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