[PATCH v4 1/2] libahci: Add support to handle HOST_IRQ_STAT as edge trigger latch.

[Suman Tripathi <stripathi@apm.com>]

This patch adds the support to handle HOST_IRQ_STAT as edge trigger
latch.

Signed-off-by: Suman Tripathi <stripathi@apm.com>
---
 drivers/ata/ahci.h    |  2 ++
 drivers/ata/libahci.c | 93 +++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 73 insertions(+), 22 deletions(-)

diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 71262e0..2df2237 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -238,6 +238,8 @@ enum {
 	AHCI_HFLAG_MULTI_MSI		= (1 << 16), /* multiple PCI MSIs */
 	AHCI_HFLAG_NO_DEVSLP		= (1 << 17), /* no device sleep */
 	AHCI_HFLAG_NO_FBS		= (1 << 18), /* no FBS */
+	AHCI_HFLAG_EDGE_TRIG_IRQ	= (1 << 19), /* HOST_IRQ_STAT behaves as
+							Edge Triggered */

 	/* ap->flags bits */

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 61a9c07..6f1a603 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1826,27 +1826,9 @@ static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
 	return IRQ_WAKE_THREAD;
 }

-static irqreturn_t ahci_single_irq_intr(int irq, void *dev_instance)
+static u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)
 {
-	struct ata_host *host = dev_instance;
-	struct ahci_host_priv *hpriv;
 	unsigned int i, handled = 0;
-	void __iomem *mmio;
-	u32 irq_stat, irq_masked;
-
-	VPRINTK("ENTER\n");
-
-	hpriv = host->private_data;
-	mmio = hpriv->mmio;
-
-	/* sigh.  0xffffffff is a valid return from h/w */
-	irq_stat = readl(mmio + HOST_IRQ_STAT);
-	if (!irq_stat)
-		return IRQ_NONE;
-
-	irq_masked = irq_stat & hpriv->port_map;
-
-	spin_lock(&host->lock);

 	for (i = 0; i < host->n_ports; i++) {
 		struct ata_port *ap;
@@ -1864,10 +1846,36 @@ static irqreturn_t ahci_single_irq_intr(int irq, void *dev_instance)
 				dev_warn(host->dev,
 					 "interrupt on disabled port %u\n", i);
 		}
-
 		handled = 1;
 	}

+	return handled;
+}
+
+static irqreturn_t ahci_level_trig_intr(int irq, void *dev_instance)
+{
+	struct ata_host *host = dev_instance;
+	struct ahci_host_priv *hpriv;
+	unsigned int rc = 0;
+	void __iomem *mmio;
+	u32 irq_stat, irq_masked;
+
+	VPRINTK("ENTER\n");
+
+	hpriv = host->private_data;
+	mmio = hpriv->mmio;
+
+	/* sigh.  0xffffffff is a valid return from h/w */
+	irq_stat = readl(mmio + HOST_IRQ_STAT);
+	if (!irq_stat)
+		return IRQ_NONE;
+
+	irq_masked = irq_stat & hpriv->port_map;
+
+	spin_lock(&host->lock);
+
+	rc = ahci_handle_port_intr(host, irq_masked);
+
 	/* HOST_IRQ_STAT behaves as level triggered latch meaning that
 	 * it should be cleared after all the port events are cleared;
 	 * otherwise, it will raise a spurious interrupt after each
@@ -1877,13 +1885,51 @@ static irqreturn_t ahci_single_irq_intr(int irq, void *dev_instance)
 	 * Also, use the unmasked value to clear interrupt as spurious
 	 * pending event on a dummy port might cause screaming IRQ.
 	 */
+
+	writel(irq_stat, mmio + HOST_IRQ_STAT);
+
+	spin_unlock(&host->lock);
+
+	VPRINTK("EXIT\n");
+
+	return IRQ_RETVAL(rc);
+}
+
+static irqreturn_t ahci_edge_trig_intr(int irq, void *dev_instance)
+{
+	struct ata_host *host = dev_instance;
+	struct ahci_host_priv *hpriv;
+	unsigned int rc = 0;
+	void __iomem *mmio;
+	u32 irq_stat, irq_masked;
+
+	VPRINTK("ENTER\n");
+
+	hpriv = host->private_data;
+	mmio = hpriv->mmio;
+
+	/* sigh.  0xffffffff is a valid return from h/w */
+	irq_stat = readl(mmio + HOST_IRQ_STAT);
+	if (!irq_stat)
+		return IRQ_NONE;
+
+	irq_masked = irq_stat & hpriv->port_map;
+
+	spin_lock(&host->lock);
+
+	/*
+	 * HOST_IRQ_STAT behaves as edge triggered latch meaning that
+	 * it should be cleared before all the port events are cleared;
+	 */
 	writel(irq_stat, mmio + HOST_IRQ_STAT);

+	rc = ahci_handle_port_intr(host, irq_masked);
+
 	spin_unlock(&host->lock);

 	VPRINTK("EXIT\n");

-	return IRQ_RETVAL(handled);
+	return IRQ_RETVAL(rc);
 }

 unsigned int ahci_qc_issue(struct ata_queued_cmd *qc)
@@ -2486,8 +2532,11 @@ int ahci_host_activate(struct ata_host *host, int irq,

 	if (hpriv->flags & AHCI_HFLAG_MULTI_MSI)
 		rc = ahci_host_activate_multi_irqs(host, irq, sht);
+	else if (hpriv->flags & AHCI_HFLAG_EDGE_TRIG_IRQ)
+		rc = ata_host_activate(host, irq, ahci_edge_trig_intr,
+				       IRQF_SHARED, sht);
 	else
-		rc = ata_host_activate(host, irq, ahci_single_irq_intr,
+		rc = ata_host_activate(host, irq, ahci_level_trig_intr,
 				       IRQF_SHARED, sht);
 	return rc;
 }
--
1.8.2.1