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 #include <asm/cputhreads.h> 46 47 #include "interrupt.h" 48 #include <asm/udbg.h> 49 50 #ifdef DEBUG 51 #define DBG(fmt...) udbg_printf(fmt) 52 #else 53 #define DBG(fmt...) 54 #endif 55 56 /* 57 * The primary thread of each non-boot processor is recorded here before 58 * smp init. 59 */ 60 static cpumask_t of_spin_map; 61 62 extern void generic_secondary_smp_init(unsigned long); 63 64 /** 65 * smp_startup_cpu() - start the given cpu 66 * 67 * At boot time, there is nothing to do for primary threads which were 68 * started from Open Firmware. For anything else, call RTAS with the 69 * appropriate start location. 70 * 71 * Returns: 72 * 0 - failure 73 * 1 - success 74 */ 75 static inline int __devinit smp_startup_cpu(unsigned int lcpu) 76 { 77 int status; 78 unsigned long start_here = __pa((u32)*((unsigned long *) 79 generic_secondary_smp_init)); 80 unsigned int pcpu; 81 int start_cpu; 82 83 if (cpu_isset(lcpu, of_spin_map)) 84 /* Already started by OF and sitting in spin loop */ 85 return 1; 86 87 pcpu = get_hard_smp_processor_id(lcpu); 88 89 /* Fixup atomic count: it exited inside IRQ handler. */ 90 task_thread_info(paca[lcpu].__current)->preempt_count = 0; 91 92 /* 93 * If the RTAS start-cpu token does not exist then presume the 94 * cpu is already spinning. 95 */ 96 start_cpu = rtas_token("start-cpu"); 97 if (start_cpu == RTAS_UNKNOWN_SERVICE) 98 return 1; 99 100 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 101 if (status != 0) { 102 printk(KERN_ERR "start-cpu failed: %i\n", status); 103 return 0; 104 } 105 106 return 1; 107 } 108 109 static void smp_iic_message_pass(int target, int msg) 110 { 111 unsigned int i; 112 113 if (target < NR_CPUS) { 114 iic_cause_IPI(target, msg); 115 } else { 116 for_each_online_cpu(i) { 117 if (target == MSG_ALL_BUT_SELF 118 && i == smp_processor_id()) 119 continue; 120 iic_cause_IPI(i, msg); 121 } 122 } 123 } 124 125 static int __init smp_iic_probe(void) 126 { 127 iic_request_IPIs(); 128 129 return cpus_weight(cpu_possible_map); 130 } 131 132 static void __devinit smp_iic_setup_cpu(int cpu) 133 { 134 if (cpu != boot_cpuid) 135 iic_setup_cpu(); 136 } 137 138 static DEFINE_SPINLOCK(timebase_lock); 139 static unsigned long timebase = 0; 140 141 static void __devinit cell_give_timebase(void) 142 { 143 spin_lock(&timebase_lock); 144 rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL); 145 timebase = get_tb(); 146 spin_unlock(&timebase_lock); 147 148 while (timebase) 149 barrier(); 150 rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL); 151 } 152 153 static void __devinit cell_take_timebase(void) 154 { 155 while (!timebase) 156 barrier(); 157 spin_lock(&timebase_lock); 158 set_tb(timebase >> 32, timebase & 0xffffffff); 159 timebase = 0; 160 spin_unlock(&timebase_lock); 161 } 162 163 static void __devinit smp_cell_kick_cpu(int nr) 164 { 165 BUG_ON(nr < 0 || nr >= NR_CPUS); 166 167 if (!smp_startup_cpu(nr)) 168 return; 169 170 /* 171 * The processor is currently spinning, waiting for the 172 * cpu_start field to become non-zero After we set cpu_start, 173 * the processor will continue on to secondary_start 174 */ 175 paca[nr].cpu_start = 1; 176 } 177 178 static int smp_cell_cpu_bootable(unsigned int nr) 179 { 180 /* Special case - we inhibit secondary thread startup 181 * during boot if the user requests it. Odd-numbered 182 * cpus are assumed to be secondary threads. 183 */ 184 if (system_state < SYSTEM_RUNNING && 185 cpu_has_feature(CPU_FTR_SMT) && 186 !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0) 187 return 0; 188 189 return 1; 190 } 191 static struct smp_ops_t bpa_iic_smp_ops = { 192 .message_pass = smp_iic_message_pass, 193 .probe = smp_iic_probe, 194 .kick_cpu = smp_cell_kick_cpu, 195 .setup_cpu = smp_iic_setup_cpu, 196 .cpu_bootable = smp_cell_cpu_bootable, 197 }; 198 199 /* This is called very early */ 200 void __init smp_init_cell(void) 201 { 202 int i; 203 204 DBG(" -> smp_init_cell()\n"); 205 206 smp_ops = &bpa_iic_smp_ops; 207 208 /* Mark threads which are still spinning in hold loops. */ 209 if (cpu_has_feature(CPU_FTR_SMT)) { 210 for_each_present_cpu(i) { 211 if (i % 2 == 0) 212 /* 213 * Even-numbered logical cpus correspond to 214 * primary threads. 215 */ 216 cpu_set(i, of_spin_map); 217 } 218 } else { 219 of_spin_map = cpu_present_map; 220 } 221 222 cpu_clear(boot_cpuid, of_spin_map); 223 224 /* Non-lpar has additional take/give timebase */ 225 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 226 smp_ops->give_timebase = cell_give_timebase; 227 smp_ops->take_timebase = cell_take_timebase; 228 } 229 230 DBG(" <- smp_init_cell()\n"); 231 } 232