1 /*
2  * ICS backend for OPAL managed interrupts.
3  *
4  * Copyright 2011 IBM Corp.
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #undef DEBUG
13 
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/irq.h>
17 #include <linux/smp.h>
18 #include <linux/interrupt.h>
19 #include <linux/init.h>
20 #include <linux/cpu.h>
21 #include <linux/of.h>
22 #include <linux/spinlock.h>
23 #include <linux/msi.h>
24 
25 #include <asm/prom.h>
26 #include <asm/smp.h>
27 #include <asm/machdep.h>
28 #include <asm/irq.h>
29 #include <asm/errno.h>
30 #include <asm/xics.h>
31 #include <asm/opal.h>
32 #include <asm/firmware.h>
33 
34 static int ics_opal_mangle_server(int server)
35 {
36 	/* No link for now */
37 	return server << 2;
38 }
39 
40 static int ics_opal_unmangle_server(int server)
41 {
42 	/* No link for now */
43 	return server >> 2;
44 }
45 
46 static void ics_opal_unmask_irq(struct irq_data *d)
47 {
48 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
49 	int64_t rc;
50 	int server;
51 
52 	pr_devel("ics-hal: unmask virq %d [hw 0x%x]\n", d->irq, hw_irq);
53 
54 	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
55 		return;
56 
57 	server = xics_get_irq_server(d->irq, d->affinity, 0);
58 	server = ics_opal_mangle_server(server);
59 
60 	rc = opal_set_xive(hw_irq, server, DEFAULT_PRIORITY);
61 	if (rc != OPAL_SUCCESS)
62 		pr_err("%s: opal_set_xive(irq=%d [hw 0x%x] server=%x)"
63 		       " error %lld\n",
64 		       __func__, d->irq, hw_irq, server, rc);
65 }
66 
67 static unsigned int ics_opal_startup(struct irq_data *d)
68 {
69 #ifdef CONFIG_PCI_MSI
70 	/*
71 	 * The generic MSI code returns with the interrupt disabled on the
72 	 * card, using the MSI mask bits. Firmware doesn't appear to unmask
73 	 * at that level, so we do it here by hand.
74 	 */
75 	if (d->msi_desc)
76 		pci_msi_unmask_irq(d);
77 #endif
78 
79 	/* unmask it */
80 	ics_opal_unmask_irq(d);
81 	return 0;
82 }
83 
84 static void ics_opal_mask_real_irq(unsigned int hw_irq)
85 {
86 	int server = ics_opal_mangle_server(xics_default_server);
87 	int64_t rc;
88 
89 	if (hw_irq == XICS_IPI)
90 		return;
91 
92 	/* Have to set XIVE to 0xff to be able to remove a slot */
93 	rc = opal_set_xive(hw_irq, server, 0xff);
94 	if (rc != OPAL_SUCCESS)
95 		pr_err("%s: opal_set_xive(0xff) irq=%u returned %lld\n",
96 		       __func__, hw_irq, rc);
97 }
98 
99 static void ics_opal_mask_irq(struct irq_data *d)
100 {
101 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
102 
103 	pr_devel("ics-hal: mask virq %d [hw 0x%x]\n", d->irq, hw_irq);
104 
105 	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
106 		return;
107 	ics_opal_mask_real_irq(hw_irq);
108 }
109 
110 static int ics_opal_set_affinity(struct irq_data *d,
111 				 const struct cpumask *cpumask,
112 				 bool force)
113 {
114 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
115 	__be16 oserver;
116 	int16_t server;
117 	int8_t priority;
118 	int64_t rc;
119 	int wanted_server;
120 
121 	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
122 		return -1;
123 
124 	rc = opal_get_xive(hw_irq, &oserver, &priority);
125 	if (rc != OPAL_SUCCESS) {
126 		pr_err("%s: opal_get_xive(irq=%d [hw 0x%x]) error %lld\n",
127 		       __func__, d->irq, hw_irq, rc);
128 		return -1;
129 	}
130 	server = be16_to_cpu(oserver);
131 
132 	wanted_server = xics_get_irq_server(d->irq, cpumask, 1);
133 	if (wanted_server < 0) {
134 		pr_warning("%s: No online cpus in the mask %*pb for irq %d\n",
135 			   __func__, cpumask_pr_args(cpumask), d->irq);
136 		return -1;
137 	}
138 	server = ics_opal_mangle_server(wanted_server);
139 
140 	pr_devel("ics-hal: set-affinity irq %d [hw 0x%x] server: 0x%x/0x%x\n",
141 		 d->irq, hw_irq, wanted_server, server);
142 
143 	rc = opal_set_xive(hw_irq, server, priority);
144 	if (rc != OPAL_SUCCESS) {
145 		pr_err("%s: opal_set_xive(irq=%d [hw 0x%x] server=%x)"
146 		       " error %lld\n",
147 		       __func__, d->irq, hw_irq, server, rc);
148 		return -1;
149 	}
150 	return IRQ_SET_MASK_OK;
151 }
152 
153 static struct irq_chip ics_opal_irq_chip = {
154 	.name = "OPAL ICS",
155 	.irq_startup = ics_opal_startup,
156 	.irq_mask = ics_opal_mask_irq,
157 	.irq_unmask = ics_opal_unmask_irq,
158 	.irq_eoi = NULL, /* Patched at init time */
159 	.irq_set_affinity = ics_opal_set_affinity
160 };
161 
162 static int ics_opal_map(struct ics *ics, unsigned int virq);
163 static void ics_opal_mask_unknown(struct ics *ics, unsigned long vec);
164 static long ics_opal_get_server(struct ics *ics, unsigned long vec);
165 
166 static int ics_opal_host_match(struct ics *ics, struct device_node *node)
167 {
168 	return 1;
169 }
170 
171 /* Only one global & state struct ics */
172 static struct ics ics_hal = {
173 	.map		= ics_opal_map,
174 	.mask_unknown	= ics_opal_mask_unknown,
175 	.get_server	= ics_opal_get_server,
176 	.host_match	= ics_opal_host_match,
177 };
178 
179 static int ics_opal_map(struct ics *ics, unsigned int virq)
180 {
181 	unsigned int hw_irq = (unsigned int)virq_to_hw(virq);
182 	int64_t rc;
183 	__be16 server;
184 	int8_t priority;
185 
186 	if (WARN_ON(hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS))
187 		return -EINVAL;
188 
189 	/* Check if HAL knows about this interrupt */
190 	rc = opal_get_xive(hw_irq, &server, &priority);
191 	if (rc != OPAL_SUCCESS)
192 		return -ENXIO;
193 
194 	irq_set_chip_and_handler(virq, &ics_opal_irq_chip, handle_fasteoi_irq);
195 	irq_set_chip_data(virq, &ics_hal);
196 
197 	return 0;
198 }
199 
200 static void ics_opal_mask_unknown(struct ics *ics, unsigned long vec)
201 {
202 	int64_t rc;
203 	__be16 server;
204 	int8_t priority;
205 
206 	/* Check if HAL knows about this interrupt */
207 	rc = opal_get_xive(vec, &server, &priority);
208 	if (rc != OPAL_SUCCESS)
209 		return;
210 
211 	ics_opal_mask_real_irq(vec);
212 }
213 
214 static long ics_opal_get_server(struct ics *ics, unsigned long vec)
215 {
216 	int64_t rc;
217 	__be16 server;
218 	int8_t priority;
219 
220 	/* Check if HAL knows about this interrupt */
221 	rc = opal_get_xive(vec, &server, &priority);
222 	if (rc != OPAL_SUCCESS)
223 		return -1;
224 	return ics_opal_unmangle_server(be16_to_cpu(server));
225 }
226 
227 int __init ics_opal_init(void)
228 {
229 	if (!firmware_has_feature(FW_FEATURE_OPAL))
230 		return -ENODEV;
231 
232 	/* We need to patch our irq chip's EOI to point to the
233 	 * right ICP
234 	 */
235 	ics_opal_irq_chip.irq_eoi = icp_ops->eoi;
236 
237 	/* Register ourselves */
238 	xics_register_ics(&ics_hal);
239 
240 	pr_info("ICS OPAL backend registered\n");
241 
242 	return 0;
243 }
244