1 files changed, 133 insertions, 0 deletions
diff --git a/arch/arm/mach-spear/platsmp.c b/arch/arm/mach-spear/platsmp.c
new file mode 100644
index 000000000..97fbda998
--- /dev/null
+++ b/arch/arm/mach-spear/platsmp.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm/mach-spear13xx/platsmp.c
+ *
+ * based upon linux/arch/arm/mach-realview/platsmp.c
+ *
+ * Copyright (C) 2012 ST Microelectronics Ltd.
+ * Shiraz Hashim <shiraz.linux.kernel@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/io.h>
+#include <linux/smp.h>
+#include <asm/cacheflush.h>
+#include <asm/smp_scu.h>
+#include "spear.h"
+#include "generic.h"
+
+/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */
+volatile int spear_pen_release = -1;
+
+/*
+ * XXX CARGO CULTED CODE - DO NOT COPY XXX
+ *
+ * Write spear_pen_release in a way that is guaranteed to be visible to
+ * all observers, irrespective of whether they're taking part in coherency
+ * or not.  This is necessary for the hotplug code to work reliably.
+ */
+static void spear_write_pen_release(int val)
+{
+	spear_pen_release = val;
+	smp_wmb();
+	sync_cache_w(&spear_pen_release);
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+static void __iomem *scu_base = IOMEM(VA_SCU_BASE);
+
+static void spear13xx_secondary_init(unsigned int cpu)
+{
+	/*
+	 * let the primary processor know we're out of the
+	 * pen, then head off into the C entry point
+	 */
+	spear_write_pen_release(-1);
+
+	/*
+	 * Synchronise with the boot thread.
+	 */
+	spin_lock(&boot_lock);
+	spin_unlock(&boot_lock);
+}
+
+static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	unsigned long timeout;
+
+	/*
+	 * set synchronisation state between this boot processor
+	 * and the secondary one
+	 */
+	spin_lock(&boot_lock);
+
+	/*
+	 * The secondary processor is waiting to be released from
+	 * the holding pen - release it, then wait for it to flag
+	 * that it has been released by resetting spear_pen_release.
+	 *
+	 * Note that "spear_pen_release" is the hardware CPU ID, whereas
+	 * "cpu" is Linux's internal ID.
+	 */
+	spear_write_pen_release(cpu);
+
+	timeout = jiffies + (1 * HZ);
+	while (time_before(jiffies, timeout)) {
+		smp_rmb();
+		if (spear_pen_release == -1)
+			break;
+
+		udelay(10);
+	}
+
+	/*
+	 * now the secondary core is starting up let it run its
+	 * calibrations, then wait for it to finish
+	 */
+	spin_unlock(&boot_lock);
+
+	return spear_pen_release != -1 ? -ENOSYS : 0;
+}
+
+/*
+ * Initialise the CPU possible map early - this describes the CPUs
+ * which may be present or become present in the system.
+ */
+static void __init spear13xx_smp_init_cpus(void)
+{
+	unsigned int i, ncores = scu_get_core_count(scu_base);
+
+	if (ncores > nr_cpu_ids) {
+		pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
+			ncores, nr_cpu_ids);
+		ncores = nr_cpu_ids;
+	}
+
+	for (i = 0; i < ncores; i++)
+		set_cpu_possible(i, true);
+}
+
+static void __init spear13xx_smp_prepare_cpus(unsigned int max_cpus)
+{
+
+	scu_enable(scu_base);
+
+	/*
+	 * Write the address of secondary startup into the system-wide location
+	 * (presently it is in SRAM). The BootMonitor waits until it receives a
+	 * soft interrupt, and then the secondary CPU branches to this address.
+	 */
+	__raw_writel(__pa_symbol(spear13xx_secondary_startup), SYS_LOCATION);
+}
+
+const struct smp_operations spear13xx_smp_ops __initconst = {
+       .smp_init_cpus		= spear13xx_smp_init_cpus,
+       .smp_prepare_cpus	= spear13xx_smp_prepare_cpus,
+       .smp_secondary_init	= spear13xx_secondary_init,
+       .smp_boot_secondary	= spear13xx_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+       .cpu_die			= spear13xx_cpu_die,
+#endif
+};