sh: CPU hotplug support for SH-X3 SMP.

This wires up CPU hotplug for SH-X3 SMP CPUs. Presently only secondary
cores can be hotplugged given that the boot CPU has to contend with the
broadcast timer. When real local timers are implemented this restriction
can be lifted.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/cpu/sh4a/smp-shx3.c

@@ -9,16 +9,22 @@
  * for more details.
  */
 #include <linux/init.h>
+#include <linux/kernel.h>
 #include <linux/cpumask.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/cpu.h>
+#include <asm/sections.h>
 
 #define STBCR_REG(phys_id) (0xfe400004 | (phys_id << 12))
 #define RESET_REG(phys_id) (0xfe400008 | (phys_id << 12))
 
 #define STBCR_MSTP	0x00000001
 #define STBCR_RESET	0x00000002
+#define STBCR_SLEEP	0x00000004
 #define STBCR_LTSLP	0x80000000
 
 static irqreturn_t ipi_interrupt_handler(int irq, void *arg)
@@ -110,10 +116,51 @@ static void shx3_send_ipi(unsigned int cpu, unsigned int message)
 	__raw_writel(1 << (message << 2), addr); /* C0INTICI..CnINTICI */
 }
 
+static void shx3_update_boot_vector(unsigned int cpu)
+{
+	__raw_writel(STBCR_MSTP, STBCR_REG(cpu));
+	while (!(__raw_readl(STBCR_REG(cpu)) & STBCR_MSTP))
+		cpu_relax();
+	__raw_writel(STBCR_RESET, STBCR_REG(cpu));
+}
+
+static int __cpuinit
+shx3_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned int)hcpu;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		shx3_update_boot_vector(cpu);
+		break;
+	case CPU_ONLINE:
+		pr_info("CPU %u is now online\n", cpu);
+		break;
+	case CPU_DEAD:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata shx3_cpu_notifier = {
+	.notifier_call		= shx3_cpu_callback,
+};
+
+static int __cpuinit register_shx3_cpu_notifier(void)
+{
+	register_hotcpu_notifier(&shx3_cpu_notifier);
+	return 0;
+}
+late_initcall(register_shx3_cpu_notifier);
+
 struct plat_smp_ops shx3_smp_ops = {
 	.smp_setup		= shx3_smp_setup,
 	.prepare_cpus		= shx3_prepare_cpus,
 	.start_cpu		= shx3_start_cpu,
 	.smp_processor_id	= shx3_smp_processor_id,
 	.send_ipi		= shx3_send_ipi,
+	.cpu_die		= native_cpu_die,
+	.cpu_disable		= native_cpu_disable,
+	.play_dead		= native_play_dead,
 };