[PATCH v15 4/6] reboot: extend psc_reason with power-on and reset causes

[Faruque Ansari <faruque.ansari@oss.qualcomm.com>]

psc_reason covered only the protection reasons. Extend it to mirror the
full POWER_ON_REASON_* vocabulary - power-on, watchdog, software,
external, RTC, reset button, CPU clock and crystal failures - so a
provider can report why the system last powered on, not only why it was
shut down. New values are appended to keep the existing numeric ABI.

Co-developed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Faruque Ansari <faruque.ansari@oss.qualcomm.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>

changes v15:
- add a static_assert() tying ARRAY_SIZE(psc_reason_descs) to
  PSCR_REASON_COUNT, so a future enum addition without a matching
  table entry fails the build instead of silently reading a hole
  (Matti Vaittinen)
- Add Reviewed-by tags from Matti Vaittinen.
changes v12:
- new patch
---
 include/linux/reboot.h | 28 ++++++++++++++++++++++++++++
 kernel/reboot.c        | 12 ++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 4c5327dd7645..13f004ad1066 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -225,9 +225,28 @@ extern void orderly_reboot(void);
  *	management errors, or an unrecoverable hardware fault requiring
  *	immediate response.
  *
+ * @PSCR_POWER_ON: Regular cold power-on (e.g. via a PMIC power-on request).
+ *
+ * @PSCR_WATCHDOG: Reset caused by a watchdog timeout.
+ *
+ * @PSCR_SOFTWARE: Software-initiated reset or reboot.
+ *
+ * @PSCR_EXTERNAL: Reset asserted through an external pin or reset input.
+ *
+ * @PSCR_RTC: Wake-up or power-on triggered by the RTC.
+ *
+ * @PSCR_RESET_BUTTON: Reset triggered by a user reset button.
+ *
+ * @PSCR_CPU_CLK_FAIL: Reset caused by a CPU clock failure.
+ *
+ * @PSCR_XTAL_FAIL: Reset caused by a crystal oscillator failure.
+ *
  * @PSCR_REASON_COUNT: Number of defined power state change reasons. This
  *	value is useful for range checking and potential future extensions
  *	while maintaining compatibility.
+ *
+ * The reasons mirror the POWER_ON_REASON_* strings in
+ * <linux/power/power_on_reason.h>; keep the two in sync when extending.
  */
 enum psc_reason {
 	PSCR_UNKNOWN,
@@ -236,6 +255,15 @@ enum psc_reason {
 	PSCR_REGULATOR_FAILURE,
 	PSCR_OVER_TEMPERATURE,
 	PSCR_EC_PANIC,
+	/* Append new reasons here; the numeric order is ABI. */
+	PSCR_POWER_ON,
+	PSCR_WATCHDOG,
+	PSCR_SOFTWARE,
+	PSCR_EXTERNAL,
+	PSCR_RTC,
+	PSCR_RESET_BUTTON,
+	PSCR_CPU_CLK_FAIL,
+	PSCR_XTAL_FAIL,
 
 	/* Number of reasons */
 	PSCR_REASON_COUNT,
diff --git a/kernel/reboot.c b/kernel/reboot.c
index e53fb31bad06..7094c7a8f315 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -7,7 +7,9 @@
 
 #define pr_fmt(fmt)	"reboot: " fmt
 
+#include <linux/array_size.h>
 #include <linux/atomic.h>
+#include <linux/build_bug.h>
 #include <linux/ctype.h>
 #include <linux/export.h>
 #include <linux/kexec.h>
@@ -1102,7 +1104,17 @@ static const struct psc_reason_desc psc_reason_descs[] = {
 	[PSCR_REGULATOR_FAILURE] = { "regulator-failure", POWER_ON_REASON_REGULATOR_FAILURE },
 	[PSCR_OVER_TEMPERATURE]	 = { "over-temperature",  POWER_ON_REASON_OVER_TEMPERATURE },
 	[PSCR_EC_PANIC]		 = { "ec-panic",	  POWER_ON_REASON_EC_PANIC },
+	[PSCR_POWER_ON]		 = { "power-on",	  POWER_ON_REASON_REGULAR },
+	[PSCR_WATCHDOG]		 = { "watchdog",	  POWER_ON_REASON_WATCHDOG },
+	[PSCR_SOFTWARE]		 = { "software",	  POWER_ON_REASON_SOFTWARE },
+	[PSCR_EXTERNAL]		 = { "external",	  POWER_ON_REASON_EXTERNAL },
+	[PSCR_RTC]		 = { "rtc",		  POWER_ON_REASON_RTC },
+	[PSCR_RESET_BUTTON]	 = { "reset-button",	  POWER_ON_REASON_RST_BTN },
+	[PSCR_CPU_CLK_FAIL]	 = { "cpu-clock-failure", POWER_ON_REASON_CPU_CLK_FAIL },
+	[PSCR_XTAL_FAIL]	 = { "crystal-failure",	  POWER_ON_REASON_XTAL_FAIL },
 };
+static_assert(ARRAY_SIZE(psc_reason_descs) == PSCR_REASON_COUNT,
+	      "psc_reason_descs[] must have an entry for every psc_reason");
 
 /**
  * psc_reason_to_str - Human-readable label for a power state change reason.

-- 
2.34.1