2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 * RajeshwarR: Dec 11, 2007
9 * -- Added support for Inter Processor Interrupts
11 * Vineetg: Nov 1st, 2007
12 * -- Initial Write (Borrowed heavily from ARM)
15 #include <linux/spinlock.h>
16 #include <linux/sched.h>
17 #include <linux/interrupt.h>
18 #include <linux/profile.h>
20 #include <linux/cpu.h>
21 #include <linux/irq.h>
22 #include <linux/atomic.h>
23 #include <linux/cpumask.h>
24 #include <linux/reboot.h>
25 #include <asm/processor.h>
26 #include <asm/setup.h>
27 #include <asm/mach_desc.h>
29 arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
30 arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
32 struct plat_smp_ops plat_smp_ops;
34 /* XXX: per cpu ? Only needed once in early seconday boot */
35 struct task_struct *secondary_idle_tsk;
37 /* Called from start_kernel */
38 void __init smp_prepare_boot_cpu(void)
43 * Initialise the CPU possible map early - this describes the CPUs
44 * which may be present or become present in the system.
46 void __init smp_init_cpus(void)
50 for (i = 0; i < NR_CPUS; i++)
51 set_cpu_possible(i, true);
54 /* called from init ( ) => process 1 */
55 void __init smp_prepare_cpus(unsigned int max_cpus)
60 * Initialise the present map, which describes the set of CPUs
61 * actually populated at the present time.
63 for (i = 0; i < max_cpus; i++)
64 set_cpu_present(i, true);
67 void __init smp_cpus_done(unsigned int max_cpus)
73 * After power-up, a non Master CPU needs to wait for Master to kick start it
75 * The default implementation halts
77 * This relies on platform specific support allowing Master to directly set
78 * this CPU's PC (to be @first_lines_of_secondary() and kick start it.
80 * In lack of such h/w assist, platforms can override this function
81 * - make this function busy-spin on a token, eventually set by Master
82 * (from arc_platform_smp_wakeup_cpu())
83 * - Once token is available, jump to @first_lines_of_secondary
86 * Alert: can NOT use stack here as it has not been determined/setup for CPU.
87 * If it turns out to be elaborate, it's better to code it in assembly
90 void __weak arc_platform_smp_wait_to_boot(int cpu)
93 * As a hack for debugging - since debugger will single-step over the
94 * FLAG insn - wrap the halt itself it in a self loop
102 const char *arc_platform_smp_cpuinfo(void)
104 return plat_smp_ops.info;
108 * The very first "C" code executed by secondary
109 * Called from asm stub in head.S
110 * "current"/R25 already setup by low level boot code
112 void start_kernel_secondary(void)
114 struct mm_struct *mm = &init_mm;
115 unsigned int cpu = smp_processor_id();
117 /* MMU, Caches, Vector Table, Interrupts etc */
120 atomic_inc(&mm->mm_users);
121 atomic_inc(&mm->mm_count);
122 current->active_mm = mm;
123 cpumask_set_cpu(cpu, mm_cpumask(mm));
125 notify_cpu_starting(cpu);
126 set_cpu_online(cpu, true);
128 pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
130 if (machine_desc->init_smp)
131 machine_desc->init_smp(cpu);
133 arc_local_timer_setup();
137 cpu_startup_entry(CPUHP_ONLINE);
141 * Called from kernel_init( ) -> smp_init( ) - for each CPU
143 * At this point, Secondary Processor is "HALT"ed:
144 * -It booted, but was halted in head.S
145 * -It was configured to halt-on-reset
146 * So need to wake it up.
148 * Essential requirements being where to run from (PC) and stack (SP)
150 int __cpu_up(unsigned int cpu, struct task_struct *idle)
152 unsigned long wait_till;
154 secondary_idle_tsk = idle;
156 pr_info("Idle Task [%d] %p", cpu, idle);
157 pr_info("Trying to bring up CPU%u ...\n", cpu);
159 if (plat_smp_ops.cpu_kick)
160 plat_smp_ops.cpu_kick(cpu,
161 (unsigned long)first_lines_of_secondary);
163 /* wait for 1 sec after kicking the secondary */
164 wait_till = jiffies + HZ;
165 while (time_before(jiffies, wait_till)) {
170 if (!cpu_online(cpu)) {
171 pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
175 secondary_idle_tsk = NULL;
183 int __init setup_profiling_timer(unsigned int multiplier)
188 /*****************************************************************************/
189 /* Inter Processor Interrupt Handling */
190 /*****************************************************************************/
200 * In arches with IRQ for each msg type (above), receiver can use IRQ-id to
201 * figure out what msg was sent. For those which don't (ARC has dedicated IPI
202 * IRQ), the msg-type needs to be conveyed via per-cpu data
205 static DEFINE_PER_CPU(unsigned long, ipi_data);
207 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
209 unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
210 unsigned long old, new;
213 pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
215 local_irq_save(flags);
218 * Atomically write new msg bit (in case others are writing too),
219 * and read back old value
222 new = old = *ipi_data_ptr;
224 } while (cmpxchg(ipi_data_ptr, old, new) != old);
227 * Call the platform specific IPI kick function, but avoid if possible:
228 * Only do so if there's no pending msg from other concurrent sender(s).
229 * Otherwise, recevier will see this msg as well when it takes the
230 * IPI corresponding to that msg. This is true, even if it is already in
231 * IPI handler, because !@old means it has not yet dequeued the msg(s)
232 * so @new msg can be a free-loader
234 if (plat_smp_ops.ipi_send && !old)
235 plat_smp_ops.ipi_send(cpu);
237 local_irq_restore(flags);
240 static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
244 for_each_cpu(cpu, callmap)
245 ipi_send_msg_one(cpu, msg);
248 void smp_send_reschedule(int cpu)
250 ipi_send_msg_one(cpu, IPI_RESCHEDULE);
253 void smp_send_stop(void)
255 struct cpumask targets;
256 cpumask_copy(&targets, cpu_online_mask);
257 cpumask_clear_cpu(smp_processor_id(), &targets);
258 ipi_send_msg(&targets, IPI_CPU_STOP);
261 void arch_send_call_function_single_ipi(int cpu)
263 ipi_send_msg_one(cpu, IPI_CALL_FUNC);
266 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
268 ipi_send_msg(mask, IPI_CALL_FUNC);
272 * ipi_cpu_stop - handle IPI from smp_send_stop()
274 static void ipi_cpu_stop(void)
279 static inline void __do_IPI(unsigned long msg)
287 generic_smp_call_function_interrupt();
295 pr_warn("IPI with unexpected msg %ld\n", msg);
300 * arch-common ISR to handle for inter-processor interrupts
301 * Has hooks for platform specific IPI
303 irqreturn_t do_IPI(int irq, void *dev_id)
305 unsigned long pending;
307 pr_debug("IPI [%ld] received on cpu %d\n",
308 *this_cpu_ptr(&ipi_data), smp_processor_id());
310 if (plat_smp_ops.ipi_clear)
311 plat_smp_ops.ipi_clear(irq);
314 * "dequeue" the msg corresponding to this IPI (and possibly other
315 * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
317 pending = xchg(this_cpu_ptr(&ipi_data), 0);
320 unsigned long msg = __ffs(pending);
322 pending &= ~(1U << msg);
329 * API called by platform code to hookup arch-common ISR to their IPI IRQ
331 static DEFINE_PER_CPU(int, ipi_dev);
333 int smp_ipi_irq_setup(int cpu, int irq)
335 int *dev = per_cpu_ptr(&ipi_dev, cpu);
337 arc_request_percpu_irq(irq, cpu, do_IPI, "IPI Interrupt", dev);