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