sysreset: Add a way to find the last reset

We have a method to return the last reset as a string for humans, but not
a method that allows it to be used programmatically. Add a new method that
returns the last reset as an enum.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/sysreset.h

@@ -11,6 +11,7 @@ enum sysreset_t {
 	SYSRESET_WARM,	/* Reset CPU, keep GPIOs active */
 	SYSRESET_COLD,	/* Reset CPU and GPIOs */
 	SYSRESET_POWER,	/* Reset PMIC (remove and restore power) */
+	SYSRESET_POWER_OFF,	/* Turn off power */
 
 	SYSRESET_COUNT,
 };
@@ -37,6 +38,14 @@ struct sysreset_ops {
 	 * @return 0 if OK, -ve on error
 	 */
 	int (*get_status)(struct udevice *dev, char *buf, int size);
+
+	/**
+	 * get_last() - get information on the last reset
+	 *
+	 * @dev:	Device to check
+	 * @return last reset state (enum sysreset_t) or -ve error
+	 */
+	int (*get_last)(struct udevice *dev);
 };
 
 #define sysreset_get_ops(dev)        ((struct sysreset_ops *)(dev)->driver->ops)
@@ -59,6 +68,14 @@ int sysreset_request(struct udevice *dev, enum sysreset_t type);
  */
 int sysreset_get_status(struct udevice *dev, char *buf, int size);
 
+/**
+ * sysreset_get_last() - get information on the last reset
+ *
+ * @dev:	Device to check
+ * @return last reset state (enum sysreset_t) or -ve error
+ */
+int sysreset_get_last(struct udevice *dev);
+
 /**
  * sysreset_walk() - cause a system reset
  *
@@ -73,6 +90,19 @@ int sysreset_get_status(struct udevice *dev, char *buf, int size);
  */
 int sysreset_walk(enum sysreset_t type);
 
+/**
+ * sysreset_get_last_walk() - get information on the last reset
+ *
+ * This works through the available sysreset devices until it finds one that can
+ * perform a reset. If the provided sysreset type is not available, the next one
+ * will be tried.
+ *
+ * If no device prives the information, this function returns -ENOENT
+ *
+ * @return last reset state (enum sysreset_t) or -ve error
+ */
+int sysreset_get_last_walk(void);
+
 /**
  * sysreset_walk_halt() - try to reset, otherwise halt
  *