Add support for the LiteX SD-Card device, LiteSDCard.

LiteSDCard is a simple SD-Card interface available as part of the LiteX
environment, used with various RISC-V and other FPGA based SoCs.

New in v4:

Doc/dt/bindings/mmc/litex,mmc.yaml:

  - fixed `dt_binding_check` errors uncovered by Rob's script

drivers/mmc/host/litex_mmc.c:

  - struct litex_mmc_host fields re-ordered so that `pahole` reports
    no holes in either 32- or 64-bit builds
  - litex_mmc_set_bus_width() now encapsulates check for
    host->is_bus_width_set
  - litex_mmc_request() - factor out dma data setup into separate
    helper function: litex_mmc_do_dma()

New in v3:

 MAINTAINERS:

 - picked up acked-by Joel
 - added listing for liteeth driver
 - added Joel as additional co-maintainer (thanks!)

 Doc/dt/bindings/mmc/litex,mmc.yaml:

 - picked up r/b Geert Uytterhoeven [off-list ref] in DT
   bindings document (please let me know if that was premature, and
   happy to take further review if needed :)
 - add dedicated DT property for source clock frequency

 drivers/mmc/host/litex_mmc.c:

 - fixed function signature (no line split), and naming (litex_mmc_*)
 - more informative MODULE_AUTHOR() entries
   - also added matching "Copyright" entries in file header
 - fixed description in Kconfig
 - fixed DT documentation
 - removed magic constants
 - removed litex_map_status(), have sdcard_wait_done() return *real*
   error codes directly instead.
 - streamlined litex_mmc_reponse_len()
 - call litex_mmc_set_bus_width() only once, and ensure it returns
   correct error code(s)
 - use readx_poll_timeout() -- more concise -- instead of
   read_poll_timeout()
 - use dev_err() in litex_mmc_send_cmd() (instead of pr_err())
 - litex_mmc_setclk() will update host->clock before returning
 - separate irq initialization into its own function,
   litex_mmc_irq_init()
 - document rationale for f_min, f_max
 - use dmam_alloc_coherent(), which simplifies cleanup significantly
 - large `if (data) { ... }` block in litex_mmc_request() left as-is,
   there are too many variables shared with the rest of the parent
   function body to easily separate (e.g., `len`, `transfer`, `direct`).
   If this is indeed a blocker, I can take another shot at refactoring
   it in a future revision!
 - bump dma_set_mask_and_coherent() to 64-bits on suitable
   architectures
 - clock source picked up from dedicated DT clock reference property
 - remove gpio card-detect logic (needs testing and a dt binding
   example before being eligible for upstream inclusion)

quoted

New in v2:
  - reword info message in litex_set_clk()
  - streamline code in litex_map_status()
  - fix typos in Kconfig (thanks Randy Dunlap [off-list ref])
  - improvements suggested by Stafford Horne [off-list ref]
    - allow COMPILE_TEST in Kconfig
    - use read_poll_timeout() when waiting for cmd/data/DMA
      xfer completion
  - include interrupt.h (thanks kernel test robot [off-list ref])

Gabriel Somlo (3):
  MAINTAINERS: co-maintain LiteX platform
  dt-bindings: mmc: Add bindings for LiteSDCard
  mmc: Add driver for LiteX's LiteSDCard interface

 .../devicetree/bindings/mmc/litex,mmc.yaml    |  72 ++
 MAINTAINERS                                   |   9 +-
 drivers/mmc/host/Kconfig                      |   9 +
 drivers/mmc/host/Makefile                     |   1 +
 drivers/mmc/host/litex_mmc.c                  | 654 ++++++++++++++++++
 5 files changed, 743 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/mmc/litex,mmc.yaml
 create mode 100644 drivers/mmc/host/litex_mmc.c

-- 
2.31.1