s390: convert interrupt handling to use generic hardirq

With the introduction of PCI it became apparent that s390 should
convert to generic hardirqs as too many drivers do not have the
correct dependency for GENERIC_HARDIRQS. On the architecture
level s390 does not have irq lines. It has external interrupts,
I/O interrupts and adapter interrupts. This patch hard-codes all
external interrupts as irq #1, all I/O interrupts as irq #2 and
all adapter interrupts as irq #3. The additional information from
the lowcore associated with the interrupt is stored in the
pt_regs of the interrupt frame, where the interrupt handler can
pick it up. For PCI/MSI interrupts the adapter interrupt handler
scans the relevant bit fields and calls generic_handle_irq with
the virtual irq number for the MSI interrupt.

Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 42 insertions, 28 deletions

diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index 6ead6d076445..d028fd800c9c 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -81,17 +81,34 @@ void unregister_adapter_interrupt(struct airq_struct *airq)
 }
 EXPORT_SYMBOL(unregister_adapter_interrupt);
 
-void do_adapter_IO(u8 isc)
+static irqreturn_t do_airq_interrupt(int irq, void *dummy)
 {
+	struct tpi_info *tpi_info;
 	struct airq_struct *airq;
 	struct hlist_head *head;
 
-	head = &airq_lists[isc];
+	__this_cpu_write(s390_idle.nohz_delay, 1);
+	tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
+	head = &airq_lists[tpi_info->isc];
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(airq, head, list)
 		if ((*airq->lsi_ptr & airq->lsi_mask) != 0)
 			airq->handler(airq);
 	rcu_read_unlock();
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction airq_interrupt = {
+	.name	 = "AIO",
+	.handler = do_airq_interrupt,
+};
+
+void __init init_airq_interrupts(void)
+{
+	irq_set_chip_and_handler(THIN_INTERRUPT,
+				 &dummy_irq_chip, handle_percpu_irq);
+	setup_irq(THIN_INTERRUPT, &airq_interrupt);
 }
 
 /**
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 4eeb4a6bf207..d7da67a31c77 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -561,37 +561,23 @@ out:
 }
 
 /*
- * do_IRQ() handles all normal I/O device IRQ's (the special
- *	    SMP cross-CPU interrupts have their own specific
- *	    handlers).
- *
+ * do_cio_interrupt() handles all normal I/O device IRQ's
  */
-void __irq_entry do_IRQ(struct pt_regs *regs)
+static irqreturn_t do_cio_interrupt(int irq, void *dummy)
 {
-	struct tpi_info *tpi_info = (struct tpi_info *) &regs->int_code;
+	struct tpi_info *tpi_info;
 	struct subchannel *sch;
 	struct irb *irb;
-	struct pt_regs *old_regs;
 
-	old_regs = set_irq_regs(regs);
-	irq_enter();
 	__this_cpu_write(s390_idle.nohz_delay, 1);
-	if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
-		/* Serve timer interrupts first. */
-		clock_comparator_work();
-
-	kstat_incr_irqs_this_cpu(IO_INTERRUPT, NULL);
+	tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
 	irb = (struct irb *) &S390_lowcore.irb;
-	if (tpi_info->adapter_IO) {
-		do_adapter_IO(tpi_info->isc);
-		goto out;
-	}
 	sch = (struct subchannel *)(unsigned long) tpi_info->intparm;
 	if (!sch) {
 		/* Clear pending interrupt condition. */
 		inc_irq_stat(IRQIO_CIO);
 		tsch(tpi_info->schid, irb);
-		goto out;
+		return IRQ_HANDLED;
 	}
 	spin_lock(sch->lock);
 	/* Store interrupt response block to lowcore. */
@@ -606,9 +592,23 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
 	} else
 		inc_irq_stat(IRQIO_CIO);
 	spin_unlock(sch->lock);
-out:
-	irq_exit();
-	set_irq_regs(old_regs);
+
+	return IRQ_HANDLED;
+}
+
+static struct irq_desc *irq_desc_io;
+
+static struct irqaction io_interrupt = {
+	.name	 = "IO",
+	.handler = do_cio_interrupt,
+};
+
+void __init init_cio_interrupts(void)
+{
+	irq_set_chip_and_handler(IO_INTERRUPT,
+				 &dummy_irq_chip, handle_percpu_irq);
+	setup_irq(IO_INTERRUPT, &io_interrupt);
+	irq_desc_io = irq_to_desc(IO_INTERRUPT);
 }
 
 #ifdef CONFIG_CCW_CONSOLE
@@ -635,7 +635,7 @@ void cio_tsch(struct subchannel *sch)
 		local_bh_disable();
 		irq_enter();
 	}
-	kstat_incr_irqs_this_cpu(IO_INTERRUPT, NULL);
+	kstat_incr_irqs_this_cpu(IO_INTERRUPT, irq_desc_io);
 	if (sch->driver && sch->driver->irq)
 		sch->driver->irq(sch);
 	else
diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index d62f5e7f3cf1..d42f67412bd8 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -121,9 +121,6 @@ extern int cio_commit_config(struct subchannel *sch);
 int cio_tm_start_key(struct subchannel *sch, struct tcw *tcw, u8 lpm, u8 key);
 int cio_tm_intrg(struct subchannel *sch);
 
-void do_adapter_IO(u8 isc);
-void do_IRQ(struct pt_regs *);
-
 /* Use with care. */
 #ifdef CONFIG_CCW_CONSOLE
 extern struct subchannel *cio_probe_console(void);