ntb: idt: Alter the driver info comments

Since IDT PCIe-switch temperature sensor is now always available
irregardless of the EEPROM/BIOS settings, Kconfig and in-code
description should be properly altered. In addition lets update
the driver copyright lines.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

ntb: idt: Discard temperature sensor IRQ handler

IDT PCIe-switch temperature sensor interface is very broken. First
of all only a few combinations of TMPCTL threshold enable bits
really cause the interrupts unmasked. Even if an individual bit
indicates the event unmasked, corresponding IRQ just isn't generated.
Most of the threshold enable bits combinations are in fact useless and
non of them can help to create a fully functional alarm interface.
So to speak, we can't create a well defined hwmon alarms based on
the IDT PCI-switch threshold IRQs.

Secondly a single threshold IRQ (not a combination of thresholds) can
be successfully enabled without the issue described above. But in this
case we experienced an enormous number of interrupts generated by
the chip if the temperature got near the enabled threshold value. Filter
adjustment didn't help much. It also doesn't provide a hysteresis settings.
Due to the temperature sample fluctuations near the threshold the
interrupts spate makes the system nearly unusable until the temperature
value finally settled so being pushed either to be fully higher or lower
the threshold.

All of these issues makes the temperature sensor alarm interface useless
and even at some point dangerous to be used in the driver. In this case
it is safer to completely discard it and disable the temperature alarm
interrupts.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

ntb: idt: Add basic hwmon sysfs interface

IDT PCIe switches provide an embedded temperature sensor working
within [0; 127.5]C with resolution of 0.5C. They also can generate
a PCIe upstream interrupt in case if the temperature passes through
specified thresholds. Since this thresholds interface is very broken
the created hwmon-sysfs interface exposes only the next set of hwmon
nodes: current input temperature, lowest and highest values measured,
history resetting, value offset. HWmon alarm interface isn't provided.

IDT PCIe switch also've got an ADC/filter settings of the sensor.
This driver doesn't expose them to the hwmon-sysfs interface at the
moment, except the offset node.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

ntb: idt: Alter temperature read method

In order to create a hwmon interface for the IDT PCIe-switch temperature
sensor the already available reader method should be improved. Particularly
we need to redesign it so one would be able to read temperature/offset
values from registers of the passed types. Since IDT sensor interface
provides temperature in unsigned format 0:7:1 (7 bits for real value
and one for fraction) we also need to have helpers for the typical sysfs
temperature data type conversion to and from this format. Even though
the IDT PCIe-switch provided temperature offset got the same but signed
type it can be translated by these methods too.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

NTB: Add IDT 89HPESxNTx PCIe-switches support

IDT 89HPESxNTx device series is PCIe-switches, which support
Non-Transparent bridging between domains connected to the device ports.
Since new NTB API exposes multi-port interface and messaging API, the
IDT NT-functions can be now supported in the kernel. This driver adds
the following functionality:
1) Multi-port NTB API to have information of possible NT-functions
activated in compliance with available device ports.
2) Memory windows of direct and look up table based address translation
with all possible combinations of BARs setup.
3) Traditional doorbell NTB API.
4) One-on-one messaging NTB API.

There are some IDT PCIe-switch setups, which must be done before any of
the NTB peers started. It can be performed either by system BIOS via
IDT SMBus-slave interface or by pre-initialized IDT PCIe-switch EEPROM:
1) NT-functions of corresponding ports must be activated using
SWPARTxCTL and SWPORTxCTL registers.
2) BAR0 must be configured to expose NT-function configuration
registers map.
3) The rest of the BARs must have at least one memory window
configured, otherwise the driver will just return an error.
Temperature sensor of IDT PCIe-switches can be also optionally
activated by BIOS or EEPROM.
(See IDT documentations for details of how the pre-initialization can
be done)

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>