1 /*
2 * linux/arch/arm/mach-realview/platsmp.c
3 *
4 * Copyright (C) 2002 ARM Ltd.
5 * All Rights Reserved
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11 #include <linux/init.h>
12 #include <linux/errno.h>
13 #include <linux/delay.h>
14 #include <linux/device.h>
15 #include <linux/smp.h>
16
17 #include <asm/cacheflush.h>
18 #include <asm/hardware/arm_scu.h>
19 #include <asm/hardware.h>
20 #include <asm/io.h>
21 #include <asm/mach-types.h>
22
23 extern void realview_secondary_startup(void);
24
25 /*
26 * control for which core is the next to come out of the secondary
27 * boot "holding pen"
28 */
29 volatile int __cpuinitdata pen_release = -1;
30
31 static unsigned int __init get_core_count(void)
32 {
33 unsigned int ncores;
34
35 if (machine_is_realview_eb() && core_tile_eb11mp()) {
36 ncores = __raw_readl(__io_address(REALVIEW_EB11MP_SCU_BASE) + SCU_CONFIG);
37 ncores = (ncores & 0x03) + 1;
38 } else
39 ncores = 1;
40
41 return ncores;
42 }
43
44 static DEFINE_SPINLOCK(boot_lock);
45
46 void __cpuinit platform_secondary_init(unsigned int cpu)
47 {
48 /*
49 * the primary core may have used a "cross call" soft interrupt
50 * to get this processor out of WFI in the BootMonitor - make
51 * sure that we are no longer being sent this soft interrupt
52 */
53 smp_cross_call_done(cpumask_of_cpu(cpu));
54
55 /*
56 * if any interrupts are already enabled for the primary
57 * core (e.g. timer irq), then they will not have been enabled
58 * for us: do so
59 */
60 gic_cpu_init(0, __io_address(REALVIEW_EB11MP_GIC_CPU_BASE));
61
62 /*
63 * let the primary processor know we're out of the
64 * pen, then head off into the C entry point
65 */
66 pen_release = -1;
67 smp_wmb();
68
69 /*
70 * Synchronise with the boot thread.
71 */
72 spin_lock(&boot_lock);
73 spin_unlock(&boot_lock);
74 }
75
76 int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
77 {
78 unsigned long timeout;
79
80 /*
81 * set synchronisation state between this boot processor
82 * and the secondary one
83 */
84 spin_lock(&boot_lock);
85
86 /*
87 * The secondary processor is waiting to be released from
88 * the holding pen - release it, then wait for it to flag
89 * that it has been released by resetting pen_release.
90 *
91 * Note that "pen_release" is the hardware CPU ID, whereas
92 * "cpu" is Linux's internal ID.
93 */
94 pen_release = cpu;
95 flush_cache_all();
96
97 /*
98 * XXX
99 *
100 * This is a later addition to the booting protocol: the
101 * bootMonitor now puts secondary cores into WFI, so
102 * poke_milo() no longer gets the cores moving; we need
103 * to send a soft interrupt to wake the secondary core.
104 * Use smp_cross_call() for this, since there's little
105 * point duplicating the code here
106 */
107 smp_cross_call(cpumask_of_cpu(cpu));
108
109 timeout = jiffies + (1 * HZ);
110 while (time_before(jiffies, timeout)) {
111 smp_rmb();
112 if (pen_release == -1)
113 break;
114
115 udelay(10);
116 }
117
118 /*
119 * now the secondary core is starting up let it run its
120 * calibrations, then wait for it to finish
121 */
122 spin_unlock(&boot_lock);
123
124 return pen_release != -1 ? -ENOSYS : 0;
125 }
126
127 static void __init poke_milo(void)
128 {
129 extern void secondary_startup(void);
130
131 /* nobody is to be released from the pen yet */
132 pen_release = -1;
133
134 /*
135 * write the address of secondary startup into the system-wide
136 * flags register, then clear the bottom two bits, which is what
137 * BootMonitor is waiting for
138 */
139 #if 1
140 #define REALVIEW_SYS_FLAGSS_OFFSET 0x30
141 __raw_writel(virt_to_phys(realview_secondary_startup),
142 __io_address(REALVIEW_SYS_BASE) +
143 REALVIEW_SYS_FLAGSS_OFFSET);
144 #define REALVIEW_SYS_FLAGSC_OFFSET 0x34
145 __raw_writel(3,
146 __io_address(REALVIEW_SYS_BASE) +
147 REALVIEW_SYS_FLAGSC_OFFSET);
148 #endif
149
150 mb();
151 }
152
153 /*
154 * Initialise the CPU possible map early - this describes the CPUs
155 * which may be present or become present in the system.
156 */
157 void __init smp_init_cpus(void)
158 {
159 unsigned int i, ncores = get_core_count();
160
161 for (i = 0; i < ncores; i++)
162 cpu_set(i, cpu_possible_map);
163 }
164
165 void __init smp_prepare_cpus(unsigned int max_cpus)
166 {
167 unsigned int ncores = get_core_count();
168 unsigned int cpu = smp_processor_id();
169 int i;
170
171 /* sanity check */
172 if (ncores == 0) {
173 printk(KERN_ERR
174 "Realview: strange CM count of 0? Default to 1\n");
175
176 ncores = 1;
177 }
178
179 if (ncores > NR_CPUS) {
180 printk(KERN_WARNING
181 "Realview: no. of cores (%d) greater than configured "
182 "maximum of %d - clipping\n",
183 ncores, NR_CPUS);
184 ncores = NR_CPUS;
185 }
186
187 smp_store_cpu_info(cpu);
188
189 /*
190 * are we trying to boot more cores than exist?
191 */
192 if (max_cpus > ncores)
193 max_cpus = ncores;
194
195 #ifdef CONFIG_LOCAL_TIMERS
196 /*
197 * Enable the local timer for primary CPU. If the device is
198 * dummy (!CONFIG_LOCAL_TIMERS), it was already registers in
199 * realview_timer_init
200 */
201 if (machine_is_realview_eb() && core_tile_eb11mp())
202 local_timer_setup(cpu);
203 #endif
204
205 /*
206 * Initialise the present map, which describes the set of CPUs
207 * actually populated at the present time.
208 */
209 for (i = 0; i < max_cpus; i++)
210 cpu_set(i, cpu_present_map);
211
212 /*
213 * Do we need any more CPUs? If so, then let them know where
214 * to start. Note that, on modern versions of MILO, the "poke"
215 * doesn't actually do anything until each individual core is
216 * sent a soft interrupt to get it out of WFI
217 */
218 if (max_cpus > 1)
219 poke_milo();
220 }
221
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