1 files changed, 202 insertions, 0 deletions
diff --git a/arch/arm/mach-bcm/kona_smp.c b/arch/arm/mach-bcm/kona_smp.c
new file mode 100644
index 000000000000..66a0465528a5
--- /dev/null
+++ b/arch/arm/mach-bcm/kona_smp.c
@@ -0,0 +1,202 @@
+/*
+ * Copyright (C) 2014 Broadcom Corporation
+ * Copyright 2014 Linaro Limited
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/sched.h>
+
+#include <asm/smp.h>
+#include <asm/smp_plat.h>
+#include <asm/smp_scu.h>
+
+/* Size of mapped Cortex A9 SCU address space */
+#define CORTEX_A9_SCU_SIZE	0x58
+
+#define SECONDARY_TIMEOUT_NS	NSEC_PER_MSEC	/* 1 msec (in nanoseconds) */
+#define BOOT_ADDR_CPUID_MASK	0x3
+
+/* Name of device node property defining secondary boot register location */
+#define OF_SECONDARY_BOOT	"secondary-boot-reg"
+
+/* I/O address of register used to coordinate secondary core startup */
+static u32	secondary_boot;
+
+/*
+ * Enable the Cortex A9 Snoop Control Unit
+ *
+ * By the time this is called we already know there are multiple
+ * cores present.  We assume we're running on a Cortex A9 processor,
+ * so any trouble getting the base address register or getting the
+ * SCU base is a problem.
+ *
+ * Return 0 if successful or an error code otherwise.
+ */
+static int __init scu_a9_enable(void)
+{
+	unsigned long config_base;
+	void __iomem *scu_base;
+
+	if (!scu_a9_has_base()) {
+		pr_err("no configuration base address register!\n");
+		return -ENXIO;
+	}
+
+	/* Config base address register value is zero for uniprocessor */
+	config_base = scu_a9_get_base();
+	if (!config_base) {
+		pr_err("hardware reports only one core\n");
+		return -ENOENT;
+	}
+
+	scu_base = ioremap((phys_addr_t)config_base, CORTEX_A9_SCU_SIZE);
+	if (!scu_base) {
+		pr_err("failed to remap config base (%lu/%u) for SCU\n",
+			config_base, CORTEX_A9_SCU_SIZE);
+		return -ENOMEM;
+	}
+
+	scu_enable(scu_base);
+
+	iounmap(scu_base);	/* That's the last we'll need of this */
+
+	return 0;
+}
+
+static void __init bcm_smp_prepare_cpus(unsigned int max_cpus)
+{
+	static cpumask_t only_cpu_0 = { CPU_BITS_CPU0 };
+	struct device_node *node;
+	int ret;
+
+	BUG_ON(secondary_boot);		/* We're called only once */
+
+	/*
+	 * This function is only called via smp_ops->smp_prepare_cpu().
+	 * That only happens if a "/cpus" device tree node exists
+	 * and has an "enable-method" property that selects the SMP
+	 * operations defined herein.
+	 */
+	node = of_find_node_by_path("/cpus");
+	BUG_ON(!node);
+
+	/*
+	 * Our secondary enable method requires a "secondary-boot-reg"
+	 * property to specify a register address used to request the
+	 * ROM code boot a secondary code.  If we have any trouble
+	 * getting this we fall back to uniprocessor mode.
+	 */
+	if (of_property_read_u32(node, OF_SECONDARY_BOOT, &secondary_boot)) {
+		pr_err("%s: missing/invalid " OF_SECONDARY_BOOT " property\n",
+			node->name);
+		ret = -ENOENT;		/* Arrange to disable SMP */
+		goto out;
+	}
+
+	/*
+	 * Enable the SCU on Cortex A9 based SoCs.  If -ENOENT is
+	 * returned, the SoC reported a uniprocessor configuration.
+	 * We bail on any other error.
+	 */
+	ret = scu_a9_enable();
+out:
+	of_node_put(node);
+	if (ret) {
+		/* Update the CPU present map to reflect uniprocessor mode */
+		BUG_ON(ret != -ENOENT);
+		pr_warn("disabling SMP\n");
+		init_cpu_present(&only_cpu_0);
+	}
+}
+
+/*
+ * The ROM code has the secondary cores looping, waiting for an event.
+ * When an event occurs each core examines the bottom two bits of the
+ * secondary boot register.  When a core finds those bits contain its
+ * own core id, it performs initialization, including computing its boot
+ * address by clearing the boot register value's bottom two bits.  The
+ * core signals that it is beginning its execution by writing its boot
+ * address back to the secondary boot register, and finally jumps to
+ * that address.
+ *
+ * So to start a core executing we need to:
+ * - Encode the (hardware) CPU id with the bottom bits of the secondary
+ *   start address.
+ * - Write that value into the secondary boot register.
+ * - Generate an event to wake up the secondary CPU(s).
+ * - Wait for the secondary boot register to be re-written, which
+ *   indicates the secondary core has started.
+ */
+static int bcm_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	void __iomem *boot_reg;
+	phys_addr_t boot_func;
+	u64 start_clock;
+	u32 cpu_id;
+	u32 boot_val;
+	bool timeout = false;
+
+	cpu_id = cpu_logical_map(cpu);
+	if (cpu_id & ~BOOT_ADDR_CPUID_MASK) {
+		pr_err("bad cpu id (%u > %u)\n", cpu_id, BOOT_ADDR_CPUID_MASK);
+		return -EINVAL;
+	}
+
+	if (!secondary_boot) {
+		pr_err("required secondary boot register not specified\n");
+		return -EINVAL;
+	}
+
+	boot_reg = ioremap_nocache((phys_addr_t)secondary_boot, sizeof(u32));
+	if (!boot_reg) {
+		pr_err("unable to map boot register for cpu %u\n", cpu_id);
+		return -ENOSYS;
+	}
+
+	/*
+	 * Secondary cores will start in secondary_startup(),
+	 * defined in "arch/arm/kernel/head.S"
+	 */
+	boot_func = virt_to_phys(secondary_startup);
+	BUG_ON(boot_func & BOOT_ADDR_CPUID_MASK);
+	BUG_ON(boot_func > (phys_addr_t)U32_MAX);
+
+	/* The core to start is encoded in the low bits */
+	boot_val = (u32)boot_func | cpu_id;
+	writel_relaxed(boot_val, boot_reg);
+
+	sev();
+
+	/* The low bits will be cleared once the core has started */
+	start_clock = local_clock();
+	while (!timeout && readl_relaxed(boot_reg) == boot_val)
+		timeout = local_clock() - start_clock > SECONDARY_TIMEOUT_NS;
+
+	iounmap(boot_reg);
+
+	if (!timeout)
+		return 0;
+
+	pr_err("timeout waiting for cpu %u to start\n", cpu_id);
+
+	return -ENOSYS;
+}
+
+static struct smp_operations bcm_smp_ops __initdata = {
+	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
+	.smp_boot_secondary	= bcm_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(bcm_smp_bcm281xx, "brcm,bcm11351-cpu-method",
+			&bcm_smp_ops);