Re: sh: simplify board specific interrupt code for solution engine 7780

[Paul M. <le...@li...>]

On Mon, Aug 06, 2007 at 06:33:10PM +0900, Magnus Damm wrote:
> I understand that you want to setup your priorities somehow, but I
> think there must exist better and cleaner ways to do it. I know Paul
> was thinking about adding some function to set interrupt priority
> similar to set_irq_type(), but I wonder if it may be better to allow
> the user to select the priorities from sysfs or something. Probably
> not, at least not as a first step.
> 
> So if some generic function like set_irq_type() could be used that
> would be great - otherwise I think just adding some intc specific
> function is good enough. So this is what I would prefer something like
> this:
> 
> void board_irq_setup()
> {
>   /* first register the board specific interrupts */
>   register_intc_controller(&intc_desc);
> 
>   /* then setup interrupt priorities for this board */
>   set_irq_priority(STNIC_IRQ, 12);
>   set_irq_priority(CF_IRQ, 3);
> }
> 
> Does that solve what you are want to do?
> 
> Speaking about interrupt priorities, the irq code in
> arch/sh/boards/se/770x/irq.c seem to set a priority that is very
> similar to the IRQ value. Do you know anything about this? Is this
> priority value similar by pure coincidence, or is this related to the
> IRL interrupt number?
> 
Yes, I was thinking of something like the following.

This does restrict the range of allowable priorities at request_irq()
time, but if someone has a use case for an explicit priority,
set_irq_prio() can be used for kicking that down to the chip handler.

I would wager that 99.99999% of all use cases will fit in with
default/high/low priorities, though. If someone has a non-academic use
case that won't fit in this model, I'd be interested in hearing it.

--

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 1695054..1f7578e 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -45,6 +45,11 @@ typedef	void fastcall (*irq_flow_handler_t)(unsigned int irq,
 #define IRQ_TYPE_SENSE_MASK	0x0000000f	/* Mask of the above */
 #define IRQ_TYPE_PROBE		0x00000010	/* Probing in progress */
 
+/* IRQ priorities */
+#define IRQ_PRIO_NONE		0x00000000	/* Default priority */
+#define IRQ_PRIO_HIGH		0x00000001	/* High priority */
+#define IRQ_PRIO_LOW		0x00000002	/* Low priority */
+
 /* Internal flags */
 #define IRQ_INPROGRESS		0x00000100	/* IRQ handler active - do not enter! */
 #define IRQ_DISABLED		0x00000200	/* IRQ disabled - do not enter! */
@@ -91,6 +96,7 @@ struct msi_desc;
  * @retrigger:		resend an IRQ to the CPU
  * @set_type:		set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ
  * @set_wake:		enable/disable power-management wake-on of an IRQ
+ * @set_prio:		set the priority of an IRQ
  *
  * @release:		release function solely used by UML
  * @typename:		obsoleted by name, kept as migration helper
@@ -113,6 +119,7 @@ struct irq_chip {
 	int		(*retrigger)(unsigned int irq);
 	int		(*set_type)(unsigned int irq, unsigned int flow_type);
 	int		(*set_wake)(unsigned int irq, unsigned int on);
+	int		(*set_prio)(unsigned int irq, unsigned int prio);
 
 	/* Currently used only by UML, might disappear one day.*/
 #ifdef CONFIG_IRQ_RELEASE_METHOD
@@ -379,6 +386,7 @@ extern int set_irq_data(unsigned int irq, void *data);
 extern int set_irq_chip_data(unsigned int irq, void *data);
 extern int set_irq_type(unsigned int irq, unsigned int type);
 extern int set_irq_msi(unsigned int irq, struct msi_desc *entry);
+extern int set_irq_prio(unsigned int irq, unsigned int prio);
 
 #define get_irq_chip(irq)	(irq_desc[irq].chip)
 #define get_irq_chip_data(irq)	(irq_desc[irq].chip_data)
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 615ce97..fa7df4d 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -141,6 +141,32 @@ int set_irq_type(unsigned int irq, unsigned int type)
 EXPORT_SYMBOL(set_irq_type);
 
 /**
+ *	set_irq_prio - set the irq priority for an irq
+ *	@irq:	irq number
+ *	@prio:	interrupt priority - see include/linux/irq.h
+ */
+int set_irq_prio(unsigned int irq, unsigned int prio)
+{
+	struct irq_desc *desc;
+	unsigned long flags;
+	int ret = -ENXIO;
+
+	if (irq >= NR_IRQS) {
+		printk(KERN_ERR "Trying to set irq priority for IRQ%d\n", irq);
+		return -ENODEV;
+	}
+
+	desc = irq_desc + irq;
+	if (desc->chip->set_prio) {
+		spin_lock_irqsave(&desc->lock, flags);
+		ret = desc->chip->set_prio(irq, prio);
+		spin_unlock_irqrestore(&desc->lock, flags);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(set_irq_prio);
+
+/**
  *	set_irq_data - set irq type data for an irq
  *	@irq:	Interrupt number
  *	@data:	Pointer to interrupt specific data