1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * SMP support for BPA machines. 4 * 5 * Dave Engebretsen, Peter Bergner, and 6 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com 7 * 8 * Plus various changes from other IBM teams... 9 */ 10 11 #undef DEBUG 12 13 #include <linux/kernel.h> 14 #include <linux/sched.h> 15 #include <linux/smp.h> 16 #include <linux/interrupt.h> 17 #include <linux/delay.h> 18 #include <linux/init.h> 19 #include <linux/spinlock.h> 20 #include <linux/cache.h> 21 #include <linux/err.h> 22 #include <linux/device.h> 23 #include <linux/cpu.h> 24 #include <linux/pgtable.h> 25 26 #include <asm/ptrace.h> 27 #include <linux/atomic.h> 28 #include <asm/irq.h> 29 #include <asm/page.h> 30 #include <asm/io.h> 31 #include <asm/prom.h> 32 #include <asm/smp.h> 33 #include <asm/paca.h> 34 #include <asm/machdep.h> 35 #include <asm/cputable.h> 36 #include <asm/firmware.h> 37 #include <asm/rtas.h> 38 #include <asm/cputhreads.h> 39 #include <asm/code-patching.h> 40 41 #include "interrupt.h" 42 #include <asm/udbg.h> 43 44 #ifdef DEBUG 45 #define DBG(fmt...) udbg_printf(fmt) 46 #else 47 #define DBG(fmt...) 48 #endif 49 50 /* 51 * The Primary thread of each non-boot processor was started from the OF client 52 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop. 53 */ 54 static cpumask_t of_spin_map; 55 56 /** 57 * smp_startup_cpu() - start the given cpu 58 * 59 * At boot time, there is nothing to do for primary threads which were 60 * started from Open Firmware. For anything else, call RTAS with the 61 * appropriate start location. 62 * 63 * Returns: 64 * 0 - failure 65 * 1 - success 66 */ 67 static inline int smp_startup_cpu(unsigned int lcpu) 68 { 69 int status; 70 unsigned long start_here = 71 __pa(ppc_function_entry(generic_secondary_smp_init)); 72 unsigned int pcpu; 73 int start_cpu; 74 75 if (cpumask_test_cpu(lcpu, &of_spin_map)) 76 /* Already started by OF and sitting in spin loop */ 77 return 1; 78 79 pcpu = get_hard_smp_processor_id(lcpu); 80 81 /* 82 * If the RTAS start-cpu token does not exist then presume the 83 * cpu is already spinning. 84 */ 85 start_cpu = rtas_token("start-cpu"); 86 if (start_cpu == RTAS_UNKNOWN_SERVICE) 87 return 1; 88 89 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 90 if (status != 0) { 91 printk(KERN_ERR "start-cpu failed: %i\n", status); 92 return 0; 93 } 94 95 return 1; 96 } 97 98 static void smp_cell_setup_cpu(int cpu) 99 { 100 if (cpu != boot_cpuid) 101 iic_setup_cpu(); 102 103 /* 104 * change default DABRX to allow user watchpoints 105 */ 106 mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER); 107 } 108 109 static int smp_cell_kick_cpu(int nr) 110 { 111 if (nr < 0 || nr >= nr_cpu_ids) 112 return -EINVAL; 113 114 if (!smp_startup_cpu(nr)) 115 return -ENOENT; 116 117 /* 118 * The processor is currently spinning, waiting for the 119 * cpu_start field to become non-zero After we set cpu_start, 120 * the processor will continue on to secondary_start 121 */ 122 paca_ptrs[nr]->cpu_start = 1; 123 124 return 0; 125 } 126 127 static struct smp_ops_t bpa_iic_smp_ops = { 128 .message_pass = iic_message_pass, 129 .probe = iic_request_IPIs, 130 .kick_cpu = smp_cell_kick_cpu, 131 .setup_cpu = smp_cell_setup_cpu, 132 .cpu_bootable = smp_generic_cpu_bootable, 133 }; 134 135 /* This is called very early */ 136 void __init smp_init_cell(void) 137 { 138 int i; 139 140 DBG(" -> smp_init_cell()\n"); 141 142 smp_ops = &bpa_iic_smp_ops; 143 144 /* Mark threads which are still spinning in hold loops. */ 145 if (cpu_has_feature(CPU_FTR_SMT)) { 146 for_each_present_cpu(i) { 147 if (cpu_thread_in_core(i) == 0) 148 cpumask_set_cpu(i, &of_spin_map); 149 } 150 } else 151 cpumask_copy(&of_spin_map, cpu_present_mask); 152 153 cpumask_clear_cpu(boot_cpuid, &of_spin_map); 154 155 /* Non-lpar has additional take/give timebase */ 156 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 157 smp_ops->give_timebase = rtas_give_timebase; 158 smp_ops->take_timebase = rtas_take_timebase; 159 } 160 161 DBG(" <- smp_init_cell()\n"); 162 } 163