ACPI: NFIT: Add runtime firmware activate support
Plumb the platform specific backend for the generic libnvdimm firmware activate interface. Register dimm level operations to arm/disarm activation, and register bus level operations to report the dynamic platform-quiesce time relative to the number of dimms armed for firmware activation. A new nfit-specific bus attribute "firmware_activate_noidle" is added to allow the activation to switch between platform enforced, and OS opportunistic device quiesce. In other words, let the hibernate cycle handle in-flight device-dma rather than the platform attempting to increase PCI-E timeouts and the like. Cc: Dave Jiang <dave.jiang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
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Vishal Verma

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@@ -202,6 +202,25 @@ Description:
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functions. See the section named 'NVDIMM Root Device _DSMs' in
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the ACPI specification.
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What: /sys/bus/nd/devices/ndbusX/nfit/firmware_activate_noidle
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Date: Apr, 2020
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KernelVersion: v5.8
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Contact: linux-nvdimm@lists.01.org
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Description:
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(RW) The Intel platform implementation of firmware activate
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support exposes an option let the platform force idle devices in
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the system over the activation event, or trust that the OS will
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do it. The safe default is to let the platform force idle
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devices since the kernel is already in a suspend state, and on
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the chance that a driver does not properly quiesce bus-mastering
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after a suspend callback the platform will handle it. However,
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the activation might abort if, for example, platform firmware
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determines that the activation time exceeds the max PCI-E
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completion timeout. Since the platform does not know whether the
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OS is running the activation from a suspend context it aborts,
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but if the system owner trusts driver suspend callback to be
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sufficient then 'firmware_activation_noidle' can be
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enabled to bypass the activation abort.
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What: /sys/bus/nd/devices/regionX/nfit/range_index
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Date: Jun, 2015
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