ahci: Workaround for ThunderX Errata#22536
Due to Errata in ThunderX, HOST_IRQ_STAT should be
cleared before leaving the interrupt handler.
The patch attempts to satisfy the need.
Changes from V2:
- removed newfile
- code is now under CONFIG_ARM64
Changes from V1:
- Rebased on top of libata/for-4.6
- Moved ThunderX intr handler to new file
tj: Minor adjustments to comments.
Signed-off-by: Tirumalesh Chalamarla <tchalamarla@caviumnetworks.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index b6263b3..146dc0b 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1331,6 +1331,44 @@
{}
#endif
+#ifdef CONFIG_ARM64
+/*
+ * Due to ERRATA#22536, ThunderX needs to handle HOST_IRQ_STAT differently.
+ * Workaround is to make sure all pending IRQs are served before leaving
+ * handler.
+ */
+static irqreturn_t ahci_thunderx_irq_handler(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;
+ unsigned int handled = 1;
+
+ VPRINTK("ENTER\n");
+ hpriv = host->private_data;
+ mmio = hpriv->mmio;
+ irq_stat = readl(mmio + HOST_IRQ_STAT);
+ if (!irq_stat)
+ return IRQ_NONE;
+
+ do {
+ irq_masked = irq_stat & hpriv->port_map;
+ spin_lock(&host->lock);
+ rc = ahci_handle_port_intr(host, irq_masked);
+ if (!rc)
+ handled = 0;
+ writel(irq_stat, mmio + HOST_IRQ_STAT);
+ irq_stat = readl(mmio + HOST_IRQ_STAT);
+ spin_unlock(&host->lock);
+ } while (irq_stat);
+ VPRINTK("EXIT\n");
+
+ return IRQ_RETVAL(handled);
+}
+#endif
+
/*
* ahci_init_msix() - optionally enable per-port MSI-X otherwise defer
* to single msi.
@@ -1566,6 +1604,11 @@
if (ahci_broken_devslp(pdev))
hpriv->flags |= AHCI_HFLAG_NO_DEVSLP;
+#ifdef CONFIG_ARM64
+ if (pdev->vendor == 0x177d && pdev->device == 0xa01c)
+ hpriv->irq_handler = ahci_thunderx_irq_handler;
+#endif
+
/* save initial config */
ahci_pci_save_initial_config(pdev, hpriv);