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/hardware/gic.h>
  22 #include <asm/smp_scu.h>
  23 #include <mach/hardware.h>
  24 #include <mach/setup.h>
  25
  26 /* This is called from headsmp.S to wakeup the secondary core */
  27 extern void u8500_secondary_startup(void);
  28
  29 /*
  30  * control for which core is the next to come out of the secondary
  31  * boot "holding pen"
  32  */
  33 volatile int pen_release = -1;
  34
  35 /*
  36  * Write pen_release in a way that is guaranteed to be visible to all
  37  * observers, irrespective of whether they're taking part in coherency
  38  * or not.  This is necessary for the hotplug code to work reliably.
  39  */
  40 static void write_pen_release(int val)
  41 {
  42         pen_release = val;
  43         smp_wmb();
  44         __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
  45         outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
  46 }
  47
  48 static void __iomem *scu_base_addr(void)
  49 {
  50         if (cpu_is_u5500())
  51                 return __io_address(U5500_SCU_BASE);
  52         else if (cpu_is_u8500())
  53                 return __io_address(U8500_SCU_BASE);
  54         else
  55                 ux500_unknown_soc();
  56
  57         return NULL;
  58 }
  59
  60 static DEFINE_SPINLOCK(boot_lock);
  61
  62 void __cpuinit platform_secondary_init(unsigned int cpu)
  63 {
  64         /*
  65          * if any interrupts are already enabled for the primary
  66          * core (e.g. timer irq), then they will not have been enabled
  67          * for us: do so
  68          */
  69         gic_secondary_init(0);
  70
  71         /*
  72          * let the primary processor know we're out of the
  73          * pen, then head off into the C entry point
  74          */
  75         write_pen_release(-1);
  76
  77         /*
  78          * Synchronise with the boot thread.
  79          */
  80         spin_lock(&boot_lock);
  81         spin_unlock(&boot_lock);
  82 }
  83
  84 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  85 {
  86         unsigned long timeout;
  87
  88         /*
  89          * set synchronisation state between this boot processor
  90          * and the secondary one
  91          */
  92         spin_lock(&boot_lock);
  93
  94         /*
  95          * The secondary processor is waiting to be released from
  96          * the holding pen - release it, then wait for it to flag
  97          * that it has been released by resetting pen_release.
  98          */
  99         write_pen_release(cpu_logical_map(cpu));
 100
 101         gic_raise_softirq(cpumask_of(cpu), 1);
 102
 103         timeout = jiffies + (1 * HZ);
 104         while (time_before(jiffies, timeout)) {
 105                 if (pen_release == -1)
 106                         break;
 107         }
 108
 109         /*
 110          * now the secondary core is starting up let it run its
 111          * calibrations, then wait for it to finish
 112          */
 113         spin_unlock(&boot_lock);
 114
 115         return pen_release != -1 ? -ENOSYS : 0;
 116 }
 117
 118 static void __init wakeup_secondary(void)
 119 {
 120         void __iomem *backupram;
 121
 122         if (cpu_is_u5500())
 123                 backupram = __io_address(U5500_BACKUPRAM0_BASE);
 124         else if (cpu_is_u8500())
 125                 backupram = __io_address(U8500_BACKUPRAM0_BASE);
 126         else
 127                 ux500_unknown_soc();
 128
 129         /*
 130          * write the address of secondary startup into the backup ram register
 131          * at offset 0x1FF4, then write the magic number 0xA1FEED01 to the
 132          * backup ram register at offset 0x1FF0, which is what boot rom code
 133          * is waiting for. This would wake up the secondary core from WFE
 134          */
 135 #define UX500_CPU1_JUMPADDR_OFFSET 0x1FF4
 136         __raw_writel(virt_to_phys(u8500_secondary_startup),
 137                      backupram + UX500_CPU1_JUMPADDR_OFFSET);
 138
 139 #define UX500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
 140         __raw_writel(0xA1FEED01,
 141                      backupram + UX500_CPU1_WAKEMAGIC_OFFSET);
 142
 143         /* make sure write buffer is drained */
 144         mb();
 145 }
 146
 147 /*
 148  * Initialise the CPU possible map early - this describes the CPUs
 149  * which may be present or become present in the system.
 150  */
 151 void __init smp_init_cpus(void)
 152 {
 153         void __iomem *scu_base = scu_base_addr();
 154         unsigned int i, ncores;
 155
 156         ncores = scu_base ? scu_get_core_count(scu_base) : 1;
 157
 158         /* sanity check */
 159         if (ncores > nr_cpu_ids) {
 160                 pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
 161                         ncores, nr_cpu_ids);
 162                 ncores = nr_cpu_ids;
 163         }
 164
 165         for (i = 0; i < ncores; i++)
 166                 set_cpu_possible(i, true);
 167
 168         set_smp_cross_call(gic_raise_softirq);
 169 }
 170
 171 void __init platform_smp_prepare_cpus(unsigned int max_cpus)
 172 {
 173
 174         scu_enable(scu_base_addr());
 175         wakeup_secondary();
 176 }