1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * SMP initialisation and IPI support 4 * Based on arch/arm64/kernel/smp.c 5 * 6 * Copyright (C) 2012 ARM Ltd. 7 * Copyright (C) 2015 Regents of the University of California 8 * Copyright (C) 2017 SiFive 9 */ 10 11 #include <linux/cpu.h> 12 #include <linux/interrupt.h> 13 #include <linux/profile.h> 14 #include <linux/smp.h> 15 #include <linux/sched.h> 16 #include <linux/seq_file.h> 17 #include <linux/delay.h> 18 19 #include <asm/sbi.h> 20 #include <asm/tlbflush.h> 21 #include <asm/cacheflush.h> 22 23 enum ipi_message_type { 24 IPI_RESCHEDULE, 25 IPI_CALL_FUNC, 26 IPI_CPU_STOP, 27 IPI_MAX 28 }; 29 30 unsigned long __cpuid_to_hartid_map[NR_CPUS] = { 31 [0 ... NR_CPUS-1] = INVALID_HARTID 32 }; 33 34 void __init smp_setup_processor_id(void) 35 { 36 cpuid_to_hartid_map(0) = boot_cpu_hartid; 37 } 38 39 /* A collection of single bit ipi messages. */ 40 static struct { 41 unsigned long stats[IPI_MAX] ____cacheline_aligned; 42 unsigned long bits ____cacheline_aligned; 43 } ipi_data[NR_CPUS] __cacheline_aligned; 44 45 int riscv_hartid_to_cpuid(int hartid) 46 { 47 int i; 48 49 for (i = 0; i < NR_CPUS; i++) 50 if (cpuid_to_hartid_map(i) == hartid) 51 return i; 52 53 pr_err("Couldn't find cpu id for hartid [%d]\n", hartid); 54 return i; 55 } 56 57 void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out) 58 { 59 int cpu; 60 61 cpumask_clear(out); 62 for_each_cpu(cpu, in) 63 cpumask_set_cpu(cpuid_to_hartid_map(cpu), out); 64 } 65 66 bool arch_match_cpu_phys_id(int cpu, u64 phys_id) 67 { 68 return phys_id == cpuid_to_hartid_map(cpu); 69 } 70 71 /* Unsupported */ 72 int setup_profiling_timer(unsigned int multiplier) 73 { 74 return -EINVAL; 75 } 76 77 static void ipi_stop(void) 78 { 79 set_cpu_online(smp_processor_id(), false); 80 while (1) 81 wait_for_interrupt(); 82 } 83 84 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op) 85 { 86 struct cpumask hartid_mask; 87 int cpu; 88 89 smp_mb__before_atomic(); 90 for_each_cpu(cpu, mask) 91 set_bit(op, &ipi_data[cpu].bits); 92 smp_mb__after_atomic(); 93 94 riscv_cpuid_to_hartid_mask(mask, &hartid_mask); 95 sbi_send_ipi(cpumask_bits(&hartid_mask)); 96 } 97 98 static void send_ipi_single(int cpu, enum ipi_message_type op) 99 { 100 int hartid = cpuid_to_hartid_map(cpu); 101 102 smp_mb__before_atomic(); 103 set_bit(op, &ipi_data[cpu].bits); 104 smp_mb__after_atomic(); 105 106 sbi_send_ipi(cpumask_bits(cpumask_of(hartid))); 107 } 108 109 static inline void clear_ipi(void) 110 { 111 csr_clear(CSR_SIP, SIE_SSIE); 112 } 113 114 void riscv_software_interrupt(void) 115 { 116 unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits; 117 unsigned long *stats = ipi_data[smp_processor_id()].stats; 118 119 clear_ipi(); 120 121 while (true) { 122 unsigned long ops; 123 124 /* Order bit clearing and data access. */ 125 mb(); 126 127 ops = xchg(pending_ipis, 0); 128 if (ops == 0) 129 return; 130 131 if (ops & (1 << IPI_RESCHEDULE)) { 132 stats[IPI_RESCHEDULE]++; 133 scheduler_ipi(); 134 } 135 136 if (ops & (1 << IPI_CALL_FUNC)) { 137 stats[IPI_CALL_FUNC]++; 138 generic_smp_call_function_interrupt(); 139 } 140 141 if (ops & (1 << IPI_CPU_STOP)) { 142 stats[IPI_CPU_STOP]++; 143 ipi_stop(); 144 } 145 146 BUG_ON((ops >> IPI_MAX) != 0); 147 148 /* Order data access and bit testing. */ 149 mb(); 150 } 151 } 152 153 static const char * const ipi_names[] = { 154 [IPI_RESCHEDULE] = "Rescheduling interrupts", 155 [IPI_CALL_FUNC] = "Function call interrupts", 156 [IPI_CPU_STOP] = "CPU stop interrupts", 157 }; 158 159 void show_ipi_stats(struct seq_file *p, int prec) 160 { 161 unsigned int cpu, i; 162 163 for (i = 0; i < IPI_MAX; i++) { 164 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i, 165 prec >= 4 ? " " : ""); 166 for_each_online_cpu(cpu) 167 seq_printf(p, "%10lu ", ipi_data[cpu].stats[i]); 168 seq_printf(p, " %s\n", ipi_names[i]); 169 } 170 } 171 172 void arch_send_call_function_ipi_mask(struct cpumask *mask) 173 { 174 send_ipi_mask(mask, IPI_CALL_FUNC); 175 } 176 177 void arch_send_call_function_single_ipi(int cpu) 178 { 179 send_ipi_single(cpu, IPI_CALL_FUNC); 180 } 181 182 void smp_send_stop(void) 183 { 184 unsigned long timeout; 185 186 if (num_online_cpus() > 1) { 187 cpumask_t mask; 188 189 cpumask_copy(&mask, cpu_online_mask); 190 cpumask_clear_cpu(smp_processor_id(), &mask); 191 192 if (system_state <= SYSTEM_RUNNING) 193 pr_crit("SMP: stopping secondary CPUs\n"); 194 send_ipi_mask(&mask, IPI_CPU_STOP); 195 } 196 197 /* Wait up to one second for other CPUs to stop */ 198 timeout = USEC_PER_SEC; 199 while (num_online_cpus() > 1 && timeout--) 200 udelay(1); 201 202 if (num_online_cpus() > 1) 203 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", 204 cpumask_pr_args(cpu_online_mask)); 205 } 206 207 void smp_send_reschedule(int cpu) 208 { 209 send_ipi_single(cpu, IPI_RESCHEDULE); 210 } 211 EXPORT_SYMBOL_GPL(smp_send_reschedule); 212