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 /* Fixup atomic count: it exited inside IRQ handler. */ 82 task_thread_info(paca_ptrs[lcpu]->__current)->preempt_count = 0; 83 84 /* 85 * If the RTAS start-cpu token does not exist then presume the 86 * cpu is already spinning. 87 */ 88 start_cpu = rtas_token("start-cpu"); 89 if (start_cpu == RTAS_UNKNOWN_SERVICE) 90 return 1; 91 92 status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, lcpu); 93 if (status != 0) { 94 printk(KERN_ERR "start-cpu failed: %i\n", status); 95 return 0; 96 } 97 98 return 1; 99 } 100 101 static void smp_cell_setup_cpu(int cpu) 102 { 103 if (cpu != boot_cpuid) 104 iic_setup_cpu(); 105 106 /* 107 * change default DABRX to allow user watchpoints 108 */ 109 mtspr(SPRN_DABRX, DABRX_KERNEL | DABRX_USER); 110 } 111 112 static int smp_cell_kick_cpu(int nr) 113 { 114 if (nr < 0 || nr >= nr_cpu_ids) 115 return -EINVAL; 116 117 if (!smp_startup_cpu(nr)) 118 return -ENOENT; 119 120 /* 121 * The processor is currently spinning, waiting for the 122 * cpu_start field to become non-zero After we set cpu_start, 123 * the processor will continue on to secondary_start 124 */ 125 paca_ptrs[nr]->cpu_start = 1; 126 127 return 0; 128 } 129 130 static struct smp_ops_t bpa_iic_smp_ops = { 131 .message_pass = iic_message_pass, 132 .probe = iic_request_IPIs, 133 .kick_cpu = smp_cell_kick_cpu, 134 .setup_cpu = smp_cell_setup_cpu, 135 .cpu_bootable = smp_generic_cpu_bootable, 136 }; 137 138 /* This is called very early */ 139 void __init smp_init_cell(void) 140 { 141 int i; 142 143 DBG(" -> smp_init_cell()\n"); 144 145 smp_ops = &bpa_iic_smp_ops; 146 147 /* Mark threads which are still spinning in hold loops. */ 148 if (cpu_has_feature(CPU_FTR_SMT)) { 149 for_each_present_cpu(i) { 150 if (cpu_thread_in_core(i) == 0) 151 cpumask_set_cpu(i, &of_spin_map); 152 } 153 } else 154 cpumask_copy(&of_spin_map, cpu_present_mask); 155 156 cpumask_clear_cpu(boot_cpuid, &of_spin_map); 157 158 /* Non-lpar has additional take/give timebase */ 159 if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) { 160 smp_ops->give_timebase = rtas_give_timebase; 161 smp_ops->take_timebase = rtas_take_timebase; 162 } 163 164 DBG(" <- smp_init_cell()\n"); 165 } 166