1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright 2001 MontaVista Software Inc.
4  * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
5  *
6  * Copyright (C) 2001 Ralf Baechle
7  * Copyright (C) 2005  MIPS Technologies, Inc.	All rights reserved.
8  *	Author: Maciej W. Rozycki <macro@mips.com>
9  *
10  * This file define the irq handler for MIPS CPU interrupts.
11  */
12 
13 /*
14  * Almost all MIPS CPUs define 8 interrupt sources.  They are typically
15  * level triggered (i.e., cannot be cleared from CPU; must be cleared from
16  * device).
17  *
18  * The first two are software interrupts (i.e. not exposed as pins) which
19  * may be used for IPIs in multi-threaded single-core systems.
20  *
21  * The last one is usually the CPU timer interrupt if the counter register
22  * is present, or for old CPUs with an external FPU by convention it's the
23  * FPU exception interrupt.
24  */
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <linux/kernel.h>
28 #include <linux/irq.h>
29 #include <linux/irqchip.h>
30 #include <linux/irqdomain.h>
31 
32 #include <asm/irq_cpu.h>
33 #include <asm/mipsregs.h>
34 #include <asm/mipsmtregs.h>
35 #include <asm/setup.h>
36 
37 static struct irq_domain *irq_domain;
38 static struct irq_domain *ipi_domain;
39 
40 static inline void unmask_mips_irq(struct irq_data *d)
41 {
42 	set_c0_status(IE_SW0 << d->hwirq);
43 	irq_enable_hazard();
44 }
45 
46 static inline void mask_mips_irq(struct irq_data *d)
47 {
48 	clear_c0_status(IE_SW0 << d->hwirq);
49 	irq_disable_hazard();
50 }
51 
52 static struct irq_chip mips_cpu_irq_controller = {
53 	.name		= "MIPS",
54 	.irq_ack	= mask_mips_irq,
55 	.irq_mask	= mask_mips_irq,
56 	.irq_mask_ack	= mask_mips_irq,
57 	.irq_unmask	= unmask_mips_irq,
58 	.irq_eoi	= unmask_mips_irq,
59 	.irq_disable	= mask_mips_irq,
60 	.irq_enable	= unmask_mips_irq,
61 };
62 
63 /*
64  * Basically the same as above but taking care of all the MT stuff
65  */
66 
67 static unsigned int mips_mt_cpu_irq_startup(struct irq_data *d)
68 {
69 	unsigned int vpflags = dvpe();
70 
71 	clear_c0_cause(C_SW0 << d->hwirq);
72 	evpe(vpflags);
73 	unmask_mips_irq(d);
74 	return 0;
75 }
76 
77 /*
78  * While we ack the interrupt interrupts are disabled and thus we don't need
79  * to deal with concurrency issues.  Same for mips_cpu_irq_end.
80  */
81 static void mips_mt_cpu_irq_ack(struct irq_data *d)
82 {
83 	unsigned int vpflags = dvpe();
84 	clear_c0_cause(C_SW0 << d->hwirq);
85 	evpe(vpflags);
86 	mask_mips_irq(d);
87 }
88 
89 #ifdef CONFIG_GENERIC_IRQ_IPI
90 
91 static void mips_mt_send_ipi(struct irq_data *d, unsigned int cpu)
92 {
93 	irq_hw_number_t hwirq = irqd_to_hwirq(d);
94 	unsigned long flags;
95 	int vpflags;
96 
97 	local_irq_save(flags);
98 
99 	/* We can only send IPIs to VPEs within the local core */
100 	WARN_ON(!cpus_are_siblings(smp_processor_id(), cpu));
101 
102 	vpflags = dvpe();
103 	settc(cpu_vpe_id(&cpu_data[cpu]));
104 	write_vpe_c0_cause(read_vpe_c0_cause() | (C_SW0 << hwirq));
105 	evpe(vpflags);
106 
107 	local_irq_restore(flags);
108 }
109 
110 #endif /* CONFIG_GENERIC_IRQ_IPI */
111 
112 static struct irq_chip mips_mt_cpu_irq_controller = {
113 	.name		= "MIPS",
114 	.irq_startup	= mips_mt_cpu_irq_startup,
115 	.irq_ack	= mips_mt_cpu_irq_ack,
116 	.irq_mask	= mask_mips_irq,
117 	.irq_mask_ack	= mips_mt_cpu_irq_ack,
118 	.irq_unmask	= unmask_mips_irq,
119 	.irq_eoi	= unmask_mips_irq,
120 	.irq_disable	= mask_mips_irq,
121 	.irq_enable	= unmask_mips_irq,
122 #ifdef CONFIG_GENERIC_IRQ_IPI
123 	.ipi_send_single = mips_mt_send_ipi,
124 #endif
125 };
126 
127 asmlinkage void __weak plat_irq_dispatch(void)
128 {
129 	unsigned long pending = read_c0_cause() & read_c0_status() & ST0_IM;
130 	unsigned int virq;
131 	int irq;
132 
133 	if (!pending) {
134 		spurious_interrupt();
135 		return;
136 	}
137 
138 	pending >>= CAUSEB_IP;
139 	while (pending) {
140 		irq = fls(pending) - 1;
141 		if (IS_ENABLED(CONFIG_GENERIC_IRQ_IPI) && irq < 2)
142 			virq = irq_linear_revmap(ipi_domain, irq);
143 		else
144 			virq = irq_linear_revmap(irq_domain, irq);
145 		do_IRQ(virq);
146 		pending &= ~BIT(irq);
147 	}
148 }
149 
150 static int mips_cpu_intc_map(struct irq_domain *d, unsigned int irq,
151 			     irq_hw_number_t hw)
152 {
153 	struct irq_chip *chip;
154 
155 	if (hw < 2 && cpu_has_mipsmt) {
156 		/* Software interrupts are used for MT/CMT IPI */
157 		chip = &mips_mt_cpu_irq_controller;
158 	} else {
159 		chip = &mips_cpu_irq_controller;
160 	}
161 
162 	if (cpu_has_vint)
163 		set_vi_handler(hw, plat_irq_dispatch);
164 
165 	irq_set_chip_and_handler(irq, chip, handle_percpu_irq);
166 
167 	return 0;
168 }
169 
170 static const struct irq_domain_ops mips_cpu_intc_irq_domain_ops = {
171 	.map = mips_cpu_intc_map,
172 	.xlate = irq_domain_xlate_onecell,
173 };
174 
175 #ifdef CONFIG_GENERIC_IRQ_IPI
176 
177 struct cpu_ipi_domain_state {
178 	DECLARE_BITMAP(allocated, 2);
179 };
180 
181 static int mips_cpu_ipi_alloc(struct irq_domain *domain, unsigned int virq,
182 			      unsigned int nr_irqs, void *arg)
183 {
184 	struct cpu_ipi_domain_state *state = domain->host_data;
185 	unsigned int i, hwirq;
186 	int ret;
187 
188 	for (i = 0; i < nr_irqs; i++) {
189 		hwirq = find_first_zero_bit(state->allocated, 2);
190 		if (hwirq == 2)
191 			return -EBUSY;
192 		bitmap_set(state->allocated, hwirq, 1);
193 
194 		ret = irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq,
195 						    &mips_mt_cpu_irq_controller,
196 						    NULL);
197 		if (ret)
198 			return ret;
199 
200 		ret = irq_domain_set_hwirq_and_chip(domain->parent, virq + i, hwirq,
201 						    &mips_mt_cpu_irq_controller,
202 						    NULL);
203 
204 		if (ret)
205 			return ret;
206 
207 		ret = irq_set_irq_type(virq + i, IRQ_TYPE_LEVEL_HIGH);
208 		if (ret)
209 			return ret;
210 	}
211 
212 	return 0;
213 }
214 
215 static int mips_cpu_ipi_match(struct irq_domain *d, struct device_node *node,
216 			      enum irq_domain_bus_token bus_token)
217 {
218 	bool is_ipi;
219 
220 	switch (bus_token) {
221 	case DOMAIN_BUS_IPI:
222 		is_ipi = d->bus_token == bus_token;
223 		return (!node || (to_of_node(d->fwnode) == node)) && is_ipi;
224 	default:
225 		return 0;
226 	}
227 }
228 
229 static const struct irq_domain_ops mips_cpu_ipi_chip_ops = {
230 	.alloc	= mips_cpu_ipi_alloc,
231 	.match	= mips_cpu_ipi_match,
232 };
233 
234 static void mips_cpu_register_ipi_domain(struct device_node *of_node)
235 {
236 	struct cpu_ipi_domain_state *ipi_domain_state;
237 
238 	ipi_domain_state = kzalloc(sizeof(*ipi_domain_state), GFP_KERNEL);
239 	ipi_domain = irq_domain_add_hierarchy(irq_domain,
240 					      IRQ_DOMAIN_FLAG_IPI_SINGLE,
241 					      2, of_node,
242 					      &mips_cpu_ipi_chip_ops,
243 					      ipi_domain_state);
244 	if (!ipi_domain)
245 		panic("Failed to add MIPS CPU IPI domain");
246 	irq_domain_update_bus_token(ipi_domain, DOMAIN_BUS_IPI);
247 }
248 
249 #else /* !CONFIG_GENERIC_IRQ_IPI */
250 
251 static inline void mips_cpu_register_ipi_domain(struct device_node *of_node) {}
252 
253 #endif /* !CONFIG_GENERIC_IRQ_IPI */
254 
255 static void __init __mips_cpu_irq_init(struct device_node *of_node)
256 {
257 	/* Mask interrupts. */
258 	clear_c0_status(ST0_IM);
259 	clear_c0_cause(CAUSEF_IP);
260 
261 	irq_domain = irq_domain_add_legacy(of_node, 8, MIPS_CPU_IRQ_BASE, 0,
262 					   &mips_cpu_intc_irq_domain_ops,
263 					   NULL);
264 	if (!irq_domain)
265 		panic("Failed to add irqdomain for MIPS CPU");
266 
267 	/*
268 	 * Only proceed to register the software interrupt IPI implementation
269 	 * for CPUs which implement the MIPS MT (multi-threading) ASE.
270 	 */
271 	if (cpu_has_mipsmt)
272 		mips_cpu_register_ipi_domain(of_node);
273 }
274 
275 void __init mips_cpu_irq_init(void)
276 {
277 	__mips_cpu_irq_init(NULL);
278 }
279 
280 int __init mips_cpu_irq_of_init(struct device_node *of_node,
281 				struct device_node *parent)
282 {
283 	__mips_cpu_irq_init(of_node);
284 	return 0;
285 }
286 IRQCHIP_DECLARE(cpu_intc, "mti,cpu-interrupt-controller", mips_cpu_irq_of_init);
287