Add retry support to I2CInterface

Enhance the I2CInterface class hierarchy to support retrying failed I2C
operations.

Add an optional parameter to i2c::create() to specify the m

Add retry support to I2CInterface

Enhance the I2CInterface class hierarchy to support retrying failed I2C
operations.

Add an optional parameter to i2c::create() to specify the maximum number
of retries to perform for an I2C operation. Default to 0 retries so
that existing code will not be affected.

Testing:
* Tested each modified function
* When I2C operation succeeds
* When I2C operation fails
* When no retries are done
* When retries are done
* When retried operation succeeds
* When retried operation fails
* See complete test plan at
https://gist.github.com/smccarney/8d203a40d9984402ac495dc3d689c12d

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I2b0e782e5caaafa9908ef5625687377b959b38ff

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i2c: Initialize variable ret

The varialbe `ret` in some functions is not initialized and cause the
build warning and treated as error:

error: 'ret' may be used uninitialized

i2c: Initialize variable ret

The varialbe `ret` in some functions is not initialized and cause the
build warning and treated as error:

error: 'ret' may be used uninitialized in this function
[-Werror=maybe-uninitialized]

Fixes openbmc/phosphor-power#3.

Signed-off-by: Lei YU <yulei.sh@bytedance.com>
Change-Id: Ica6b1af434736f6fd96a1bbb9e511bf1c8fb1d7a

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Update .clang-format to latest version from docs

Signed-off-by: Brandon Wyman <bjwyman@gmail.com>
Change-Id: Ie6e7f43e7554429704dca86b21320c90aed18791

i2c: Cache adapter functionality

Enhance the I2CDevice class to cache the I2C adapter functionality
value. The adapter functionality value should not change while the
device interfa

i2c: Cache adapter functionality

Enhance the I2CDevice class to cache the I2C adapter functionality
value. The adapter functionality value should not change while the
device interface is open.

Caching the functionality value will reduce the number of ioctl() calls
by 50% when doing long sequences of I2C operations.

Tested:
* Verified adapter functionality value is cached
* Verified read() method works on a Witherspoon
* Verified close() method discards the cached functionality value

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I2b17d91ae4e21aaf52cd4cec9eddb5aab7be37e5

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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

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

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i2c: Add i2c block transaction support

The previous code always uses SMBus block read/write.
On some PSU (e.g. FP5280G2's PSU) the I2C block read/write is
required, so add that suppo

i2c: Add i2c block transaction support

The previous code always uses SMBus block read/write.
On some PSU (e.g. FP5280G2's PSU) the I2C block read/write is
required, so add that support.

Specifically, add a Mode enum class and add the parameter for block
read/write to indicate whether SMBus or I2C block read/write is to be
called.

Tested: Verify the code works on FP5280G2 with I2C block write.

Note: Currently there is no case for I2C block read, so that function is
not tested.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I5f77ffe6900d14f3703dae7241799a7b37c5a726

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i2c: Implement write function

Implement I2CDevice::write() by invoking i2c_smbus_write_xxx() APIs.
The code is referenced from i2c-tools' i2cset.c:

https://github.com/ev3dev/i2

i2c: Implement write function

Implement I2CDevice::write() by invoking i2c_smbus_write_xxx() APIs.
The code is referenced from i2c-tools' i2cset.c:

https://github.com/ev3dev/i2c-tools/blob/ev3dev-stretch/tools/i2cset.c

Tested: Verify on Witherspoon that it writes the PSU unlock upgrade
command and boot flag successfully.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I9fb014c787ef3ebb2f7793a0d012b1d652ef069f

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i2c: Implement read function

Implement I2CDevice::read() by invoking i2c_smbus_read_xxx() APIs.
The code is referenced from i2c-tools' i2cget.c:

https://github.com/ev3dev/i2c-t

i2c: Implement read function

Implement I2CDevice::read() by invoking i2c_smbus_read_xxx() APIs.
The code is referenced from i2c-tools' i2cget.c:

https://github.com/ev3dev/i2c-tools/blob/ev3dev-stretch/tools/i2cget.c

Tested: Verify on Witherspoon that it reads the PSU ppgrade mode status
register (1 byte) and CRC16 register (2 bytes) correctly.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I8759b6a35229f81120acf77f08429f7f79458b8b

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i2c: Implement open and close

Implement open() and close() function, and invoke open() on creating
I2CDevice, and invoke close() in destructor.

Tested: Manually write test codet

i2c: Implement open and close

Implement open() and close() function, and invoke open() on creating
I2CDevice, and invoke close() in destructor.

Tested: Manually write test codet and run on Witherspoon that it opens
and closes the i2c device correctly.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I709fcc80474a4a0cef067748a78256ceb76430a5

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tools: Initially add i2c tool and mock

The power-utils will invoke i2c get/set commands to the i2c device for
PSU code update.
Create a separated i2c tool because it is logically sta

tools: Initially add i2c tool and mock

The power-utils will invoke i2c get/set commands to the i2c device for
PSU code update.
Create a separated i2c tool because it is logically standalone and could
be shared for other utils.
Also add an I2CInterface and its mock to make it easier to test when
developing i2c related operations.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: If5383547e6d84c0a79610e2d2d6f2fa8ee9dc061

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