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 <linux/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/machdep.h>
39 #include <asm/cputable.h>
40 #include <asm/firmware.h>
41 #include <asm/system.h>
42 #include <asm/rtas.h>
43 #include <asm/pSeries_reconfig.h>
44 #include <asm/mpic.h>
45 #include <asm/vdso_datapage.h>
46 #include <asm/cputhreads.h>
47 #include <asm/xics.h>
48 
49 #include "plpar_wrappers.h"
50 #include "pseries.h"
51 #include "offline_states.h"
52 
53 
54 /*
55  * The Primary thread of each non-boot processor was started from the OF client
56  * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
57  */
58 static cpumask_var_t of_spin_mask;
59 
60 /* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
61 int smp_query_cpu_stopped(unsigned int pcpu)
62 {
63 	int cpu_status, status;
64 	int qcss_tok = rtas_token("query-cpu-stopped-state");
65 
66 	if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
67 		printk_once(KERN_INFO
68 			"Firmware doesn't support query-cpu-stopped-state\n");
69 		return QCSS_HARDWARE_ERROR;
70 	}
71 
72 	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
73 	if (status != 0) {
74 		printk(KERN_ERR
75 		       "RTAS query-cpu-stopped-state failed: %i\n", status);
76 		return status;
77 	}
78 
79 	return cpu_status;
80 }
81 
82 /**
83  * smp_startup_cpu() - start the given cpu
84  *
85  * At boot time, there is nothing to do for primary threads which were
86  * started from Open Firmware.  For anything else, call RTAS with the
87  * appropriate start location.
88  *
89  * Returns:
90  *	0	- failure
91  *	1	- success
92  */
93 static inline int __devinit smp_startup_cpu(unsigned int lcpu)
94 {
95 	int status;
96 	unsigned long start_here = __pa((u32)*((unsigned long *)
97 					       generic_secondary_smp_init));
98 	unsigned int pcpu;
99 	int start_cpu;
100 
101 	if (cpumask_test_cpu(lcpu, of_spin_mask))
102 		/* Already started by OF and sitting in spin loop */
103 		return 1;
104 
105 	pcpu = get_hard_smp_processor_id(lcpu);
106 
107 	/* Check to see if the CPU out of FW already for kexec */
108 	if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
109 		cpumask_set_cpu(lcpu, of_spin_mask);
110 		return 1;
111 	}
112 
113 	/* Fixup atomic count: it exited inside IRQ handler. */
114 	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
115 #ifdef CONFIG_HOTPLUG_CPU
116 	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
117 		goto out;
118 #endif
119 	/*
120 	 * If the RTAS start-cpu token does not exist then presume the
121 	 * cpu is already spinning.
122 	 */
123 	start_cpu = rtas_token("start-cpu");
124 	if (start_cpu == RTAS_UNKNOWN_SERVICE)
125 		return 1;
126 
127 	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
128 	if (status != 0) {
129 		printk(KERN_ERR "start-cpu failed: %i\n", status);
130 		return 0;
131 	}
132 
133 #ifdef CONFIG_HOTPLUG_CPU
134 out:
135 #endif
136 	return 1;
137 }
138 
139 static void __devinit smp_xics_setup_cpu(int cpu)
140 {
141 	if (cpu != boot_cpuid)
142 		xics_setup_cpu();
143 
144 	if (firmware_has_feature(FW_FEATURE_SPLPAR))
145 		vpa_init(cpu);
146 
147 	cpumask_clear_cpu(cpu, of_spin_mask);
148 #ifdef CONFIG_HOTPLUG_CPU
149 	set_cpu_current_state(cpu, CPU_STATE_ONLINE);
150 	set_default_offline_state(cpu);
151 #endif
152 }
153 
154 static int __devinit smp_pSeries_kick_cpu(int nr)
155 {
156 	BUG_ON(nr < 0 || nr >= NR_CPUS);
157 
158 	if (!smp_startup_cpu(nr))
159 		return -ENOENT;
160 
161 	/*
162 	 * The processor is currently spinning, waiting for the
163 	 * cpu_start field to become non-zero After we set cpu_start,
164 	 * the processor will continue on to secondary_start
165 	 */
166 	paca[nr].cpu_start = 1;
167 #ifdef CONFIG_HOTPLUG_CPU
168 	set_preferred_offline_state(nr, CPU_STATE_ONLINE);
169 
170 	if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
171 		long rc;
172 		unsigned long hcpuid;
173 
174 		hcpuid = get_hard_smp_processor_id(nr);
175 		rc = plpar_hcall_norets(H_PROD, hcpuid);
176 		if (rc != H_SUCCESS)
177 			printk(KERN_ERR "Error: Prod to wake up processor %d "
178 						"Ret= %ld\n", nr, rc);
179 	}
180 #endif
181 
182 	return 0;
183 }
184 
185 static int smp_pSeries_cpu_bootable(unsigned int nr)
186 {
187 	/* Special case - we inhibit secondary thread startup
188 	 * during boot if the user requests it.
189 	 */
190 	if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {
191 		if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
192 			return 0;
193 		if (smt_enabled_at_boot
194 		    && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
195 			return 0;
196 	}
197 
198 	return 1;
199 }
200 
201 static struct smp_ops_t pSeries_mpic_smp_ops = {
202 	.message_pass	= smp_mpic_message_pass,
203 	.probe		= smp_mpic_probe,
204 	.kick_cpu	= smp_pSeries_kick_cpu,
205 	.setup_cpu	= smp_mpic_setup_cpu,
206 };
207 
208 static struct smp_ops_t pSeries_xics_smp_ops = {
209 	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
210 	.cause_ipi	= NULL,	/* Filled at runtime by xics_smp_probe() */
211 	.probe		= xics_smp_probe,
212 	.kick_cpu	= smp_pSeries_kick_cpu,
213 	.setup_cpu	= smp_xics_setup_cpu,
214 	.cpu_bootable	= smp_pSeries_cpu_bootable,
215 };
216 
217 /* This is called very early */
218 static void __init smp_init_pseries(void)
219 {
220 	int i;
221 
222 	pr_debug(" -> smp_init_pSeries()\n");
223 
224 	alloc_bootmem_cpumask_var(&of_spin_mask);
225 
226 	/* Mark threads which are still spinning in hold loops. */
227 	if (cpu_has_feature(CPU_FTR_SMT)) {
228 		for_each_present_cpu(i) {
229 			if (cpu_thread_in_core(i) == 0)
230 				cpumask_set_cpu(i, of_spin_mask);
231 		}
232 	} else {
233 		cpumask_copy(of_spin_mask, cpu_present_mask);
234 	}
235 
236 	cpumask_clear_cpu(boot_cpuid, of_spin_mask);
237 
238 	/* Non-lpar has additional take/give timebase */
239 	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
240 		smp_ops->give_timebase = rtas_give_timebase;
241 		smp_ops->take_timebase = rtas_take_timebase;
242 	}
243 
244 	pr_debug(" <- smp_init_pSeries()\n");
245 }
246 
247 void __init smp_init_pseries_mpic(void)
248 {
249 	smp_ops = &pSeries_mpic_smp_ops;
250 
251 	smp_init_pseries();
252 }
253 
254 void __init smp_init_pseries_xics(void)
255 {
256 	smp_ops = &pSeries_xics_smp_ops;
257 
258 	smp_init_pseries();
259 }
260