1 /*
2  * Copyright 2011 IBM Corporation.
3  *
4  *  This program is free software; you can redistribute it and/or
5  *  modify it under the terms of the GNU General Public License
6  *  as published by the Free Software Foundation; either version
7  *  2 of the License, or (at your option) any later version.
8  *
9  */
10 
11 #include <linux/types.h>
12 #include <linux/kernel.h>
13 #include <linux/irq.h>
14 #include <linux/smp.h>
15 #include <linux/interrupt.h>
16 #include <linux/init.h>
17 #include <linux/cpu.h>
18 #include <linux/of.h>
19 #include <linux/spinlock.h>
20 #include <linux/module.h>
21 
22 #include <asm/prom.h>
23 #include <asm/io.h>
24 #include <asm/smp.h>
25 #include <asm/irq.h>
26 #include <asm/errno.h>
27 #include <asm/xics.h>
28 #include <asm/kvm_ppc.h>
29 
30 struct icp_ipl {
31 	union {
32 		u32 word;
33 		u8 bytes[4];
34 	} xirr_poll;
35 	union {
36 		u32 word;
37 		u8 bytes[4];
38 	} xirr;
39 	u32 dummy;
40 	union {
41 		u32 word;
42 		u8 bytes[4];
43 	} qirr;
44 	u32 link_a;
45 	u32 link_b;
46 	u32 link_c;
47 };
48 
49 static struct icp_ipl __iomem *icp_native_regs[NR_CPUS];
50 
51 static inline unsigned int icp_native_get_xirr(void)
52 {
53 	int cpu = smp_processor_id();
54 	unsigned int xirr;
55 
56 	/* Handled an interrupt latched by KVM */
57 	xirr = kvmppc_get_xics_latch();
58 	if (xirr)
59 		return xirr;
60 
61 	return in_be32(&icp_native_regs[cpu]->xirr.word);
62 }
63 
64 static inline void icp_native_set_xirr(unsigned int value)
65 {
66 	int cpu = smp_processor_id();
67 
68 	out_be32(&icp_native_regs[cpu]->xirr.word, value);
69 }
70 
71 static inline void icp_native_set_cppr(u8 value)
72 {
73 	int cpu = smp_processor_id();
74 
75 	out_8(&icp_native_regs[cpu]->xirr.bytes[0], value);
76 }
77 
78 static inline void icp_native_set_qirr(int n_cpu, u8 value)
79 {
80 	out_8(&icp_native_regs[n_cpu]->qirr.bytes[0], value);
81 }
82 
83 static void icp_native_set_cpu_priority(unsigned char cppr)
84 {
85 	xics_set_base_cppr(cppr);
86 	icp_native_set_cppr(cppr);
87 	iosync();
88 }
89 
90 void icp_native_eoi(struct irq_data *d)
91 {
92 	unsigned int hw_irq = (unsigned int)irqd_to_hwirq(d);
93 
94 	iosync();
95 	icp_native_set_xirr((xics_pop_cppr() << 24) | hw_irq);
96 }
97 
98 static void icp_native_teardown_cpu(void)
99 {
100 	int cpu = smp_processor_id();
101 
102 	/* Clear any pending IPI */
103 	icp_native_set_qirr(cpu, 0xff);
104 }
105 
106 static void icp_native_flush_ipi(void)
107 {
108 	/* We take the ipi irq but and never return so we
109 	 * need to EOI the IPI, but want to leave our priority 0
110 	 *
111 	 * should we check all the other interrupts too?
112 	 * should we be flagging idle loop instead?
113 	 * or creating some task to be scheduled?
114 	 */
115 
116 	icp_native_set_xirr((0x00 << 24) | XICS_IPI);
117 }
118 
119 static unsigned int icp_native_get_irq(void)
120 {
121 	unsigned int xirr = icp_native_get_xirr();
122 	unsigned int vec = xirr & 0x00ffffff;
123 	unsigned int irq;
124 
125 	if (vec == XICS_IRQ_SPURIOUS)
126 		return NO_IRQ;
127 
128 	irq = irq_find_mapping(xics_host, vec);
129 	if (likely(irq != NO_IRQ)) {
130 		xics_push_cppr(vec);
131 		return irq;
132 	}
133 
134 	/* We don't have a linux mapping, so have rtas mask it. */
135 	xics_mask_unknown_vec(vec);
136 
137 	/* We might learn about it later, so EOI it */
138 	icp_native_set_xirr(xirr);
139 
140 	return NO_IRQ;
141 }
142 
143 #ifdef CONFIG_SMP
144 
145 static void icp_native_cause_ipi(int cpu, unsigned long data)
146 {
147 	kvmppc_set_host_ipi(cpu, 1);
148 	icp_native_set_qirr(cpu, IPI_PRIORITY);
149 }
150 
151 void xics_wake_cpu(int cpu)
152 {
153 	icp_native_set_qirr(cpu, IPI_PRIORITY);
154 }
155 EXPORT_SYMBOL_GPL(xics_wake_cpu);
156 
157 static irqreturn_t icp_native_ipi_action(int irq, void *dev_id)
158 {
159 	int cpu = smp_processor_id();
160 
161 	kvmppc_set_host_ipi(cpu, 0);
162 	icp_native_set_qirr(cpu, 0xff);
163 
164 	return smp_ipi_demux();
165 }
166 
167 #endif /* CONFIG_SMP */
168 
169 static int __init icp_native_map_one_cpu(int hw_id, unsigned long addr,
170 					 unsigned long size)
171 {
172 	char *rname;
173 	int i, cpu = -1;
174 
175 	/* This may look gross but it's good enough for now, we don't quite
176 	 * have a hard -> linux processor id matching.
177 	 */
178 	for_each_possible_cpu(i) {
179 		if (!cpu_present(i))
180 			continue;
181 		if (hw_id == get_hard_smp_processor_id(i)) {
182 			cpu = i;
183 			break;
184 		}
185 	}
186 
187 	/* Fail, skip that CPU. Don't print, it's normal, some XICS come up
188 	 * with way more entries in there than you have CPUs
189 	 */
190 	if (cpu == -1)
191 		return 0;
192 
193 	rname = kasprintf(GFP_KERNEL, "CPU %d [0x%x] Interrupt Presentation",
194 			  cpu, hw_id);
195 
196 	if (!request_mem_region(addr, size, rname)) {
197 		pr_warning("icp_native: Could not reserve ICP MMIO"
198 			   " for CPU %d, interrupt server #0x%x\n",
199 			   cpu, hw_id);
200 		return -EBUSY;
201 	}
202 
203 	icp_native_regs[cpu] = ioremap(addr, size);
204 	kvmppc_set_xics_phys(cpu, addr);
205 	if (!icp_native_regs[cpu]) {
206 		pr_warning("icp_native: Failed ioremap for CPU %d, "
207 			   "interrupt server #0x%x, addr %#lx\n",
208 			   cpu, hw_id, addr);
209 		release_mem_region(addr, size);
210 		return -ENOMEM;
211 	}
212 	return 0;
213 }
214 
215 static int __init icp_native_init_one_node(struct device_node *np,
216 					   unsigned int *indx)
217 {
218 	unsigned int ilen;
219 	const u32 *ireg;
220 	int i;
221 	int reg_tuple_size;
222 	int num_servers = 0;
223 
224 	/* This code does the theorically broken assumption that the interrupt
225 	 * server numbers are the same as the hard CPU numbers.
226 	 * This happens to be the case so far but we are playing with fire...
227 	 * should be fixed one of these days. -BenH.
228 	 */
229 	ireg = of_get_property(np, "ibm,interrupt-server-ranges", &ilen);
230 
231 	/* Do that ever happen ? we'll know soon enough... but even good'old
232 	 * f80 does have that property ..
233 	 */
234 	WARN_ON((ireg == NULL) || (ilen != 2*sizeof(u32)));
235 
236 	if (ireg) {
237 		*indx = of_read_number(ireg, 1);
238 		if (ilen >= 2*sizeof(u32))
239 			num_servers = of_read_number(ireg + 1, 1);
240 	}
241 
242 	ireg = of_get_property(np, "reg", &ilen);
243 	if (!ireg) {
244 		pr_err("icp_native: Can't find interrupt reg property");
245 		return -1;
246 	}
247 
248 	reg_tuple_size = (of_n_addr_cells(np) + of_n_size_cells(np)) * 4;
249 	if (((ilen % reg_tuple_size) != 0)
250 	    || (num_servers && (num_servers != (ilen / reg_tuple_size)))) {
251 		pr_err("icp_native: ICP reg len (%d) != num servers (%d)",
252 		       ilen / reg_tuple_size, num_servers);
253 		return -1;
254 	}
255 
256 	for (i = 0; i < (ilen / reg_tuple_size); i++) {
257 		struct resource r;
258 		int err;
259 
260 		err = of_address_to_resource(np, i, &r);
261 		if (err) {
262 			pr_err("icp_native: Could not translate ICP MMIO"
263 			       " for interrupt server 0x%x (%d)\n", *indx, err);
264 			return -1;
265 		}
266 
267 		if (icp_native_map_one_cpu(*indx, r.start, resource_size(&r)))
268 			return -1;
269 
270 		(*indx)++;
271 	}
272 	return 0;
273 }
274 
275 static const struct icp_ops icp_native_ops = {
276 	.get_irq	= icp_native_get_irq,
277 	.eoi		= icp_native_eoi,
278 	.set_priority	= icp_native_set_cpu_priority,
279 	.teardown_cpu	= icp_native_teardown_cpu,
280 	.flush_ipi	= icp_native_flush_ipi,
281 #ifdef CONFIG_SMP
282 	.ipi_action	= icp_native_ipi_action,
283 	.cause_ipi	= icp_native_cause_ipi,
284 #endif
285 };
286 
287 int __init icp_native_init(void)
288 {
289 	struct device_node *np;
290 	u32 indx = 0;
291 	int found = 0;
292 
293 	for_each_compatible_node(np, NULL, "ibm,ppc-xicp")
294 		if (icp_native_init_one_node(np, &indx) == 0)
295 			found = 1;
296 	if (!found) {
297 		for_each_node_by_type(np,
298 			"PowerPC-External-Interrupt-Presentation") {
299 				if (icp_native_init_one_node(np, &indx) == 0)
300 					found = 1;
301 		}
302 	}
303 
304 	if (found == 0)
305 		return -ENODEV;
306 
307 	icp_ops = &icp_native_ops;
308 
309 	return 0;
310 }
311