1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/types.h>
3 #include <linux/kernel.h>
4 #include <linux/irq.h>
5 #include <linux/smp.h>
6 #include <linux/interrupt.h>
7 #include <linux/init.h>
8 #include <linux/cpu.h>
9 #include <linux/of.h>
10 #include <linux/spinlock.h>
11 #include <linux/msi.h>
12 
13 #include <asm/smp.h>
14 #include <asm/machdep.h>
15 #include <asm/irq.h>
16 #include <asm/errno.h>
17 #include <asm/xics.h>
18 #include <asm/rtas.h>
19 
20 /* RTAS service tokens */
21 static int ibm_get_xive;
22 static int ibm_set_xive;
23 static int ibm_int_on;
24 static int ibm_int_off;
25 
26 static void ics_rtas_unmask_irq(struct irq_data *d)
27 {
28 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
29 	int call_status;
30 	int server;
31 
32 	pr_devel("xics: unmask virq %d [hw 0x%x]\n", d->irq, hw_irq);
33 
34 	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
35 		return;
36 
37 	server = xics_get_irq_server(d->irq, irq_data_get_affinity_mask(d), 0);
38 
39 	call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq, server,
40 				DEFAULT_PRIORITY);
41 	if (call_status != 0) {
42 		printk(KERN_ERR
43 			"%s: ibm_set_xive irq %u server %x returned %d\n",
44 			__func__, hw_irq, server, call_status);
45 		return;
46 	}
47 
48 	/* Now unmask the interrupt (often a no-op) */
49 	call_status = rtas_call(ibm_int_on, 1, 1, NULL, hw_irq);
50 	if (call_status != 0) {
51 		printk(KERN_ERR "%s: ibm_int_on irq=%u returned %d\n",
52 			__func__, hw_irq, call_status);
53 		return;
54 	}
55 }
56 
57 static unsigned int ics_rtas_startup(struct irq_data *d)
58 {
59 	/* unmask it */
60 	ics_rtas_unmask_irq(d);
61 	return 0;
62 }
63 
64 static void ics_rtas_mask_real_irq(unsigned int hw_irq)
65 {
66 	int call_status;
67 
68 	if (hw_irq == XICS_IPI)
69 		return;
70 
71 	call_status = rtas_call(ibm_int_off, 1, 1, NULL, hw_irq);
72 	if (call_status != 0) {
73 		printk(KERN_ERR "%s: ibm_int_off irq=%u returned %d\n",
74 			__func__, hw_irq, call_status);
75 		return;
76 	}
77 
78 	/* Have to set XIVE to 0xff to be able to remove a slot */
79 	call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq,
80 				xics_default_server, 0xff);
81 	if (call_status != 0) {
82 		printk(KERN_ERR "%s: ibm_set_xive(0xff) irq=%u returned %d\n",
83 			__func__, hw_irq, call_status);
84 		return;
85 	}
86 }
87 
88 static void ics_rtas_mask_irq(struct irq_data *d)
89 {
90 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
91 
92 	pr_devel("xics: mask virq %d [hw 0x%x]\n", d->irq, hw_irq);
93 
94 	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
95 		return;
96 	ics_rtas_mask_real_irq(hw_irq);
97 }
98 
99 static int ics_rtas_set_affinity(struct irq_data *d,
100 				 const struct cpumask *cpumask,
101 				 bool force)
102 {
103 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
104 	int status;
105 	int xics_status[2];
106 	int irq_server;
107 
108 	if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS)
109 		return -1;
110 
111 	status = rtas_call(ibm_get_xive, 1, 3, xics_status, hw_irq);
112 
113 	if (status) {
114 		printk(KERN_ERR "%s: ibm,get-xive irq=%u returns %d\n",
115 			__func__, hw_irq, status);
116 		return -1;
117 	}
118 
119 	irq_server = xics_get_irq_server(d->irq, cpumask, 1);
120 	if (irq_server == -1) {
121 		pr_warn("%s: No online cpus in the mask %*pb for irq %d\n",
122 			__func__, cpumask_pr_args(cpumask), d->irq);
123 		return -1;
124 	}
125 
126 	pr_debug("%s: irq %d [hw 0x%x] server: 0x%x\n", __func__, d->irq,
127 		 hw_irq, irq_server);
128 
129 	status = rtas_call(ibm_set_xive, 3, 1, NULL,
130 			   hw_irq, irq_server, xics_status[1]);
131 
132 	if (status) {
133 		printk(KERN_ERR "%s: ibm,set-xive irq=%u returns %d\n",
134 			__func__, hw_irq, status);
135 		return -1;
136 	}
137 
138 	return IRQ_SET_MASK_OK;
139 }
140 
141 static struct irq_chip ics_rtas_irq_chip = {
142 	.name = "XICS",
143 	.irq_startup = ics_rtas_startup,
144 	.irq_mask = ics_rtas_mask_irq,
145 	.irq_unmask = ics_rtas_unmask_irq,
146 	.irq_eoi = NULL, /* Patched at init time */
147 	.irq_set_affinity = ics_rtas_set_affinity,
148 	.irq_set_type = xics_set_irq_type,
149 	.irq_retrigger = xics_retrigger,
150 };
151 
152 static int ics_rtas_check(struct ics *ics, unsigned int hw_irq)
153 {
154 	int status[2];
155 	int rc;
156 
157 	if (WARN_ON(hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS))
158 		return -EINVAL;
159 
160 	/* Check if RTAS knows about this interrupt */
161 	rc = rtas_call(ibm_get_xive, 1, 3, status, hw_irq);
162 	if (rc)
163 		return -ENXIO;
164 
165 	return 0;
166 }
167 
168 static void ics_rtas_mask_unknown(struct ics *ics, unsigned long vec)
169 {
170 	ics_rtas_mask_real_irq(vec);
171 }
172 
173 static long ics_rtas_get_server(struct ics *ics, unsigned long vec)
174 {
175 	int rc, status[2];
176 
177 	rc = rtas_call(ibm_get_xive, 1, 3, status, vec);
178 	if (rc)
179 		return -1;
180 	return status[0];
181 }
182 
183 static int ics_rtas_host_match(struct ics *ics, struct device_node *node)
184 {
185 	/* IBM machines have interrupt parents of various funky types for things
186 	 * like vdevices, events, etc... The trick we use here is to match
187 	 * everything here except the legacy 8259 which is compatible "chrp,iic"
188 	 */
189 	return !of_device_is_compatible(node, "chrp,iic");
190 }
191 
192 /* Only one global & state struct ics */
193 static struct ics ics_rtas = {
194 	.check		= ics_rtas_check,
195 	.mask_unknown	= ics_rtas_mask_unknown,
196 	.get_server	= ics_rtas_get_server,
197 	.host_match	= ics_rtas_host_match,
198 	.chip = &ics_rtas_irq_chip,
199 };
200 
201 __init int ics_rtas_init(void)
202 {
203 	ibm_get_xive = rtas_function_token(RTAS_FN_IBM_GET_XIVE);
204 	ibm_set_xive = rtas_function_token(RTAS_FN_IBM_SET_XIVE);
205 	ibm_int_on  = rtas_function_token(RTAS_FN_IBM_INT_ON);
206 	ibm_int_off = rtas_function_token(RTAS_FN_IBM_INT_OFF);
207 
208 	/* We enable the RTAS "ICS" if RTAS is present with the
209 	 * appropriate tokens
210 	 */
211 	if (ibm_get_xive == RTAS_UNKNOWN_SERVICE ||
212 	    ibm_set_xive == RTAS_UNKNOWN_SERVICE)
213 		return -ENODEV;
214 
215 	/* We need to patch our irq chip's EOI to point to the
216 	 * right ICP
217 	 */
218 	ics_rtas_irq_chip.irq_eoi = icp_ops->eoi;
219 
220 	/* Register ourselves */
221 	xics_register_ics(&ics_rtas);
222 
223 	return 0;
224 }
225 
226