| .. SPDX-License-Identifier: GPL-2.0 | |
| ============= | |
| NPCM Watchdog | |
| ============= | |
| The NPCM watchdog driver can report reset-cause information on | |
| ``nuvoton,npcm750-wdt`` and ``nuvoton,npcm845-wdt`` systems. | |
| Userspace can read the latched reset cause through | |
| ``WDIOC_GETBOOTSTATUS``. When ``CONFIG_WATCHDOG_SYSFS`` is enabled, the | |
| same value is also visible through ``/sys/class/watchdog/watchdogN/bootstatus``. | |
| The mapping is fixed in the driver. It exposes the SoC reset indications | |
| through the generic watchdog bootstatus flags and is not configurable from | |
| Device Tree. | |
| .. list-table:: Reset-cause mapping | |
| :header-rows: 1 | |
| * - Platform | |
| - Reset indication | |
| - Bootstatus flag | |
| - Reported meaning | |
| * - NPCM750 and NPCM845 | |
| - ``PORST`` | |
| - ``WDIOF_OVERHEAT`` | |
| - power-on reset | |
| * - NPCM750 and NPCM845 | |
| - ``CORST`` | |
| - ``WDIOF_FANFAULT`` | |
| - core reset | |
| * - NPCM750 and NPCM845 | |
| - ``SWR1RST`` | |
| - ``WDIOF_EXTERN1`` | |
| - software reset source 1 | |
| * - NPCM750 and NPCM845 | |
| - ``SWR2RST`` | |
| - ``WDIOF_EXTERN2`` | |
| - software reset source 2 | |
| * - NPCM750 and NPCM845 | |
| - ``SWR3RST`` | |
| - ``WDIOF_POWERUNDER`` | |
| - software reset source 3 | |
| * - NPCM750 | |
| - ``SWR4RST`` | |
| - ``WDIOF_POWEROVER`` | |
| - software reset source 4 | |
| * - NPCM845 | |
| - ``TIP reset`` (``INTCR2[25]``) | |
| - ``WDIOF_POWEROVER`` | |
| - TIP reset | |
| ``WDIOF_CARDRESET`` is reported only for the watchdog instance whose own | |
| reset-status bit is latched. On systems with three watchdog instances, this | |
| maps ``WD0RST``, ``WD1RST``, and ``WD2RST`` to ``watchdog0``, ``watchdog1``, | |
| and ``watchdog2`` respectively. | |
| The driver may report ``WDIOF_CARDRESET`` together with one or more of the | |
| reset-cause flags listed above. | |
| On NPCM750, the driver samples ``RESSR``. When reset bits are still latched, | |
| it clears them and stores the sampled value in ``SCRPAD2`` so later watchdog | |
| probes can report the same boot-time state. | |
| On NPCM845, the driver samples ``INTCR2``. When reset bits are still latched, | |
| it clears them and stores the sampled value in ``SCRPAD10`` so later watchdog | |
| probes can report the same boot-time state. | |
| The WPCM450 watchdog continues to operate without this reset-indication | |
| mapping. |