| Message ID | 20210926095847.38261-1-sven@svenpeter.dev (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add Apple M1 support to PASemi i2c driver | expand |
On Sun, Sep 26, 2021 at 12:00 PM Sven Peter <sven@svenpeter.dev> wrote: > > This series adds support for the I2C controller found on Apple Silicon Macs > which has quite a bit of history: > > Apple bought P.A. Semi in 2008 and it looks like a part of its legacy continues > to live on in the M1. This controller has actually been used since at least the > iPhone 4S and hasn't changed much since then. > Essentially, there are only a few differences that matter: > > - The controller no longer is a PCI device > - Starting at some iPhone an additional bit in one register > must be set in order to start transmissions. > - The reference clock and hence the clock dividers are different > > In order to add support for a platform device I first replaced PCI-specific > bits and split out the PCI driver to its own file. Then I added support > to make the clock divider configurable and converted the driver to use > managed device resources to make it a bit simpler. > > The Apple and PASemi driver will never be compiled in the same kernel > since the Apple one will run on arm64 while the original PASemi driver > will only be useful on powerpc. > I've thus followed the octeon (mips)/thunderx(arm64) approach to do the > split: I created a -core.c file which contains the shared logic and just > compile that one for both the PASemi and the new Apple driver. This looks all very good to me, I had one very minor comment. Whole series Reviewed-by: Arnd Bergmann <arnd@arndb.de>
> This looks all very good to me, I had one very minor comment. > > Whole series > > Reviewed-by: Arnd Bergmann <arnd@arndb.de> Thanks for the series and the review! Same here, looks good to me and I only had one minor comment.
Hi, This series adds support for the I2C controller found on Apple Silicon Macs which has quite a bit of history: Apple bought P.A. Semi in 2008 and it looks like a part of its legacy continues to live on in the M1. This controller has actually been used since at least the iPhone 4S and hasn't changed much since then. Essentially, there are only a few differences that matter: - The controller no longer is a PCI device - Starting at some iPhone an additional bit in one register must be set in order to start transmissions. - The reference clock and hence the clock dividers are different In order to add support for a platform device I first replaced PCI-specific bits and split out the PCI driver to its own file. Then I added support to make the clock divider configurable and converted the driver to use managed device resources to make it a bit simpler. The Apple and PASemi driver will never be compiled in the same kernel since the Apple one will run on arm64 while the original PASemi driver will only be useful on powerpc. I've thus followed the octeon (mips)/thunderx(arm64) approach to do the split: I created a -core.c file which contains the shared logic and just compile that one for both the PASemi and the new Apple driver. Now unfortunately I don't have access to any old PASemi hardware and cannot confirm that my changes haven't broken anything for those. I believe Hector was in contact with Olof a few months ago who said that he might still have an old machine on which he could test this. I'd very much appreciate if he (or anyone else for that matter :-)) could give this series a quick test on the old PASemi machines. Best, Sven Sven Peter (10): dt-bindings: i2c: Add Apple I2C controller bindings i2c: pasemi: Use io{read,write}32 i2c: pasemi: Remove usage of pci_dev i2c: pasemi: Split off common probing code i2c: pasemi: Split pci driver to its own file i2c: pasemi: Move common reset code to own function i2c: pasemi: Allow to configure bus frequency i2c: pasemi: Refactor _probe to use devm_* i2c: pasemi: Add Apple platform driver i2c: pasemi: Set enable bit for Apple variant .../devicetree/bindings/i2c/apple,i2c.yaml | 61 +++++++++ MAINTAINERS | 2 + drivers/i2c/busses/Kconfig | 11 ++ drivers/i2c/busses/Makefile | 3 + drivers/i2c/busses/i2c-pasemi-apple.c | 122 ++++++++++++++++++ .../{i2c-pasemi.c => i2c-pasemi-core.c} | 114 +++++----------- drivers/i2c/busses/i2c-pasemi-core.h | 21 +++ drivers/i2c/busses/i2c-pasemi-pci.c | 85 ++++++++++++ 8 files changed, 334 insertions(+), 85 deletions(-) create mode 100644 Documentation/devicetree/bindings/i2c/apple,i2c.yaml create mode 100644 drivers/i2c/busses/i2c-pasemi-apple.c rename drivers/i2c/busses/{i2c-pasemi.c => i2c-pasemi-core.c} (77%) create mode 100644 drivers/i2c/busses/i2c-pasemi-core.h create mode 100644 drivers/i2c/busses/i2c-pasemi-pci.c