MN10300: fix serial port vdma irq setup for SMP

The builtin SoC serial ports have no FIFOs and use a virtual DMA mechanism based on high priority IRQs to avoid overruns. These high priority interrupts are pinned to cpu#0 on SMP systems. This patch fixes a problem with SMP where the set_intr_level() interface is used to set the priority for these IRQs. The set_intr_level() function sets priority on the local cpu but on SMP systems, this code may be run on some other cpu than the one handling the interrupts. Instead of setting interrupt level explicitly, this patch uses a special irq_chip for these interrupts so that the mask/unmask methods can set the interrupt level implicitly. Signed-off-by: Mark Salter <[email protected]> Signed-off-by: David Howells <[email protected]>
mrcsosa · Dec 12, 2012 · 8d16002 · 8d16002
1 parent 7d361cb
commit 8d16002
Showing 1 changed file with 30 additions and 4 deletions.
diff --git a/arch/mn10300/kernel/mn10300-serial.c b/arch/mn10300/kernel/mn10300-serial.c
@@ -408,6 +408,34 @@ static struct irq_chip mn10300_serial_pic = {
 	.irq_unmask	= mn10300_serial_nop,
 };
 
+static void mn10300_serial_low_mask(struct irq_data *d)
+{
+	unsigned long flags;
+	u16 tmp;
+
+	flags = arch_local_cli_save();
+	GxICR(d->irq) = NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL);
+	tmp = GxICR(d->irq); /* flush write buffer */
+	arch_local_irq_restore(flags);
+}
+
+static void mn10300_serial_low_unmask(struct irq_data *d)
+{
+	unsigned long flags;
+	u16 tmp;
+
+	flags = arch_local_cli_save();
+	GxICR(d->irq) =
+		NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL) | GxICR_ENABLE;
+	tmp = GxICR(d->irq); /* flush write buffer */
+	arch_local_irq_restore(flags);
+}
+
+static struct irq_chip mn10300_serial_low_pic = {
+	.name		= "mnserial-low",
+	.irq_mask	= mn10300_serial_low_mask,
+	.irq_unmask	= mn10300_serial_low_unmask,
+};
 
 /*
  * serial virtual DMA interrupt jump table
@@ -929,10 +957,8 @@ static int mn10300_serial_startup(struct uart_port *_port)
 	pint->port = port;
 	pint->vdma = mn10300_serial_vdma_tx_handler;
 
-	set_intr_level(port->rx_irq,
-		NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL));
-	set_intr_level(port->tx_irq,
-		NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL));
+	irq_set_chip(port->rx_irq, &mn10300_serial_low_pic);
+	irq_set_chip(port->tx_irq, &mn10300_serial_low_pic);
 	irq_set_chip(port->tm_irq, &mn10300_serial_pic);
 
 	if (request_irq(port->rx_irq, mn10300_serial_interrupt,