[PATCH] sky2: support msi interrupt (revised)

This hardware supports Message Signaled interrupts.
When setting up, use software interrupt to check for bad hardware.

Signed-off-by: Stephen Hemminger <shemminger @osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/net/sky2.c

@@ -101,6 +101,10 @@ static int copybreak __read_mostly = 256;
 module_param(copybreak, int, 0);
 MODULE_PARM_DESC(copybreak, "Receive copy threshold");
 
+static int disable_msi = 0;
+module_param(disable_msi, int, 0);
+MODULE_PARM_DESC(disable_msi, "Disable Message Signaled Interrupt (MSI)");
+
 static const struct pci_device_id sky2_id_table[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_SYSKONNECT, 0x9000) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_SYSKONNECT, 0x9E00) },
@@ -3064,6 +3068,61 @@ static void __devinit sky2_show_addr(struct net_device *dev)
 		       dev->dev_addr[3], dev->dev_addr[4], dev->dev_addr[5]);
 }
 
+/* Handle software interrupt used during MSI test */
+static irqreturn_t __devinit sky2_test_intr(int irq, void *dev_id,
+					    struct pt_regs *regs)
+{
+	struct sky2_hw *hw = dev_id;
+	u32 status = sky2_read32(hw, B0_Y2_SP_ISRC2);
+
+	if (status == 0)
+		return IRQ_NONE;
+
+	if (status & Y2_IS_IRQ_SW) {
+		sky2_write8(hw, B0_CTST, CS_CL_SW_IRQ);
+		hw->msi = 1;
+	}
+	sky2_write32(hw, B0_Y2_SP_ICR, 2);
+
+	sky2_read32(hw, B0_IMSK);
+	return IRQ_HANDLED;
+}
+
+/* Test interrupt path by forcing a a software IRQ */
+static int __devinit sky2_test_msi(struct sky2_hw *hw)
+{
+	struct pci_dev *pdev = hw->pdev;
+	int i, err;
+
+	sky2_write32(hw, B0_IMSK, Y2_IS_IRQ_SW);
+
+	err = request_irq(pdev->irq, sky2_test_intr, SA_SHIRQ, DRV_NAME, hw);
+	if (err) {
+		printk(KERN_ERR PFX "%s: cannot assign irq %d\n",
+		       pci_name(pdev), pdev->irq);
+		return err;
+	}
+
+	sky2_write8(hw, B0_CTST, CS_ST_SW_IRQ);
+	wmb();
+
+	for (i = 0; i < 10; i++) {
+		barrier();
+		if (hw->msi)
+			goto found;
+		mdelay(1);
+	}
+
+	err = -EOPNOTSUPP;
+	sky2_write8(hw, B0_CTST, CS_CL_SW_IRQ);
+ found:
+	sky2_write32(hw, B0_IMSK, 0);
+
+	free_irq(pdev->irq, hw);
+
+	return err;
+}
+
 static int __devinit sky2_probe(struct pci_dev *pdev,
 				const struct pci_device_id *ent)
 {
@@ -3184,6 +3243,20 @@ static int __devinit sky2_probe(struct pci_dev *pdev,
 		}
 	}
 
+	if (!disable_msi && pci_enable_msi(pdev) == 0) {
+		err = sky2_test_msi(hw);
+		if (err == -EOPNOTSUPP) {
+			/* MSI test failed, go back to INTx mode */
+			printk(KERN_WARNING PFX "%s: No interrupt was generated using MSI, "
+			       "switching to INTx mode. Please report this failure to "
+			       "the PCI maintainer and include system chipset information.\n",
+			       pci_name(pdev));
+			pci_disable_msi(pdev);
+		}
+		else if (err)
+			goto err_out_unregister;
+	}
+
 	err = request_irq(pdev->irq, sky2_intr, SA_SHIRQ | SA_SAMPLE_RANDOM,
 			  DRV_NAME, hw);
 	if (err) {
@@ -3200,6 +3273,8 @@ static int __devinit sky2_probe(struct pci_dev *pdev,
 	return 0;
 
 err_out_unregister:
+	if (hw->msi)
+		pci_disable_msi(pdev);
 	if (dev1) {
 		unregister_netdev(dev1);
 		free_netdev(dev1);
@@ -3242,6 +3317,8 @@ static void __devexit sky2_remove(struct pci_dev *pdev)
 	sky2_read8(hw, B0_CTST);
 
 	free_irq(pdev->irq, hw);
+	if (hw->msi)
+		pci_disable_msi(pdev);
 	pci_free_consistent(pdev, STATUS_LE_BYTES, hw->st_le, hw->st_dma);
 	pci_release_regions(pdev);
 	pci_disable_device(pdev);

drivers/net/sky2.h

@@ -1841,6 +1841,7 @@ struct sky2_hw {
 	struct net_device    *dev[2];
 
 	int		     pm_cap;
+	int		     msi;
 	u8	     	     chip_id;
 	u8		     chip_rev;
 	u8		     copper;