[nrf fromtree] pm: bind the PM_S2RAM kconfig option to devicetree

Currently it is possible to have an enabled (status="okay")
"suspend-to-ram" "zephyr,power-state" in the devicetree,
CONFIG_PM=y, but CONFIG_PM_S2RAM=n

This means the presence and state of the "suspend-to-ram" power
state in the devicetree does not match the PM_S2RAM option,
despite PM_S2RAM being dependent on the devicetree state.

This commit makes the devicetree the "source of truth" for
whether one or more s2ram power states shall be included and
supported, by enabling PM_S2RAM if any s2ram power state with
status "okay" is present in the devicetree. To disable the
s2ram power state, like with any other state, disable it by
setting its state to "disabled".

The help of the now promptless PM_S2RAM config has been
updated to reflect the new meaning. It previously held
cortex-m specific implementation details, these have been
removed as these details are already present in the file
pointed to as well (arch/arm/core/cortex_m/pm_s2ram.c
line 22)

Signed-off-by: Bjarki Arge Andreasen <[email protected]>
(cherry picked from commit 4626f6b)

Author: bjarki-andreasen

samples/boards/nordic/spis_wakeup/prj.conf

@@ -3,7 +3,6 @@ CONFIG_SPI_SLAVE=y
 CONFIG_GPIO=y
 
 CONFIG_PM=y
-CONFIG_PM_S2RAM=y
 CONFIG_PM_S2RAM_CUSTOM_MARKING=y
 CONFIG_PM_DEVICE=y
 CONFIG_PM_DEVICE_RUNTIME=y

samples/boards/nordic/spis_wakeup/wakeup_trigger/prj.conf

@@ -3,7 +3,6 @@ CONFIG_SPI_NRFX_WAKE_TIMEOUT_US=500
 CONFIG_GPIO=y
 
 CONFIG_PM=y
-CONFIG_PM_S2RAM=y
 CONFIG_PM_S2RAM_CUSTOM_MARKING=y
 CONFIG_PM_DEVICE=y
 CONFIG_PM_DEVICE_RUNTIME=y

samples/boards/st/power_mgmt/suspend_to_ram/prj.conf

@@ -2,7 +2,6 @@ CONFIG_PM=y
 CONFIG_PM_DEVICE=y
 CONFIG_PM_DEVICE_RUNTIME=y
 CONFIG_PM_DEVICE_SYSTEM_MANAGED=y
-CONFIG_PM_S2RAM=y
 CONFIG_ADC=y
 CONFIG_ENTROPY_GENERATOR=y
 CONFIG_SPI=y

subsys/pm/Kconfig

@@ -33,14 +33,17 @@ config PM_STATS
 	help
 	  Enable System Power Management Stats.
 
+DT_POWER_STATE_COMPAT := zephyr,power-state
+
 config PM_S2RAM
-	bool "Suspend-to-RAM (S2RAM)"
+	bool
+	default y
 	depends on ARCH_HAS_SUSPEND_TO_RAM
+	depends on $(dt_compat_any_has_prop,$(DT_POWER_STATE_COMPAT),power-state-name,suspend-to-ram)
 	help
-	  This option enables suspend-to-RAM (S2RAM).
-	  When enabled on Cortex-M, and a 'zephyr,memory-region' compatible node with nodelabel
-	  'pm_s2ram' is defined in DT, _cpu_context symbol (located in arch/arm/core/cortex_m/pm_s2ram.c)
-	  is placed in linker section given by 'zephyr,memory-region' property of aforementioned node.
+	  This option enables the SoC specific implementations of suspend-to-ram (S2RAM)
+	  sleep states if PM is enabled and one or more suspend-to-ram sleep states are
+	  enabled in the devicetree.
 
 config PM_S2RAM_CUSTOM_MARKING
 	bool "Use custom marking functions"