genirq: record trigger type

Genirq hasn't previously recorded the trigger type used by any given IRQ,
although some irq_chip support has done so.  That data can be useful when
troubleshooting.  This patch records it in the relevant irq_desc.status
bits, and improves consistency between the two driver-visible calls
affected:

 - Make set_irq_type() usage match request_irq() usage:
    * IRQ_TYPE_NONE should be a NOP; succeed, so irq_chip methods
      won't have to handle that case any more (many do it wrong).
    * IRQ_TYPE_PROBE is ignored; any buggy out-of-tree callers
      might need to switch over to the real IRQ probing code.
    * emit the same diagnostics (from shared utility code)

 - Their kerneldoc now reflects usage:
    * request_irq() flags include IRQF_TRIGGER_* to specify
      active edge(s)/level ... docs previously omitted that
    * set_irq_type() is declared in <linux/irq.h> so callers
      should use the (bit-equivalent) IRQ_TYPE_* symbols there

Also: adds a warning about shared IRQs that don't end up using the
requested trigger mode; and fix an unrelated "sparse" warning.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 29 insertions, 10 deletions

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index d663338cb4a8..5203a599d211 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -111,9 +111,9 @@ int set_irq_chip(unsigned int irq, struct irq_chip *chip)
 EXPORT_SYMBOL(set_irq_chip);
 
 /**
- *      set_irq_type - set the irq type for an irq
+ *      set_irq_type - set the irq trigger type for an irq
  *      @irq:   irq number
- *      @type:  interrupt type - see include/linux/interrupt.h
+ *      @type:  IRQ_TYPE_{LEVEL,EDGE}_* value - see include/linux/irq.h
  */
 int set_irq_type(unsigned int irq, unsigned int type)
 {
@@ -127,11 +127,12 @@ int set_irq_type(unsigned int irq, unsigned int type)
         }
 
         desc = irq_desc + irq;
-        if (desc->chip->set_type) {
-                spin_lock_irqsave(&desc->lock, flags);
-                ret = desc->chip->set_type(irq, type);
-                spin_unlock_irqrestore(&desc->lock, flags);
-        }
+        if (type == IRQ_TYPE_NONE)
+                return 0;
+
+        spin_lock_irqsave(&desc->lock, flags);
+        ret = __irq_set_trigger(desc, irq, flags);
+        spin_unlock_irqrestore(&desc->lock, flags);
         return ret;
 }
 EXPORT_SYMBOL(set_irq_type);
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 08a849a22447..422dd00c8bd3 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -10,6 +10,9 @@ extern void irq_chip_set_defaults(struct irq_chip *chip);
 /* Set default handler: */
 extern void compat_irq_chip_set_default_handler(struct irq_desc *desc);
 
+extern int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
+                unsigned long flags);
+
 #ifdef CONFIG_PROC_FS
 extern void register_irq_proc(unsigned int irq);
 extern void register_handler_proc(unsigned int irq, struct irqaction *action);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index d62f69ba7453..e59157b591f8 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -216,7 +216,7 @@ void enable_irq(unsigned int irq)
 }
 EXPORT_SYMBOL(enable_irq);
 
-int set_irq_wake_real(unsigned int irq, unsigned int on)
+static int set_irq_wake_real(unsigned int irq, unsigned int on)
 {
         struct irq_desc *desc = irq_desc + irq;
         int ret = -ENXIO;
@@ -305,10 +305,11 @@ void compat_irq_chip_set_default_handler(struct irq_desc *desc)
                 desc->handle_irq = NULL;
 }
 
-static int __irq_set_trigger(struct irq_chip *chip, unsigned int irq,
+int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
                 unsigned long flags)
 {
         int ret;
+        struct irq_chip *chip = desc->chip;
 
         if (!chip || !chip->set_type) {
                 /*
@@ -326,6 +327,11 @@ static int __irq_set_trigger(struct irq_chip *chip, unsigned int irq,
                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
                                 (int)(flags & IRQF_TRIGGER_MASK),
                                 irq, chip->set_type);
+        else {
+                /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
+                desc->status &= ~IRQ_TYPE_SENSE_MASK;
+                desc->status |= flags & IRQ_TYPE_SENSE_MASK;
+        }
 
         return ret;
 }
@@ -404,7 +410,7 @@ int setup_irq(unsigned int irq, struct irqaction *new)
 
                 /* Setup the type (level, edge polarity) if configured: */
                 if (new->flags & IRQF_TRIGGER_MASK) {
-                        ret = __irq_set_trigger(desc->chip, irq, new->flags);
+                        ret = __irq_set_trigger(desc, irq, new->flags);
 
                         if (ret) {
                                 spin_unlock_irqrestore(&desc->lock, flags);
@@ -430,6 +436,14 @@ int setup_irq(unsigned int irq, struct irqaction *new)
 
                 /* Set default affinity mask once everything is setup */
                 irq_select_affinity(irq);
+
+        } else if ((new->flags & IRQF_TRIGGER_MASK)
+                        && (new->flags & IRQF_TRIGGER_MASK)
+                                != (desc->status & IRQ_TYPE_SENSE_MASK)) {
+                /* hope the handler works with the actual trigger mode... */
+                pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
+                                irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
+                                (int)(new->flags & IRQF_TRIGGER_MASK));
         }
 
         *p = new;
@@ -586,6 +600,7 @@ EXPORT_SYMBOL(free_irq);
  *      IRQF_SHARED             Interrupt is shared
  *      IRQF_DISABLED   Disable local interrupts while processing
  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
+ *      IRQF_TRIGGER_*          Specify active edge(s) or level
  *
  */
 int request_irq(unsigned int irq, irq_handler_t handler,