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/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/cputhreads.h> 45 46 #include "interrupt.h" 47 #include <asm/udbg.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 was started from the OF client 57 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. 58 */ 59 static cpumask_t of_spin_map; 60 61 /** 62 * smp_startup_cpu() - start the given cpu 63 * 64 * At boot time, there is nothing to do for primary threads which were 65 * started from Open Firmware. For anything else, call RTAS with the 66 * appropriate start location. 67 * 68 * Returns: 69 * 0 - failure 70 * 1 - success 71 */ 72 static inline int __devinit smp_startup_cpu(unsigned int lcpu) 73 { 74 int status; 75 unsigned long start_here = __pa((u32)*((unsigned long *) 76 generic_secondary_smp_init)); 77 unsigned int pcpu; 78 int start_cpu; 79 80 if (cpumask_test_cpu(lcpu, &of_spin_map)) 81 /* Already started by OF and sitting in spin loop */ 82 return 1; 83 84 pcpu = get_hard_smp_processor_id(lcpu); 85 86 /* Fixup atomic count: it exited inside IRQ handler. */ 87 task_thread_info(paca[lcpu].__current)->preempt_count = 0; 88 89 /* 90 * If the RTAS start-cpu token does not exist then presume the 91 * cpu is already spinning. 92 */ 93 start_cpu = rtas_token("start-cpu"); 94 if (start_cpu == RTAS_UNKNOWN_SERVICE) 95 return 1; 96 97 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 98 if (status != 0) { 99 printk(KERN_ERR "start-cpu failed: %i\n", status); 100 return 0; 101 } 102 103 return 1; 104 } 105 106 static int __init smp_iic_probe(void) 107 { 108 iic_request_IPIs(); 109 110 return cpumask_weight(cpu_possible_mask); 111 } 112 113 static void __devinit smp_cell_setup_cpu(int cpu) 114 { 115 if (cpu != boot_cpuid) 116 iic_setup_cpu(); 117 118 /* 119 * change default DABRX to allow user watchpoints 120 */ 121 mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER); 122 } 123 124 static int __devinit smp_cell_kick_cpu(int nr) 125 { 126 BUG_ON(nr < 0 || nr >= NR_CPUS); 127 128 if (!smp_startup_cpu(nr)) 129 return -ENOENT; 130 131 /* 132 * The processor is currently spinning, waiting for the 133 * cpu_start field to become non-zero After we set cpu_start, 134 * the processor will continue on to secondary_start 135 */ 136 paca[nr].cpu_start = 1; 137 138 return 0; 139 } 140 141 static int smp_cell_cpu_bootable(unsigned int nr) 142 { 143 /* Special case - we inhibit secondary thread startup 144 * during boot if the user requests it. Odd-numbered 145 * cpus are assumed to be secondary threads. 146 */ 147 if (system_state < SYSTEM_RUNNING && 148 cpu_has_feature(CPU_FTR_SMT) && 149 !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0) 150 return 0; 151 152 return 1; 153 } 154 static struct smp_ops_t bpa_iic_smp_ops = { 155 .message_pass = iic_message_pass, 156 .probe = smp_iic_probe, 157 .kick_cpu = smp_cell_kick_cpu, 158 .setup_cpu = smp_cell_setup_cpu, 159 .cpu_bootable = smp_cell_cpu_bootable, 160 }; 161 162 /* This is called very early */ 163 void __init smp_init_cell(void) 164 { 165 int i; 166 167 DBG(" -> smp_init_cell()\n"); 168 169 smp_ops = &bpa_iic_smp_ops; 170 171 /* Mark threads which are still spinning in hold loops. */ 172 if (cpu_has_feature(CPU_FTR_SMT)) { 173 for_each_present_cpu(i) { 174 if (cpu_thread_in_core(i) == 0) 175 cpumask_set_cpu(i, &of_spin_map); 176 } 177 } else 178 cpumask_copy(&of_spin_map, cpu_present_mask); 179 180 cpumask_clear_cpu(boot_cpuid, &of_spin_map); 181 182 /* Non-lpar has additional take/give timebase */ 183 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 184 smp_ops->give_timebase = rtas_give_timebase; 185 smp_ops->take_timebase = rtas_take_timebase; 186 } 187 188 DBG(" <- smp_init_cell()\n"); 189 } 190