Tegra: pmc: helper function to find last ON CPU

This patch adds a helper function to find the last standing CPU
in a cluster.

Change-Id: Id018f1958f458c772c7b0c52af8ddf7532b1cec5
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

plat/nvidia/tegra/common/drivers/pmc/pmc.c

@@ -17,7 +17,7 @@
 
 /* Module IDs used during power ungate procedure */
 static const uint32_t pmc_cpu_powergate_id[4] = {
-	0, /* CPU 0 */
+	14, /* CPU 0 */
 	9, /* CPU 1 */
 	10, /* CPU 2 */
 	11 /* CPU 3 */
@@ -97,6 +97,31 @@ void tegra_pmc_lock_cpu_vectors(void)
 	tegra_pmc_write_32(PMC_SECURE_DISABLE3, val);
 }
 
+/*******************************************************************************
+ * Find out if this is the last standing CPU
+ ******************************************************************************/
+bool tegra_pmc_is_last_on_cpu(void)
+{
+	int i, cpu = read_mpidr() & MPIDR_CPU_MASK;
+	uint32_t val = tegra_pmc_read_32(PMC_PWRGATE_STATUS);;
+	bool status = true;
+
+	/* check if this is the last standing CPU */
+	for (i = 0; i < PLATFORM_MAX_CPUS_PER_CLUSTER; i++) {
+
+		/* skip the current CPU */
+		if (i == cpu)
+			continue;
+
+		/* are other CPUs already power gated? */
+		if ((val & ((uint32_t)1 << pmc_cpu_powergate_id[i])) != 0U) {
+			status = false;
+		}
+	}
+
+	return status;
+}
+
 /*******************************************************************************
  * Restart the system
  ******************************************************************************/

plat/nvidia/tegra/include/drivers/pmc.h

 /*
- * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,6 +9,7 @@
 
 #include <lib/mmio.h>
 #include <lib/utils_def.h>
+#include <stdbool.h>
 
 #include <tegra_def.h>
 
@@ -36,9 +37,10 @@ static inline void tegra_pmc_write_32(uint32_t off, uint32_t val)
 	mmio_write_32(TEGRA_PMC_BASE + off, val);
 }
 
+void tegra_pmc_cpu_on(int32_t cpu);
 void tegra_pmc_cpu_setup(uint64_t reset_addr);
+bool tegra_pmc_is_last_on_cpu(void);
 void tegra_pmc_lock_cpu_vectors(void);
-void tegra_pmc_cpu_on(int32_t cpu);
 __dead2 void tegra_pmc_system_reset(void);
 
 #endif /* PMC_H */