arch/arm/mach-ux500/platsmp.c

   1 /*
   2  * Copyright (C) 2002 ARM Ltd.
   3  * Copyright (C) 2008 STMicroelctronics.
   4  * Copyright (C) 2009 ST-Ericsson.
   5  * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
   6  *
   7  * This file is based on arm realview platform
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13 #include <linux/init.h>
  14 #include <linux/errno.h>
  15 #include <linux/delay.h>
  16 #include <linux/device.h>
  17 #include <linux/smp.h>
  18 #include <linux/io.h>
  19
  20 #include <asm/cacheflush.h>
  21 #include <asm/localtimer.h>
  22 #include <asm/smp_scu.h>
  23 #include <mach/hardware.h>
  24
  25 /*
  26  * control for which core is the next to come out of the secondary
  27  * boot "holding pen"
  28  */
  29 volatile int __cpuinitdata pen_release = -1;
  30
  31 static unsigned int __init get_core_count(void)
  32 {
  33         return scu_get_core_count(__io_address(UX500_SCU_BASE));
  34 }
  35
  36 static DEFINE_SPINLOCK(boot_lock);
  37
  38 void __cpuinit platform_secondary_init(unsigned int cpu)
  39 {
  40         trace_hardirqs_off();
  41
  42         /*
  43          * if any interrupts are already enabled for the primary
  44          * core (e.g. timer irq), then they will not have been enabled
  45          * for us: do so
  46          */
  47         gic_cpu_init(0, __io_address(UX500_GIC_CPU_BASE));
  48
  49         /*
  50          * let the primary processor know we're out of the
  51          * pen, then head off into the C entry point
  52          */
  53         pen_release = -1;
  54
  55         /*
  56          * Synchronise with the boot thread.
  57          */
  58         spin_lock(&boot_lock);
  59         spin_unlock(&boot_lock);
  60 }
  61
  62 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  63 {
  64         unsigned long timeout;
  65
  66         /*
  67          * set synchronisation state between this boot processor
  68          * and the secondary one
  69          */
  70         spin_lock(&boot_lock);
  71
  72         /*
  73          * The secondary processor is waiting to be released from
  74          * the holding pen - release it, then wait for it to flag
  75          * that it has been released by resetting pen_release.
  76          */
  77         pen_release = cpu;
  78         __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
  79         outer_clean_range(__pa(&pen_release), __pa(&pen_release) + 1);
  80
  81         smp_cross_call(cpumask_of(cpu));
  82
  83         timeout = jiffies + (1 * HZ);
  84         while (time_before(jiffies, timeout)) {
  85                 if (pen_release == -1)
  86                         break;
  87         }
  88
  89         /*
  90          * now the secondary core is starting up let it run its
  91          * calibrations, then wait for it to finish
  92          */
  93         spin_unlock(&boot_lock);
  94
  95         return pen_release != -1 ? -ENOSYS : 0;
  96 }
  97
  98 static void __init wakeup_secondary(void)
  99 {
 100         /* nobody is to be released from the pen yet */
 101         pen_release = -1;
 102
 103         /*
 104          * write the address of secondary startup into the backup ram register
 105          * at offset 0x1FF4, then write the magic number 0xA1FEED01 to the
 106          * backup ram register at offset 0x1FF0, which is what boot rom code
 107          * is waiting for. This would wake up the secondary core from WFE
 108          */
 109 #define U8500_CPU1_JUMPADDR_OFFSET 0x1FF4
 110         __raw_writel(virt_to_phys(u8500_secondary_startup),
 111                 __io_address(UX500_BACKUPRAM0_BASE) +
 112                 U8500_CPU1_JUMPADDR_OFFSET);
 113
 114 #define U8500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
 115         __raw_writel(0xA1FEED01,
 116                 __io_address(UX500_BACKUPRAM0_BASE) +
 117                 U8500_CPU1_WAKEMAGIC_OFFSET);
 118
 119         /* make sure write buffer is drained */
 120         mb();
 121 }
 122
 123 /*
 124  * Initialise the CPU possible map early - this describes the CPUs
 125  * which may be present or become present in the system.
 126  */
 127 void __init smp_init_cpus(void)
 128 {
 129         unsigned int i, ncores = get_core_count();
 130
 131         for (i = 0; i < ncores; i++)
 132                 set_cpu_possible(i, true);
 133 }
 134
 135 void __init smp_prepare_cpus(unsigned int max_cpus)
 136 {
 137         unsigned int ncores = get_core_count();
 138         unsigned int cpu = smp_processor_id();
 139         int i;
 140
 141         /* sanity check */
 142         if (ncores == 0) {
 143                 printk(KERN_ERR
 144                        "U8500: strange CM count of 0? Default to 1\n");
 145                 ncores = 1;
 146         }
 147
 148         if (ncores > num_possible_cpus())       {
 149                 printk(KERN_WARNING
 150                        "U8500: no. of cores (%d) greater than configured "
 151                        "maximum of %d - clipping\n",
 152                        ncores, num_possible_cpus());
 153                 ncores = num_possible_cpus();
 154         }
 155
 156         smp_store_cpu_info(cpu);
 157
 158         /*
 159          * are we trying to boot more cores than exist?
 160          */
 161         if (max_cpus > ncores)
 162                 max_cpus = ncores;
 163
 164         /*
 165          * Initialise the present map, which describes the set of CPUs
 166          * actually populated at the present time.
 167          */
 168         for (i = 0; i < max_cpus; i++)
 169                 set_cpu_present(i, true);
 170
 171         if (max_cpus > 1) {
 172                 /*
 173                  * Enable the local timer or broadcast device for the
 174                  * boot CPU, but only if we have more than one CPU.
 175                  */
 176                 percpu_timer_setup();
 177                 scu_enable(__io_address(UX500_SCU_BASE));
 178                 wakeup_secondary();
 179         }
 180 }