1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/module.h>
4 #include <linux/init.h>
5 #include <linux/kernel.h>
6 #include <linux/mm.h>
7 #include <linux/sched.h>
8 #include <linux/kernel_stat.h>
9 #include <linux/notifier.h>
10 #include <linux/cpu.h>
11 #include <linux/percpu.h>
12 #include <linux/delay.h>
13 #include <linux/err.h>
14 #include <linux/irq.h>
15 #include <linux/irq_work.h>
16 #include <linux/irqdomain.h>
17 #include <linux/of.h>
18 #include <linux/seq_file.h>
19 #include <linux/sched/task_stack.h>
20 #include <linux/sched/mm.h>
21 #include <linux/sched/hotplug.h>
22 #include <asm/irq.h>
23 #include <asm/traps.h>
24 #include <asm/sections.h>
25 #include <asm/mmu_context.h>
26 #ifdef CONFIG_CPU_HAS_FPU
27 #include <abi/fpu.h>
28 #endif
29 
30 enum ipi_message_type {
31 	IPI_EMPTY,
32 	IPI_RESCHEDULE,
33 	IPI_CALL_FUNC,
34 	IPI_IRQ_WORK,
35 	IPI_MAX
36 };
37 
38 struct ipi_data_struct {
39 	unsigned long bits ____cacheline_aligned;
40 	unsigned long stats[IPI_MAX] ____cacheline_aligned;
41 };
42 static DEFINE_PER_CPU(struct ipi_data_struct, ipi_data);
43 
handle_ipi(int irq,void * dev)44 static irqreturn_t handle_ipi(int irq, void *dev)
45 {
46 	unsigned long *stats = this_cpu_ptr(&ipi_data)->stats;
47 
48 	while (true) {
49 		unsigned long ops;
50 
51 		ops = xchg(&this_cpu_ptr(&ipi_data)->bits, 0);
52 		if (ops == 0)
53 			return IRQ_HANDLED;
54 
55 		if (ops & (1 << IPI_RESCHEDULE)) {
56 			stats[IPI_RESCHEDULE]++;
57 			scheduler_ipi();
58 		}
59 
60 		if (ops & (1 << IPI_CALL_FUNC)) {
61 			stats[IPI_CALL_FUNC]++;
62 			generic_smp_call_function_interrupt();
63 		}
64 
65 		if (ops & (1 << IPI_IRQ_WORK)) {
66 			stats[IPI_IRQ_WORK]++;
67 			irq_work_run();
68 		}
69 
70 		BUG_ON((ops >> IPI_MAX) != 0);
71 	}
72 
73 	return IRQ_HANDLED;
74 }
75 
76 static void (*send_arch_ipi)(const struct cpumask *mask);
77 
78 static int ipi_irq;
set_send_ipi(void (* func)(const struct cpumask * mask),int irq)79 void __init set_send_ipi(void (*func)(const struct cpumask *mask), int irq)
80 {
81 	if (send_arch_ipi)
82 		return;
83 
84 	send_arch_ipi = func;
85 	ipi_irq = irq;
86 }
87 
88 static void
send_ipi_message(const struct cpumask * to_whom,enum ipi_message_type operation)89 send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation)
90 {
91 	int i;
92 
93 	for_each_cpu(i, to_whom)
94 		set_bit(operation, &per_cpu_ptr(&ipi_data, i)->bits);
95 
96 	smp_mb();
97 	send_arch_ipi(to_whom);
98 }
99 
100 static const char * const ipi_names[] = {
101 	[IPI_EMPTY]		= "Empty interrupts",
102 	[IPI_RESCHEDULE]	= "Rescheduling interrupts",
103 	[IPI_CALL_FUNC]		= "Function call interrupts",
104 	[IPI_IRQ_WORK]		= "Irq work interrupts",
105 };
106 
arch_show_interrupts(struct seq_file * p,int prec)107 int arch_show_interrupts(struct seq_file *p, int prec)
108 {
109 	unsigned int cpu, i;
110 
111 	for (i = 0; i < IPI_MAX; i++) {
112 		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
113 			   prec >= 4 ? " " : "");
114 		for_each_online_cpu(cpu)
115 			seq_printf(p, "%10lu ",
116 				per_cpu_ptr(&ipi_data, cpu)->stats[i]);
117 		seq_printf(p, " %s\n", ipi_names[i]);
118 	}
119 
120 	return 0;
121 }
122 
arch_send_call_function_ipi_mask(struct cpumask * mask)123 void arch_send_call_function_ipi_mask(struct cpumask *mask)
124 {
125 	send_ipi_message(mask, IPI_CALL_FUNC);
126 }
127 
arch_send_call_function_single_ipi(int cpu)128 void arch_send_call_function_single_ipi(int cpu)
129 {
130 	send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);
131 }
132 
ipi_stop(void * unused)133 static void ipi_stop(void *unused)
134 {
135 	while (1);
136 }
137 
smp_send_stop(void)138 void smp_send_stop(void)
139 {
140 	on_each_cpu(ipi_stop, NULL, 1);
141 }
142 
smp_send_reschedule(int cpu)143 void smp_send_reschedule(int cpu)
144 {
145 	send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
146 }
147 
148 #ifdef CONFIG_IRQ_WORK
arch_irq_work_raise(void)149 void arch_irq_work_raise(void)
150 {
151 	send_ipi_message(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
152 }
153 #endif
154 
smp_prepare_boot_cpu(void)155 void __init smp_prepare_boot_cpu(void)
156 {
157 }
158 
smp_prepare_cpus(unsigned int max_cpus)159 void __init smp_prepare_cpus(unsigned int max_cpus)
160 {
161 }
162 
163 static int ipi_dummy_dev;
164 
setup_smp_ipi(void)165 void __init setup_smp_ipi(void)
166 {
167 	int rc;
168 
169 	if (ipi_irq == 0)
170 		return;
171 
172 	rc = request_percpu_irq(ipi_irq, handle_ipi, "IPI Interrupt",
173 				&ipi_dummy_dev);
174 	if (rc)
175 		panic("%s IRQ request failed\n", __func__);
176 
177 	enable_percpu_irq(ipi_irq, 0);
178 }
179 
setup_smp(void)180 void __init setup_smp(void)
181 {
182 	struct device_node *node = NULL;
183 	int cpu;
184 
185 	for_each_of_cpu_node(node) {
186 		if (!of_device_is_available(node))
187 			continue;
188 
189 		if (of_property_read_u32(node, "reg", &cpu))
190 			continue;
191 
192 		if (cpu >= NR_CPUS)
193 			continue;
194 
195 		set_cpu_possible(cpu, true);
196 		set_cpu_present(cpu, true);
197 	}
198 }
199 
200 extern void _start_smp_secondary(void);
201 
202 volatile unsigned int secondary_hint;
203 volatile unsigned int secondary_hint2;
204 volatile unsigned int secondary_ccr;
205 volatile unsigned int secondary_stack;
206 volatile unsigned int secondary_msa1;
207 volatile unsigned int secondary_pgd;
208 
__cpu_up(unsigned int cpu,struct task_struct * tidle)209 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
210 {
211 	unsigned long mask = 1 << cpu;
212 
213 	secondary_stack =
214 		(unsigned int) task_stack_page(tidle) + THREAD_SIZE - 8;
215 	secondary_hint = mfcr("cr31");
216 	secondary_hint2 = mfcr("cr<21, 1>");
217 	secondary_ccr  = mfcr("cr18");
218 	secondary_msa1 = read_mmu_msa1();
219 	secondary_pgd = mfcr("cr<29, 15>");
220 
221 	/*
222 	 * Because other CPUs are in reset status, we must flush data
223 	 * from cache to out and secondary CPUs use them in
224 	 * csky_start_secondary(void)
225 	 */
226 	mtcr("cr17", 0x22);
227 
228 	if (mask & mfcr("cr<29, 0>")) {
229 		send_arch_ipi(cpumask_of(cpu));
230 	} else {
231 		/* Enable cpu in SMP reset ctrl reg */
232 		mask |= mfcr("cr<29, 0>");
233 		mtcr("cr<29, 0>", mask);
234 	}
235 
236 	/* Wait for the cpu online */
237 	while (!cpu_online(cpu));
238 
239 	secondary_stack = 0;
240 
241 	return 0;
242 }
243 
smp_cpus_done(unsigned int max_cpus)244 void __init smp_cpus_done(unsigned int max_cpus)
245 {
246 }
247 
setup_profiling_timer(unsigned int multiplier)248 int setup_profiling_timer(unsigned int multiplier)
249 {
250 	return -EINVAL;
251 }
252 
csky_start_secondary(void)253 void csky_start_secondary(void)
254 {
255 	struct mm_struct *mm = &init_mm;
256 	unsigned int cpu = smp_processor_id();
257 
258 	mtcr("cr31", secondary_hint);
259 	mtcr("cr<21, 1>", secondary_hint2);
260 	mtcr("cr18", secondary_ccr);
261 
262 	mtcr("vbr", vec_base);
263 
264 	flush_tlb_all();
265 	write_mmu_pagemask(0);
266 
267 #ifdef CONFIG_CPU_HAS_FPU
268 	init_fpu();
269 #endif
270 
271 	enable_percpu_irq(ipi_irq, 0);
272 
273 	mmget(mm);
274 	mmgrab(mm);
275 	current->active_mm = mm;
276 	cpumask_set_cpu(cpu, mm_cpumask(mm));
277 
278 	notify_cpu_starting(cpu);
279 	set_cpu_online(cpu, true);
280 
281 	pr_info("CPU%u Online: %s...\n", cpu, __func__);
282 
283 	local_irq_enable();
284 	preempt_disable();
285 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
286 }
287 
288 #ifdef CONFIG_HOTPLUG_CPU
__cpu_disable(void)289 int __cpu_disable(void)
290 {
291 	unsigned int cpu = smp_processor_id();
292 
293 	set_cpu_online(cpu, false);
294 
295 	irq_migrate_all_off_this_cpu();
296 
297 	clear_tasks_mm_cpumask(cpu);
298 
299 	return 0;
300 }
301 
__cpu_die(unsigned int cpu)302 void __cpu_die(unsigned int cpu)
303 {
304 	if (!cpu_wait_death(cpu, 5)) {
305 		pr_crit("CPU%u: shutdown failed\n", cpu);
306 		return;
307 	}
308 	pr_notice("CPU%u: shutdown\n", cpu);
309 }
310 
arch_cpu_idle_dead(void)311 void arch_cpu_idle_dead(void)
312 {
313 	idle_task_exit();
314 
315 	cpu_report_death();
316 
317 	while (!secondary_stack)
318 		arch_cpu_idle();
319 
320 	local_irq_disable();
321 
322 	asm volatile(
323 		"mov	sp, %0\n"
324 		"mov	r8, %0\n"
325 		"jmpi	csky_start_secondary"
326 		:
327 		: "r" (secondary_stack));
328 }
329 #endif
330