From: Mario Six Date: Mon, 15 Oct 2018 07:24:15 +0000 (+0200) Subject: regmap: Add overview documentation X-Git-Url: http://git.dujemihanovic.xyz/?a=commitdiff_plain;h=a6d4b0608b79023c703ca2ad1cbdfa784160449b;p=u-boot.git regmap: Add overview documentation Add some overview documentation that explains the purpose and some of the features and limitations of the regmap interface. Reviewed-by: Bin Meng Signed-off-by: Mario Six --- diff --git a/include/regmap.h b/include/regmap.h index 98860c2732..b2b733fda6 100644 --- a/include/regmap.h +++ b/include/regmap.h @@ -7,6 +7,33 @@ #ifndef __REGMAP_H #define __REGMAP_H +/** + * DOC: Overview + * + * Regmaps are an abstraction mechanism that allows device drivers to access + * register maps irrespective of the underlying bus architecture. This entails + * that for devices that support multiple busses (e.g. I2C and SPI for a GPIO + * expander chip) only one driver has to be written. This driver will + * instantiate a regmap with a backend depending on the bus the device is + * attached to, and use the regmap API to access the register map through that + * bus transparently. + * + * Read and write functions are supplied, which can read/write data of + * arbitrary length from/to the regmap. + * + * The endianness of regmap accesses is selectable for each map through device + * tree settings via the boolean "little-endian", "big-endian", and + * "native-endian" properties. + * + * Furthermore, the register map described by a regmap can be split into + * multiple disjoint areas called ranges. In this way, register maps with + * "holes", i.e. areas of addressable memory that are not part of the register + * map, can be accessed in a concise manner. + * + * Currently, only a bare "mem" backend for regmaps is supported, which + * accesses the register map as regular IO-mapped memory. + */ + /** * enum regmap_size_t - Access sizes for regmap reads and writes *