ARM: shmobile: Update r8a7779 to check SCU for hotplug

Update the r8a7779 CPU Hotplug code to use SCU PSR
to wait for the target CPU core. Previously the
shared code in hotplug.c was used to let cpu_kill()
wait for cpu_die(). With this change in place the
r8a7779 SMP code does not depend on hotplug.c anymore.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/mach-shmobile/smp-r8a7779.c

@@ -26,6 +26,7 @@
 #include <linux/irqchip/arm-gic.h>
 #include <mach/common.h>
 #include <mach/r8a7779.h>
+#include <asm/cacheflush.h>
 #include <asm/smp_plat.h>
 #include <asm/smp_scu.h>
 #include <asm/smp_twd.h>
@@ -68,6 +69,16 @@ void __init r8a7779_register_twd(void)
 }
 #endif
 
+static int r8a7779_scu_psr_core_disabled(int cpu)
+{
+	unsigned long mask = 3 << (cpu * 8);
+
+	if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
+		return 1;
+
+	return 0;
+}
+
 static void modify_scu_cpu_psr(unsigned long set, unsigned long clr)
 {
 	void __iomem *scu_base = shmobile_scu_base;
@@ -89,9 +100,6 @@ static int r8a7779_platform_cpu_kill(unsigned int cpu)
 
 	cpu = cpu_logical_map(cpu);
 
-	/* disable cache coherency */
-	modify_scu_cpu_psr(3 << (cpu * 8), 0);
-
 	if (cpu < ARRAY_SIZE(r8a7779_ch_cpu))
 		ch = r8a7779_ch_cpu[cpu];
 
@@ -110,7 +118,7 @@ static int __maybe_unused r8a7779_cpu_kill(unsigned int cpu)
 	 * finish before asking SoC-specific code to power off the CPU core.
 	 */
 	for (k = 0; k < 1000; k++) {
-		if (shmobile_cpu_is_dead(cpu))
+		if (r8a7779_scu_psr_core_disabled(cpu))
 			return r8a7779_platform_cpu_kill(cpu);
 
 		mdelay(1);
@@ -119,6 +127,24 @@ static int __maybe_unused r8a7779_cpu_kill(unsigned int cpu)
 	return 0;
 }
 
+static void __maybe_unused r8a7779_cpu_die(unsigned int cpu)
+{
+	dsb();
+	flush_cache_all();
+
+	/* disable cache coherency */
+	modify_scu_cpu_psr(3 << (cpu * 8), 0);
+
+	/* Endless loop until power off from r8a7779_cpu_kill() */
+	while (1)
+		cpu_do_idle();
+}
+
+static int __maybe_unused r8a7779_cpu_disable(unsigned int cpu)
+{
+	/* only CPU1->3 have power domains, do not allow hotplug of CPU0 */
+	return cpu == 0 ? -EPERM : 0;
+}
 
 static void __cpuinit r8a7779_secondary_init(unsigned int cpu)
 {
@@ -179,7 +205,7 @@ struct smp_operations r8a7779_smp_ops  __initdata = {
 	.smp_boot_secondary	= r8a7779_boot_secondary,
 #ifdef CONFIG_HOTPLUG_CPU
 	.cpu_kill		= r8a7779_cpu_kill,
-	.cpu_die		= shmobile_cpu_die,
-	.cpu_disable		= shmobile_cpu_disable,
+	.cpu_die		= r8a7779_cpu_die,
+	.cpu_disable		= r8a7779_cpu_disable,
 #endif
 };