[PATCH v3 00/29] arm: semihosting: Cleanups and new features

[Sean Anderson <sean.anderson@seco.com>]

This cleans up the semihosting code and adds the following new features:

- hostfs support (like sandbox)
- support for being used as a SPL boot device
- serial device support
- falling back to normal drivers if semihosting is disabled

The main device affected by these changes is vexpress64, so I'd appreciate
if Andre (or anyone else) could try booting.

These changes are motivated by bringup for ls1046a. When forcing JTAG
boot, this device disables most communication peripherals, including
serial and ethernet devices. This appears to be fixed in later
generation devices, but we are stuck with it for now. Semihosting
provides an easy way to run a few console commands.

The patches in this series are organized as follows:

0-4: rST conversions and other documentation updates
5-9: Semihosting cleanups
10-14: Filesystem support (including SPL boot device)
15-16: Serial support
16: Documentation update
17: JTAG boot support for LS1046A
19-25: Semihosting fallback
26-29: DM puts support

The last two groups of patches are "bonus;" the first 17 patches stand
on their own. The last two groups could be broken out as separate
series, but I have kept them in this one to help with my sanity (and not
have to deal with too many outstanding series).

Patch 14 depends on [1] to apply cleanly. Patch 17 depends on [2] for
correctness. This series should be applied to u-boot/next (in
particular, the EROFS series must have been applied).

[1] https://lore.kernel.org/u-boot/CACRpkdZ+9fmNjC_mvrbPa9-iuTQVd8UkJ7Zpe7cL0c5vZygsVw@mail.gmail.com/T/
[2] https://lore.kernel.org/u-boot/20220222183840.1355337-2-sean.anderson@seco.com/

Changes in v3:
- Add a config for puts to reduce the impact on the (vast majority) of
  boards which don't need it.
- Add additional documentation for QEMU and OpenOCD
- Add dummy device number for hostfs
- Add test for putc/puts
- Fix loading the wrong EL's SPSR
- Fix null pointer dereference in _serial_puts caused by a missing
  return.
- Make FALLBACK depend on ARM64
- Make puts return the number of characters written on success, instead
  of reusing the len parameter.
- Reorder Kconfigs to group SEMIHOSTING_FALLBACK after SEMIHOSTING
  (instead of after SPL_SEMIHOSTING_FALLBACK)
- Update commit message to describe an alternate implementation
- Use SYS_ERRNO instead of SYS_ISERROR, since the latter is not
  implemented in older QEMUs.

Changes in v2:
- Add implementation of puts for DM
- Add migration instructions for smhload
- Add myself as a reviewer
- Add semihosting fallback implementation
- Compile arch/arm/lib/semihosting.o in SPL
- Document debug uart
- Fix baud numbers being off by 10
- Fix typos in commit message
- Make CONFIG_SPL_SEMIHOSTING depend on SPL
- Rebase on Andre's series
- Rename non-DM driver struct to match format of other drivers

Sean Anderson (29):
  doc: Convert semihosting readme to rST
  nxp: ls1046ardb: Convert README to rST
  doc: ls1046ardb: Expand boot mode section
  doc: ls1046ardb: Document debug uart
  arm: smh: Add semihosting entry to MAINTAINERS
  arm: smh: Export semihosting functions
  arm: smh: Use numeric modes for smh_open
  arm: smh: Return errno on error
  arm: smh: Document functions in header
  arm: smh: Add some file manipulation commands
  spl: Add semihosting boot method
  fs: Add semihosting filesystem
  cmd: fdt: Use start/size for chosen instead of start/end
  arm: smh: Remove smhload command
  arm: smh: Add some functions for working with the host console
  serial: Add semihosting driver
  doc: smh: Update semihosting documentation
  ls1046ardb: Add support for JTAG boot
  arm64: Save esr in pt_regs
  arm64: Save spsr in pt_regs
  arm64: Import some ESR and SPSR defines from Linux
  arm: smh: Add option to detect semihosting
  arm64: Catch non-emulated semihosting calls
  serial: smh: Initialize serial only if semihosting is enabled
  arm64: ls1046a: Support semihosting fallback
  serial: dm: Add support for puts
  serial: sandbox: Implement puts
  test: serial: Add test for putc/puts
  serial: smh: Implement puts for DM

 MAINTAINERS                             |   5 +
 arch/arm/Kconfig                        |  47 +++-
 arch/arm/cpu/armv8/exceptions.S         |   9 +-
 arch/arm/cpu/armv8/fsl-layerscape/spl.c |   3 +
 arch/arm/include/asm/esr.h              | 343 ++++++++++++++++++++++++
 arch/arm/include/asm/proc-armv/ptrace.h |  75 ++++++
 arch/arm/include/asm/spl.h              |   1 +
 arch/arm/include/asm/u-boot-arm.h       |   7 +-
 arch/arm/lib/Makefile                   |   2 +-
 arch/arm/lib/interrupts_64.c            |  80 ++++--
 arch/arm/lib/semihosting.c              | 230 ++++++++--------
 arch/arm/mach-imx/imx8m/soc.c           |   4 +-
 arch/sandbox/include/asm/serial.h       |   6 +
 board/freescale/ls1046ardb/MAINTAINERS  |   1 +
 board/freescale/ls1046ardb/README       |  76 ------
 board/freescale/ls1046ardb/ls1046ardb.c |  11 +
 cmd/fdt.c                               |   6 +-
 common/spl/Makefile                     |   1 +
 common/spl/spl_semihosting.c            |  71 +++++
 disk/part.c                             |   4 +-
 doc/README.semihosting                  |  38 ---
 doc/board/nxp/index.rst                 |   1 +
 doc/board/nxp/ls1046ardb.rst            | 191 +++++++++++++
 doc/usage/index.rst                     |   1 +
 doc/usage/semihosting.rst               | 107 ++++++++
 drivers/serial/Kconfig                  |  37 +++
 drivers/serial/Makefile                 |   1 +
 drivers/serial/sandbox.c                |  38 ++-
 drivers/serial/serial-uclass.c          |  26 +-
 drivers/serial/serial.c                 |   2 +
 drivers/serial/serial_semihosting.c     | 187 +++++++++++++
 fs/Makefile                             |   1 +
 fs/fs.c                                 |  20 ++
 fs/semihostingfs.c                      | 115 ++++++++
 include/configs/ls1046ardb.h            |   2 +
 include/configs/vexpress_aemv8.h        |  10 +-
 include/fs.h                            |   1 +
 include/semihosting.h                   | 149 ++++++++++
 include/semihostingfs.h                 |  21 ++
 include/serial.h                        |  19 ++
 test/dm/serial.c                        |  19 ++
 41 files changed, 1689 insertions(+), 279 deletions(-)
 create mode 100644 arch/arm/include/asm/esr.h
 delete mode 100644 board/freescale/ls1046ardb/README
 create mode 100644 common/spl/spl_semihosting.c
 delete mode 100644 doc/README.semihosting
 create mode 100644 doc/board/nxp/ls1046ardb.rst
 create mode 100644 doc/usage/semihosting.rst
 create mode 100644 drivers/serial/serial_semihosting.c
 create mode 100644 fs/semihostingfs.c
 create mode 100644 include/semihosting.h
 create mode 100644 include/semihostingfs.h

-- 
2.25.1