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/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/device.h> 27 #include <linux/cpu.h> 28 29 #include <asm/ptrace.h> 30 #include <linux/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/machdep.h> 39 #include <asm/cputable.h> 40 #include <asm/firmware.h> 41 #include <asm/rtas.h> 42 #include <asm/cputhreads.h> 43 44 #include "interrupt.h" 45 #include <asm/udbg.h> 46 47 #ifdef DEBUG 48 #define DBG(fmt...) udbg_printf(fmt) 49 #else 50 #define DBG(fmt...) 51 #endif 52 53 /* 54 * The Primary thread of each non-boot processor was started from the OF client 55 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. 56 */ 57 static cpumask_t of_spin_map; 58 59 /** 60 * smp_startup_cpu() - start the given cpu 61 * 62 * At boot time, there is nothing to do for primary threads which were 63 * started from Open Firmware. For anything else, call RTAS with the 64 * appropriate start location. 65 * 66 * Returns: 67 * 0 - failure 68 * 1 - success 69 */ 70 static inline int __devinit smp_startup_cpu(unsigned int lcpu) 71 { 72 int status; 73 unsigned long start_here = __pa((u32)*((unsigned long *) 74 generic_secondary_smp_init)); 75 unsigned int pcpu; 76 int start_cpu; 77 78 if (cpumask_test_cpu(lcpu, &of_spin_map)) 79 /* Already started by OF and sitting in spin loop */ 80 return 1; 81 82 pcpu = get_hard_smp_processor_id(lcpu); 83 84 /* Fixup atomic count: it exited inside IRQ handler. */ 85 task_thread_info(paca[lcpu].__current)->preempt_count = 0; 86 87 /* 88 * If the RTAS start-cpu token does not exist then presume the 89 * cpu is already spinning. 90 */ 91 start_cpu = rtas_token("start-cpu"); 92 if (start_cpu == RTAS_UNKNOWN_SERVICE) 93 return 1; 94 95 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 96 if (status != 0) { 97 printk(KERN_ERR "start-cpu failed: %i\n", status); 98 return 0; 99 } 100 101 return 1; 102 } 103 104 static int __init smp_iic_probe(void) 105 { 106 iic_request_IPIs(); 107 108 return cpumask_weight(cpu_possible_mask); 109 } 110 111 static void __devinit smp_cell_setup_cpu(int cpu) 112 { 113 if (cpu != boot_cpuid) 114 iic_setup_cpu(); 115 116 /* 117 * change default DABRX to allow user watchpoints 118 */ 119 mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER); 120 } 121 122 static int __devinit smp_cell_kick_cpu(int nr) 123 { 124 BUG_ON(nr < 0 || nr >= NR_CPUS); 125 126 if (!smp_startup_cpu(nr)) 127 return -ENOENT; 128 129 /* 130 * The processor is currently spinning, waiting for the 131 * cpu_start field to become non-zero After we set cpu_start, 132 * the processor will continue on to secondary_start 133 */ 134 paca[nr].cpu_start = 1; 135 136 return 0; 137 } 138 139 static int smp_cell_cpu_bootable(unsigned int nr) 140 { 141 /* Special case - we inhibit secondary thread startup 142 * during boot if the user requests it. Odd-numbered 143 * cpus are assumed to be secondary threads. 144 */ 145 if (system_state < SYSTEM_RUNNING && 146 cpu_has_feature(CPU_FTR_SMT) && 147 !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0) 148 return 0; 149 150 return 1; 151 } 152 static struct smp_ops_t bpa_iic_smp_ops = { 153 .message_pass = iic_message_pass, 154 .probe = smp_iic_probe, 155 .kick_cpu = smp_cell_kick_cpu, 156 .setup_cpu = smp_cell_setup_cpu, 157 .cpu_bootable = smp_cell_cpu_bootable, 158 }; 159 160 /* This is called very early */ 161 void __init smp_init_cell(void) 162 { 163 int i; 164 165 DBG(" -> smp_init_cell()\n"); 166 167 smp_ops = &bpa_iic_smp_ops; 168 169 /* Mark threads which are still spinning in hold loops. */ 170 if (cpu_has_feature(CPU_FTR_SMT)) { 171 for_each_present_cpu(i) { 172 if (cpu_thread_in_core(i) == 0) 173 cpumask_set_cpu(i, &of_spin_map); 174 } 175 } else 176 cpumask_copy(&of_spin_map, cpu_present_mask); 177 178 cpumask_clear_cpu(boot_cpuid, &of_spin_map); 179 180 /* Non-lpar has additional take/give timebase */ 181 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 182 smp_ops->give_timebase = rtas_give_timebase; 183 smp_ops->take_timebase = rtas_take_timebase; 184 } 185 186 DBG(" <- smp_init_cell()\n"); 187 } 188