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/config.h> 18 #include <linux/kernel.h> 19 #include <linux/module.h> 20 #include <linux/sched.h> 21 #include <linux/smp.h> 22 #include <linux/interrupt.h> 23 #include <linux/delay.h> 24 #include <linux/init.h> 25 #include <linux/spinlock.h> 26 #include <linux/cache.h> 27 #include <linux/err.h> 28 #include <linux/sysdev.h> 29 #include <linux/cpu.h> 30 31 #include <asm/ptrace.h> 32 #include <asm/atomic.h> 33 #include <asm/irq.h> 34 #include <asm/page.h> 35 #include <asm/pgtable.h> 36 #include <asm/io.h> 37 #include <asm/prom.h> 38 #include <asm/smp.h> 39 #include <asm/paca.h> 40 #include <asm/time.h> 41 #include <asm/machdep.h> 42 #include <asm/cputable.h> 43 #include <asm/firmware.h> 44 #include <asm/system.h> 45 #include <asm/rtas.h> 46 47 #include "interrupt.h" 48 49 #ifdef DEBUG 50 #define DBG(fmt...) udbg_printf(fmt) 51 #else 52 #define DBG(fmt...) 53 #endif 54 55 /* 56 * The primary thread of each non-boot processor is recorded here before 57 * smp init. 58 */ 59 static cpumask_t of_spin_map; 60 61 extern void pSeries_secondary_smp_init(unsigned long); 62 63 /** 64 * smp_startup_cpu() - start the given cpu 65 * 66 * At boot time, there is nothing to do for primary threads which were 67 * started from Open Firmware. For anything else, call RTAS with the 68 * appropriate start location. 69 * 70 * Returns: 71 * 0 - failure 72 * 1 - success 73 */ 74 static inline int __devinit smp_startup_cpu(unsigned int lcpu) 75 { 76 int status; 77 unsigned long start_here = __pa((u32)*((unsigned long *) 78 pSeries_secondary_smp_init)); 79 unsigned int pcpu; 80 int start_cpu; 81 82 if (cpu_isset(lcpu, of_spin_map)) 83 /* Already started by OF and sitting in spin loop */ 84 return 1; 85 86 pcpu = get_hard_smp_processor_id(lcpu); 87 88 /* Fixup atomic count: it exited inside IRQ handler. */ 89 paca[lcpu].__current->thread_info->preempt_count = 0; 90 91 /* 92 * If the RTAS start-cpu token does not exist then presume the 93 * cpu is already spinning. 94 */ 95 start_cpu = rtas_token("start-cpu"); 96 if (start_cpu == RTAS_UNKNOWN_SERVICE) 97 return 1; 98 99 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 100 if (status != 0) { 101 printk(KERN_ERR "start-cpu failed: %i\n", status); 102 return 0; 103 } 104 105 return 1; 106 } 107 108 static void smp_iic_message_pass(int target, int msg) 109 { 110 unsigned int i; 111 112 if (target < NR_CPUS) { 113 iic_cause_IPI(target, msg); 114 } else { 115 for_each_online_cpu(i) { 116 if (target == MSG_ALL_BUT_SELF 117 && i == smp_processor_id()) 118 continue; 119 iic_cause_IPI(i, msg); 120 } 121 } 122 } 123 124 static int __init smp_iic_probe(void) 125 { 126 iic_request_IPIs(); 127 128 return cpus_weight(cpu_possible_map); 129 } 130 131 static void __devinit smp_iic_setup_cpu(int cpu) 132 { 133 if (cpu != boot_cpuid) 134 iic_setup_cpu(); 135 } 136 137 static DEFINE_SPINLOCK(timebase_lock); 138 static unsigned long timebase = 0; 139 140 static void __devinit cell_give_timebase(void) 141 { 142 spin_lock(&timebase_lock); 143 rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL); 144 timebase = get_tb(); 145 spin_unlock(&timebase_lock); 146 147 while (timebase) 148 barrier(); 149 rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL); 150 } 151 152 static void __devinit cell_take_timebase(void) 153 { 154 while (!timebase) 155 barrier(); 156 spin_lock(&timebase_lock); 157 set_tb(timebase >> 32, timebase & 0xffffffff); 158 timebase = 0; 159 spin_unlock(&timebase_lock); 160 } 161 162 static void __devinit smp_cell_kick_cpu(int nr) 163 { 164 BUG_ON(nr < 0 || nr >= NR_CPUS); 165 166 if (!smp_startup_cpu(nr)) 167 return; 168 169 /* 170 * The processor is currently spinning, waiting for the 171 * cpu_start field to become non-zero After we set cpu_start, 172 * the processor will continue on to secondary_start 173 */ 174 paca[nr].cpu_start = 1; 175 } 176 177 static int smp_cell_cpu_bootable(unsigned int nr) 178 { 179 /* Special case - we inhibit secondary thread startup 180 * during boot if the user requests it. Odd-numbered 181 * cpus are assumed to be secondary threads. 182 */ 183 if (system_state < SYSTEM_RUNNING && 184 cpu_has_feature(CPU_FTR_SMT) && 185 !smt_enabled_at_boot && nr % 2 != 0) 186 return 0; 187 188 return 1; 189 } 190 static struct smp_ops_t bpa_iic_smp_ops = { 191 .message_pass = smp_iic_message_pass, 192 .probe = smp_iic_probe, 193 .kick_cpu = smp_cell_kick_cpu, 194 .setup_cpu = smp_iic_setup_cpu, 195 .cpu_bootable = smp_cell_cpu_bootable, 196 }; 197 198 /* This is called very early */ 199 void __init smp_init_cell(void) 200 { 201 int i; 202 203 DBG(" -> smp_init_cell()\n"); 204 205 smp_ops = &bpa_iic_smp_ops; 206 207 /* Mark threads which are still spinning in hold loops. */ 208 if (cpu_has_feature(CPU_FTR_SMT)) { 209 for_each_present_cpu(i) { 210 if (i % 2 == 0) 211 /* 212 * Even-numbered logical cpus correspond to 213 * primary threads. 214 */ 215 cpu_set(i, of_spin_map); 216 } 217 } else { 218 of_spin_map = cpu_present_map; 219 } 220 221 cpu_clear(boot_cpuid, of_spin_map); 222 223 /* Non-lpar has additional take/give timebase */ 224 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 225 smp_ops->give_timebase = cell_give_timebase; 226 smp_ops->take_timebase = cell_take_timebase; 227 } 228 229 DBG(" <- smp_init_cell()\n"); 230 } 231