Implement a system-wide suspend driver for the Andes AE350 platform.
This driver supports Andes-specific deep sleep (suspend to RAM) and
light sleep (suspend to standby) functionalities via the ATCSMU.
The major differences between deep sleep and light sleep are:
- Power Domain and Resume Path: Deep sleep powers down the core domain.
Consequently, harts waking from deep sleep resume from the reset
vector. Light sleep utilizes clock gating to the core domain; harts
maintain state and resume execution at the instruction immediately
following the WFI instruction.
- Primary Hart Wakeup: In both modes, the primary hart is woken by
UART or RTC alarm interrupts. In deep sleep, the primary hart is
additionally responsible for re-enabling the Last Level Cache (LLC)
and restoring Andes-specific CSRs.
- Secondary Hart Wakeup: In light sleep, secondary harts are woken
by an IPI sent from the primary hart. In deep sleep, they are
woken by an ATCSMU hardware wake-up command. Furthermore,
secondary harts must restore Andes-specific CSRs when returning
from deep sleep.
Signed-off-by: Ben Zong-You Xie <ben717@andestech.com>
Signed-off-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Link: https://lore.kernel.org/r/20251229071914.1451587-6-ben717@andestech.com
Signed-off-by: Anup Patel <anup@brainfault.org>
