diff options
Diffstat (limited to 'kernel/irq/autoprobe.c')
| -rw-r--r-- | kernel/irq/autoprobe.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/kernel/irq/autoprobe.c b/kernel/irq/autoprobe.c new file mode 100644 index 000000000..ae60cae24 --- /dev/null +++ b/kernel/irq/autoprobe.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar + * + * This file contains the interrupt probing code and driver APIs. + */ + +#include <linux/irq.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/delay.h> +#include <linux/async.h> + +#include "internals.h" + +/* + * Autodetection depends on the fact that any interrupt that + * comes in on to an unassigned handler will get stuck with + * "IRQS_WAITING" cleared and the interrupt disabled. + */ +static DEFINE_MUTEX(probing_active); + +/** + * probe_irq_on - begin an interrupt autodetect + * + * Commence probing for an interrupt. The interrupts are scanned + * and a mask of potential interrupt lines is returned. + * + */ +unsigned long probe_irq_on(void) +{ + struct irq_desc *desc; + unsigned long mask = 0; + int i; + + /* + * quiesce the kernel, or at least the asynchronous portion + */ + async_synchronize_full(); + mutex_lock(&probing_active); + /* + * something may have generated an irq long ago and we want to + * flush such a longstanding irq before considering it as spurious. + */ + for_each_irq_desc_reverse(i, desc) { + raw_spin_lock_irq(&desc->lock); + if (!desc->action && irq_settings_can_probe(desc)) { + /* + * Some chips need to know about probing in + * progress: + */ + if (desc->irq_data.chip->irq_set_type) + desc->irq_data.chip->irq_set_type(&desc->irq_data, + IRQ_TYPE_PROBE); + irq_activate_and_startup(desc, IRQ_NORESEND); + } + raw_spin_unlock_irq(&desc->lock); + } + + /* Wait for longstanding interrupts to trigger. */ + msleep(20); + + /* + * enable any unassigned irqs + * (we must startup again here because if a longstanding irq + * happened in the previous stage, it may have masked itself) + */ + for_each_irq_desc_reverse(i, desc) { + raw_spin_lock_irq(&desc->lock); + if (!desc->action && irq_settings_can_probe(desc)) { + desc->istate |= IRQS_AUTODETECT | IRQS_WAITING; + if (irq_activate_and_startup(desc, IRQ_NORESEND)) + desc->istate |= IRQS_PENDING; + } + raw_spin_unlock_irq(&desc->lock); + } + + /* + * Wait for spurious interrupts to trigger + */ + msleep(100); + + /* + * Now filter out any obviously spurious interrupts + */ + for_each_irq_desc(i, desc) { + raw_spin_lock_irq(&desc->lock); + + if (desc->istate & IRQS_AUTODETECT) { + /* It triggered already - consider it spurious. */ + if (!(desc->istate & IRQS_WAITING)) { + desc->istate &= ~IRQS_AUTODETECT; + irq_shutdown_and_deactivate(desc); + } else + if (i < 32) + mask |= 1 << i; + } + raw_spin_unlock_irq(&desc->lock); + } + + return mask; +} +EXPORT_SYMBOL(probe_irq_on); + +/** + * probe_irq_mask - scan a bitmap of interrupt lines + * @val: mask of interrupts to consider + * + * Scan the interrupt lines and return a bitmap of active + * autodetect interrupts. The interrupt probe logic state + * is then returned to its previous value. + * + * Note: we need to scan all the irq's even though we will + * only return autodetect irq numbers - just so that we reset + * them all to a known state. + */ +unsigned int probe_irq_mask(unsigned long val) +{ + unsigned int mask = 0; + struct irq_desc *desc; + int i; + + for_each_irq_desc(i, desc) { + raw_spin_lock_irq(&desc->lock); + if (desc->istate & IRQS_AUTODETECT) { + if (i < 16 && !(desc->istate & IRQS_WAITING)) + mask |= 1 << i; + + desc->istate &= ~IRQS_AUTODETECT; + irq_shutdown_and_deactivate(desc); + } + raw_spin_unlock_irq(&desc->lock); + } + mutex_unlock(&probing_active); + + return mask & val; +} +EXPORT_SYMBOL(probe_irq_mask); + +/** + * probe_irq_off - end an interrupt autodetect + * @val: mask of potential interrupts (unused) + * + * Scans the unused interrupt lines and returns the line which + * appears to have triggered the interrupt. If no interrupt was + * found then zero is returned. If more than one interrupt is + * found then minus the first candidate is returned to indicate + * their is doubt. + * + * The interrupt probe logic state is returned to its previous + * value. + * + * BUGS: When used in a module (which arguably shouldn't happen) + * nothing prevents two IRQ probe callers from overlapping. The + * results of this are non-optimal. + */ +int probe_irq_off(unsigned long val) +{ + int i, irq_found = 0, nr_of_irqs = 0; + struct irq_desc *desc; + + for_each_irq_desc(i, desc) { + raw_spin_lock_irq(&desc->lock); + + if (desc->istate & IRQS_AUTODETECT) { + if (!(desc->istate & IRQS_WAITING)) { + if (!nr_of_irqs) + irq_found = i; + nr_of_irqs++; + } + desc->istate &= ~IRQS_AUTODETECT; + irq_shutdown_and_deactivate(desc); + } + raw_spin_unlock_irq(&desc->lock); + } + mutex_unlock(&probing_active); + + if (nr_of_irqs > 1) + irq_found = -irq_found; + + return irq_found; +} +EXPORT_SYMBOL(probe_irq_off); + |