1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright 2016 IBM Corporation.
4  */
5 #include <linux/types.h>
6 #include <linux/kernel.h>
7 #include <linux/irq.h>
8 #include <linux/smp.h>
9 #include <linux/interrupt.h>
10 #include <linux/cpu.h>
11 #include <linux/of.h>
12 
13 #include <asm/smp.h>
14 #include <asm/irq.h>
15 #include <asm/errno.h>
16 #include <asm/xics.h>
17 #include <asm/io.h>
18 #include <asm/opal.h>
19 #include <asm/kvm_ppc.h>
20 
21 static void icp_opal_teardown_cpu(void)
22 {
23 	int hw_cpu = hard_smp_processor_id();
24 
25 	/* Clear any pending IPI */
26 	opal_int_set_mfrr(hw_cpu, 0xff);
27 }
28 
29 static void icp_opal_flush_ipi(void)
30 {
31 	/*
32 	 * We take the ipi irq but and never return so we need to EOI the IPI,
33 	 * but want to leave our priority 0.
34 	 *
35 	 * Should we check all the other interrupts too?
36 	 * Should we be flagging idle loop instead?
37 	 * Or creating some task to be scheduled?
38 	 */
39 	if (opal_int_eoi((0x00 << 24) | XICS_IPI) > 0)
40 		force_external_irq_replay();
41 }
42 
43 static unsigned int icp_opal_get_xirr(void)
44 {
45 	unsigned int kvm_xirr;
46 	__be32 hw_xirr;
47 	int64_t rc;
48 
49 	/* Handle an interrupt latched by KVM first */
50 	kvm_xirr = kvmppc_get_xics_latch();
51 	if (kvm_xirr)
52 		return kvm_xirr;
53 
54 	/* Then ask OPAL */
55 	rc = opal_int_get_xirr(&hw_xirr, false);
56 	if (rc < 0)
57 		return 0;
58 	return be32_to_cpu(hw_xirr);
59 }
60 
61 static unsigned int icp_opal_get_irq(void)
62 {
63 	unsigned int xirr;
64 	unsigned int vec;
65 	unsigned int irq;
66 
67 	xirr = icp_opal_get_xirr();
68 	vec = xirr & 0x00ffffff;
69 	if (vec == XICS_IRQ_SPURIOUS)
70 		return 0;
71 
72 	irq = irq_find_mapping(xics_host, vec);
73 	if (likely(irq)) {
74 		xics_push_cppr(vec);
75 		return irq;
76 	}
77 
78 	/* We don't have a linux mapping, so have rtas mask it. */
79 	xics_mask_unknown_vec(vec);
80 
81 	/* We might learn about it later, so EOI it */
82 	if (opal_int_eoi(xirr) > 0)
83 		force_external_irq_replay();
84 
85 	return 0;
86 }
87 
88 static void icp_opal_set_cpu_priority(unsigned char cppr)
89 {
90 	/*
91 	 * Here be dragons. The caller has asked to allow only IPI's and not
92 	 * external interrupts. But OPAL XIVE doesn't support that. So instead
93 	 * of allowing no interrupts allow all. That's still not right, but
94 	 * currently the only caller who does this is xics_migrate_irqs_away()
95 	 * and it works in that case.
96 	 */
97 	if (cppr >= DEFAULT_PRIORITY)
98 		cppr = LOWEST_PRIORITY;
99 
100 	xics_set_base_cppr(cppr);
101 	opal_int_set_cppr(cppr);
102 	iosync();
103 }
104 
105 static void icp_opal_eoi(struct irq_data *d)
106 {
107 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
108 	int64_t rc;
109 
110 	iosync();
111 	rc = opal_int_eoi((xics_pop_cppr() << 24) | hw_irq);
112 
113 	/*
114 	 * EOI tells us whether there are more interrupts to fetch.
115 	 *
116 	 * Some HW implementations might not be able to send us another
117 	 * external interrupt in that case, so we force a replay.
118 	 */
119 	if (rc > 0)
120 		force_external_irq_replay();
121 }
122 
123 #ifdef CONFIG_SMP
124 
125 static void icp_opal_cause_ipi(int cpu)
126 {
127 	int hw_cpu = get_hard_smp_processor_id(cpu);
128 
129 	kvmppc_set_host_ipi(cpu);
130 	opal_int_set_mfrr(hw_cpu, IPI_PRIORITY);
131 }
132 
133 static irqreturn_t icp_opal_ipi_action(int irq, void *dev_id)
134 {
135 	int cpu = smp_processor_id();
136 
137 	kvmppc_clear_host_ipi(cpu);
138 	opal_int_set_mfrr(get_hard_smp_processor_id(cpu), 0xff);
139 
140 	return smp_ipi_demux();
141 }
142 
143 /*
144  * Called when an interrupt is received on an off-line CPU to
145  * clear the interrupt, so that the CPU can go back to nap mode.
146  */
147 void icp_opal_flush_interrupt(void)
148 {
149 	unsigned int xirr;
150 	unsigned int vec;
151 
152 	do {
153 		xirr = icp_opal_get_xirr();
154 		vec = xirr & 0x00ffffff;
155 		if (vec == XICS_IRQ_SPURIOUS)
156 			break;
157 		if (vec == XICS_IPI) {
158 			/* Clear pending IPI */
159 			int cpu = smp_processor_id();
160 			kvmppc_clear_host_ipi(cpu);
161 			opal_int_set_mfrr(get_hard_smp_processor_id(cpu), 0xff);
162 		} else {
163 			pr_err("XICS: hw interrupt 0x%x to offline cpu, "
164 			       "disabling\n", vec);
165 			xics_mask_unknown_vec(vec);
166 		}
167 
168 		/* EOI the interrupt */
169 	} while (opal_int_eoi(xirr) > 0);
170 }
171 
172 #endif /* CONFIG_SMP */
173 
174 static const struct icp_ops icp_opal_ops = {
175 	.get_irq	= icp_opal_get_irq,
176 	.eoi		= icp_opal_eoi,
177 	.set_priority	= icp_opal_set_cpu_priority,
178 	.teardown_cpu	= icp_opal_teardown_cpu,
179 	.flush_ipi	= icp_opal_flush_ipi,
180 #ifdef CONFIG_SMP
181 	.ipi_action	= icp_opal_ipi_action,
182 	.cause_ipi	= icp_opal_cause_ipi,
183 #endif
184 };
185 
186 int icp_opal_init(void)
187 {
188 	struct device_node *np;
189 
190 	np = of_find_compatible_node(NULL, NULL, "ibm,opal-intc");
191 	if (!np)
192 		return -ENODEV;
193 
194 	icp_ops = &icp_opal_ops;
195 
196 	printk("XICS: Using OPAL ICP fallbacks\n");
197 
198 	return 0;
199 }
200 
201