Add CONFIG_SET_SHARC_IDLE, to force SHARC's idle register on boot.

arch/arm/include/asm/arch-adi/sc5xx/sc5xx_sharc_idle.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * (C) Copyright 2024 - Analog Devices, Inc.
+ */
+
+#ifndef _SC5XX_SHARC_IDLE_H_
+#define _SC5XX_SHARC_IDLE_H_
+
+#define ADI_RCU_REG_BASE 0x3108c000
+
+/* Register offsets */
+#define ADI_RCU_REG_MSG				0x6c
+#define ADI_RCU_REG_MSG_SET			0x70
+#define ADI_RCU_REG_MSG_CLR			0x74
+
+/* Bit values for the RCU0_MSG register */
+#define RCU0_MSG_C0IDLE			0x00000100		/* Core 0 Idle */
+#define RCU0_MSG_C1IDLE			0x00000200		/* Core 1 Idle */
+#define RCU0_MSG_C2IDLE			0x00000400		/* Core 2 Idle */
+
+#ifdef CONFIG_SET_SHARC_IDLE
+/**
+ * set_sharc_cores_idle() - set the idle flag in RCU_MSG for the SHARC cores. 
+ * 
+ * Returns: 0 on success, an error code otherwise.
+ */
+int set_sharc_cores_idle(void);
+#endif // CONFIG_SET_SHARC_IDLE
+
+#endif // _SC5XX_SHARC_IDLE_H_

arch/arm/mach-sc5xx/Kconfig

@@ -204,6 +204,10 @@ config ADI_SPL_FORCE_BMODE
 	  5 = QSPI -> OSPI
 	  6 = QSPI -> eMMC
 
+config SET_SHARC_IDLE
+	bool "Force the SHARC cores' idle register to be set during boot"
+	default n
+
 config CLKIN_HZ
 	int "CLKIN_HZ"
 	default 25000000

arch/arm/mach-sc5xx/Makefile

@@ -15,3 +15,4 @@ obj-y += sc59x/sc59x-shared.o
 endif
 
 obj-$(CONFIG_SPL_BUILD) += spl.o
+obj-$(CONFIG_SPL_BUILD) += sc5xx_sharc_idle.o

arch/arm/mach-sc5xx/sc5xx_sharc_idle.c

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * (C) Copyright 2024 - Analog Devices, Inc.
+ */
+
+#include <asm/io.h>
+#include <asm/arch-adi/sc5xx/sc5xx_sharc_idle.h>
+#include <log.h>
+
+#ifdef CONFIG_SET_SHARC_IDLE
+static int sharc_set_idle(unsigned int coreid) {
+	writew(RCU0_MSG_C0IDLE << coreid, ADI_RCU_REG_BASE + ADI_RCU_REG_MSG_SET);
+
+	return 0;
+}
+
+extern int set_sharc_cores_idle(void) {
+    debug("Setting the SHARC cores to IDLE...\n");
+
+	int ret;
+
+    for (int c = 1; c <= 2; c++) {
+        ret = sharc_set_idle(c);
+        if (ret) {
+            printf("Error setting SHARC Core%d idle.\n", c - 1);
+            return ret;
+        }
+    }
+
+	return 0;
+}
+#endif // CONFIG_SET_SHARC_IDLE

arch/arm/mach-sc5xx/spl.c

@@ -224,6 +224,12 @@ void board_init_f(ulong dummy)
 		panic("spl_early_init() failed\n");
 
 	preloader_console_init();
+
+#ifdef CONFIG_SET_SHARC_IDLE
+	ret = set_sharc_cores_idle();
+	if (ret)
+		printf("Warn: failed to set SHARC cores idle (%d)\n", ret);
+#endif
 }
 
 #ifdef CONFIG_ADI_FALCON