xref: /openbmc/linux/arch/sh/kernel/cpu/sh2/smp-j2.c (revision 4bdc0d67)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SMP support for J2 processor
4  *
5  * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.
6  */
7 
8 #include <linux/smp.h>
9 #include <linux/interrupt.h>
10 #include <linux/io.h>
11 #include <linux/of_address.h>
12 #include <linux/of_irq.h>
13 #include <asm/cmpxchg.h>
14 
15 DEFINE_PER_CPU(unsigned, j2_ipi_messages);
16 
17 extern u32 *sh2_cpuid_addr;
18 static u32 *j2_ipi_trigger;
19 static int j2_ipi_irq;
20 
j2_ipi_interrupt_handler(int irq,void * arg)21 static irqreturn_t j2_ipi_interrupt_handler(int irq, void *arg)
22 {
23 	unsigned cpu = hard_smp_processor_id();
24 	volatile unsigned *pmsg = &per_cpu(j2_ipi_messages, cpu);
25 	unsigned messages, i;
26 
27 	do messages = *pmsg;
28 	while (cmpxchg(pmsg, messages, 0) != messages);
29 
30 	if (!messages) return IRQ_NONE;
31 
32 	for (i=0; i<SMP_MSG_NR; i++)
33 		if (messages & (1U<<i))
34 			smp_message_recv(i);
35 
36 	return IRQ_HANDLED;
37 }
38 
j2_smp_setup(void)39 static void j2_smp_setup(void)
40 {
41 }
42 
j2_prepare_cpus(unsigned int max_cpus)43 static void j2_prepare_cpus(unsigned int max_cpus)
44 {
45 	struct device_node *np;
46 	unsigned i, max = 1;
47 
48 	np = of_find_compatible_node(NULL, NULL, "jcore,ipi-controller");
49 	if (!np)
50 		goto out;
51 
52 	j2_ipi_irq = irq_of_parse_and_map(np, 0);
53 	j2_ipi_trigger = of_iomap(np, 0);
54 	if (!j2_ipi_irq || !j2_ipi_trigger)
55 		goto out;
56 
57 	np = of_find_compatible_node(NULL, NULL, "jcore,cpuid-mmio");
58 	if (!np)
59 		goto out;
60 
61 	sh2_cpuid_addr = of_iomap(np, 0);
62 	if (!sh2_cpuid_addr)
63 		goto out;
64 
65 	if (request_irq(j2_ipi_irq, j2_ipi_interrupt_handler, IRQF_PERCPU,
66 			"ipi", (void *)j2_ipi_interrupt_handler) != 0)
67 		goto out;
68 
69 	max = max_cpus;
70 out:
71 	/* Disable any cpus past max_cpus, or all secondaries if we didn't
72 	 * get the necessary resources to support SMP. */
73 	for (i=max; i<NR_CPUS; i++) {
74 		set_cpu_possible(i, false);
75 		set_cpu_present(i, false);
76 	}
77 }
78 
j2_start_cpu(unsigned int cpu,unsigned long entry_point)79 static void j2_start_cpu(unsigned int cpu, unsigned long entry_point)
80 {
81 	struct device_node *np;
82 	u32 regs[2];
83 	void __iomem *release, *initpc;
84 
85 	if (!cpu) return;
86 
87 	np = of_get_cpu_node(cpu, NULL);
88 	if (!np) return;
89 
90 	if (of_property_read_u32_array(np, "cpu-release-addr", regs, 2)) return;
91 	release = ioremap(regs[0], sizeof(u32));
92 	initpc = ioremap(regs[1], sizeof(u32));
93 
94 	__raw_writel(entry_point, initpc);
95 	__raw_writel(1, release);
96 
97 	iounmap(initpc);
98 	iounmap(release);
99 
100 	pr_info("J2 SMP: requested start of cpu %u\n", cpu);
101 }
102 
j2_smp_processor_id(void)103 static unsigned int j2_smp_processor_id(void)
104 {
105 	return __raw_readl(sh2_cpuid_addr);
106 }
107 
j2_send_ipi(unsigned int cpu,unsigned int message)108 static void j2_send_ipi(unsigned int cpu, unsigned int message)
109 {
110 	volatile unsigned *pmsg;
111 	unsigned old;
112 	unsigned long val;
113 
114 	/* There is only one IPI interrupt shared by all messages, so
115 	 * we keep a separate interrupt flag per message type in sw. */
116 	pmsg = &per_cpu(j2_ipi_messages, cpu);
117 	do old = *pmsg;
118 	while (cmpxchg(pmsg, old, old|(1U<<message)) != old);
119 
120 	/* Generate the actual interrupt by writing to CCRn bit 28. */
121 	val = __raw_readl(j2_ipi_trigger + cpu);
122 	__raw_writel(val | (1U<<28), j2_ipi_trigger + cpu);
123 }
124 
125 static struct plat_smp_ops j2_smp_ops = {
126 	.smp_setup		= j2_smp_setup,
127 	.prepare_cpus		= j2_prepare_cpus,
128 	.start_cpu		= j2_start_cpu,
129 	.smp_processor_id	= j2_smp_processor_id,
130 	.send_ipi		= j2_send_ipi,
131 	.cpu_die		= native_cpu_die,
132 	.cpu_disable		= native_cpu_disable,
133 	.play_dead		= native_play_dead,
134 };
135 
136 CPU_METHOD_OF_DECLARE(j2_cpu_method, "jcore,spin-table", &j2_smp_ops);
137