
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* @read_flag_mask: Mask to be set in the top byte of the register when doing
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* a read.
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* @write_flag_mask: Mask to be set in the top byte of the register when doing
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* a write. If both read_flag_mask and write_flag_mask are
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* empty the regmap_bus default masks are used.
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*
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* @cache_type: The actual cache type.
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* @reg_defaults_raw: Power on reset values for registers (for use with
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* register cache support).
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* @num_reg_defaults_raw: Number of elements in reg_defaults_raw.
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*/
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struct regmap_config {
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int reg_bits;
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int val_bits;
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bool (*writeable_reg)(struct device *dev, unsigned int reg);
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bool (*readable_reg)(struct device *dev, unsigned int reg);
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bool (*volatile_reg)(struct device *dev, unsigned int reg);
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bool (*precious_reg)(struct device *dev, unsigned int reg);
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unsigned int max_register;
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struct reg_default *reg_defaults;
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unsigned int num_reg_defaults;
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enum regcache_type cache_type;
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const void *reg_defaults_raw;
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unsigned int num_reg_defaults_raw;
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u8 read_flag_mask;
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u8 write_flag_mask;
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};
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typedef int (*regmap_hw_write)(struct device *dev, const void *data,
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size_t count);
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typedef int (*regmap_hw_gather_write)(struct device *dev,
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const void *reg, size_t reg_len,
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const void *val, size_t val_len);
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typedef int (*regmap_hw_read)(struct device *dev,
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const void *reg_buf, size_t reg_size,
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void *val_buf, size_t val_size);
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/**
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* Description of a hardware bus for the register map infrastructure.
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*
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* @write: Write operation.
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* @gather_write: Write operation with split register/value, return -ENOTSUPP
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* if not implemented on a given device.
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* @read: Read operation. Data is returned in the buffer used to transmit
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* data.
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* @read_flag_mask: Mask to be set in the top byte of the register when doing
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* a read.
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*/
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struct regmap_bus {
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regmap_hw_write write;
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regmap_hw_gather_write gather_write;
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regmap_hw_read read;
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u8 read_flag_mask;
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};
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struct regmap *regmap_init(struct device *dev,
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const struct regmap_bus *bus,
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const struct regmap_config *config);
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struct regmap *regmap_init_i2c(struct i2c_client *i2c,
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const struct regmap_config *config);
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struct regmap *regmap_init_spi(struct spi_device *dev,
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const struct regmap_config *config);
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void regmap_exit(struct regmap *map);
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int regmap_write(struct regmap *map, unsigned int reg, unsigned int val);
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int regmap_raw_write(struct regmap *map, unsigned int reg,
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const void *val, size_t val_len);
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int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);
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int regmap_raw_read(struct regmap *map, unsigned int reg,
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void *val, size_t val_len);
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int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
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size_t val_count);
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int regmap_update_bits(struct regmap *map, unsigned int reg,
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unsigned int mask, unsigned int val);
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#endif
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