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Reset i2c slave devices during init on mpc5xxx cpus

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Reset any i2c devices that may have been interrupted during a system reset.
Normally this would be accomplished by clocking the line until SCL and SDA
are released and then sending a start condtiion (From an Atmel datasheet).
There is no direct access to the i2c pins so instead create start commands
through the i2c interface.  Send a start command then delay for the SDA Hold
time, repeat this by disabling/enabling the bus a total of 9 times.

Signed-off-by: Eric Millbrandt <emillbrandt@dekaresearch.com>
This commit is contained in:
Eric Millbrandt
2009-09-03 08:09:44 -05:00
committed by Heiko Schocher
parent 9f23ca42b3
commit 5da71efa18
3 changed files with 57 additions and 0 deletions
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@@ -1366,6 +1366,13 @@ The following options need to be configured:
therefore be cleared to 0 (See, eg, MPC823e User's Manual
p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
CONFIG_SYS_I2C_INIT_MPC5XXX
When a board is reset during an i2c bus transfer
chips might think that the current transfer is still
in progress. Reset the slave devices by sending start
commands until the slave device responds.
That's all that's required for CONFIG_HARD_I2C.
If you use the software i2c interface (CONFIG_SOFT_I2C)