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 b6263b3996ab19b1235f17af243aab43cb7d944d..146dc0b8ec61752c03278cf5121061aaaf4c27ce 100644 (file)
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1331,6 +1331,44 @@ static inline void ahci_gtf_filter_workaround(struct ata_host *host)
 {}
 #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 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
        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);