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Current we will attempt to start an I2C transaction until it succeeds.
In the event that the OCC does not release the lock on an I2C bus this
results in an async token being held forever and the kernel thread that
started the transaction will block forever while waiting for an async
completion message. Fix this by limiting the number of attempts to
start the transaction.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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The TPM code has a wrapper around the main i2c API to allow synchronous use.
Move it into core/i2c.c so it can be used by other possible users. In
particular, a future patch will use this to drive OpenCAPI device resets
during boot time.
Cc: Claudio Carvalho <cclaudio@linux.vnet.ibm.com>
Cc: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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This patch adds support to share the I2C engines with host and OCC.
OCC uses I2C engines to read DIMM temperatures and to communicate with
GPU. OCC Flag register is used for locking between host and OCC. Host
requests for the bus by setting a bit in OCC Flag register. OCC sends
an interrupt to indicate the change in ownership.
Originally-from: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
[stewart@linux.vnet.ibm.com: Pretty heavily rework logic, including
fixing bus owner change and separating out occ lock from sensor cache]
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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In TPM 2.0 Firmware 1.3.0.1 and 1.3.1.0 (at least) there exists
a bug where if you send the wrong thing to the TPM it may lock the
bus, with no way of recovery except powering the TPM off/on.
On our current systems, the only way to power the TPM off/on is to pull
the power on the system (*NOT* just power off/on to host from BMC).
So, this patch adds the ability to do things to the i2c request really
early on, well before it hits any hardware, such as quickly drop it.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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Doing everything asynchronously is brilliant, it's exactly what we
want to do.
Except... the tpm driver wants to do things synchronously, which isn't
so cool.
For reasons that are not yet completely known, we spend an awful lot of
time in the main thread *not* running pollers (potentially seconds), which
doesn't bode well for I2C timeouts.
Since the TPM measure is done in a secondary thread, we do *not* run pollers
there either (as of 323c8aeb54bd4e0b9004091fcbb4a9daeda2f576 - which is
roughly as of skiboot 2.1.1).
But we still need to crank the i2c state machine, so we introduce a call
to do just that. It will return how long the poll interval should be, so
that we can time_wait() for a more appropriate time for whatever i2c
implementation is sitting behind things.
Without this, it was "easy" to get to a situation where the i2c state machine
wasn't cranked at all, and you'd hit the i2c timeout (for the issued operation)
before the poller to crank i2c was ever called.
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Tested-by: Claudio Carvalho <cclaudio@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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Prior to PCI enumeration, the PHB slot's power state might be changed
during fundamental reset. The fundamental reset is implemented by state
machine and it's driven by a polling mechanism in predetermined interval
(A). On the other hand, PCI slot's power supply is controlled by I2C
chip on Firenze platform. It means the PCI slot's power supply state is
changed through I2C request which has a timeout timer running in variable
interval (B).
Comparing to (A), (B) is small and short. That means I2C timeout is reached
before first poll running in interval of (A). It's unexpected behaviour.
This allows to set I2C request timeout ((B)) to avoid the issue.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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Define SRCs of I2C component and interface with the existing
skiboot 'errorlog' infrasturcute for commiting the logs. Add the
i2c specific OPAL error codes to differentiate various types of
errors during i2c operations.
To ease debugging, dump the i2c register contents, 'master' and
'request' structure bits in case any error occured during transfer
on the bus. Minor clean-ups as well.
Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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We only poll the masters for the chip that got the interrupt
and we improve the running of the timers as well.
We user the new TIMER_POLL facility to replace the use of the
OPAL poller, which simplifies the code further.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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And start adding interfaces to lookup i2c busses.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This updates the i2c driver significantly, using a simpler state machine,
using the new timer for timeouts, and fixing a number of issues. I also
changed the Linux interface so I've changed the token number since some
builds have been done with the old code already.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Fixed few bugs and clean up a lot. Renamed the state machine variables
to make more sense. A new helper 'p8_i2c_check_work' to avoid hitting
deep call stack after request complete.
Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This patch adds the generic i2c driver infrastructure to handle multiple i2c
master cores present in the system and exposes structures and interfaces for
the client to perform I/O on the i2c slave devices.
The driver adds the capability to queue multiple requests from client and
let clients notified asynchronously after completion. It does that by
handling the i2c interrupt or through OPAL poller in the absence of
interrupt.
Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
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