The HiFive 1 rev b includes a watchdog module based on a 32-bit
counter. The watchdog timer is in the always-on domain device of
HiFive 1 rev b, so this patch added the AON device to the sifive_e
machine. This patch only implemented the functionality of the
watchdog timer, not all the functionality of the AON device.

You can test the patchset by the QTest tests/qtest/sifive-e-aon-watchdog-test.c

Changes since v1 ( Thank Alistair for the feedback ):
- Use the register field macro.
- Delete the public create function. The board creates the aon device itself.
- Keep all variable declarations at the top of the code block.

Changes since v2 ( Thank Alistair for the feedback ):
- Delete the declaration and definition of the create function.

Changes since v3 ( Thank Alistair and Thomas for the feedback ):
- Use `device_class_set_props()` for the properties in sifive_e_aon device.
- Add SPDX identifier in QTEST.
- Use libqtest.h in QTEST.
- Let the statements on one line as long as they still fit into 80 columns.

Tommy Wu (3):
  hw/misc: sifive_e_aon: Support the watchdog timer of HiFive 1 rev b.
  hw/riscv: sifive_e: Support the watchdog timer of HiFive 1 rev b.
  tests/qtest: sifive-e-aon-watchdog-test.c: Add QTest of watchdog of
    sifive_e

 hw/misc/Kconfig                          |   3 +
 hw/misc/meson.build                      |   1 +
 hw/misc/sifive_e_aon.c                   | 326 ++++++++++++++++
 hw/riscv/Kconfig                         |   1 +
 hw/riscv/sifive_e.c                      |  13 +-
 include/hw/misc/sifive_e_aon.h           |  60 +++
 include/hw/riscv/sifive_e.h              |   8 +-
 tests/qtest/meson.build                  |   3 +
 tests/qtest/sifive-e-aon-watchdog-test.c | 450 +++++++++++++++++++++++
 9 files changed, 860 insertions(+), 5 deletions(-)
 create mode 100644 hw/misc/sifive_e_aon.c
 create mode 100644 include/hw/misc/sifive_e_aon.h
 create mode 100644 tests/qtest/sifive-e-aon-watchdog-test.c

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2.27.0