lib: sbi: Allow platform to influence cold boot HART selection

We add an optional cold_boot_allowed() platform callback which allows
platform support to decide which HARTs can do cold boot initialization.

If this platform callback is not available then any HART can do cold
boot initialization.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>

include/sbi/sbi_platform.h

@@ -65,6 +65,9 @@ enum sbi_platform_features {
 
 /** Platform functions */
 struct sbi_platform_operations {
+	/* Check if specified HART is allowed to do cold boot */
+	bool (*cold_boot_allowed)(u32 hartid);
+
 	/* Platform nascent initialization */
 	int (*nascent_init)(void);
 
@@ -356,6 +359,23 @@ static inline bool sbi_platform_hart_invalid(const struct sbi_platform *plat,
 	return false;
 }
 
+/**
+ * Check whether given HART is allowed to do cold boot
+ *
+ * @param plat pointer to struct sbi_platform
+ * @param hartid HART ID
+ *
+ * @return true if HART is allowed to do cold boot and false otherwise
+ */
+static inline bool sbi_platform_cold_boot_allowed(
+					const struct sbi_platform *plat,
+					u32 hartid)
+{
+	if (plat && sbi_platform_ops(plat)->cold_boot_allowed)
+		return sbi_platform_ops(plat)->cold_boot_allowed(hartid);
+	return true;
+}
+
 /**
  * Nascent (very early) initialization for current HART
  *

lib/sbi/sbi_init.c

@@ -498,8 +498,11 @@ void __noreturn sbi_init(struct sbi_scratch *scratch)
 	 * HARTs which satisfy above condition.
 	 */
 
-	if (next_mode_supported && atomic_xchg(&coldboot_lottery, 1) == 0)
+	if (sbi_platform_cold_boot_allowed(plat, hartid)) {
-		coldboot = true;
+		if (next_mode_supported &&
+		    atomic_xchg(&coldboot_lottery, 1) == 0)
+			coldboot = true;
+	}
 
 	/*
 	 * Do platform specific nascent (very early) initialization so