[PATCH v2 00/23] ata: ahci: Add DWC/Baikal-T1 AHCI SATA support

[Serge Semin]

The main goal of this patchset was to add Baikal-T1 AHCI SATA specifics
support into the kernel AHCI subsystem. On the way of doing that we
figured out that mainly these specifics are actually DWC AHCI SATA
controller features, but still there were some Baikal-T1 SoC platform
peculiarities which we had to take into account. So the patchset
introduces two AHCI SATA controllers support and one AHCI SATA driver
with a series of preparation, optimization and cleanup patches.

The series starts used to start with converting the legacy AHCI SATA
controllers text-based DT-bindings to the DT-schema. But turned out that
has already been done in kernel v5.17. So instead we suggest to improve
the bindings usability by splitting up the AHCI DT bindings into two
schemas: one common AHCI SATA controller yaml-file, which can be reused by
any AHCI-compatible controller utilizing the kernel AHCI library
functions, and DT-bindings for the generic AHCI SATA devices indicated by
the "generic-ahci" compatible string and implemented in the
ahci_platform.c driver. Note after doing that we had to fix the
sata-common.yaml file SATA port IDs constraint.

Then a series of generic preparations-cleanups goes. First of all it
concerns the device-managed methods usage in the framework of the CSR
space remapping and the clocks requesting and enabling. Note since the
clocks handlers are requested and kept in the generic AHCI library it
seemed a good idea to add an AHCI-platform generic method to find and get
a particular clock handler from the pool of the requested ones. It was
used later in the series in the DWC/Baikal-T1-specific code. Secondly we
suggested to at least sanity check the number of SATA ports DT-sub-nodes
before using it further.  Thirdly the ports-implemented DT-property
parsing was moved from the AHCI platform-driver to the AHCI-library so to
be used by the non-generic AHCI drivers if required (DT-schema is
accordingly fixed too). Finally due to having the shared-reset control
support we had to add a new AHCI-resource getter flag -
AHCI_PLATFORM_RST_TRIGGER, which indicated using a trigger-like reset
control. For such platforms the controller reset will be performed by
means of the reset_control_reset() and reset_control_rearm() methods.
AHCI-library reset functions encapsulating the way the reset procedure is
performed have been also added.

After that goes a patches series with the platform-specific
AHCI-capabilities initialization. The suggested functionality will be
useful for the platforms with no BIOS, comprehensive bootloader/firmware
installed. In that case the AHCI-related platform-specifics like drive
staggered spin-up, mechanical presence switch attached or FIS-based
switching capability usage, etc will be left uninitialized with no generic
way to be indicated as available if required. We suggested to use the AHCI
device tree node and its ports sub-nodes for that. AHCI-platform library
will be responsible fo the corresponding DT-properties parsing and
pre-initialization of the internal capability registers cache, which will
be then flashed back to the corresponding CSR after HBA reset. Thus a
supposed to be firmware-work will be done by means of the AHCI-library and
the DT-data. A set of the preparations/cleanups required to be done before
introducing the feature.  First the DT-properties indicating the
corresponding capability availability were described in the common AHCI
DT-binding schema. Second we needed to add the enum items with the AHCI
Port CMD fields, which hadn't been added so far. Thirdly we suggested to
discard one of the port-map internal storage (force_port_map) in favor of
re-using another one (save_port_map) in order to simplify the port-map
initialization interface a bit by getting rid from a redundant variable.
Finally after discarding the double AHCI-version read procedure and
changing the __ahci_port_base() method prototype the platform
firmware-specific caps initialization functionality was introduced.

The main part of the series goes afterwards. A dedicated DWC AHCI SATA
controller driver was introduced together with the corresponding
DT-binding schema pre-patch. Note the driver built mode is activated
synchronously with the generic AHCI-platform driver by default so
automatically to be integrated into the kernel for the DWC AHCI-based
platforms which relied on activating the generic AHCI SATA controller
driver. Aside with the generic resources getting and AHCI-host
initialization, the driver implements the DWC-specific setups. In
particular it checks whether the platform capabilities activated by the
firmware (see the functionality described above) are actually supported by
the controller. It's done by means of the vendor-specific registers. Then
it makes sure that the embedded 1ms timer interval, which is used for the
DevSleep and CCC features, is correctly initialized based on the
application clock rate.  The last but not least the driver provides a way
to tune the DMA-interface performance up by setting the Tx/Rx transactions
maximum size up. The required values are specified by means of the
"snps,tx-ts-max" and snps,rx-ts-max" DT-properties.

Finally we suggest to extend the DWC AHCI SATA controller driver
functionality with a way to add the DWC-AHCI-based platform-specific
quirks. Indeed there are many DWC AHCI-based controllers and just a few of
them are diverged too much to be handled by a dedicated AHCI-driver. The
rest of them most likely can work well either with a generic version of
the driver or require a simple normally platform-specific quirk to get up
and running. Such platforms can define a platform-data in the DWC AHCI
driver with a set of the controller-specific flags and initialization
functions. Those functions will be called at the corresponding stages of
the device probe/resume/remove procedures so to be performing the platform
setups/cleanups.

After the denoted above functionality is added we can finally introduce
the Baikal-T1 AHCI SATA controller support into the DWC AHCI SATA driver.
The controller is based on the DWC AHCI SATA IP-core v4.10a and can work
well with the generic DWC AHCI driver. The only peculiarity of it is
connected with the SATA Ports reference clock source. It can be supplied
either from the internal SoC PLL or from the chip pads. Currently we have
to prefer selecting the signal coming from the pads if the corresponding
clock source is specified because the link doesn't get stably established
when the internal clock signal is activated. In addition the platform has
trigger-based reset signals so the corresponding flag must be passed to
the generic AHCI-resource getter.

Link: https://lore.kernel.org/linux-ide/20220324001628.13028-1-Sergey.Semin@xxxxxxxxxxxxxxxxxxxx/
Changelog v2:
- Rebase from kernel v5.17 to v5.18-rc3. (@Rob)
- Rebase onto the already available AHCI DT schema. As a result two more
  patches have been added. (@Rob)
- Rename 'syscon' property to 'baikal,bt1-syscon'. (@Rob)
- Replace min/max constraints of the snps,{tx,rx}-ts-max property with
  enum [ 1, 2, 4, ..., 1024 ]. (@Rob)
- Use dlemoal/libata.git git tree for the LIBATA SATA AHCI SYNOPSYS
  DWC driver (@Damien).
- Change the local objects prefix from 'dwc_ahci_' to 'ahci_dwc_',
  from 'bt1_ahci_' to 'ahci_bt1_'. (@Damien)
- Use LLDD term in place of 'glue-driver'. (@Damien)
- Convert the ahci_platform_assert_rsts() method to returning int status
  (@Damien).
- Drop the else word from the DT child_nodes value checking if-else-if
  statement (@Damien) and convert the after-else part into the ternary
  operator-based statement.
- Convert to checking the error-case first in the devm_clk_bulk_get_all()
  method invocation. (@Damien)
- Drop the rc variable initialization in the ahci_platform_get_resources()
  method. (@Damien)
- Add comma and replace "channel" with "SATA port" in the reg property
  description of the sata-common.yaml schema. (@Damien)

Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx>
Cc: Pavel Parkhomenko <Pavel.Parkhomenko@xxxxxxxxxxxxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: linux-ide@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx

Serge Semin (23):
  dt-bindings: ata: ahci-platform: Drop dma-coherent property
    declaration
  dt-bindings: ata: ahci-platform: Detach common AHCI bindings
  dt-bindings: ata: ahci-platform: Clarify common AHCI props constraints
  dt-bindings: ata: sata: Extend number of SATA ports
  ata: libahci_platform: Explicitly set rc on devres_alloc failure
  ata: libahci_platform: Convert to using platform devm-ioremap methods
  ata: libahci_platform: Convert to using devm bulk clocks API
  ata: libahci_platform: Add function returning a clock-handle by id
  ata: libahci_platform: Sanity check the DT child nodes number
  ata: libahci_platform: Parse ports-implemented property in resources
    getter
  ata: libahci_platform: Introduce reset assertion/deassertion methods
  dt-bindings: ata: ahci: Add platform capability properties
  ata: libahci: Extend port-cmd flags set with port capabilities
  ata: libahci: Discard redundant force_port_map parameter
  ata: libahci: Don't read AHCI version twice in the save-config method
  ata: ahci: Convert __ahci_port_base to accepting hpriv as arguments
  ata: ahci: Introduce firmware-specific caps initialization
  dt-bindings: ata: ahci: Add DWC AHCI SATA controller DT schema
  ata: ahci: Add DWC AHCI SATA controller support
  dt-bindings: ata: ahci: Add Baikal-T1 AHCI SATA controller DT schema
  ata: ahci-dwc: Add platform-specific quirks support
  ata: ahci-dwc: Add Baikal-T1 AHCI SATA interface support
  MAINTAINERS: Add maintainers for DWC AHCI SATA driver

 .../devicetree/bindings/ata/ahci-common.yaml  | 188 +++++++
 .../bindings/ata/ahci-platform.yaml           |  89 +--
 .../bindings/ata/baikal,bt1-ahci.yaml         | 127 +++++
 .../devicetree/bindings/ata/sata-common.yaml  |   7 +-
 .../bindings/ata/snps,dwc-ahci.yaml           | 123 ++++
 MAINTAINERS                                   |   9 +
 drivers/ata/Kconfig                           |  11 +
 drivers/ata/Makefile                          |   1 +
 drivers/ata/ahci.c                            |   4 +-
 drivers/ata/ahci.h                            |  21 +-
 drivers/ata/ahci_dwc.c                        | 526 ++++++++++++++++++
 drivers/ata/ahci_mtk.c                        |   2 -
 drivers/ata/ahci_platform.c                   |   5 -
 drivers/ata/ahci_st.c                         |   3 -
 drivers/ata/libahci.c                         |  63 ++-
 drivers/ata/libahci_platform.c                | 236 ++++++--
 include/linux/ahci_platform.h                 |   8 +-
 17 files changed, 1258 insertions(+), 165 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/ata/ahci-common.yaml
 create mode 100644 Documentation/devicetree/bindings/ata/baikal,bt1-ahci.yaml
 create mode 100644 Documentation/devicetree/bindings/ata/snps,dwc-ahci.yaml
 create mode 100644 drivers/ata/ahci_dwc.c

-- 
2.35.1