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[Bug 1001397] I2C driver for Kinetic microcontrollers


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--- Comment #11 from Ilija Kocho <ilijak@siva.com.mk> 2012-01-11 20:32:34 GMT ---
Hi Tomas, thank you for the update and here are my first notes:

ISR priority
Cortex-M NVIC implements priority arbitration with most significant /n/ bits
implemented. Consequently in Kinetis (4 bits) they are bits 7..4 so priorities
range 0x00, 0x10,..,0xf0. But this is not end of the story for eCos. Please
visit this thread for full explanation (both references and follow-ups):
http://ecos.sourceware.org/ml/ecos-devel/2010-11/msg00007.html

It would be good to have configurable ISR priority. I understand that some
drivers do not provide such control, but IMO that ISR priority manipulation may
be important for tuning system behavior. And it is just a cdl per bus.

I2C buses
It would be good that unused buses are inactive - not present. Then user (or
higher level I2C driver) activates the necessary bus by implementing respective
interface. 

Also some parameters such as speed should be private to the bus. I can imagine
two devices using separate buses at different speeds simultaneously.

Also we don't need 2 init functions. Instead you can place parameters such as
CYGHWR_IO_I2C_FREESCALE_I2Cx_PIN_SDA, etc. in the bus structure (or some const
if you wish to save some RAM).

Ilija

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