tree 2f0e600d9a1a5fef6ebedde96540416fbca20e39
parent 1d103428e50ec000372e6b1c2bccc8ee92ddbc89
author Shawn McCarney <shawnmm@us.ibm.com> 1576024544 -0600
committer Shawn McCarney <shawnmm@us.ibm.com> 1576045584 -0600

i2c: Support explicit open/close and re-open

Add the ability to explicitly open and close the I2CInterface/I2CDevice.
Also add support to re-open the I2CInterface/I2CDevice after it was
closed.

This support is needed for use cases like the following:

* I2C device information (bus and address) is parsed from a
  configuration file at standby.  However, an I2C connection to the
  device should not be opened yet.   The device may not have power until
  the system has been booted.  Additionally, if the device is a FRU,
  it could be replaced (remove + add) while at standby, leading to
  communication errors.

* The device is sometimes bound to a device driver.  The I2C connection
  should only be open during the time periods when the device driver
  is not bound.

Tested:
* Verified create() function with default value of OPEN, explicit value
  of OPEN, and explicit value of CLOSED.
* Verified device interface can be explicitly opened, closed, and
  re-opened.
* Verified read() and write() functions still work when device interface
  is open.
* Verified open() fails with appropriate error if already open.
* Verified read() fails with appropriate error if not open.
* Verified write() fails with appropriate error if not open.
* Verified close() fails with appropriate error if not open.

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I0182966f0b0614eac0de69eb95d960035f9d0426