1 /*
2  * SMP support for pSeries machines.
3  *
4  * Dave Engebretsen, Peter Bergner, and
5  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
6  *
7  * Plus various changes from other IBM teams...
8  *
9  *      This program is free software; you can redistribute it and/or
10  *      modify it under the terms of the GNU General Public License
11  *      as published by the Free Software Foundation; either version
12  *      2 of the License, or (at your option) any later version.
13  */
14 
15 
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/sched.h>
19 #include <linux/smp.h>
20 #include <linux/interrupt.h>
21 #include <linux/delay.h>
22 #include <linux/init.h>
23 #include <linux/spinlock.h>
24 #include <linux/cache.h>
25 #include <linux/err.h>
26 #include <linux/sysdev.h>
27 #include <linux/cpu.h>
28 
29 #include <asm/ptrace.h>
30 #include <asm/atomic.h>
31 #include <asm/irq.h>
32 #include <asm/page.h>
33 #include <asm/pgtable.h>
34 #include <asm/io.h>
35 #include <asm/prom.h>
36 #include <asm/smp.h>
37 #include <asm/paca.h>
38 #include <asm/time.h>
39 #include <asm/machdep.h>
40 #include "xics.h"
41 #include <asm/cputable.h>
42 #include <asm/firmware.h>
43 #include <asm/system.h>
44 #include <asm/rtas.h>
45 #include <asm/pSeries_reconfig.h>
46 #include <asm/mpic.h>
47 #include <asm/vdso_datapage.h>
48 #include <asm/cputhreads.h>
49 
50 #include "plpar_wrappers.h"
51 #include "pseries.h"
52 
53 
54 /*
55  * The primary thread of each non-boot processor is recorded here before
56  * smp init.
57  */
58 static cpumask_t of_spin_map;
59 
60 extern void generic_secondary_smp_init(unsigned long);
61 
62 /**
63  * smp_startup_cpu() - start the given cpu
64  *
65  * At boot time, there is nothing to do for primary threads which were
66  * started from Open Firmware.  For anything else, call RTAS with the
67  * appropriate start location.
68  *
69  * Returns:
70  *	0	- failure
71  *	1	- success
72  */
73 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
74 {
75 	int status;
76 	unsigned long start_here = __pa((u32)*((unsigned long *)
77 					       generic_secondary_smp_init));
78 	unsigned int pcpu;
79 	int start_cpu;
80 
81 	if (cpu_isset(lcpu, of_spin_map))
82 		/* Already started by OF and sitting in spin loop */
83 		return 1;
84 
85 	pcpu = get_hard_smp_processor_id(lcpu);
86 
87 	/* Fixup atomic count: it exited inside IRQ handler. */
88 	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
89 
90 	/*
91 	 * If the RTAS start-cpu token does not exist then presume the
92 	 * cpu is already spinning.
93 	 */
94 	start_cpu = rtas_token("start-cpu");
95 	if (start_cpu == RTAS_UNKNOWN_SERVICE)
96 		return 1;
97 
98 	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
99 	if (status != 0) {
100 		printk(KERN_ERR "start-cpu failed: %i\n", status);
101 		return 0;
102 	}
103 
104 	return 1;
105 }
106 
107 #ifdef CONFIG_XICS
108 static inline void smp_xics_do_message(int cpu, int msg)
109 {
110 	set_bit(msg, &xics_ipi_message[cpu].value);
111 	mb();
112 	xics_cause_IPI(cpu);
113 }
114 
115 static void smp_xics_message_pass(int target, int msg)
116 {
117 	unsigned int i;
118 
119 	if (target < NR_CPUS) {
120 		smp_xics_do_message(target, msg);
121 	} else {
122 		for_each_online_cpu(i) {
123 			if (target == MSG_ALL_BUT_SELF
124 			    && i == smp_processor_id())
125 				continue;
126 			smp_xics_do_message(i, msg);
127 		}
128 	}
129 }
130 
131 static int __init smp_xics_probe(void)
132 {
133 	xics_request_IPIs();
134 
135 	return cpus_weight(cpu_possible_map);
136 }
137 
138 static void __devinit smp_xics_setup_cpu(int cpu)
139 {
140 	if (cpu != boot_cpuid)
141 		xics_setup_cpu();
142 
143 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
144 		vpa_init(cpu);
145 
146 	cpu_clear(cpu, of_spin_map);
147 
148 }
149 #endif /* CONFIG_XICS */
150 
151 static DEFINE_SPINLOCK(timebase_lock);
152 static unsigned long timebase = 0;
153 
154 static void __devinit pSeries_give_timebase(void)
155 {
156 	spin_lock(&timebase_lock);
157 	rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
158 	timebase = get_tb();
159 	spin_unlock(&timebase_lock);
160 
161 	while (timebase)
162 		barrier();
163 	rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
164 }
165 
166 static void __devinit pSeries_take_timebase(void)
167 {
168 	while (!timebase)
169 		barrier();
170 	spin_lock(&timebase_lock);
171 	set_tb(timebase >> 32, timebase & 0xffffffff);
172 	timebase = 0;
173 	spin_unlock(&timebase_lock);
174 }
175 
176 static void __devinit smp_pSeries_kick_cpu(int nr)
177 {
178 	BUG_ON(nr < 0 || nr >= NR_CPUS);
179 
180 	if (!smp_startup_cpu(nr))
181 		return;
182 
183 	/*
184 	 * The processor is currently spinning, waiting for the
185 	 * cpu_start field to become non-zero After we set cpu_start,
186 	 * the processor will continue on to secondary_start
187 	 */
188 	paca[nr].cpu_start = 1;
189 }
190 
191 static int smp_pSeries_cpu_bootable(unsigned int nr)
192 {
193 	/* Special case - we inhibit secondary thread startup
194 	 * during boot if the user requests it.  Odd-numbered
195 	 * cpus are assumed to be secondary threads.
196 	 */
197 	if (system_state < SYSTEM_RUNNING &&
198 	    cpu_has_feature(CPU_FTR_SMT) &&
199 	    !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
200 		return 0;
201 
202 	return 1;
203 }
204 #ifdef CONFIG_MPIC
205 static struct smp_ops_t pSeries_mpic_smp_ops = {
206 	.message_pass	= smp_mpic_message_pass,
207 	.probe		= smp_mpic_probe,
208 	.kick_cpu	= smp_pSeries_kick_cpu,
209 	.setup_cpu	= smp_mpic_setup_cpu,
210 };
211 #endif
212 #ifdef CONFIG_XICS
213 static struct smp_ops_t pSeries_xics_smp_ops = {
214 	.message_pass	= smp_xics_message_pass,
215 	.probe		= smp_xics_probe,
216 	.kick_cpu	= smp_pSeries_kick_cpu,
217 	.setup_cpu	= smp_xics_setup_cpu,
218 	.cpu_bootable	= smp_pSeries_cpu_bootable,
219 };
220 #endif
221 
222 /* This is called very early */
223 static void __init smp_init_pseries(void)
224 {
225 	int i;
226 
227 	pr_debug(" -> smp_init_pSeries()\n");
228 
229 	/* Mark threads which are still spinning in hold loops. */
230 	if (cpu_has_feature(CPU_FTR_SMT)) {
231 		for_each_present_cpu(i) {
232 			if (i % 2 == 0)
233 				/*
234 				 * Even-numbered logical cpus correspond to
235 				 * primary threads.
236 				 */
237 				cpu_set(i, of_spin_map);
238 		}
239 	} else {
240 		of_spin_map = cpu_present_map;
241 	}
242 
243 	cpu_clear(boot_cpuid, of_spin_map);
244 
245 	/* Non-lpar has additional take/give timebase */
246 	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
247 		smp_ops->give_timebase = pSeries_give_timebase;
248 		smp_ops->take_timebase = pSeries_take_timebase;
249 	}
250 
251 	pr_debug(" <- smp_init_pSeries()\n");
252 }
253 
254 #ifdef CONFIG_MPIC
255 void __init smp_init_pseries_mpic(void)
256 {
257 	smp_ops = &pSeries_mpic_smp_ops;
258 
259 	smp_init_pseries();
260 }
261 #endif
262 
263 void __init smp_init_pseries_xics(void)
264 {
265 	smp_ops = &pSeries_xics_smp_ops;
266 
267 	smp_init_pseries();
268 }
269