text: /*
   * plat smp support for CSR Marco dual-core SMP SoCs
   *
   * Copyright (c) 2012 Cambridge Silicon Radio Limited, a CSR plc group company.
   *
   * Licensed under GPLv2 or later.
   */
  
  #include <linux/init.h>
  #include <linux/smp.h>
  #include <linux/delay.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <asm/page.h>
  #include <asm/mach/map.h>
  #include <asm/smp_plat.h>
  #include <asm/smp_scu.h>
  #include <asm/cacheflush.h>
  #include <asm/cputype.h>
  
  #include "common.h"
  
  static void __iomem *clk_base;
  
  static DEFINE_SPINLOCK(boot_lock);
  
  /* XXX prima2_pen_release is cargo culted code - DO NOT COPY XXX */
  volatile int prima2_pen_release = -1;
  
  static void sirfsoc_secondary_init(unsigned int cpu)
  {
  	/*
  	 * let the primary processor know we're out of the
  	 * pen, then head off into the C entry point
  	 */
  	prima2_pen_release = -1;
  	smp_wmb();
  
  	/*
  	 * Synchronise with the boot thread.
  	 */
  	spin_lock(&boot_lock);
  	spin_unlock(&boot_lock);
  }
  
  static const struct of_device_id clk_ids[]  = {
  	{ .compatible = "sirf,atlas7-clkc" },
  	{},
  };
  
  static int sirfsoc_boot_secondary(unsigned int cpu, struct task_struct *idle)
  {
  	unsigned long timeout;
  	struct device_node *np;
  
  	np = of_find_matching_node(NULL, clk_ids);
  	if (!np)
  		return -ENODEV;
  
  	clk_base = of_iomap(np, 0);
  	if (!clk_base)
  		return -ENOMEM;
  
  	/*
  	 * write the address of secondary startup into the clkc register
  	 * at offset 0x2bC, then write the magic number 0x3CAF5D62 to the
  	 * clkc register at offset 0x2b8, which is what boot rom code is
  	 * waiting for. This would wake up the secondary core from WFE
  	 */
  #define SIRFSOC_CPU1_JUMPADDR_OFFSET 0x2bc
  	__raw_writel(__pa_symbol(sirfsoc_secondary_startup),
  		clk_base + SIRFSOC_CPU1_JUMPADDR_OFFSET);
  
  #define SIRFSOC_CPU1_WAKEMAGIC_OFFSET 0x2b8
  	__raw_writel(0x3CAF5D62,
  		clk_base + SIRFSOC_CPU1_WAKEMAGIC_OFFSET);
  
  	/* make sure write buffer is drained */
  	mb();
  
  	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 prima2_pen_release.
  	 *
  	 * Note that "prima2_pen_release" is the hardware CPU ID, whereas
  	 * "cpu" is Linux's internal ID.
  	 */
  	prima2_pen_release = cpu_logical_map(cpu);
  	sync_cache_w(&prima2_pen_release);
  
  	/*
  	 * Send the secondary CPU SEV, thereby causing the boot monitor to read
  	 * the JUMPADDR and WAKEMAGIC, and branch to the address found there.
  	 */
  	dsb_sev();
  
  	timeout = jiffies + (1 * HZ);
  	while (time_before(jiffies, timeout)) {
  		smp_rmb();
  		if (prima2_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 prima2_pen_release != -1 ? -ENOSYS : 0;
  }
  
  const struct smp_operations sirfsoc_smp_ops __initconst = {
  	.smp_secondary_init     = sirfsoc_secondary_init,
  	.smp_boot_secondary     = sirfsoc_boot_secondary,
  #ifdef CONFIG_HOTPLUG_CPU
  	.cpu_die                = sirfsoc_cpu_die,
  #endif
  };
  