Add some overview documentation that explains the purpose and some of the features and limitations of the regmap interface.
Reviewed-by: Bin Meng <bmeng...@gmail.com> Signed-off-by: Mario Six <mario....@gdsys.cc> --- v10 -> v11: No changes v9 -> v10: No changes v8 -> v9: * Amended for inclusion of endianness setting via DT v7 -> v8: New in v8 --- include/regmap.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) 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 * -- 2.18.1 _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
