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authorVineet Gupta <vgupta@synopsys.com>2013-01-18 15:12:23 +0530
committerVineet Gupta <vgupta@synopsys.com>2013-02-15 23:16:02 +0530
commit41195d236e84458bebd4fdc218610a92231ac791 (patch)
treec0049630c1a21a071c9c942086041029ebdf2866 /arch/arc/kernel/smp.c
parent0ef88a54aa341f754707414500158addbf35c780 (diff)
ARC: SMP support
ARC common code to enable a SMP system + ISS provided SMP extensions. ARC700 natively lacks SMP support, hence some of the core features are are only enabled if SoCs have the necessary h/w pixie-dust. This includes: -Inter Processor Interrupts (IPI) -Cache coherency -load-locked/store-conditional ... The low level exception handling would be completely broken in SMP because we don't have hardware assisted stack switching. Thus a fair bit of this code is repurposing the MMU_SCRATCH reg for event handler prologues to keep them re-entrant. Many thanks to Rajeshwar Ranga for his initial "major" contributions to SMP Port (back in 2008), and to Noam Camus and Gilad Ben-Yossef for help with resurrecting that in 3.2 kernel (2012). Note that this platform code is again singleton design pattern - so multiple SMP platforms won't build at the moment - this deficiency is addressed in subsequent patches within this series. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com> Cc: Noam Camus <noamc@ezchip.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Diffstat (limited to 'arch/arc/kernel/smp.c')
-rw-r--r--arch/arc/kernel/smp.c320
1 files changed, 320 insertions, 0 deletions
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
new file mode 100644
index 000000000000..1f762ad6969b
--- /dev/null
+++ b/arch/arc/kernel/smp.c
@@ -0,0 +1,320 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * RajeshwarR: Dec 11, 2007
+ * -- Added support for Inter Processor Interrupts
+ *
+ * Vineetg: Nov 1st, 2007
+ * -- Initial Write (Borrowed heavily from ARM)
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/profile.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/irq.h>
+#include <linux/delay.h>
+#include <linux/atomic.h>
+#include <linux/percpu.h>
+#include <linux/cpumask.h>
+#include <linux/spinlock_types.h>
+#include <linux/reboot.h>
+#include <asm/processor.h>
+#include <asm/setup.h>
+
+arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+
+/* XXX: per cpu ? Only needed once in early seconday boot */
+struct task_struct *secondary_idle_tsk;
+
+/* Called from start_kernel */
+void __init smp_prepare_boot_cpu(void)
+{
+}
+
+/*
+ * Initialise the CPU possible map early - this describes the CPUs
+ * which may be present or become present in the system.
+ */
+void __init smp_init_cpus(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < NR_CPUS; i++)
+ set_cpu_possible(i, true);
+}
+
+/* called from init ( ) => process 1 */
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+ int i;
+
+ /*
+ * Initialise the present map, which describes the set of CPUs
+ * actually populated at the present time.
+ */
+ for (i = 0; i < max_cpus; i++)
+ set_cpu_present(i, true);
+}
+
+void __init smp_cpus_done(unsigned int max_cpus)
+{
+
+}
+
+/*
+ * After power-up, a non Master CPU needs to wait for Master to kick start it
+ *
+ * The default implementation halts
+ *
+ * This relies on platform specific support allowing Master to directly set
+ * this CPU's PC (to be @first_lines_of_secondary() and kick start it.
+ *
+ * In lack of such h/w assist, platforms can override this function
+ * - make this function busy-spin on a token, eventually set by Master
+ * (from arc_platform_smp_wakeup_cpu())
+ * - Once token is available, jump to @first_lines_of_secondary
+ * (using inline asm).
+ *
+ * Alert: can NOT use stack here as it has not been determined/setup for CPU.
+ * If it turns out to be elaborate, it's better to code it in assembly
+ *
+ */
+void __attribute__((weak)) arc_platform_smp_wait_to_boot(int cpu)
+{
+ /*
+ * As a hack for debugging - since debugger will single-step over the
+ * FLAG insn - wrap the halt itself it in a self loop
+ */
+ __asm__ __volatile__(
+ "1: \n"
+ " flag 1 \n"
+ " b 1b \n");
+}
+
+/*
+ * The very first "C" code executed by secondary
+ * Called from asm stub in head.S
+ * "current"/R25 already setup by low level boot code
+ */
+void __cpuinit start_kernel_secondary(void)
+{
+ struct mm_struct *mm = &init_mm;
+ unsigned int cpu = smp_processor_id();
+
+ /* MMU, Caches, Vector Table, Interrupts etc */
+ setup_processor();
+
+ atomic_inc(&mm->mm_users);
+ atomic_inc(&mm->mm_count);
+ current->active_mm = mm;
+
+ notify_cpu_starting(cpu);
+ set_cpu_online(cpu, true);
+
+ pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
+
+ arc_platform_smp_init_cpu();
+
+ arc_local_timer_setup(cpu);
+
+ local_irq_enable();
+ preempt_disable();
+ cpu_idle();
+}
+
+/*
+ * Called from kernel_init( ) -> smp_init( ) - for each CPU
+ *
+ * At this point, Secondary Processor is "HALT"ed:
+ * -It booted, but was halted in head.S
+ * -It was configured to halt-on-reset
+ * So need to wake it up.
+ *
+ * Essential requirements being where to run from (PC) and stack (SP)
+*/
+int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
+{
+ unsigned long wait_till;
+
+ secondary_idle_tsk = idle;
+
+ pr_info("Idle Task [%d] %p", cpu, idle);
+ pr_info("Trying to bring up CPU%u ...\n", cpu);
+
+ arc_platform_smp_wakeup_cpu(cpu,
+ (unsigned long)first_lines_of_secondary);
+
+ /* wait for 1 sec after kicking the secondary */
+ wait_till = jiffies + HZ;
+ while (time_before(jiffies, wait_till)) {
+ if (cpu_online(cpu))
+ break;
+ }
+
+ if (!cpu_online(cpu)) {
+ pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
+ return -1;
+ }
+
+ secondary_idle_tsk = NULL;
+
+ return 0;
+}
+
+/*
+ * not supported here
+ */
+int __init setup_profiling_timer(unsigned int multiplier)
+{
+ return -EINVAL;
+}
+
+/*****************************************************************************/
+/* Inter Processor Interrupt Handling */
+/*****************************************************************************/
+
+/*
+ * structures for inter-processor calls
+ * A Collection of single bit ipi messages
+ *
+ */
+
+/*
+ * TODO_rajesh investigate tlb message types.
+ * IPI Timer not needed because each ARC has an individual Interrupting Timer
+ */
+enum ipi_msg_type {
+ IPI_NOP = 0,
+ IPI_RESCHEDULE = 1,
+ IPI_CALL_FUNC,
+ IPI_CALL_FUNC_SINGLE,
+ IPI_CPU_STOP
+};
+
+struct ipi_data {
+ unsigned long bits;
+};
+
+static DEFINE_PER_CPU(struct ipi_data, ipi_data);
+
+static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
+{
+ unsigned long flags;
+ unsigned int cpu;
+
+ local_irq_save(flags);
+
+ for_each_cpu(cpu, callmap) {
+ struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
+ set_bit(msg, &ipi->bits);
+ }
+
+ /* Call the platform specific cross-CPU call function */
+ arc_platform_ipi_send(callmap);
+
+ local_irq_restore(flags);
+}
+
+void smp_send_reschedule(int cpu)
+{
+ ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
+}
+
+void smp_send_stop(void)
+{
+ struct cpumask targets;
+ cpumask_copy(&targets, cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), &targets);
+ ipi_send_msg(&targets, IPI_CPU_STOP);
+}
+
+void arch_send_call_function_single_ipi(int cpu)
+{
+ ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
+}
+
+void arch_send_call_function_ipi_mask(const struct cpumask *mask)
+{
+ ipi_send_msg(mask, IPI_CALL_FUNC);
+}
+
+/*
+ * ipi_cpu_stop - handle IPI from smp_send_stop()
+ */
+static void ipi_cpu_stop(unsigned int cpu)
+{
+ machine_halt();
+}
+
+static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
+{
+ unsigned long msg = 0;
+
+ do {
+ msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
+
+ switch (msg) {
+ case IPI_RESCHEDULE:
+ scheduler_ipi();
+ break;
+
+ case IPI_CALL_FUNC:
+ generic_smp_call_function_interrupt();
+ break;
+
+ case IPI_CALL_FUNC_SINGLE:
+ generic_smp_call_function_single_interrupt();
+ break;
+
+ case IPI_CPU_STOP:
+ ipi_cpu_stop(cpu);
+ break;
+ }
+ } while (msg < BITS_PER_LONG);
+
+}
+
+/*
+ * arch-common ISR to handle for inter-processor interrupts
+ * Has hooks for platform specific IPI
+ */
+irqreturn_t do_IPI(int irq, void *dev_id)
+{
+ int cpu = smp_processor_id();
+ struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
+ unsigned long ops;
+
+ arc_platform_ipi_clear(cpu, irq);
+
+ /*
+ * XXX: is this loop really needed
+ * And do we need to move ipi_clean inside
+ */
+ while ((ops = xchg(&ipi->bits, 0)) != 0)
+ __do_IPI(&ops, ipi, cpu);
+
+ return IRQ_HANDLED;
+}
+
+/*
+ * API called by platform code to hookup arch-common ISR to their IPI IRQ
+ */
+static DEFINE_PER_CPU(int, ipi_dev);
+int smp_ipi_irq_setup(int cpu, int irq)
+{
+ int *dev_id = &per_cpu(ipi_dev, smp_processor_id());
+ return request_percpu_irq(irq, do_IPI, "IPI Interrupt", dev_id);
+}