1 /* 2 * arch/arm/mach-sti/platsmp.c 3 * 4 * Copyright (C) 2013 STMicroelectronics (R&D) Limited. 5 * http://www.st.com 6 * 7 * Cloned from linux/arch/arm/mach-vexpress/platsmp.c 8 * 9 * Copyright (C) 2002 ARM Ltd. 10 * All Rights Reserved 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License version 2 as 14 * published by the Free Software Foundation. 15 */ 16 #include <linux/init.h> 17 #include <linux/errno.h> 18 #include <linux/delay.h> 19 #include <linux/smp.h> 20 #include <linux/io.h> 21 #include <linux/of.h> 22 #include <linux/of_address.h> 23 24 #include <asm/cacheflush.h> 25 #include <asm/smp_plat.h> 26 #include <asm/smp_scu.h> 27 28 #include "smp.h" 29 30 static void write_pen_release(int val) 31 { 32 pen_release = val; 33 smp_wmb(); 34 sync_cache_w(&pen_release); 35 } 36 37 static DEFINE_SPINLOCK(boot_lock); 38 39 static void sti_secondary_init(unsigned int cpu) 40 { 41 trace_hardirqs_off(); 42 43 /* 44 * let the primary processor know we're out of the 45 * pen, then head off into the C entry point 46 */ 47 write_pen_release(-1); 48 49 /* 50 * Synchronise with the boot thread. 51 */ 52 spin_lock(&boot_lock); 53 spin_unlock(&boot_lock); 54 } 55 56 static int sti_boot_secondary(unsigned int cpu, struct task_struct *idle) 57 { 58 unsigned long timeout; 59 60 /* 61 * set synchronisation state between this boot processor 62 * and the secondary one 63 */ 64 spin_lock(&boot_lock); 65 66 /* 67 * The secondary processor is waiting to be released from 68 * the holding pen - release it, then wait for it to flag 69 * that it has been released by resetting pen_release. 70 * 71 * Note that "pen_release" is the hardware CPU ID, whereas 72 * "cpu" is Linux's internal ID. 73 */ 74 write_pen_release(cpu_logical_map(cpu)); 75 76 /* 77 * Send the secondary CPU a soft interrupt, thereby causing 78 * it to jump to the secondary entrypoint. 79 */ 80 arch_send_wakeup_ipi_mask(cpumask_of(cpu)); 81 82 timeout = jiffies + (1 * HZ); 83 while (time_before(jiffies, timeout)) { 84 smp_rmb(); 85 if (pen_release == -1) 86 break; 87 88 udelay(10); 89 } 90 91 /* 92 * now the secondary core is starting up let it run its 93 * calibrations, then wait for it to finish 94 */ 95 spin_unlock(&boot_lock); 96 97 return pen_release != -1 ? -ENOSYS : 0; 98 } 99 100 static void __init sti_smp_prepare_cpus(unsigned int max_cpus) 101 { 102 void __iomem *scu_base = NULL; 103 struct device_node *np = of_find_compatible_node( 104 NULL, NULL, "arm,cortex-a9-scu"); 105 if (np) { 106 scu_base = of_iomap(np, 0); 107 scu_enable(scu_base); 108 of_node_put(np); 109 } 110 } 111 112 struct smp_operations __initdata sti_smp_ops = { 113 .smp_prepare_cpus = sti_smp_prepare_cpus, 114 .smp_secondary_init = sti_secondary_init, 115 .smp_boot_secondary = sti_boot_secondary, 116 }; 117