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/sched.h>
18#include <linux/smp.h>
19#include <linux/interrupt.h>
20#include <linux/delay.h>
21#include <linux/init.h>
22#include <linux/spinlock.h>
23#include <linux/cache.h>
24#include <linux/err.h>
25#include <linux/device.h>
26#include <linux/cpu.h>
27
28#include <asm/ptrace.h>
29#include <linux/atomic.h>
30#include <asm/irq.h>
31#include <asm/page.h>
32#include <asm/pgtable.h>
33#include <asm/io.h>
34#include <asm/prom.h>
35#include <asm/smp.h>
36#include <asm/paca.h>
37#include <asm/machdep.h>
38#include <asm/cputable.h>
39#include <asm/firmware.h>
40#include <asm/rtas.h>
41#include <asm/mpic.h>
42#include <asm/vdso_datapage.h>
43#include <asm/cputhreads.h>
44#include <asm/xics.h>
45#include <asm/dbell.h>
46#include <asm/plpar_wrappers.h>
47#include <asm/code-patching.h>
48
49#include "pseries.h"
50#include "offline_states.h"
51
52
53/*
54 * The Primary thread of each non-boot processor was started from the OF client
55 * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
56 */
57static cpumask_var_t of_spin_mask;
58
59/*
60 * If we multiplex IPI mechanisms, store the appropriate XICS IPI mechanism here
61 */
62static void  (*xics_cause_ipi)(int cpu, unsigned long data);
63
64/* Query where a cpu is now.  Return codes #defined in plpar_wrappers.h */
65int smp_query_cpu_stopped(unsigned int pcpu)
66{
67	int cpu_status, status;
68	int qcss_tok = rtas_token("query-cpu-stopped-state");
69
70	if (qcss_tok == RTAS_UNKNOWN_SERVICE) {
71		printk_once(KERN_INFO
72			"Firmware doesn't support query-cpu-stopped-state\n");
73		return QCSS_HARDWARE_ERROR;
74	}
75
76	status = rtas_call(qcss_tok, 1, 2, &cpu_status, pcpu);
77	if (status != 0) {
78		printk(KERN_ERR
79		       "RTAS query-cpu-stopped-state failed: %i\n", status);
80		return status;
81	}
82
83	return cpu_status;
84}
85
86/**
87 * smp_startup_cpu() - start the given cpu
88 *
89 * At boot time, there is nothing to do for primary threads which were
90 * started from Open Firmware.  For anything else, call RTAS with the
91 * appropriate start location.
92 *
93 * Returns:
94 *	0	- failure
95 *	1	- success
96 */
97static inline int smp_startup_cpu(unsigned int lcpu)
98{
99	int status;
100	unsigned long start_here =
101			__pa(ppc_function_entry(generic_secondary_smp_init));
102	unsigned int pcpu;
103	int start_cpu;
104
105	if (cpumask_test_cpu(lcpu, of_spin_mask))
106		/* Already started by OF and sitting in spin loop */
107		return 1;
108
109	pcpu = get_hard_smp_processor_id(lcpu);
110
111	/* Check to see if the CPU out of FW already for kexec */
112	if (smp_query_cpu_stopped(pcpu) == QCSS_NOT_STOPPED){
113		cpumask_set_cpu(lcpu, of_spin_mask);
114		return 1;
115	}
116
117	/* Fixup atomic count: it exited inside IRQ handler. */
118	task_thread_info(paca[lcpu].__current)->preempt_count	= 0;
119#ifdef CONFIG_HOTPLUG_CPU
120	if (get_cpu_current_state(lcpu) == CPU_STATE_INACTIVE)
121		goto out;
122#endif
123	/*
124	 * If the RTAS start-cpu token does not exist then presume the
125	 * cpu is already spinning.
126	 */
127	start_cpu = rtas_token("start-cpu");
128	if (start_cpu == RTAS_UNKNOWN_SERVICE)
129		return 1;
130
131	status = rtas_call(start_cpu, 3, 1, NULL, pcpu, start_here, pcpu);
132	if (status != 0) {
133		printk(KERN_ERR "start-cpu failed: %i\n", status);
134		return 0;
135	}
136
137#ifdef CONFIG_HOTPLUG_CPU
138out:
139#endif
140	return 1;
141}
142
143static void smp_xics_setup_cpu(int cpu)
144{
145	if (cpu != boot_cpuid)
146		xics_setup_cpu();
147	if (cpu_has_feature(CPU_FTR_DBELL))
148		doorbell_setup_this_cpu();
149
150	if (firmware_has_feature(FW_FEATURE_SPLPAR))
151		vpa_init(cpu);
152
153	cpumask_clear_cpu(cpu, of_spin_mask);
154#ifdef CONFIG_HOTPLUG_CPU
155	set_cpu_current_state(cpu, CPU_STATE_ONLINE);
156	set_default_offline_state(cpu);
157#endif
158}
159
160static int smp_pSeries_kick_cpu(int nr)
161{
162	BUG_ON(nr < 0 || nr >= NR_CPUS);
163
164	if (!smp_startup_cpu(nr))
165		return -ENOENT;
166
167	/*
168	 * The processor is currently spinning, waiting for the
169	 * cpu_start field to become non-zero After we set cpu_start,
170	 * the processor will continue on to secondary_start
171	 */
172	paca[nr].cpu_start = 1;
173#ifdef CONFIG_HOTPLUG_CPU
174	set_preferred_offline_state(nr, CPU_STATE_ONLINE);
175
176	if (get_cpu_current_state(nr) == CPU_STATE_INACTIVE) {
177		long rc;
178		unsigned long hcpuid;
179
180		hcpuid = get_hard_smp_processor_id(nr);
181		rc = plpar_hcall_norets(H_PROD, hcpuid);
182		if (rc != H_SUCCESS)
183			printk(KERN_ERR "Error: Prod to wake up processor %d "
184						"Ret= %ld\n", nr, rc);
185	}
186#endif
187
188	return 0;
189}
190
191/* Only used on systems that support multiple IPI mechanisms */
192static void pSeries_cause_ipi_mux(int cpu, unsigned long data)
193{
194	if (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id())))
195		doorbell_cause_ipi(cpu, data);
196	else
197		xics_cause_ipi(cpu, data);
198}
199
200static __init void pSeries_smp_probe(void)
201{
202	xics_smp_probe();
203
204	if (cpu_has_feature(CPU_FTR_DBELL)) {
205		xics_cause_ipi = smp_ops->cause_ipi;
206		smp_ops->cause_ipi = pSeries_cause_ipi_mux;
207	}
208}
209
210static struct smp_ops_t pSeries_mpic_smp_ops = {
211	.message_pass	= smp_mpic_message_pass,
212	.probe		= smp_mpic_probe,
213	.kick_cpu	= smp_pSeries_kick_cpu,
214	.setup_cpu	= smp_mpic_setup_cpu,
215};
216
217static struct smp_ops_t pSeries_xics_smp_ops = {
218	.message_pass	= NULL,	/* Use smp_muxed_ipi_message_pass */
219	.cause_ipi	= NULL,	/* Filled at runtime by pSeries_smp_probe() */
220	.probe		= pSeries_smp_probe,
221	.kick_cpu	= smp_pSeries_kick_cpu,
222	.setup_cpu	= smp_xics_setup_cpu,
223	.cpu_bootable	= smp_generic_cpu_bootable,
224};
225
226/* This is called very early */
227static void __init smp_init_pseries(void)
228{
229	int i;
230
231	pr_debug(" -> smp_init_pSeries()\n");
232
233	alloc_bootmem_cpumask_var(&of_spin_mask);
234
235	/*
236	 * Mark threads which are still spinning in hold loops
237	 *
238	 * We know prom_init will not have started them if RTAS supports
239	 * query-cpu-stopped-state.
240	 */
241	if (rtas_token("query-cpu-stopped-state") == RTAS_UNKNOWN_SERVICE) {
242		if (cpu_has_feature(CPU_FTR_SMT)) {
243			for_each_present_cpu(i) {
244				if (cpu_thread_in_core(i) == 0)
245					cpumask_set_cpu(i, of_spin_mask);
246			}
247		} else
248			cpumask_copy(of_spin_mask, cpu_present_mask);
249
250		cpumask_clear_cpu(boot_cpuid, of_spin_mask);
251	}
252
253	/* Non-lpar has additional take/give timebase */
254	if (rtas_token("freeze-time-base") != RTAS_UNKNOWN_SERVICE) {
255		smp_ops->give_timebase = rtas_give_timebase;
256		smp_ops->take_timebase = rtas_take_timebase;
257	}
258
259	pr_debug(" <- smp_init_pSeries()\n");
260}
261
262void __init smp_init_pseries_mpic(void)
263{
264	smp_ops = &pSeries_mpic_smp_ops;
265
266	smp_init_pseries();
267}
268
269void __init smp_init_pseries_xics(void)
270{
271	smp_ops = &pSeries_xics_smp_ops;
272
273	smp_init_pseries();
274}
275