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_plat.h>
  23 #include <asm/smp_scu.h>
  24 #include <mach/hardware.h>
  25 #include <mach/setup.h>
  26
  27 /* This is called from headsmp.S to wakeup the secondary core */
  28 extern void u8500_secondary_startup(void);
  29
  30 /*
  31  * control for which core is the next to come out of the secondary
  32  * boot "holding pen"
  33  */
  34 volatile int pen_release = -1;
  35
  36 /*
  37  * Write pen_release in a way that is guaranteed to be visible to all
  38  * observers, irrespective of whether they're taking part in coherency
  39  * or not.  This is necessary for the hotplug code to work reliably.
  40  */
  41 static void write_pen_release(int val)
  42 {
  43         pen_release = val;
  44         smp_wmb();
  45         __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
  46         outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
  47 }
  48
  49 static void __iomem *scu_base_addr(void)
  50 {
  51         if (cpu_is_u5500())
  52                 return __io_address(U5500_SCU_BASE);
  53         else if (cpu_is_u8500())
  54                 return __io_address(U8500_SCU_BASE);
  55         else
  56                 ux500_unknown_soc();
  57
  58         return NULL;
  59 }
  60
  61 static DEFINE_SPINLOCK(boot_lock);
  62
  63 void __cpuinit platform_secondary_init(unsigned int cpu)
  64 {
  65         /*
  66          * if any interrupts are already enabled for the primary
  67          * core (e.g. timer irq), then they will not have been enabled
  68          * for us: do so
  69          */
  70         gic_secondary_init(0);
  71
  72         /*
  73          * let the primary processor know we're out of the
  74          * pen, then head off into the C entry point
  75          */
  76         write_pen_release(-1);
  77
  78         /*
  79          * Synchronise with the boot thread.
  80          */
  81         spin_lock(&boot_lock);
  82         spin_unlock(&boot_lock);
  83 }
  84
  85 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  86 {
  87         unsigned long timeout;
  88
  89         /*
  90          * set synchronisation state between this boot processor
  91          * and the secondary one
  92          */
  93         spin_lock(&boot_lock);
  94
  95         /*
  96          * The secondary processor is waiting to be released from
  97          * the holding pen - release it, then wait for it to flag
  98          * that it has been released by resetting pen_release.
  99          */
 100         write_pen_release(cpu_logical_map(cpu));
 101
 102         smp_send_reschedule(cpu);
 103
 104         timeout = jiffies + (1 * HZ);
 105         while (time_before(jiffies, timeout)) {
 106                 if (pen_release == -1)
 107                         break;
 108         }
 109
 110         /*
 111          * now the secondary core is starting up let it run its
 112          * calibrations, then wait for it to finish
 113          */
 114         spin_unlock(&boot_lock);
 115
 116         return pen_release != -1 ? -ENOSYS : 0;
 117 }
 118
 119 static void __init wakeup_secondary(void)
 120 {
 121         void __iomem *backupram;
 122
 123         if (cpu_is_u5500())
 124                 backupram = __io_address(U5500_BACKUPRAM0_BASE);
 125         else if (cpu_is_u8500())
 126                 backupram = __io_address(U8500_BACKUPRAM0_BASE);
 127         else
 128                 ux500_unknown_soc();
 129
 130         /*
 131          * write the address of secondary startup into the backup ram register
 132          * at offset 0x1FF4, then write the magic number 0xA1FEED01 to the
 133          * backup ram register at offset 0x1FF0, which is what boot rom code
 134          * is waiting for. This would wake up the secondary core from WFE
 135          */
 136 #define UX500_CPU1_JUMPADDR_OFFSET 0x1FF4
 137         __raw_writel(virt_to_phys(u8500_secondary_startup),
 138                      backupram + UX500_CPU1_JUMPADDR_OFFSET);
 139
 140 #define UX500_CPU1_WAKEMAGIC_OFFSET 0x1FF0
 141         __raw_writel(0xA1FEED01,
 142                      backupram + UX500_CPU1_WAKEMAGIC_OFFSET);
 143
 144         /* make sure write buffer is drained */
 145         mb();
 146 }
 147
 148 /*
 149  * Initialise the CPU possible map early - this describes the CPUs
 150  * which may be present or become present in the system.
 151  */
 152 void __init smp_init_cpus(void)
 153 {
 154         void __iomem *scu_base = scu_base_addr();
 155         unsigned int i, ncores;
 156
 157         ncores = scu_base ? scu_get_core_count(scu_base) : 1;
 158
 159         /* sanity check */
 160         if (ncores > nr_cpu_ids) {
 161                 pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
 162                         ncores, nr_cpu_ids);
 163                 ncores = nr_cpu_ids;
 164         }
 165
 166         for (i = 0; i < ncores; i++)
 167                 set_cpu_possible(i, true);
 168
 169         set_smp_cross_call(gic_raise_softirq);
 170 }
 171
 172 void __init platform_smp_prepare_cpus(unsigned int max_cpus)
 173 {
 174
 175         scu_enable(scu_base_addr());
 176         wakeup_secondary();
 177 }