[RFC 2/3] zImage: SMP hold

[Geoff Levand]

Add SMP secondary hold helper routines to the powerpc zImage bootwrapper.  For
platforms which are entered with multiple cpus.  These routines can be used to
hold the secondary cpus until the kernel is ready for entry.

Signed-off-by: Geoff Levand <geoffrey.levand at am.sony.com>

---
 arch/powerpc/boot/main.c |   42 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 42 insertions(+)

--- ps3-linux-dev.orig/arch/powerpc/boot/main.c
+++ ps3-linux-dev/arch/powerpc/boot/main.c
@@ -290,6 +290,44 @@ static void set_cmdline(char *buf)
 		setprop(devp, "bootargs", buf, strlen(buf) + 1);
 }
 
+static volatile kernel_entry_t smp_secondary_entry = 0;
+
+/**
+ * smp_secondary_hold - Hold any secondary cpus until kernel is ready to enter.
+ * @cpu_id: Hardware cpu id.
+ *
+ * Called from the early entry code.
+ */
+
+void smp_secondary_hold(unsigned int cpu_id)
+{
+	while(!smp_secondary_entry)
+		(void)0;
+
+	printf("%s:%d: released cpu (%u)\n", __func__, __LINE__, cpu_id);
+
+	smp_secondary_entry(0, 0, NULL);
+
+	printf("Error: secondary cpu (%u) returned to bootwrapper!\n",
+		cpu_id);
+	exit();
+}
+
+/**
+ * smp_secondary_release - Release any secondary cpus.
+ * @kentry: The kernel entry for secondary cpus.
+ *
+ * Typically called by the primary cpu after the kernel is ready for entry.
+ */
+
+static void smp_secondary_release(kernel_entry_t kentry)
+{
+	printf("%s:%d\n", __func__, __LINE__);
+	smp_secondary_entry = kentry;
+
+	/* Do we need to yield to the secondary cpus here??? */
+}
+
 struct platform_ops platform_ops;
 struct dt_ops dt_ops;
 struct console_ops console_ops;
@@ -340,7 +378,10 @@ void start(unsigned long a1, unsigned lo
 	if (console_ops.close)
 		console_ops.close();
 
 	kentry = (kernel_entry_t) vmlinux.addr;
+
+	smp_secondary_release(kentry);
+
 	if (ft_addr)
 		kentry(ft_addr, 0, NULL);
 	else