linux-next/arch/arm/mach-zynq/platsmp.c

/*
 * This file contains Xilinx specific SMP code, used to start up
 * the second processor.
 *
 * Copyright (C) 2011-2013 Xilinx
 *
 * based on linux/arch/arm/mach-realview/platsmp.c
 *
 * Copyright (C) 2002 ARM Ltd.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/cacheflush.h>
#include <asm/smp_scu.h>
#include <linux/irqchip/arm-gic.h>
#include "common.h"

/*
 * Store number of cores in the system
 * Because of scu_get_core_count() must be in __init section and can't
 * be called from zynq_cpun_start() because it is in __cpuinit section.
 */
static int ncores;

/* Secondary CPU kernel startup is a 2 step process. The primary CPU
 * starts the secondary CPU by giving it the address of the kernel and
 * then sending it an event to wake it up. The secondary CPU then
 * starts the kernel and tells the primary CPU it's up and running.
 */
static void __cpuinit zynq_secondary_init(unsigned int cpu)
{
	/*
	 * if any interrupts are already enabled for the primary
	 * core (e.g. timer irq), then they will not have been enabled
	 * for us: do so
	 */
	gic_secondary_init(0);
}

int __cpuinit zynq_cpun_start(u32 address, int cpu)
{
	u32 trampoline_code_size = &zynq_secondary_trampoline_end -
						&zynq_secondary_trampoline;

	if (cpu > ncores) {
		pr_warn("CPU No. is not available in the system\n");
		return -1;
	}

	/* MS: Expectation that SLCR are directly map and accessible */
	/* Not possible to jump to non aligned address */
	if (!(address & 3) && (!address || (address >= trampoline_code_size))) {
		/* Store pointer to ioremap area which points to address 0x0 */
		static u8 __iomem *zero;
		u32 trampoline_size = &zynq_secondary_trampoline_jump -
						&zynq_secondary_trampoline;

		zynq_slcr_cpu_stop(cpu);

		if (__pa(PAGE_OFFSET)) {
			zero = ioremap(0, trampoline_code_size);
			if (!zero) {
				pr_warn("BOOTUP jump vectors not accessible\n");
				return -1;
			}
		} else {
			zero = (__force u8 __iomem *)PAGE_OFFSET;
		}

		/*
		 * This is elegant way how to jump to any address
		 * 0x0: Load address at 0x8 to r0
		 * 0x4: Jump by mov instruction
		 * 0x8: Jumping address
		 */
		memcpy((__force void *)zero, &zynq_secondary_trampoline,
						trampoline_size);
		writel(address, zero + trampoline_size);

		flush_cache_all();
		outer_flush_range(0, trampoline_code_size);
		smp_wmb();

		if (__pa(PAGE_OFFSET))
			iounmap(zero);

		zynq_slcr_cpu_start(cpu);

		return 0;
	}

	pr_warn("Can't start CPU%d: Wrong starting address %x\n", cpu, address);

	return -1;
}
EXPORT_SYMBOL(zynq_cpun_start);

static int __cpuinit zynq_boot_secondary(unsigned int cpu,
						struct task_struct *idle)
{
	return zynq_cpun_start(virt_to_phys(secondary_startup), cpu);
}

/*
 * Initialise the CPU possible map early - this describes the CPUs
 * which may be present or become present in the system.
 */
static void __init zynq_smp_init_cpus(void)
{
	int i;

	ncores = scu_get_core_count(zynq_scu_base);

	for (i = 0; i < ncores && i < CONFIG_NR_CPUS; i++)
		set_cpu_possible(i, true);
}

static void __init zynq_smp_prepare_cpus(unsigned int max_cpus)
{
	int i;

	/*
	 * Initialise the present map, which describes the set of CPUs
	 * actually populated at the present time.
	 */
	for (i = 0; i < max_cpus; i++)
		set_cpu_present(i, true);

	scu_enable(zynq_scu_base);
}

struct smp_operations zynq_smp_ops __initdata = {
	.smp_init_cpus		= zynq_smp_init_cpus,
	.smp_prepare_cpus	= zynq_smp_prepare_cpus,
	.smp_secondary_init	= zynq_secondary_init,
	.smp_boot_secondary	= zynq_boot_secondary,
};