1 files changed, 125 insertions, 0 deletions
diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c
new file mode 100644
index 000000000..056772c26
--- /dev/null
+++ b/arch/arm64/kernel/smp_spin_table.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Spin Table SMP initialisation
+ *
+ * Copyright (C) 2013 ARM Ltd.
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/smp.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cpu_ops.h>
+#include <asm/cputype.h>
+#include <asm/io.h>
+#include <asm/smp_plat.h>
+
+extern void secondary_holding_pen(void);
+volatile unsigned long __section(".mmuoff.data.read")
+secondary_holding_pen_release = INVALID_HWID;
+
+static phys_addr_t cpu_release_addr[NR_CPUS];
+
+/*
+ * Write secondary_holding_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 write_pen_release(u64 val)
+{
+	void *start = (void *)&secondary_holding_pen_release;
+	unsigned long size = sizeof(secondary_holding_pen_release);
+
+	secondary_holding_pen_release = val;
+	__flush_dcache_area(start, size);
+}
+
+
+static int smp_spin_table_cpu_init(unsigned int cpu)
+{
+	struct device_node *dn;
+	int ret;
+
+	dn = of_get_cpu_node(cpu, NULL);
+	if (!dn)
+		return -ENODEV;
+
+	/*
+	 * Determine the address from which the CPU is polling.
+	 */
+	ret = of_property_read_u64(dn, "cpu-release-addr",
+				   &cpu_release_addr[cpu]);
+	if (ret)
+		pr_err("CPU %d: missing or invalid cpu-release-addr property\n",
+		       cpu);
+
+	of_node_put(dn);
+
+	return ret;
+}
+
+static int smp_spin_table_cpu_prepare(unsigned int cpu)
+{
+	__le64 __iomem *release_addr;
+
+	if (!cpu_release_addr[cpu])
+		return -ENODEV;
+
+	/*
+	 * The cpu-release-addr may or may not be inside the linear mapping.
+	 * As ioremap_cache will either give us a new mapping or reuse the
+	 * existing linear mapping, we can use it to cover both cases. In
+	 * either case the memory will be MT_NORMAL.
+	 */
+	release_addr = ioremap_cache(cpu_release_addr[cpu],
+				     sizeof(*release_addr));
+	if (!release_addr)
+		return -ENOMEM;
+
+	/*
+	 * We write the release address as LE regardless of the native
+	 * endianness of the kernel. Therefore, any boot-loaders that
+	 * read this address need to convert this address to the
+	 * boot-loader's endianness before jumping. This is mandated by
+	 * the boot protocol.
+	 */
+	writeq_relaxed(__pa_symbol(secondary_holding_pen), release_addr);
+	__flush_dcache_area((__force void *)release_addr,
+			    sizeof(*release_addr));
+
+	/*
+	 * Send an event to wake up the secondary CPU.
+	 */
+	sev();
+
+	iounmap(release_addr);
+
+	return 0;
+}
+
+static int smp_spin_table_cpu_boot(unsigned int cpu)
+{
+	/*
+	 * Update the pen release flag.
+	 */
+	write_pen_release(cpu_logical_map(cpu));
+
+	/*
+	 * Send an event, causing the secondaries to read pen_release.
+	 */
+	sev();
+
+	return 0;
+}
+
+const struct cpu_operations smp_spin_table_ops = {
+	.name		= "spin-table",
+	.cpu_init	= smp_spin_table_cpu_init,
+	.cpu_prepare	= smp_spin_table_cpu_prepare,
+	.cpu_boot	= smp_spin_table_cpu_boot,
+};