ahci: use pci_alloc_irq_vectors

Use the new pci_alloc_irq_vectors API to allocate MSI-X and MSI vectors.
The big advantage over the old code is that we can use the same API for
MSI and MSI-X, and that we don't need to store the MSI-X vector mapping
in driver-private data structures.

This first conversion keeps the probe order as-is: MSI-X multi vector,
MSI multi vector, MSI single vector, MSI-X single vector and last a
single least legacy interrupt line.  There is one small change of
behavior: we now check the "MSI Revert to Single Message" flag for
MSI-X in addition to MSI.

Because the API to find the Linux IRQ number for a MSI/MSI-X vector
is PCI specific, but libahaci is bus-agnostic I had to a
get_irq_vector function pointer to struct ahci_host_priv.  The
alternative would be to move the multi-vector case of ahci_host_activate
to ahci.c and just call ata_host_activate directly from the others
users of ahci_host_activate.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/ahci.c

@@ -1400,142 +1400,56 @@ static irqreturn_t ahci_thunderx_irq_handler(int irq, void *dev_instance)
 }
 #endif
 
-/*
- * ahci_init_msix() - optionally enable per-port MSI-X otherwise defer
- * to single msi.
- */
-static int ahci_init_msix(struct pci_dev *pdev, unsigned int n_ports,
-			  struct ahci_host_priv *hpriv, unsigned long flags)
+static int ahci_get_irq_vector(struct ata_host *host, int port)
 {
-	int nvec, i, rc;
-
-	/* Do not init MSI-X if MSI is disabled for the device */
-	if (hpriv->flags & AHCI_HFLAG_NO_MSI)
-		return -ENODEV;
-
-	nvec = pci_msix_vec_count(pdev);
-	if (nvec < 0)
-		return nvec;
-
-	/*
-	 * Proper MSI-X implementations will have a vector per-port.
-	 * Barring that, we prefer single-MSI over single-MSIX.  If this
-	 * check fails (not enough MSI-X vectors for all ports) we will
-	 * be called again with the flag clear iff ahci_init_msi()
-	 * fails.
-	 */
-	if (flags & AHCI_HFLAG_MULTI_MSIX) {
-		if (nvec < n_ports)
-			return -ENODEV;
-		nvec = n_ports;
-	} else if (nvec) {
-		nvec = 1;
-	} else {
-		/*
-		 * Emit dev_err() since this was the non-legacy irq
-		 * method of last resort.
-		 */
-		rc = -ENODEV;
-		goto fail;
-	}
-
-	for (i = 0; i < nvec; i++)
-		hpriv->msix[i].entry = i;
-	rc = pci_enable_msix_exact(pdev, hpriv->msix, nvec);
-	if (rc < 0)
-		goto fail;
-
-	if (nvec > 1)
-		hpriv->flags |= AHCI_HFLAG_MULTI_MSIX;
-	hpriv->irq = hpriv->msix[0].vector; /* for single msi-x */
-
-	return nvec;
-fail:
-	dev_err(&pdev->dev,
-		"failed to enable MSI-X with error %d, # of vectors: %d\n",
-		rc, nvec);
-
-	return rc;
+	return pci_irq_vector(to_pci_dev(host->dev), port);
 }
 
 static int ahci_init_msi(struct pci_dev *pdev, unsigned int n_ports,
 			struct ahci_host_priv *hpriv)
 {
-	int rc, nvec;
+	int nvec;
 
 	if (hpriv->flags & AHCI_HFLAG_NO_MSI)
 		return -ENODEV;
 
-	nvec = pci_msi_vec_count(pdev);
-	if (nvec < 0)
-		return nvec;
-
 	/*
 	 * If number of MSIs is less than number of ports then Sharing Last
 	 * Message mode could be enforced. In this case assume that advantage
 	 * of multipe MSIs is negated and use single MSI mode instead.
 	 */
-	if (nvec < n_ports)
-		goto single_msi;
-
-	rc = pci_enable_msi_exact(pdev, nvec);
-	if (rc == -ENOSPC)
-		goto single_msi;
-	if (rc < 0)
-		return rc;
-
-	/* fallback to single MSI mode if the controller enforced MRSM mode */
-	if (readl(hpriv->mmio + HOST_CTL) & HOST_MRSM) {
-		pci_disable_msi(pdev);
-		printk(KERN_INFO "ahci: MRSM is on, fallback to single MSI\n");
-		goto single_msi;
-	}
-
-	if (nvec > 1)
+	nvec = pci_alloc_irq_vectors(pdev, n_ports, INT_MAX,
+			PCI_IRQ_MSIX | PCI_IRQ_MSI);
+	if (nvec > 0) {
+		if (!(readl(hpriv->mmio + HOST_CTL) & HOST_MRSM)) {
+			hpriv->get_irq_vector = ahci_get_irq_vector;
 			hpriv->flags |= AHCI_HFLAG_MULTI_MSI;
-
-	goto out;
-
-single_msi:
-	nvec = 1;
-
-	rc = pci_enable_msi(pdev);
-	if (rc < 0)
-		return rc;
-out:
-	hpriv->irq = pdev->irq;
-
 			return nvec;
-}
-
-static int ahci_init_interrupts(struct pci_dev *pdev, unsigned int n_ports,
-				struct ahci_host_priv *hpriv)
-{
-	int nvec;
+		}
 
 		/*
-	 * Try to enable per-port MSI-X.  If the host is not capable
-	 * fall back to single MSI before finally attempting single
-	 * MSI-X.
+		 * Fallback to single MSI mode if the controller enforced MRSM
+		 * mode.
 		 */
-	nvec = ahci_init_msix(pdev, n_ports, hpriv, AHCI_HFLAG_MULTI_MSIX);
-	if (nvec >= 0)
-		return nvec;
+		printk(KERN_INFO "ahci: MRSM is on, fallback to single MSI\n");
+		pci_free_irq_vectors(pdev);
+	}
 
-	nvec = ahci_init_msi(pdev, n_ports, hpriv);
-	if (nvec >= 0)
+	/*
+	 * -ENOSPC indicated we don't have enough vectors.  Don't bother trying
+	 * a single vectors for any other error:
+	 */
+	if (nvec < 0 && nvec != -ENOSPC)
 		return nvec;
 
-	/* try single-msix */
-	nvec = ahci_init_msix(pdev, n_ports, hpriv, 0);
-	if (nvec >= 0)
+	/*
+	 * If the host is not capable of supporting per-port vectors, fall
+	 * back to single MSI before finally attempting single MSI-X.
+	 */
+	nvec = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
+	if (nvec == 1)
 		return nvec;
-
-	/* legacy intx interrupts */
-	pci_intx(pdev, 1);
-	hpriv->irq = pdev->irq;
-
-	return 0;
+	return pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSIX);
 }
 
 static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
@@ -1698,11 +1612,12 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!host)
 		return -ENOMEM;
 	host->private_data = hpriv;
-	hpriv->msix = devm_kzalloc(&pdev->dev,
-			sizeof(struct msix_entry) * n_ports, GFP_KERNEL);
-	if (!hpriv->msix)
-		return -ENOMEM;
-	ahci_init_interrupts(pdev, n_ports, hpriv);
+
+	if (ahci_init_msi(pdev, n_ports, hpriv) < 0) {
+		/* legacy intx interrupts */
+		pci_intx(pdev, 1);
+	}
+	hpriv->irq = pdev->irq;
 
 	if (!(hpriv->cap & HOST_CAP_SSS) || ahci_ignore_sss)
 		host->flags |= ATA_HOST_PARALLEL_SCAN;

drivers/ata/ahci.h

@@ -242,12 +242,10 @@ enum {
 	AHCI_HFLAG_NO_FBS		= (1 << 18), /* no FBS */
 
 #ifdef CONFIG_PCI_MSI
-	AHCI_HFLAG_MULTI_MSI		= (1 << 20), /* multiple PCI MSIs */
-	AHCI_HFLAG_MULTI_MSIX		= (1 << 21), /* per-port MSI-X */
+	AHCI_HFLAG_MULTI_MSI		= (1 << 20), /* per-port MSI(-X) */
 #else
 	/* compile out MSI infrastructure */
 	AHCI_HFLAG_MULTI_MSI		= 0,
-	AHCI_HFLAG_MULTI_MSIX		= 0,
 #endif
 	AHCI_HFLAG_WAKE_BEFORE_STOP	= (1 << 22), /* wake before DMA stop */
 
@@ -351,7 +349,6 @@ struct ahci_host_priv {
 	 * the PHY position in this array.
 	 */
 	struct phy		**phys;
-	struct msix_entry	*msix;		/* Optional MSI-X support */
 	unsigned		nports;		/* Number of ports */
 	void			*plat_data;	/* Other platform data */
 	unsigned int		irq;		/* interrupt line */
@@ -362,22 +359,11 @@ struct ahci_host_priv {
 	 */
 	void			(*start_engine)(struct ata_port *ap);
 	irqreturn_t 		(*irq_handler)(int irq, void *dev_instance);
-};
 
-#ifdef CONFIG_PCI_MSI
-static inline int ahci_irq_vector(struct ahci_host_priv *hpriv, int port)
-{
-	if (hpriv->flags & AHCI_HFLAG_MULTI_MSIX)
-		return hpriv->msix[port].vector;
-	else
-		return hpriv->irq + port;
-}
-#else
-static inline int ahci_irq_vector(struct ahci_host_priv *hpriv, int port)
-{
-	return hpriv->irq;
-}
-#endif
+	/* only required for per-port MSI(-X) support */
+	int			(*get_irq_vector)(struct ata_host *host,
+						  int port);
+};
 
 extern int ahci_ignore_sss;
 

drivers/ata/libahci.c

@@ -2378,7 +2378,7 @@ static int ahci_port_start(struct ata_port *ap)
 	/*
 	 * Switch to per-port locking in case each port has its own MSI vector.
 	 */
-	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX)) {
+	if (hpriv->flags & AHCI_HFLAG_MULTI_MSI) {
 		spin_lock_init(&pp->lock);
 		ap->lock = &pp->lock;
 	}
@@ -2520,7 +2520,7 @@ static int ahci_host_activate_multi_irqs(struct ata_host *host,
 	 */
 	for (i = 0; i < host->n_ports; i++) {
 		struct ahci_port_priv *pp = host->ports[i]->private_data;
-		int irq = ahci_irq_vector(hpriv, i);
+		int irq = hpriv->get_irq_vector(host, i);
 
 		/* Do not receive interrupts sent by dummy ports */
 		if (!pp) {
@@ -2556,10 +2556,15 @@ int ahci_host_activate(struct ata_host *host, struct scsi_host_template *sht)
 	int irq = hpriv->irq;
 	int rc;
 
-	if (hpriv->flags & (AHCI_HFLAG_MULTI_MSI | AHCI_HFLAG_MULTI_MSIX)) {
+	if (hpriv->flags & AHCI_HFLAG_MULTI_MSI) {
 		if (hpriv->irq_handler)
 			dev_warn(host->dev,
 			         "both AHCI_HFLAG_MULTI_MSI flag set and custom irq handler implemented\n");
+		if (!hpriv->get_irq_vector) {
+			dev_err(host->dev,
+				"AHCI_HFLAG_MULTI_MSI requires ->get_irq_vector!\n");
+			return -EIO;
+		}
 
 		rc = ahci_host_activate_multi_irqs(host, sht);
 	} else {