1/* 2 * SMP support for BPA machines. 3 * 4 * Dave Engebretsen, Peter Bergner, and 5 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com 6 * 7 * Plus various changes from other IBM teams... 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 */ 14 15#undef DEBUG 16 17#include <linux/kernel.h> 18#include <linux/module.h> 19#include <linux/sched.h> 20#include <linux/smp.h> 21#include <linux/interrupt.h> 22#include <linux/delay.h> 23#include <linux/init.h> 24#include <linux/spinlock.h> 25#include <linux/cache.h> 26#include <linux/err.h> 27#include <linux/sysdev.h> 28#include <linux/cpu.h> 29 30#include <asm/ptrace.h> 31#include <asm/atomic.h> 32#include <asm/irq.h> 33#include <asm/page.h> 34#include <asm/pgtable.h> 35#include <asm/io.h> 36#include <asm/prom.h> 37#include <asm/smp.h> 38#include <asm/paca.h> 39#include <asm/time.h> 40#include <asm/machdep.h> 41#include <asm/cputable.h> 42#include <asm/firmware.h> 43#include <asm/system.h> 44#include <asm/rtas.h> 45 46#include "interrupt.h" 47 48#ifdef DEBUG 49#define DBG(fmt...) udbg_printf(fmt) 50#else 51#define DBG(fmt...) 52#endif 53 54/* 55 * The primary thread of each non-boot processor is recorded here before 56 * smp init. 57 */ 58static cpumask_t of_spin_map; 59 60extern void generic_secondary_smp_init(unsigned long); 61 62/** 63 * smp_startup_cpu() - start the given cpu 64 * 65 * At boot time, there is nothing to do for primary threads which were 66 * started from Open Firmware. For anything else, call RTAS with the 67 * appropriate start location. 68 * 69 * Returns: 70 * 0 - failure 71 * 1 - success 72 */ 73static inline int __devinit smp_startup_cpu(unsigned int lcpu) 74{ 75 int status; 76 unsigned long start_here = __pa((u32)*((unsigned long *) 77 generic_secondary_smp_init)); 78 unsigned int pcpu; 79 int start_cpu; 80 81 if (cpu_isset(lcpu, of_spin_map)) 82 /* Already started by OF and sitting in spin loop */ 83 return 1; 84 85 pcpu = get_hard_smp_processor_id(lcpu); 86 87 /* Fixup atomic count: it exited inside IRQ handler. */ 88 task_thread_info(paca[lcpu].__current)->preempt_count = 0; 89 90 /* 91 * If the RTAS start-cpu token does not exist then presume the 92 * cpu is already spinning. 93 */ 94 start_cpu = rtas_token("start-cpu"); 95 if (start_cpu == RTAS_UNKNOWN_SERVICE) 96 return 1; 97 98 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 99 if (status != 0) { 100 printk(KERN_ERR "start-cpu failed: %i\n", status); 101 return 0; 102 } 103 104 return 1; 105} 106 107static void smp_iic_message_pass(int target, int msg) 108{ 109 unsigned int i; 110 111 if (target < NR_CPUS) { 112 iic_cause_IPI(target, msg); 113 } else { 114 for_each_online_cpu(i) { 115 if (target == MSG_ALL_BUT_SELF 116 && i == smp_processor_id()) 117 continue; 118 iic_cause_IPI(i, msg); 119 } 120 } 121} 122 123static int __init smp_iic_probe(void) 124{ 125 iic_request_IPIs(); 126 127 return cpus_weight(cpu_possible_map); 128} 129 130static void __devinit smp_iic_setup_cpu(int cpu) 131{ 132 if (cpu != boot_cpuid) 133 iic_setup_cpu(); 134} 135 136static DEFINE_SPINLOCK(timebase_lock); 137static unsigned long timebase = 0; 138 139static void __devinit cell_give_timebase(void) 140{ 141 spin_lock(&timebase_lock); 142 rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL); 143 timebase = get_tb(); 144 spin_unlock(&timebase_lock); 145 146 while (timebase) 147 barrier(); 148 rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL); 149} 150 151static void __devinit cell_take_timebase(void) 152{ 153 while (!timebase) 154 barrier(); 155 spin_lock(&timebase_lock); 156 set_tb(timebase >> 32, timebase & 0xffffffff); 157 timebase = 0; 158 spin_unlock(&timebase_lock); 159} 160 161static void __devinit smp_cell_kick_cpu(int nr) 162{ 163 BUG_ON(nr < 0 || nr >= NR_CPUS); 164 165 if (!smp_startup_cpu(nr)) 166 return; 167 168 /* 169 * The processor is currently spinning, waiting for the 170 * cpu_start field to become non-zero After we set cpu_start, 171 * the processor will continue on to secondary_start 172 */ 173 paca[nr].cpu_start = 1; 174} 175 176static int smp_cell_cpu_bootable(unsigned int nr) 177{ 178 /* Special case - we inhibit secondary thread startup 179 * during boot if the user requests it. Odd-numbered 180 * cpus are assumed to be secondary threads. 181 */ 182 if (system_state < SYSTEM_RUNNING && 183 cpu_has_feature(CPU_FTR_SMT) && 184 !smt_enabled_at_boot && nr % 2 != 0) 185 return 0; 186 187 return 1; 188} 189static struct smp_ops_t bpa_iic_smp_ops = { 190 .message_pass = smp_iic_message_pass, 191 .probe = smp_iic_probe, 192 .kick_cpu = smp_cell_kick_cpu, 193 .setup_cpu = smp_iic_setup_cpu, 194 .cpu_bootable = smp_cell_cpu_bootable, 195}; 196 197/* This is called very early */ 198void __init smp_init_cell(void) 199{ 200 int i; 201 202 DBG(" -> smp_init_cell()\n"); 203 204 smp_ops = &bpa_iic_smp_ops; 205 206 /* Mark threads which are still spinning in hold loops. */ 207 if (cpu_has_feature(CPU_FTR_SMT)) { 208 for_each_present_cpu(i) { 209 if (i % 2 == 0) 210 /* 211 * Even-numbered logical cpus correspond to 212 * primary threads. 213 */ 214 cpu_set(i, of_spin_map); 215 } 216 } else { 217 of_spin_map = cpu_present_map; 218 } 219 220 cpu_clear(boot_cpuid, of_spin_map); 221 222 /* Non-lpar has additional take/give timebase */ 223 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 224 smp_ops->give_timebase = cell_give_timebase; 225 smp_ops->take_timebase = cell_take_timebase; 226 } 227 228 DBG(" <- smp_init_cell()\n"); 229} 230