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
 23enum ipi_message_type {
 24	IPI_RESCHEDULE,
 25	IPI_CALL_FUNC,
 26	IPI_CPU_STOP,
 27	IPI_MAX
 28};
 29
 30unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
 31	[0 ... NR_CPUS-1] = INVALID_HARTID
 32};
 33
 34void __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.  */
 40static struct {
 41	unsigned long stats[IPI_MAX] ____cacheline_aligned;
 42	unsigned long bits ____cacheline_aligned;
 43} ipi_data[NR_CPUS] __cacheline_aligned;
 44
 45int 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
 57void 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
 66bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 67{
 68	return phys_id == cpuid_to_hartid_map(cpu);
 69}
 70
 71/* Unsupported */
 72int setup_profiling_timer(unsigned int multiplier)
 73{
 74	return -EINVAL;
 75}
 76
 77static void ipi_stop(void)
 78{
 79	set_cpu_online(smp_processor_id(), false);
 80	while (1)
 81		wait_for_interrupt();
 82}
 83
 84static 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
 98static 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
109static inline void clear_ipi(void)
110{
111	csr_clear(CSR_SIP, SIE_SSIE);
112}
113
114void 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
153static 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
159void 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
172void arch_send_call_function_ipi_mask(struct cpumask *mask)
173{
174	send_ipi_mask(mask, IPI_CALL_FUNC);
175}
176
177void arch_send_call_function_single_ipi(int cpu)
178{
179	send_ipi_single(cpu, IPI_CALL_FUNC);
180}
181
182void 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
207void smp_send_reschedule(int cpu)
208{
209	send_ipi_single(cpu, IPI_RESCHEDULE);
210}
211EXPORT_SYMBOL_GPL(smp_send_reschedule);