lib: sbi_hsm: Call a device hook during hart resume

Non-retentive suspend states may require platform-specific actions
during resume. For example, firmware may need to save and restore the
values of custom CSRs. Add a hook to support this.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>

include/sbi/sbi_hsm.h

@@ -37,6 +37,14 @@ struct sbi_hsm_device {
 	 * specified resume address
 	 */
 	int (*hart_suspend)(u32 suspend_type, ulong raddr);
+
+	/**
+	 * Perform platform-specific actions to resume from a suspended state.
+	 *
+	 * This includes restoring any platform state that was lost during
+	 * non-retentive suspend.
+	 */
+	void (*hart_resume)(void);
 };
 
 struct sbi_domain;