1 files changed, 345 insertions, 0 deletions
diff --git a/arch/arm/mach-bcm/platsmp.c b/arch/arm/mach-bcm/platsmp.c
new file mode 100644
index 000000000..7d954830e
--- /dev/null
+++ b/arch/arm/mach-bcm/platsmp.c
@@ -0,0 +1,345 @@
+/*
+ * Copyright (C) 2014-2015 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/cpumask.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/irqchip/irq-bcm2836.h>
+#include <linux/jiffies.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/sched.h>
+#include <linux/sched/clock.h>
+#include <linux/smp.h>
+
+#include <asm/cacheflush.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"
+#define MPIDR_CPUID_BITMASK	0x3
+
+/*
+ * 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 u32 secondary_boot_addr_for(unsigned int cpu)
+{
+	u32 secondary_boot_addr = 0;
+	struct device_node *cpu_node = of_get_cpu_node(cpu, NULL);
+
+        if (!cpu_node) {
+		pr_err("Failed to find device tree node for CPU%u\n", cpu);
+		return 0;
+	}
+
+	if (of_property_read_u32(cpu_node,
+				 OF_SECONDARY_BOOT,
+				 &secondary_boot_addr))
+		pr_err("required secondary boot register not specified for CPU%u\n",
+			cpu);
+
+	of_node_put(cpu_node);
+
+	return secondary_boot_addr;
+}
+
+static int nsp_write_lut(unsigned int cpu)
+{
+	void __iomem *sku_rom_lut;
+	phys_addr_t secondary_startup_phy;
+	const u32 secondary_boot_addr = secondary_boot_addr_for(cpu);
+
+	if (!secondary_boot_addr)
+		return -EINVAL;
+
+	sku_rom_lut = ioremap_nocache((phys_addr_t)secondary_boot_addr,
+				      sizeof(phys_addr_t));
+	if (!sku_rom_lut) {
+		pr_warn("unable to ioremap SKU-ROM LUT register for cpu %u\n", cpu);
+		return -ENOMEM;
+	}
+
+	secondary_startup_phy = __pa_symbol(secondary_startup);
+	BUG_ON(secondary_startup_phy > (phys_addr_t)U32_MAX);
+
+	writel_relaxed(secondary_startup_phy, sku_rom_lut);
+
+	/* Ensure the write is visible to the secondary core */
+	smp_wmb();
+
+	iounmap(sku_rom_lut);
+
+	return 0;
+}
+
+static void __init bcm_smp_prepare_cpus(unsigned int max_cpus)
+{
+	const cpumask_t only_cpu_0 = { CPU_BITS_CPU0 };
+
+	/* Enable the SCU on Cortex A9 based SoCs */
+	if (scu_a9_enable()) {
+		/* Update the CPU present map to reflect uniprocessor mode */
+		pr_warn("failed to enable A9 SCU - 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 kona_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;
+	const u32 secondary_boot_addr = secondary_boot_addr_for(cpu);
+
+	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_addr)
+		return -EINVAL;
+
+	boot_reg = ioremap_nocache((phys_addr_t)secondary_boot_addr,
+				   sizeof(phys_addr_t));
+	if (!boot_reg) {
+		pr_err("unable to map boot register for cpu %u\n", cpu_id);
+		return -ENOMEM;
+	}
+
+	/*
+	 * Secondary cores will start in secondary_startup(),
+	 * defined in "arch/arm/kernel/head.S"
+	 */
+	boot_func = __pa_symbol(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 -ENXIO;
+}
+
+/* Cluster Dormant Control command to bring CPU into a running state */
+#define CDC_CMD			6
+#define CDC_CMD_OFFSET		0
+#define CDC_CMD_REG(cpu)	(CDC_CMD_OFFSET + 4*(cpu))
+
+/*
+ * BCM23550 has a Cluster Dormant Control block that keeps the core in
+ * idle state. A command needs to be sent to the block to bring the CPU
+ * into running state.
+ */
+static int bcm23550_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	void __iomem *cdc_base;
+	struct device_node *dn;
+	char *name;
+	int ret;
+
+	/* Make sure a CDC node exists before booting the
+	 * secondary core.
+	 */
+	name = "brcm,bcm23550-cdc";
+	dn = of_find_compatible_node(NULL, NULL, name);
+	if (!dn) {
+		pr_err("unable to find cdc node\n");
+		return -ENODEV;
+	}
+
+	cdc_base = of_iomap(dn, 0);
+	of_node_put(dn);
+
+	if (!cdc_base) {
+		pr_err("unable to remap cdc base register\n");
+		return -ENOMEM;
+	}
+
+	/* Boot the secondary core */
+	ret = kona_boot_secondary(cpu, idle);
+	if (ret)
+		goto out;
+
+	/* Bring this CPU to RUN state so that nIRQ nFIQ
+	 * signals are unblocked.
+	 */
+	writel_relaxed(CDC_CMD, cdc_base + CDC_CMD_REG(cpu));
+
+out:
+	iounmap(cdc_base);
+
+	return ret;
+}
+
+static int nsp_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	int ret;
+
+	/*
+	 * After wake up, secondary core branches to the startup
+	 * address programmed at SKU ROM LUT location.
+	 */
+	ret = nsp_write_lut(cpu);
+	if (ret) {
+		pr_err("unable to write startup addr to SKU ROM LUT\n");
+		goto out;
+	}
+
+	/* Send a CPU wakeup interrupt to the secondary core */
+	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+
+out:
+	return ret;
+}
+
+static int bcm2836_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	void __iomem *intc_base;
+	struct device_node *dn;
+	char *name;
+
+	name = "brcm,bcm2836-l1-intc";
+	dn = of_find_compatible_node(NULL, NULL, name);
+	if (!dn) {
+		pr_err("unable to find intc node\n");
+		return -ENODEV;
+	}
+
+	intc_base = of_iomap(dn, 0);
+	of_node_put(dn);
+
+	if (!intc_base) {
+		pr_err("unable to remap intc base register\n");
+		return -ENOMEM;
+	}
+
+	writel(virt_to_phys(secondary_startup),
+	       intc_base + LOCAL_MAILBOX3_SET0 + 16 * cpu);
+
+	dsb(sy);
+	sev();
+
+	iounmap(intc_base);
+
+	return 0;
+}
+
+static const struct smp_operations kona_smp_ops __initconst = {
+	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
+	.smp_boot_secondary	= kona_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(bcm_smp_bcm281xx, "brcm,bcm11351-cpu-method",
+			&kona_smp_ops);
+
+static const struct smp_operations bcm23550_smp_ops __initconst = {
+	.smp_boot_secondary	= bcm23550_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(bcm_smp_bcm23550, "brcm,bcm23550",
+			&bcm23550_smp_ops);
+
+static const struct smp_operations nsp_smp_ops __initconst = {
+	.smp_prepare_cpus	= bcm_smp_prepare_cpus,
+	.smp_boot_secondary	= nsp_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(bcm_smp_nsp, "brcm,bcm-nsp-smp", &nsp_smp_ops);
+
+const struct smp_operations bcm2836_smp_ops __initconst = {
+	.smp_boot_secondary	= bcm2836_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(bcm_smp_bcm2836, "brcm,bcm2836-smp", &bcm2836_smp_ops);