arch/arm/mach-omap2/omap-smp.c

   1 /*
   2  * OMAP4 SMP source file. It contains platform specific fucntions
   3  * needed for the linux smp kernel.
   4  *
   5  * Copyright (C) 2009 Texas Instruments, Inc.
   6  *
   7  * Author:
   8  *      Santosh Shilimkar <santosh.shilimkar@ti.com>
   9  *
  10  * Platform file needed for the OMAP4 SMP. This file is based on arm
  11  * realview smp platform.
  12  * * Copyright (c) 2002 ARM Limited.
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License version 2 as
  16  * published by the Free Software Foundation.
  17  */
  18 #include <linux/init.h>
  19 #include <linux/device.h>
  20 #include <linux/jiffies.h>
  21 #include <linux/smp.h>
  22 #include <linux/io.h>
  23
  24 #include <asm/localtimer.h>
  25 #include <asm/smp_scu.h>
  26 #include <mach/hardware.h>
  27
  28 /* Registers used for communicating startup information */
  29 #define OMAP4_AUXCOREBOOT_REG0          (OMAP44XX_VA_WKUPGEN_BASE + 0x800)
  30 #define OMAP4_AUXCOREBOOT_REG1          (OMAP44XX_VA_WKUPGEN_BASE + 0x804)
  31
  32 /* SCU base address */
  33 static void __iomem *scu_base = OMAP44XX_VA_SCU_BASE;
  34
  35 /*
  36  * Use SCU config register to count number of cores
  37  */
  38 static inline unsigned int get_core_count(void)
  39 {
  40         if (scu_base)
  41                 return scu_get_core_count(scu_base);
  42         return 1;
  43 }
  44
  45 static DEFINE_SPINLOCK(boot_lock);
  46
  47 void __cpuinit platform_secondary_init(unsigned int cpu)
  48 {
  49         trace_hardirqs_off();
  50
  51         /*
  52          * If any interrupts are already enabled for the primary
  53          * core (e.g. timer irq), then they will not have been enabled
  54          * for us: do so
  55          */
  56
  57         gic_cpu_init(0, OMAP2_IO_ADDRESS(OMAP44XX_GIC_CPU_BASE));
  58
  59         /*
  60          * Synchronise with the boot thread.
  61          */
  62         spin_lock(&boot_lock);
  63         spin_unlock(&boot_lock);
  64 }
  65
  66 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
  67 {
  68         unsigned long timeout;
  69
  70         /*
  71          * Set synchronisation state between this boot processor
  72          * and the secondary one
  73          */
  74         spin_lock(&boot_lock);
  75
  76         /*
  77          * Update the AuxCoreBoot1 with boot state for secondary core.
  78          * omap_secondary_startup() routine will hold the secondary core till
  79          * the AuxCoreBoot1 register is updated with cpu state
  80          * A barrier is added to ensure that write buffer is drained
  81          */
  82         __raw_writel(cpu, OMAP4_AUXCOREBOOT_REG1);
  83         smp_wmb();
  84
  85         timeout = jiffies + (1 * HZ);
  86         while (time_before(jiffies, timeout))
  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 0;
  96 }
  97
  98 static void __init wakeup_secondary(void)
  99 {
 100         /*
 101          * Write the address of secondary startup routine into the
 102          * AuxCoreBoot0 where ROM code will jump and start executing
 103          * on secondary core once out of WFE
 104          * A barrier is added to ensure that write buffer is drained
 105          */
 106         __raw_writel(virt_to_phys(omap_secondary_startup),         \
 107                                         OMAP4_AUXCOREBOOT_REG0);
 108         smp_wmb();
 109
 110         /*
 111          * Send a 'sev' to wake the secondary core from WFE.
 112          */
 113         set_event();
 114         mb();
 115 }
 116
 117 /*
 118  * Initialise the CPU possible map early - this describes the CPUs
 119  * which may be present or become present in the system.
 120  */
 121 void __init smp_init_cpus(void)
 122 {
 123         unsigned int i, ncores = get_core_count();
 124
 125         for (i = 0; i < ncores; i++)
 126                 set_cpu_possible(i, true);
 127 }
 128
 129 void __init smp_prepare_cpus(unsigned int max_cpus)
 130 {
 131         unsigned int ncores = get_core_count();
 132         unsigned int cpu = smp_processor_id();
 133         int i;
 134
 135         /* sanity check */
 136         if (ncores == 0) {
 137                 printk(KERN_ERR
 138                        "OMAP4: strange core count of 0? Default to 1\n");
 139                 ncores = 1;
 140         }
 141
 142         if (ncores > NR_CPUS) {
 143                 printk(KERN_WARNING
 144                        "OMAP4: no. of cores (%d) greater than configured "
 145                        "maximum of %d - clipping\n",
 146                        ncores, NR_CPUS);
 147                 ncores = NR_CPUS;
 148         }
 149         smp_store_cpu_info(cpu);
 150
 151         /*
 152          * are we trying to boot more cores than exist?
 153          */
 154         if (max_cpus > ncores)
 155                 max_cpus = ncores;
 156
 157         /*
 158          * Initialise the present map, which describes the set of CPUs
 159          * actually populated at the present time.
 160          */
 161         for (i = 0; i < max_cpus; i++)
 162                 set_cpu_present(i, true);
 163
 164         if (max_cpus > 1) {
 165                 /*
 166                  * Enable the local timer or broadcast device for the
 167                  * boot CPU, but only if we have more than one CPU.
 168                  */
 169                 percpu_timer_setup();
 170
 171                 /*
 172                  * Initialise the SCU and wake up the secondary core using
 173                  * wakeup_secondary().
 174                  */
 175                 scu_enable(scu_base);
 176                 wakeup_secondary();
 177         }
 178 }