p8-i2c: Remove force reset
p8-i2c: Remove force reset

Force reset was added as an attempt to work around some issues with TPM
devices locking up their I2C bus. In that particular case the problem
was that the device would hold the SCL line down permanently due to a
device firmware bug. The force reset doesn't actually do anything to
alleviate the situation here, it just happens to reset the internal
master state enough to make the I2C driver appear to work until
something tries to access the bus again.

On P9 systems with secure boot enabled there is the added problem
of the "diagostic mode" not being supported on I2C masters A,B,C and
D. Diagnostic mode allows the SCL and SDA lines to be driven directly
by software. Without this force reset is impossible to implement.

This patch removes the force reset functionality entirely since:

	a) it doesn't do what it's supposed to, and
	b) it's butt ugly code

Additionally, turn p8_i2c_reset_engine() into p8_i2c_reset_port().
There's no need to reset every port on a master in response to an
error that occurred on a specific port.

Signed-off-by: Oliver O'Halloran <3dfaff8fa6ae977f042064a112a6aac576279b9b@gmail.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.ibm.com>

shenki/skiboot,open-power/skiboot,shenki/skiboot,legoater/skiboot,qemu/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,qemu/skiboot,open-power/skiboot,open-power/skiboot,legoater/skiboot,legoater/skiboot,open-power/skiboot,shenki/skiboot,legoater/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,legoater/skiboot,open-power/skiboot,qemu/skiboot,stewart-ibm/skiboot