mmc: Add LiteSDCard mmc driver

New in v11:
- picked up r/b from Andy
drivers/mmc/host/litex_mmc.c:
- defensive coding of litex_mmc_interrupt() return logic
- remove dev member of struct litex_mmc_host, only used during probe

Quoted 150 lines

New in v10:
drivers/mmc/host/litex_mmc.c:
- group linux/mmc/* includes by themselves
- clean-up of return style (multiple locations throughout source)
- create mmc_free_host() wrapper for use with devm_add_action_or_reset()
- use GFP_KERNEL with dmam_alloc_coherent()

Quoted 142 lines

New in v9:
drivers/mmc/host/Kconfig:
- fix OF dependency
drivers/mmc/host/litex_mmc.c:
- remove linux/of.h include, no longer needed since dropping of_match_ptr()
- add linux/mod_devicetable.h include
- use devm_action_or_reset() to devm-ify mmc_alloc_host(), and obviate the need to call mmc_free_host() explicitly during either probe() error path or during remove()

Quoted 131 lines

New in v8:
commit blurbs:
- cosmetic editing of descriptions
- removed Cc: lines
drivers/mmc/host/litex_mmc.c:
- fix file header comment (for real, this time)
- add explicit bits.h include
- remove of_match_ptr() wrapper from around .of_match_table argument
- fix devm ordering issues: use devm_request_irq(), which precludes the need to call free_irq() on probe() error path or from remove()

Quoted 120 lines

New in v7:

drivers/mmc/host/Kconfig:
- added module name in LiteSDCard Kconfig entry

drivers/mmc/host/litex_mmc.c:
- fixed comment formatting, ordering, and capitalization throughout the entire file
- sorted header #include statements
- removed redundant parantheses in readx_poll_timeout() condition
- explicit handling of readx_poll_timeout() timeout scenarios
- dev_err() used in litex_mmc_sdcard_wait_done()
- use memcpy_fromio() to grab command response
- no need to apply 0xffff mask to a 32-bit value right-shifted by 16 (host->resp[3])
- use clamp() instead of min(max(...)...)
- reworked platform_get_irq_optional() error handling logic
- no need to explicitly zero host->irq, kzalloc() does that already
- added missing free_irq() in litex_mmc_probe() error path
- reordered calls inside litex_mmc_remove() (calling mmc_free_host() before free_irq()

Quoted 98 lines

New in v6:

drivers/mmc/host/litex_mmc.c:
- fix handling of deferred probe vs. platform_get_irq_optional()
- don't #ifdef dma_set_mask_and_coherent(), since it automatically does the right thing on both 32- and 64-bit DMA capable arches
- remove MMC_CAP2_FULL_PWR_CYCLE, add MMC_CAP2_NO_MMC to list of hardcoded capabilities during litex_mmc_probe()
- hardcode mmc->ocr_avail to the full 2.7-3.6V range allowed by the SDCard spec (the LiteSDCard device doesn't accept software configuration)

Quoted 86 lines

New in v5:

MAINTAINERS:

- picked up a/b Mateusz

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

- picked up r/b Rob, Joel

drivers/mmc/host/litex_mmc.c:

- shorten #define constant names (cosmetic, make them less unwieldy)
- picked up r/b Joel

Quoted 71 lines

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()

Quoted 56 lines

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 <[email protected]> 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 9 lines

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

New in v11:
- picked up r/b from Andy
drivers/mmc/host/litex_mmc.c:
- defensive coding of litex_mmc_interrupt() return logic
- remove dev member of struct litex_mmc_host, only used during probe

Quoted 99 lines

New in v10:
drivers/mmc/host/litex_mmc.c:
- group linux/mmc/* includes by themselves
- clean-up of return style (multiple locations throughout source)
- create mmc_free_host() wrapper for use with devm_add_action_or_reset()
- use GFP_KERNEL with dmam_alloc_coherent()

Quoted 91 lines

New in v9:
drivers/mmc/host/Kconfig:
- fix OF dependency
drivers/mmc/host/litex_mmc.c:
- remove linux/of.h include, no longer needed since dropping of_match_ptr()
- add linux/mod_devicetable.h include
- use devm_action_or_reset() to devm-ify mmc_alloc_host(), and obviate the need to call mmc_free_host() explicitly during either probe() error path or during remove()

Quoted 80 lines

New in v8:
- remove Cc: lines from commit blurb
drivers/mmc/host/litex_mmc.c:
- fix file header comment (for real, this time)
- add explicit bits.h include
- remove of_match_ptr() wrapper from around .of_match_table argument
- fix devm ordering issues: use devm_request_irq(), which precludes the need to call free_irq() on probe() error path or from remove()

Quoted 71 lines

New in v7:
drivers/mmc/host/Kconfig:
- added module name in LiteSDCard Kconfig entry
drivers/mmc/host/litex_mmc.c:
- fixed comment formatting, ordering, and capitalization throughout the entire file
- sorted header #include statements
- removed redundant parantheses in readx_poll_timeout() condition
- explicit handling of readx_poll_timeout() timeout scenarios
- dev_err() used in litex_mmc_sdcard_wait_done()
- use memcpy_fromio() to grab command response
- no need to apply 0xffff mask to a 32-bit value right-shifted by 16 (host->resp[3])
- use clamp() instead of min(max(...)...)
- reworked platform_get_irq_optional() error handling logic
- no need to explicitly zero host->irq, kzalloc() does that already
- added missing free_irq() in litex_mmc_probe() error path
- reordered calls inside litex_mmc_remove() (calling mmc_free_host() before free_irq()

Quoted 51 lines

New in v6:
- fix handling of deferred probe vs. platform_get_irq_optional()
- don't #ifdef dma_set_mask_and_coherent(), since it automatically does the right thing on both 32- and 64-bit DMA capable arches
- remove MMC_CAP2_FULL_PWR_CYCLE, add MMC_CAP2_NO_MMC to list of hardcoded capabilities during litex_mmc_probe()
- hardcode mmc->ocr_avail to the full 2.7-3.6V range allowed by the SDCard spec (the LiteSDCard device doesn't accept software configuration)

Quoted 41 lines

New in v5:
- shorter #define constant names (cosmetic, make them less unwieldy)
- picked up reviewed-by Joel

Quoted 37 lines

New in v4:
- struct litex_mmc_host fields re-ordered so that pahole reports no holes on 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()

Quoted 29 lines

New in v3:
- 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 and dependencies in Kconfig
- 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
- 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)
- 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!