Call for testing: spi-mem driver for Aspeed SMC controllers

[Tao Ren]

Thank you Cedric and Joel! I have AST2400, AST2500 and AST2600 OpenBMC
platforms and I can test these patches. It may take a few days as I'm
just back from holiday (need to catch up at work), but I should be able
to share my findings by middle this week.


Cheers,

Tao

On Sun, Feb 27, 2022 at 07:53:37PM +0100, Cédric Le Goater wrote:
> On 2/25/22 06:29, Joel Stanley wrote:
> > Cedric has authored a new drive for the SPI NOR devices on the ASPEED
> > SoCs. It supports 2400, 2500 and 2600. It is written using the spi-mem
> > subsystem, which should mean it can go upstream.
> > 
> > This is great news, as our current driver is half upstream, half in
> > the openbmc tree, due to some issues getting it merged as part of the
> > spi-nor subsystem.
> > 
> > It would be great to have testing. I've created a commit that patches
> > in support to whatever kernel tree you're using. Hopefully this makes
> > it easier to test atop your internal branches:
> > 
> > https://gerrit.openbmc-project.xyz/c/openbmc/openbmc/+/51551
> > 
> > Cherry pick this commit into your tree, and see how it goes, and report back.
> > 
> > I plan to switch the openbmc tree to this driver when we next rebase
> > the kernel. We could also backport it to dev-5.15 as an option.
> > 
> > You can direct testing results to this thread, or reply directly to
> > the upstream thread:
> > 
> > https://lore.kernel.org/all/20220214094231.3753686-1-clg@kaod.org/
> 
> or grab the v2 from :
> 
>   https://github.com/legoater/linux/tree/openbmc-5.15
> 
> I have addressed the comments on driver bind/unbind.
> 
> Thanks,
> 
> C.
> 
> > 
> > Cheers,
> > 
> > Joel
> > 
> > ---------- Forwarded message ---------
> > From: Cédric Le Goater <clg at kaod.org>
> > Date: Mon, 14 Feb 2022 at 09:42
> > Subject: [PATCH 00/10] spi: spi-mem: Add driver for Aspeed SMC controllers
> > To: <linux-spi at vger.kernel.org>, <linux-mtd at lists.infradead.org>
> > Cc: Mark Brown <broonie at kernel.org>, Tudor Ambarus
> > <tudor.ambarus at microchip.com>, Pratyush Yadav <p.yadav at ti.com>, Miquel
> > Raynal <miquel.raynal at bootlin.com>, Richard Weinberger
> > <richard at nod.at>, Vignesh Raghavendra <vigneshr at ti.com>,
> > <linux-aspeed at lists.ozlabs.org>, Joel Stanley <joel at jms.id.au>, Andrew
> > Jeffery <andrew at aj.id.au>, Chin-Ting Kuo
> > <chin-ting_kuo at aspeedtech.com>, <devicetree at vger.kernel.org>, Rob
> > Herring <robh+dt at kernel.org>, <linux-arm-kernel at lists.infradead.org>,
> > <linux-kernel at vger.kernel.org>, Cédric Le Goater <clg at kaod.org>
> > 
> > 
> > Hi,
> > 
> > This series adds a new SPI driver using the spi-mem interface for the
> > Aspeed static memory controllers of the AST2600, AST2500 and AST2400
> > SoCs.
> > 
> >   * AST2600 Firmware SPI Memory Controller (FMC)
> >   * AST2600 SPI Flash Controller (SPI1 and SPI2)
> >   * AST2500 Firmware SPI Memory Controller (FMC)
> >   * AST2500 SPI Flash Controller (SPI1 and SPI2)
> >   * AST2400 New Static Memory Controller (also referred as FMC)
> >   * AST2400 SPI Flash Controller (SPI)
> > 
> > It is based on the current OpenBMC kernel driver [1], using directly
> > the MTD SPI-NOR interface and on a patchset [2] previously proposed
> > adding support for the AST2600 only. This driver takes a slightly
> > different approach to cover all 6 controllers.
> > 
> > It does not make use of the controller register disabling Address and
> > Data byte lanes because is not available on the AST2400 SoC. We could
> > introduce a specific handler for new features available on recent SoCs
> > if needed. As there is not much difference on performance, the driver
> > chooses the common denominator: "User mode" which has been heavily
> > tested in [1]. "User mode" is also used as a fall back method when
> > flash device mapping window is too small.
> > 
> > Problems to address with spi-mem were the configuration of the mapping
> > windows and the calibration of the read timings. The driver handles
> > them in the direct mapping handler when some knowledge on the size of
> > the flash device is know. It is not perfect but not incorrect either.
> > The algorithm is one from [1] because it doesn't require the DMA
> > registers which are not available on all controllers.
> > 
> > Direct mapping for writes is not supported (yet). I have seen some
> > corruption with writes and I preferred to use the safer and proven
> > method of the initial driver [1]. We can improve that later.
> > 
> > The driver supports Quad SPI RX transfers on the AST2600 SoC but it
> > didn't have the expected results. Therefore it is not activated yet.
> > This needs more tests.
> > 
> > The series does not remove the current Aspeed SMC driver but prepares
> > ground for its removal by changing its CONFIG option. This last step
> > can be addressed as a followup when the new driver using the spi-mem
> > interface has been sufficiently exposed.
> > 
> > Tested on:
> > 
> >   * OpenPOWER Palmetto (AST2400)
> >   * Evaluation board (AST2500)
> >   * OpenPOWER Witherspoon (AST2500)
> >   * Evaluation board (AST2600 A0)
> >   * Rainier board (AST2600)
> > 
> > [1] https://github.com/openbmc/linux/blob/dev-5.15/drivers/mtd/spi-nor/controllers/aspeed-smc.c
> > [2] https://patchwork.ozlabs.org/project/linux-aspeed/list/?series=212394
> > 
> > Thanks,
> > 
> > C.
> > 
> > Cédric Le Goater (10):
> >    mtd: spi-nor: aspeed: Rename Kconfig option
> >    dt-bindings: spi: Add Aspeed SMC controllers device tree binding
> >    spi: spi-mem: Add driver for Aspeed SMC controllers
> >    spi: aspeed: Add support for direct mapping
> >    spi: aspeed: Adjust direct mapping to device size
> >    spi: aspeed: Workaround AST2500 limitations
> >    spi: aspeed: Add support for the AST2400 SPI controller
> >    spi: aspeed: Calibrate read timings
> >    ARM: dts: aspeed: Enable Dual SPI RX transfers
> >    spi: aspeed: Activate new spi-mem driver
> > 
> >   drivers/spi/spi-aspeed-smc.c                  | 1241 +++++++++++++++++
> >   .../bindings/spi/aspeed,ast2600-fmc.yaml      |   92 ++
> >   arch/arm/boot/dts/aspeed-g4.dtsi              |    6 +
> >   arch/arm/boot/dts/aspeed-g5.dtsi              |    7 +
> >   arch/arm/boot/dts/aspeed-g6.dtsi              |    8 +
> >   drivers/mtd/spi-nor/controllers/Kconfig       |    4 +-
> >   drivers/mtd/spi-nor/controllers/Makefile      |    2 +-
> >   drivers/spi/Kconfig                           |   11 +
> >   drivers/spi/Makefile                          |    1 +
> >   9 files changed, 1369 insertions(+), 3 deletions(-)
> >   create mode 100644 drivers/spi/spi-aspeed-smc.c
> >   create mode 100644
> > Documentation/devicetree/bindings/spi/aspeed,ast2600-fmc.yaml
> > 
> > --
> > 2.34.1
>