xtensa: implement CPU hotplug
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c
index 46bdd14..1c7a209 100644
--- a/arch/xtensa/kernel/smp.c
+++ b/arch/xtensa/kernel/smp.c
@@ -40,6 +40,11 @@
# endif
#endif
+static void system_invalidate_dcache_range(unsigned long start,
+ unsigned long size);
+static void system_flush_invalidate_dcache_range(unsigned long start,
+ unsigned long size);
+
/* IPI (Inter Process Interrupt) */
#define IPI_IRQ 0
@@ -106,7 +111,7 @@
static int boot_secondary_processors = 1; /* Set with xt-gdb via .xt-gdb */
static DECLARE_COMPLETION(cpu_running);
-void __init secondary_start_kernel(void)
+void secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
@@ -174,6 +179,9 @@
__func__, cpu, run_stall_mask, get_er(MPSCORE));
}
+#ifdef CONFIG_HOTPLUG_CPU
+unsigned long cpu_start_id __cacheline_aligned;
+#endif
unsigned long cpu_start_ccount;
static int boot_secondary(unsigned int cpu, struct task_struct *ts)
@@ -182,6 +190,11 @@
unsigned long ccount;
int i;
+#ifdef CONFIG_HOTPLUG_CPU
+ cpu_start_id = cpu;
+ system_flush_invalidate_dcache_range(
+ (unsigned long)&cpu_start_id, sizeof(cpu_start_id));
+#endif
smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1);
for (i = 0; i < 2; ++i) {
@@ -234,6 +247,85 @@
return ret;
}
+#ifdef CONFIG_HOTPLUG_CPU
+
+/*
+ * __cpu_disable runs on the processor to be shutdown.
+ */
+int __cpu_disable(void)
+{
+ unsigned int cpu = smp_processor_id();
+
+ /*
+ * Take this CPU offline. Once we clear this, we can't return,
+ * and we must not schedule until we're ready to give up the cpu.
+ */
+ set_cpu_online(cpu, false);
+
+ /*
+ * OK - migrate IRQs away from this CPU
+ */
+ migrate_irqs();
+
+ /*
+ * Flush user cache and TLB mappings, and then remove this CPU
+ * from the vm mask set of all processes.
+ */
+ local_flush_cache_all();
+ local_flush_tlb_all();
+ invalidate_page_directory();
+
+ clear_tasks_mm_cpumask(cpu);
+
+ return 0;
+}
+
+static void platform_cpu_kill(unsigned int cpu)
+{
+ smp_call_function_single(0, mx_cpu_stop, (void *)cpu, true);
+}
+
+/*
+ * called on the thread which is asking for a CPU to be shutdown -
+ * waits until shutdown has completed, or it is timed out.
+ */
+void __cpu_die(unsigned int cpu)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+ while (time_before(jiffies, timeout)) {
+ system_invalidate_dcache_range((unsigned long)&cpu_start_id,
+ sizeof(cpu_start_id));
+ if (cpu_start_id == -cpu) {
+ platform_cpu_kill(cpu);
+ return;
+ }
+ }
+ pr_err("CPU%u: unable to kill\n", cpu);
+}
+
+void arch_cpu_idle_dead(void)
+{
+ cpu_die();
+}
+/*
+ * Called from the idle thread for the CPU which has been shutdown.
+ *
+ * Note that we disable IRQs here, but do not re-enable them
+ * before returning to the caller. This is also the behaviour
+ * of the other hotplug-cpu capable cores, so presumably coming
+ * out of idle fixes this.
+ */
+void __ref cpu_die(void)
+{
+ idle_task_exit();
+ local_irq_disable();
+ __asm__ __volatile__(
+ " movi a2, cpu_restart\n"
+ " jx a2\n");
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
enum ipi_msg_type {
IPI_RESCHEDULE = 0,
IPI_CALL_FUNC,
@@ -463,3 +555,37 @@
};
on_each_cpu(ipi_flush_icache_range, &fd, 1);
}
+
+/* ------------------------------------------------------------------------- */
+
+static void ipi_invalidate_dcache_range(void *arg)
+{
+ struct flush_data *fd = arg;
+ __invalidate_dcache_range(fd->addr1, fd->addr2);
+}
+
+static void system_invalidate_dcache_range(unsigned long start,
+ unsigned long size)
+{
+ struct flush_data fd = {
+ .addr1 = start,
+ .addr2 = size,
+ };
+ on_each_cpu(ipi_invalidate_dcache_range, &fd, 1);
+}
+
+static void ipi_flush_invalidate_dcache_range(void *arg)
+{
+ struct flush_data *fd = arg;
+ __flush_invalidate_dcache_range(fd->addr1, fd->addr2);
+}
+
+static void system_flush_invalidate_dcache_range(unsigned long start,
+ unsigned long size)
+{
+ struct flush_data fd = {
+ .addr1 = start,
+ .addr2 = size,
+ };
+ on_each_cpu(ipi_flush_invalidate_dcache_range, &fd, 1);
+}
