[PATCH v6 0/7] gpu: nova-core: expose the logging buffers via debugfs

[Timur Tabi <ttabi@nvidia.com>]

GSP-RM writes its printf message to "logging buffers", which are blocks
memory allocated by the driver.  The messages are encoded, so exposing
the buffers as debugfs entries allows the buffers to be extracted and
decoded by a special application.

When the driver loads, a /sys/kernel/debug/nova_core root entry is
created.  To do this, the normal module_pci_driver! macro call is
replaced with an explicit initialization function, as this allows
that debugfs entry to be created once for all GPUs.

Then in each GPU's initialization, a subdirectory based on the PCI
BDF name is created, and the logging buffer entries are created under
that.

These entries are gated on a CONFIG_NOVA_CORE_DEBUGFS Kconfig option.

Note: the debugfs entry has a file size of 0, because debugfs defaults
a 0 size and the Rust abstractions do not adjust it for the same of
the object.  Nouveau makes this adjustment manually in the driver.

Changes since v5:
1. Replaced the debugfs::BinaryWriter implementation for LogBuffer with
one for CoherentAllocation<u8>, and moved it from gsp.rs to dma.rs.
2. Updated the DEBUGFS_ROOT drop to ensure the devices are unregistered (
and thus all the device-specific debugfs entries are removed) before the
driver itself is unregistered (which removes the top-level nova_core entry).
3. Updated several SAFETY comments.
4. Removed all references to PCI in device::name
5. Removed debugfs::Dir::empty()
6. Replaced UserSliceWriter::write_buffer with write_dma
7. Replaced BinaryWriter for LogBuffer with BinaryWriter for CoherentAllocation<u8>

Timur Tabi (7):
  rust: device: add device name method
  rust: uaccess: add write_dma() for copying from DMA buffers to
    userspace
  gpu: nova-core: implement BinaryWriter for CoherentAllocation<u8>
  gpu: nova-core: Replace module_pci_driver! with explicit module init
  gpu: nova-core: use pin projection in method boot()
  gpu: nova-core: create debugfs root in module init
  gpu: nova-core: create GSP-RM logging buffers debugfs entries

 drivers/gpu/nova-core/Kconfig      | 13 ++++++++
 drivers/gpu/nova-core/gsp.rs       | 46 +++++++++++++++++++++-----
 drivers/gpu/nova-core/gsp/boot.rs  | 14 ++++----
 drivers/gpu/nova-core/nova_core.rs | 53 ++++++++++++++++++++++++++++--
 rust/helpers/device.c              |  5 +++
 rust/kernel/device.rs              | 10 ++++++
 rust/kernel/dma.rs                 | 36 +++++++++++++++++++-
 rust/kernel/uaccess.rs             | 41 +++++++++++++++++++++++
 8 files changed, 201 insertions(+), 17 deletions(-)


base-commit: cea7b66a80412e2a5b74627b89ae25f1d0110a4b
-- 
2.52.0