[PATCH 0/6] mmc: exynos_dw_mmc: Disable FMP for Exynos850

[Sam Protsenko]

When doing USB boot [1,2] on E850-96 board (based on Exynos850 SoC) it
was found the eMMC becomes non-functional. The reason why it happens is
that the FMP (Flash Memory Protector) is enabled in FMPSECURITY register
(eMMC block) during USB boot.

In regular boot from eMMC the FMP is disabled by some early bootloader:

    FMPSECURITY[31:0] = 0xcfe2_e492

But when performing USB boot, this register keeps its reset value:

    FMPSECURITY[31:0] = 0xffe2_e492

which leads to non-functional eMMC, because the next two bits are
enabled in this case:

    - FMP_ON[29] = 1: FMP encryption is enabled for eMMC
    - MMC_SFR_PROT_ON = 1: SFR memory region (peripheral registers)
                           protection is enabled for eMMC block

That makes eMMC inaccessible from U-Boot.

This patch series implements disabling FMP on Exynos850 to make eMMC
functional when U-Boot is executed during USB boot. The per-patch
breakdown:

  - patches 1-3: cleanup
  - patches 4-6: adding FMP disabling quirk and enabling it on E850

Patches are supposed to be applied in the same order as they appear in
the series, to keep the dependencies straight. The series is expected to
go either through Minkyu's (Samsung) tree, or Peng Fan's MMC tree.

[1] https://gitlab.com/LinaroLtd/e850-96/tools/dltool
[2] https://docs.u-boot.org/en/latest/board/samsung/e850-96.html#flashing-overview

Sam Protsenko (6):
  mmc: exynos_dw_mmc: Extend dm_dwmci_ops without code duplication
  mmc: dw_mmc: Do not export dwmci_send_cmd() and dwmci_set_ios()
  mmc: exynos_dw_mmc: Improve coding style
  mmc: exynos_dw_mmc: Add quirk for disabling FMP
  mmc: exynos_dw_mmc: Add exynos850 compatible
  mmc: exynos_dw_mmc: Disable FMP for Exynos850 chip

 arch/arm/mach-exynos/include/mach/dwmmc.h |  6 ++
 drivers/mmc/dw_mmc.c                      |  6 +-
 drivers/mmc/exynos_dw_mmc.c               | 78 ++++++++++++++++-------
 include/dwmmc.h                           |  3 -
 4 files changed, 65 insertions(+), 28 deletions(-)


base-commit: 1071cc85bc4d1416fd93a063ba4abdd2d17ae0db
-- 
2.39.5