| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647 |
- ==================================
- TWserial device subsystem analysis
- ==================================
- Tomas Hlavacek<tmshlvck@gmail.com>
- 2012-03-21
- I) Overview
- -----------
- U-Boot currently implements one common API for TWSerial devices. The interface
- is defined in include/tws.h and comprises of functions:
- int tws_read(uchar *buffer, int len);
- int tws_write(uchar *buffer, int len);
- The functions are implemented by a proper device driver in drivers/twserial
- directory and the driver to be compiled in is selected in a Makefile. There is
- only one driver present now.
- The driver depends on ad-hoc code in board specific data, namely functions:
- void tws_ce(unsigned bit);
- void tws_wr(unsigned bit);
- void tws_clk(unsigned bit);
- void tws_data(unsigned bit);
- unsigned tws_data_read(void);
- void tws_data_config_output(unsigned output);
- implemented in include/configs/inka4x0.h .
- II) Approach
- ------------
- U-Boot TWserial drivers exports two simple functions and therefore the conversion
- of the driver and creating a core for it is not needed. It should be consolidated
- with include/configs/inka4x0.h and taken to the misc/ dir.
- III) Analysis of in-tree drivers
- --------------------------------
- 1) drivers/twserial/soft_tws.c
- ------------------------------
- The driver is the only TWserial driver. The ad-hoc part in
- include/configs/inka4x0.h and the core soft_tws driver should be consolidated
- to one compact driver and moved to misc/ .
|
