[PATCH][RFT] AHCI message signalled interrupt (MSI) support

[Jeff Garzik <jgarzik@pobox.com>]

This adds a more-efficient interrupt delivery mechanism to AHCI, once 
tested, it will become the default for all MSI-capable systems.

	Jeff



diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -152,6 +152,7 @@ struct ahci_sg {
 
 struct ahci_host_priv {
 	unsigned long		flags;
+	unsigned int		have_msi; /* is PCI MSI enabled? */
 	u32			cap;	/* cache of HOST_CAP register */
 	u32			port_map; /* cache of HOST_PORTS_IMPL reg */
 };
@@ -182,6 +183,7 @@ static void ahci_qc_prep(struct ata_queu
 static u8 ahci_check_status(struct ata_port *ap);
 static u8 ahci_check_err(struct ata_port *ap);
 static inline int ahci_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc);
+static void ahci_remove_one (struct pci_dev *pdev);
 
 static Scsi_Host_Template ahci_sht = {
 	.module			= THIS_MODULE,
@@ -271,7 +273,7 @@ static struct pci_driver ahci_pci_driver
 	.name			= DRV_NAME,
 	.id_table		= ahci_pci_tbl,
 	.probe			= ahci_init_one,
-	.remove			= ata_pci_remove_one,
+	.remove			= ahci_remove_one,
 };
 
 
@@ -876,15 +878,19 @@ static int ahci_host_init(struct ata_pro
 }
 
 /* move to PCI layer, integrate w/ MSI stuff */
-static void pci_enable_intx(struct pci_dev *pdev)
+static void pci_intx(struct pci_dev *pdev, int enable)
 {
-	u16 pci_command;
+	u16 pci_command, new;
 
 	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
-	if (pci_command & PCI_COMMAND_INTX_DISABLE) {
-		pci_command &= ~PCI_COMMAND_INTX_DISABLE;
+
+	if (enable)
+		new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
+	else
+		new = pci_command | PCI_COMMAND_INTX_DISABLE;
+
+	if (new != pci_command)
 		pci_write_config_word(pdev, PCI_COMMAND, pci_command);
-	}
 }
 
 static void ahci_print_info(struct ata_probe_ent *probe_ent)
@@ -966,7 +972,7 @@ static int ahci_init_one (struct pci_dev
 	unsigned long base;
 	void *mmio_base;
 	unsigned int board_idx = (unsigned int) ent->driver_data;
-	int pci_dev_busy = 0;
+	int have_msi, pci_dev_busy = 0;
 	int rc;
 
 	VPRINTK("ENTER\n");
@@ -984,12 +990,17 @@ static int ahci_init_one (struct pci_dev
 		goto err_out;
 	}
 
-	pci_enable_intx(pdev);
+	if (pci_enable_msi(pdev) == 0)
+		have_msi = 1;
+	else {
+		pci_intx(pdev, 1);
+		have_msi = 0;
+	}
 
 	probe_ent = kmalloc(sizeof(*probe_ent), GFP_KERNEL);
 	if (probe_ent == NULL) {
 		rc = -ENOMEM;
-		goto err_out_regions;
+		goto err_out_msi;
 	}
 
 	memset(probe_ent, 0, sizeof(*probe_ent));
@@ -1022,6 +1033,8 @@ static int ahci_init_one (struct pci_dev
 	probe_ent->mmio_base = mmio_base;
 	probe_ent->private_data = hpriv;
 
+	hpriv->have_msi = have_msi;
+
 	/* initialize adapter */
 	rc = ahci_host_init(probe_ent);
 	if (rc)
@@ -1041,7 +1054,11 @@ err_out_iounmap:
 	iounmap(mmio_base);
 err_out_free_ent:
 	kfree(probe_ent);
-err_out_regions:
+err_out_msi:
+	if (have_msi)
+		pci_disable_msi(pdev);
+	else
+		pci_intx(pdev, 0);
 	pci_release_regions(pdev);
 err_out:
 	if (!pci_dev_busy)
@@ -1049,6 +1066,42 @@ err_out:
 	return rc;
 }
 
+static void ahci_remove_one (struct pci_dev *pdev)
+{
+	struct device *dev = pci_dev_to_dev(pdev);
+	struct ata_host_set *host_set = dev_get_drvdata(dev);
+	struct ahci_host_priv *hpriv = host_set->private_data;
+	struct ata_port *ap;
+	unsigned int i;
+	int have_msi;
+
+	for (i = 0; i < host_set->n_ports; i++) {
+		ap = host_set->ports[i];
+
+		scsi_remove_host(ap->host);
+	}
+
+	have_msi = hpriv->have_msi;
+	free_irq(host_set->irq, host_set);
+	host_set->ops->host_stop(host_set);
+	iounmap(host_set->mmio_base);
+
+	for (i = 0; i < host_set->n_ports; i++) {
+		ap = host_set->ports[i];
+
+		ata_scsi_release(ap->host);
+		scsi_host_put(ap->host);
+	}
+
+	if (have_msi)
+		pci_disable_msi(pdev);
+	else
+		pci_intx(pdev, 0);
+	pci_release_regions(pdev);
+	kfree(host_set);
+	pci_disable_device(pdev);
+	dev_set_drvdata(dev, NULL);
+}
 
 static int __init ahci_init(void)
 {