cregit-Linux how code gets into the kernel

Release 4.11 arch/arm/mach-spear/platsmp.c

/*
 * arch/arm/mach-spear13xx/platsmp.c
 *
 * based upon linux/arch/arm/mach-realview/platsmp.c
 *
 * Copyright (C) 2012 ST Microelectronics Ltd.
 * Shiraz Hashim <shiraz.linux.kernel@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/delay.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/smp.h>
#include <asm/cacheflush.h>
#include <asm/smp_scu.h>
#include <mach/spear.h>
#include "generic.h"

/*
 * Write 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(int val) { pen_release = val; smp_wmb(); sync_cache_w(&pen_release); }

Contributors

PersonTokensPropCommitsCommitProp
Russell King22100.00%1100.00%
Total22100.00%1100.00%

static DEFINE_SPINLOCK(boot_lock); static void __iomem *scu_base = IOMEM(VA_SCU_BASE);
static void spear13xx_secondary_init(unsigned int cpu) { /* * let the primary processor know we're out of the * pen, then head off into the C entry point */ write_pen_release(-1); /* * Synchronise with the boot thread. */ spin_lock(&boot_lock); spin_unlock(&boot_lock); }

Contributors

PersonTokensPropCommitsCommitProp
Viresh Kumar2583.33%133.33%
Russell King310.00%133.33%
Arnd Bergmann26.67%133.33%
Total30100.00%3100.00%


static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle) { unsigned long timeout; /* * set synchronisation state between this boot processor * and the secondary one */ 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 pen_release. * * Note that "pen_release" is the hardware CPU ID, whereas * "cpu" is Linux's internal ID. */ write_pen_release(cpu); timeout = jiffies + (1 * HZ); while (time_before(jiffies, timeout)) { smp_rmb(); if (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 pen_release != -1 ? -ENOSYS : 0; }

Contributors

PersonTokensPropCommitsCommitProp
Viresh Kumar8294.25%133.33%
Russell King33.45%133.33%
Arnd Bergmann22.30%133.33%
Total87100.00%3100.00%

/* * Initialise the CPU possible map early - this describes the CPUs * which may be present or become present in the system. */
static void __init spear13xx_smp_init_cpus(void) { unsigned int i, ncores = scu_get_core_count(scu_base); if (ncores > nr_cpu_ids) { pr_warn("SMP: %u cores greater than maximum (%u), clipping\n", ncores, nr_cpu_ids); ncores = nr_cpu_ids; } for (i = 0; i < ncores; i++) set_cpu_possible(i, true); }

Contributors

PersonTokensPropCommitsCommitProp
Viresh Kumar5996.72%150.00%
Arnd Bergmann23.28%150.00%
Total61100.00%2100.00%


static void __init spear13xx_smp_prepare_cpus(unsigned int max_cpus) { scu_enable(scu_base); /* * Write the address of secondary startup into the system-wide location * (presently it is in SRAM). The BootMonitor waits until it receives a * soft interrupt, and then the secondary CPU branches to this address. */ __raw_writel(__pa_symbol(spear13xx_secondary_startup), SYS_LOCATION); }

Contributors

PersonTokensPropCommitsCommitProp
Viresh Kumar2488.89%133.33%
Arnd Bergmann27.41%133.33%
Florian Fainelli13.70%133.33%
Total27100.00%3100.00%

const struct smp_operations spear13xx_smp_ops __initconst = { .smp_init_cpus = spear13xx_smp_init_cpus, .smp_prepare_cpus = spear13xx_smp_prepare_cpus, .smp_secondary_init = spear13xx_secondary_init, .smp_boot_secondary = spear13xx_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU .cpu_die = spear13xx_cpu_die, #endif };

Overall Contributors

PersonTokensPropCommitsCommitProp
Viresh Kumar22973.87%225.00%
Arnd Bergmann4815.48%225.00%
Russell King299.35%112.50%
Masahiro Yamada20.65%112.50%
Florian Fainelli10.32%112.50%
Rob Herring10.32%112.50%
Total310100.00%8100.00%
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