1 /* 2 * SMP support for pSeries 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 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/sched.h> 19 #include <linux/smp.h> 20 #include <linux/interrupt.h> 21 #include <linux/delay.h> 22 #include <linux/init.h> 23 #include <linux/spinlock.h> 24 #include <linux/cache.h> 25 #include <linux/err.h> 26 #include <linux/sysdev.h> 27 #include <linux/cpu.h> 28 29 #include <asm/ptrace.h> 30 #include <asm/atomic.h> 31 #include <asm/irq.h> 32 #include <asm/page.h> 33 #include <asm/pgtable.h> 34 #include <asm/io.h> 35 #include <asm/prom.h> 36 #include <asm/smp.h> 37 #include <asm/paca.h> 38 #include <asm/time.h> 39 #include <asm/machdep.h> 40 #include <asm/cputable.h> 41 #include <asm/firmware.h> 42 #include <asm/system.h> 43 #include <asm/rtas.h> 44 #include <asm/pSeries_reconfig.h> 45 #include <asm/mpic.h> 46 #include <asm/vdso_datapage.h> 47 #include <asm/cputhreads.h> 48 49 #include "plpar_wrappers.h" 50 #include "pseries.h" 51 #include "xics.h" 52 53 54 /* 55 * The Primary thread of each non-boot processor was started from the OF client 56 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. 57 */ 58 static cpumask_t of_spin_map; 59 60 extern 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 */ 73 static 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, pcpu); 99 if (status != 0) { 100 printk(KERN_ERR "start-cpu failed: %i\n", status); 101 return 0; 102 } 103 104 return 1; 105 } 106 107 #ifdef CONFIG_XICS 108 static void __devinit smp_xics_setup_cpu(int cpu) 109 { 110 if (cpu != boot_cpuid) 111 xics_setup_cpu(); 112 113 if (firmware_has_feature(FW_FEATURE_SPLPAR)) 114 vpa_init(cpu); 115 116 cpu_clear(cpu, of_spin_map); 117 118 } 119 #endif /* CONFIG_XICS */ 120 121 static DEFINE_SPINLOCK(timebase_lock); 122 static unsigned long timebase = 0; 123 124 static void __devinit pSeries_give_timebase(void) 125 { 126 spin_lock(&timebase_lock); 127 rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL); 128 timebase = get_tb(); 129 spin_unlock(&timebase_lock); 130 131 while (timebase) 132 barrier(); 133 rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL); 134 } 135 136 static void __devinit pSeries_take_timebase(void) 137 { 138 while (!timebase) 139 barrier(); 140 spin_lock(&timebase_lock); 141 set_tb(timebase >> 32, timebase & 0xffffffff); 142 timebase = 0; 143 spin_unlock(&timebase_lock); 144 } 145 146 static void __devinit smp_pSeries_kick_cpu(int nr) 147 { 148 BUG_ON(nr < 0 || nr >= NR_CPUS); 149 150 if (!smp_startup_cpu(nr)) 151 return; 152 153 /* 154 * The processor is currently spinning, waiting for the 155 * cpu_start field to become non-zero After we set cpu_start, 156 * the processor will continue on to secondary_start 157 */ 158 paca[nr].cpu_start = 1; 159 } 160 161 static int smp_pSeries_cpu_bootable(unsigned int nr) 162 { 163 /* Special case - we inhibit secondary thread startup 164 * during boot if the user requests it. 165 */ 166 if (system_state < SYSTEM_RUNNING && 167 cpu_has_feature(CPU_FTR_SMT) && 168 !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0) 169 return 0; 170 171 return 1; 172 } 173 #ifdef CONFIG_MPIC 174 static struct smp_ops_t pSeries_mpic_smp_ops = { 175 .message_pass = smp_mpic_message_pass, 176 .probe = smp_mpic_probe, 177 .kick_cpu = smp_pSeries_kick_cpu, 178 .setup_cpu = smp_mpic_setup_cpu, 179 }; 180 #endif 181 #ifdef CONFIG_XICS 182 static struct smp_ops_t pSeries_xics_smp_ops = { 183 .message_pass = smp_xics_message_pass, 184 .probe = smp_xics_probe, 185 .kick_cpu = smp_pSeries_kick_cpu, 186 .setup_cpu = smp_xics_setup_cpu, 187 .cpu_bootable = smp_pSeries_cpu_bootable, 188 }; 189 #endif 190 191 /* This is called very early */ 192 static void __init smp_init_pseries(void) 193 { 194 int i; 195 196 pr_debug(" -> smp_init_pSeries()\n"); 197 198 /* Mark threads which are still spinning in hold loops. */ 199 if (cpu_has_feature(CPU_FTR_SMT)) { 200 for_each_present_cpu(i) { 201 if (cpu_thread_in_core(i) == 0) 202 cpu_set(i, of_spin_map); 203 } 204 } else { 205 of_spin_map = cpu_present_map; 206 } 207 208 cpu_clear(boot_cpuid, of_spin_map); 209 210 /* Non-lpar has additional take/give timebase */ 211 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 212 smp_ops->give_timebase = pSeries_give_timebase; 213 smp_ops->take_timebase = pSeries_take_timebase; 214 } 215 216 pr_debug(" <- smp_init_pSeries()\n"); 217 } 218 219 #ifdef CONFIG_MPIC 220 void __init smp_init_pseries_mpic(void) 221 { 222 smp_ops = &pSeries_mpic_smp_ops; 223 224 smp_init_pseries(); 225 } 226 #endif 227 228 void __init smp_init_pseries_xics(void) 229 { 230 smp_ops = &pSeries_xics_smp_ops; 231 232 smp_init_pseries(); 233 } 234