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Diffstat (limited to 'cpukit/libi2c/README_libi2c')
| -rw-r--r-- | cpukit/libi2c/README_libi2c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/cpukit/libi2c/README_libi2c b/cpukit/libi2c/README_libi2c index e28fe9c1f1..1dd48faede 100644 --- a/cpukit/libi2c/README_libi2c +++ b/cpukit/libi2c/README_libi2c @@ -109,6 +109,28 @@ Any subsequent call to this function will be silently ignored. Typically the BSP startup code will perform this initialization. +A proper place for initializing the i2c layer and populating it +with busses and device drivers (see 'Bus Registration' and +'Device/Driver Registration' below) is the 'predriver_hook' +where most facilities (such as malloc, libio) are already +available. Note, however, that 'stdio' is not yet functional +at this point and all i2c bus and device drivers should carefully +avoid using stdio so that other drivers which may build on top +of i2c devices may be initialized properly (this may happen +just after 'predriver_hook' when stdio is still not available). +E.g., drivers listed in the configuration table are initialized +during this step. + +Note that while 'libi2c' could be initialized from the rtems +configuration table like other drivers there is no easy +way of populating the i2c framework with bus- and device- +drivers at this point (unless a special 'i2c' configuration +table describing the bus layout is implemented in the future). + +For the time being, we must rely on the BSP (predriver_hook) +to initialize the i2c system if it is used by other drivers +(e.g., the RTC driver may have to use a i2c device). + =================== Bus Registration =================== |