patch-2.3.16 linux/arch/sh/kernel/irq.c

• Lines: 486
• Date: Mon Aug 30 18:12:59 1999
• Orig file: v2.3.15/linux/arch/sh/kernel/irq.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.15/linux/arch/sh/kernel/irq.c linux/arch/sh/kernel/irq.c
@@ -0,0 +1,485 @@
+/*
+ * linux/arch/sh/kernel/irq.c
+ *
+ *	Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
+ *
+ *
+ *  SuperH version:  Copyright (C) 1999  Niibe Yutaka
+ */
+
+/*
+ * IRQs are in fact implemented a bit like signal handlers for the kernel.
+ * Naturally it's not a 1:1 relation, but there are similarities.
+ */
+
+#include <linux/ptrace.h>
+#include <linux/errno.h>
+#include <linux/kernel_stat.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/ioport.h>
+#include <linux/interrupt.h>
+#include <linux/timex.h>
+#include <linux/malloc.h>
+#include <linux/random.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/io.h>
+#include <asm/bitops.h>
+#include <asm/smp.h>
+#include <asm/pgtable.h>
+#include <asm/delay.h>
+#include <asm/irq.h>
+#include <linux/irq.h>
+
+
+unsigned int local_bh_count[NR_CPUS];
+unsigned int local_irq_count[NR_CPUS];
+
+/*
+ * Micro-access to controllers is serialized over the whole
+ * system. We never hold this lock when we call the actual
+ * IRQ handler.
+ */
+spinlock_t irq_controller_lock = SPIN_LOCK_UNLOCKED;
+/*
+ * Controller mappings for all interrupt sources:
+ */
+irq_desc_t irq_desc[NR_IRQS] = { [0 ... NR_IRQS-1] = { 0, &no_irq_type, }};
+
+/*
+ * Special irq handlers.
+ */
+
+void no_action(int cpl, void *dev_id, struct pt_regs *regs) { }
+
+/*
+ * Generic, controller-independent functions:
+ */
+
+int get_irq_list(char *buf)
+{
+	int i, j;
+	struct irqaction * action;
+	char *p = buf;
+
+	p += sprintf(p, "           ");
+	for (j=0; j<smp_num_cpus; j++)
+		p += sprintf(p, "CPU%d       ",j);
+	*p++ = '\n';
+
+	for (i = 0 ; i < NR_IRQS ; i++) {
+		action = irq_desc[i].action;
+		if (!action) 
+			continue;
+		p += sprintf(p, "%3d: ",i);
+		p += sprintf(p, "%10u ", kstat_irqs(i));
+		p += sprintf(p, " %14s", irq_desc[i].handler->typename);
+		p += sprintf(p, "  %s", action->name);
+
+		for (action=action->next; action; action = action->next) {
+			p += sprintf(p, ", %s", action->name);
+		}
+		*p++ = '\n';
+	}
+	return p - buf;
+}
+
+/*
+ * This should really return information about whether
+ * we should do bottom half handling etc. Right now we
+ * end up _always_ checking the bottom half, which is a
+ * waste of time and is not what some drivers would
+ * prefer.
+ */
+int handle_IRQ_event(unsigned int irq, struct pt_regs * regs, struct irqaction * action)
+{
+	int status;
+	int cpu = smp_processor_id();
+
+	irq_enter(cpu, irq);
+
+	status = 1;	/* Force the "do bottom halves" bit */
+
+	if (!(action->flags & SA_INTERRUPT))
+		__sti();
+
+	do {
+		status |= action->flags;
+		action->handler(irq, action->dev_id, regs);
+		action = action->next;
+	} while (action);
+	if (status & SA_SAMPLE_RANDOM)
+		add_interrupt_randomness(irq);
+	__cli();
+
+	irq_exit(cpu, irq);
+
+	return status;
+}
+
+/*
+ * Generic enable/disable code: this just calls
+ * down into the PIC-specific version for the actual
+ * hardware disable after having gotten the irq
+ * controller lock. 
+ */
+void disable_irq_nosync(unsigned int irq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&irq_controller_lock, flags);
+	if (!irq_desc[irq].depth++) {
+		irq_desc[irq].status |= IRQ_DISABLED;
+		irq_desc[irq].handler->disable(irq);
+	}
+	spin_unlock_irqrestore(&irq_controller_lock, flags);
+}
+
+/*
+ * Synchronous version of the above, making sure the IRQ is
+ * no longer running on any other IRQ..
+ */
+void disable_irq(unsigned int irq)
+{
+	disable_irq_nosync(irq);
+
+	if (!local_irq_count[smp_processor_id()]) {
+		do {
+			barrier();
+		} while (irq_desc[irq].status & IRQ_INPROGRESS);
+	}
+}
+
+void enable_irq(unsigned int irq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&irq_controller_lock, flags);
+	switch (irq_desc[irq].depth) {
+	case 1: {
+		unsigned int status = irq_desc[irq].status & ~IRQ_DISABLED;
+		irq_desc[irq].status = status;
+		if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
+			irq_desc[irq].status = status | IRQ_REPLAY;
+			hw_resend_irq(irq_desc[irq].handler,irq);
+		}
+		irq_desc[irq].handler->enable(irq);
+		/* fall-through */
+	}
+	default:
+		irq_desc[irq].depth--;
+		break;
+	case 0:
+		printk("enable_irq() unbalanced from %p\n",
+		       __builtin_return_address(0));
+	}
+	spin_unlock_irqrestore(&irq_controller_lock, flags);
+}
+
+/*
+ * do_IRQ handles all normal device IRQ's.
+ */
+asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
+		      unsigned long r6, unsigned long r7,
+		      struct pt_regs regs)
+{	
+	/* 
+	 * We ack quickly, we don't want the irq controller
+	 * thinking we're snobs just because some other CPU has
+	 * disabled global interrupts (we have already done the
+	 * INT_ACK cycles, it's too late to try to pretend to the
+	 * controller that we aren't taking the interrupt).
+	 *
+	 * 0 return value means that this irq is already being
+	 * handled by some other CPU. (or is disabled)
+	 */
+	int irq;
+	int cpu = smp_processor_id();
+	irq_desc_t *desc;
+	struct irqaction * action;
+	unsigned int status;
+
+	/* Get IRQ number */
+	asm volatile("stc	r2_bank,%0\n\t"
+		     "shlr2	%0\n\t"
+		     "shlr2	%0\n\t"
+		     "shlr	%0\n\t"
+		     "add	#-16,%0\n\t"
+		     :"=z" (irq));
+
+	kstat.irqs[cpu][irq]++;
+	desc = irq_desc + irq;
+	spin_lock(&irq_controller_lock);
+	irq_desc[irq].handler->ack(irq);
+	/*
+	   REPLAY is when Linux resends an IRQ that was dropped earlier
+	   WAITING is used by probe to mark irqs that are being tested
+	   */
+	status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
+	status |= IRQ_PENDING; /* we _want_ to handle it */
+
+	/*
+	 * If the IRQ is disabled for whatever reason, we cannot
+	 * use the action we have.
+	 */
+	action = NULL;
+	if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
+		action = desc->action;
+		status &= ~IRQ_PENDING; /* we commit to handling */
+		status |= IRQ_INPROGRESS; /* we are handling it */
+	}
+	desc->status = status;
+	spin_unlock(&irq_controller_lock);
+
+	/*
+	 * If there is no IRQ handler or it was disabled, exit early.
+	   Since we set PENDING, if another processor is handling
+	   a different instance of this same irq, the other processor
+	   will take care of it.
+	 */
+	if (!action)
+		return 1;
+
+	/*
+	 * Edge triggered interrupts need to remember
+	 * pending events.
+	 * This applies to any hw interrupts that allow a second
+	 * instance of the same irq to arrive while we are in do_IRQ
+	 * or in the handler. But the code here only handles the _second_
+	 * instance of the irq, not the third or fourth. So it is mostly
+	 * useful for irq hardware that does not mask cleanly in an
+	 * SMP environment.
+	 */
+	for (;;) {
+		handle_IRQ_event(irq, &regs, action);
+		spin_lock(&irq_controller_lock);
+		
+		if (!(desc->status & IRQ_PENDING))
+			break;
+		desc->status &= ~IRQ_PENDING;
+		spin_unlock(&irq_controller_lock);
+	}
+	desc->status &= ~IRQ_INPROGRESS;
+	if (!(desc->status & IRQ_DISABLED)){
+			irq_desc[irq].handler->end(irq);
+	}
+	spin_unlock(&irq_controller_lock);
+
+	/*
+	 * This should be conditional: we should really get
+	 * a return code from the irq handler to tell us
+	 * whether the handler wants us to do software bottom
+	 * half handling or not..
+	 */
+	if (1) {
+		if (bh_active & bh_mask)
+			do_bottom_half();
+	}
+	return 1;
+}
+
+int request_irq(unsigned int irq, 
+		void (*handler)(int, void *, struct pt_regs *),
+		unsigned long irqflags, 
+		const char * devname,
+		void *dev_id)
+{
+	int retval;
+	struct irqaction * action;
+
+	if (irq >= NR_IRQS)
+		return -EINVAL;
+	if (!handler)
+		return -EINVAL;
+
+	action = (struct irqaction *)
+			kmalloc(sizeof(struct irqaction), GFP_KERNEL);
+	if (!action)
+		return -ENOMEM;
+
+	action->handler = handler;
+	action->flags = irqflags;
+	action->mask = 0;
+	action->name = devname;
+	action->next = NULL;
+	action->dev_id = dev_id;
+
+	retval = setup_irq(irq, action);
+	if (retval)
+		kfree(action);
+	return retval;
+}
+		
+void free_irq(unsigned int irq, void *dev_id)
+{
+	struct irqaction **p;
+	unsigned long flags;
+
+	if (irq >= NR_IRQS)
+		return;
+
+	spin_lock_irqsave(&irq_controller_lock,flags);
+	p = &irq_desc[irq].action;
+	for (;;) {
+		struct irqaction * action = *p;
+		if (action) {
+			struct irqaction **pp = p;
+			p = &action->next;
+			if (action->dev_id != dev_id)
+				continue;
+
+			/* Found it - now remove it from the list of entries */
+			*pp = action->next;
+			if (irq_desc[irq].action)
+				break;
+			irq_desc[irq].status |= IRQ_DISABLED;
+			irq_desc[irq].handler->shutdown(irq);
+			break;
+		}
+		printk("Trying to free free IRQ%d\n",irq);
+		break;
+	}
+	spin_unlock_irqrestore(&irq_controller_lock,flags);
+}
+
+/*
+ * IRQ autodetection code..
+ *
+ * This depends on the fact that any interrupt that
+ * comes in on to an unassigned handler will get stuck
+ * with "IRQ_WAITING" cleared and the interrupt
+ * disabled.
+ */
+unsigned long probe_irq_on(void)
+{
+	unsigned int i;
+	unsigned long delay;
+
+	/*
+	 * first, enable any unassigned irqs
+	 */
+	spin_lock_irq(&irq_controller_lock);
+	for (i = NR_IRQS-1; i > 0; i--) {
+		if (!irq_desc[i].action) {
+			irq_desc[i].status |= IRQ_AUTODETECT | IRQ_WAITING;
+			if(irq_desc[i].handler->startup(i))
+				irq_desc[i].status |= IRQ_PENDING;
+		}
+	}
+	spin_unlock_irq(&irq_controller_lock);
+
+	/*
+	 * Wait for spurious interrupts to trigger
+	 */
+	for (delay = jiffies + HZ/10; time_after(delay, jiffies); )
+		/* about 100ms delay */ synchronize_irq();
+
+	/*
+	 * Now filter out any obviously spurious interrupts
+	 */
+	spin_lock_irq(&irq_controller_lock);
+	for (i=0; i<NR_IRQS; i++) {
+		unsigned int status = irq_desc[i].status;
+
+		if (!(status & IRQ_AUTODETECT))
+			continue;
+		
+		/* It triggered already - consider it spurious. */
+		if (!(status & IRQ_WAITING)) {
+			irq_desc[i].status = status & ~IRQ_AUTODETECT;
+			irq_desc[i].handler->shutdown(i);
+		}
+	}
+	spin_unlock_irq(&irq_controller_lock);
+
+	return 0x12345678;
+}
+
+int probe_irq_off(unsigned long unused)
+{
+	int i, irq_found, nr_irqs;
+
+	if (unused != 0x12345678)
+		printk("Bad IRQ probe from %lx\n", (&unused)[-1]);
+
+	nr_irqs = 0;
+	irq_found = 0;
+	spin_lock_irq(&irq_controller_lock);
+	for (i=0; i<NR_IRQS; i++) {
+		unsigned int status = irq_desc[i].status;
+
+		if (!(status & IRQ_AUTODETECT))
+			continue;
+
+		if (!(status & IRQ_WAITING)) {
+			if (!nr_irqs)
+				irq_found = i;
+			nr_irqs++;
+		}
+		irq_desc[i].status = status & ~IRQ_AUTODETECT;
+		irq_desc[i].handler->shutdown(i);
+	}
+	spin_unlock_irq(&irq_controller_lock);
+
+	if (nr_irqs > 1)
+		irq_found = -irq_found;
+	return irq_found;
+}
+
+int setup_irq(unsigned int irq, struct irqaction * new)
+{
+	int shared = 0;
+	struct irqaction *old, **p;
+	unsigned long flags;
+
+	/*
+	 * Some drivers like serial.c use request_irq() heavily,
+	 * so we have to be careful not to interfere with a
+	 * running system.
+	 */
+	if (new->flags & SA_SAMPLE_RANDOM) {
+		/*
+		 * This function might sleep, we want to call it first,
+		 * outside of the atomic block.
+		 * Yes, this might clear the entropy pool if the wrong
+		 * driver is attempted to be loaded, without actually
+		 * installing a new handler, but is this really a problem,
+		 * only the sysadmin is able to do this.
+		 */
+		rand_initialize_irq(irq);
+	}
+
+	/*
+	 * The following block of code has to be executed atomically
+	 */
+	spin_lock_irqsave(&irq_controller_lock,flags);
+	p = &irq_desc[irq].action;
+	if ((old = *p) != NULL) {
+		/* Can't share interrupts unless both agree to */
+		if (!(old->flags & new->flags & SA_SHIRQ)) {
+			spin_unlock_irqrestore(&irq_controller_lock,flags);
+			return -EBUSY;
+		}
+
+		/* add new interrupt at end of irq queue */
+		do {
+			p = &old->next;
+			old = *p;
+		} while (old);
+		shared = 1;
+	}
+
+	*p = new;
+
+	if (!shared) {
+		irq_desc[irq].depth = 0;
+		irq_desc[irq].status &= ~IRQ_DISABLED;
+		irq_desc[irq].handler->startup(irq);
+	}
+	spin_unlock_irqrestore(&irq_controller_lock,flags);
+	return 0;
+}