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Subject[PATCH 2/4] PCI: Support multiple MSI
Date
Add the new API pci_enable_msi_block() to allow drivers to
request multiple MSIs. Reimplement pci_enable_msi in terms
of pci_enable_msi_block. Add a default implementation of
arch_setup_msi_block() that only allows one MSI to be requested.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
---
arch/powerpc/kernel/msi.c | 2 +-
drivers/pci/msi.c | 109 +++++++++++++++++++++++++++++----------------
include/linux/msi.h | 3 +-
include/linux/pci.h | 6 ++-
4 files changed, 77 insertions(+), 43 deletions(-)
diff --git a/arch/powerpc/kernel/msi.c b/arch/powerpc/kernel/msi.c
index c62d101..317c7c8 100644
--- a/arch/powerpc/kernel/msi.c
+++ b/arch/powerpc/kernel/msi.c
@@ -32,7 +32,7 @@ int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
return ppc_md.setup_msi_irqs(dev, nvec, type);
}

-void arch_teardown_msi_irqs(struct pci_dev *dev)
+void arch_teardown_msi_irqs(struct pci_dev *dev, int nvec)
{
return ppc_md.teardown_msi_irqs(dev);
}
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 92992a8..6cbdf11 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -40,18 +40,31 @@ arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *entry)
}

int __attribute__ ((weak))
+arch_setup_msi_block(struct pci_dev *pdev, struct msi_desc *desc, int nvec)
+{
+ if (nvec > 1)
+ return 1;
+ return arch_setup_msi_irq(pdev, desc);
+}
+
+int __attribute__ ((weak))
arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
{
- struct msi_desc *entry;
+ struct msi_desc *desc;
int ret;

- list_for_each_entry(entry, &dev->msi_list, list) {
- ret = arch_setup_msi_irq(dev, entry);
- if (ret)
- return ret;
+ if (type == PCI_CAP_ID_MSI) {
+ desc = list_first_entry(&dev->msi_list, struct msi_desc, list);
+ ret = arch_setup_msi_block(dev, desc, nvec);
+ } else {
+ list_for_each_entry(desc, &dev->msi_list, list) {
+ ret = arch_setup_msi_irq(dev, desc);
+ if (ret)
+ break;
+ }
}

- return 0;
+ return ret;
}

void __attribute__ ((weak)) arch_teardown_msi_irq(unsigned int irq)
@@ -60,13 +73,16 @@ void __attribute__ ((weak)) arch_teardown_msi_irq(unsigned int irq)
}

void __attribute__ ((weak))
-arch_teardown_msi_irqs(struct pci_dev *dev)
+arch_teardown_msi_irqs(struct pci_dev *dev, int nvec)
{
struct msi_desc *entry;

list_for_each_entry(entry, &dev->msi_list, list) {
- if (entry->irq != 0)
- arch_teardown_msi_irq(entry->irq);
+ int i;
+ if (entry->irq == 0)
+ continue;
+ for (i = 0; i < nvec; i++)
+ arch_teardown_msi_irq(entry->irq + i);
}
}

@@ -350,7 +366,7 @@ EXPORT_SYMBOL_GPL(pci_restore_msi_state);
* multiple messages. A return of zero indicates the successful setup
* of an entry zero with the new MSI irq or non-zero for otherwise.
**/
-static int msi_capability_init(struct pci_dev *dev)
+static int msi_capability_init(struct pci_dev *dev, int nr_irqs)
{
struct msi_desc *entry;
int pos, ret;
@@ -394,7 +410,7 @@ static int msi_capability_init(struct pci_dev *dev)
list_add_tail(&entry->list, &dev->msi_list);

/* Configure MSI capability structure */
- ret = arch_setup_msi_irqs(dev, 1, PCI_CAP_ID_MSI);
+ ret = arch_setup_msi_irqs(dev, nr_irqs, PCI_CAP_ID_MSI);
if (ret) {
msi_free_irqs(dev);
return ret;
@@ -546,36 +562,47 @@ static int pci_msi_check_device(struct pci_dev* dev, int nvec, int type)
}

/**
- * pci_enable_msi - configure device's MSI capability structure
- * @dev: pointer to the pci_dev data structure of MSI device function
+ * pci_enable_msi_block - configure device's MSI capability structure
+ * @pdev: Device to configure
+ * @nr_irqs: Number of IRQs requested
+ *
+ * Allocate IRQs for a device with the MSI capability.
+ * This function returns a negative errno if an error occurs. On success,
+ * this function returns the number of IRQs actually allocated. Since
+ * MSIs are required to be a power of two, the number of IRQs allocated
+ * may be rounded up to the next power of two (if the number requested is
+ * not a power of two). Fewer IRQs than requested may be allocated if the
+ * system does not have the resources for the full number.
*
- * Setup the MSI capability structure of device function with
- * a single MSI irq upon its software driver call to request for
- * MSI mode enabled on its hardware device function. A return of zero
- * indicates the successful setup of an entry zero with the new MSI
- * irq or non-zero for otherwise.
+ * If successful, the @pdev's irq member will be updated to the lowest new
+ * IRQ allocated; the other IRQs allocated to this device will be consecutive.
**/
-int pci_enable_msi(struct pci_dev* dev)
+int pci_enable_msi_block(struct pci_dev *pdev, unsigned int nr_irqs)
{
int status;

- status = pci_msi_check_device(dev, 1, PCI_CAP_ID_MSI);
+ /* MSI only supports up to 32 interrupts */
+ if (nr_irqs > 32)
+ return 32;
+
+ status = pci_msi_check_device(pdev, nr_irqs, PCI_CAP_ID_MSI);
if (status)
return status;

- WARN_ON(!!dev->msi_enabled);
+ WARN_ON(!!pdev->msi_enabled);

- /* Check whether driver already requested for MSI-X irqs */
- if (dev->msix_enabled) {
+ /* Check whether driver already requested MSI-X irqs */
+ if (pdev->msix_enabled) {
printk(KERN_INFO "PCI: %s: Can't enable MSI. "
"Device already has MSI-X enabled\n",
- pci_name(dev));
+ pci_name(pdev));
return -EINVAL;
}
- status = msi_capability_init(dev);
+
+ status = msi_capability_init(pdev, nr_irqs);
return status;
}
-EXPORT_SYMBOL(pci_enable_msi);
+EXPORT_SYMBOL(pci_enable_msi_block);

void pci_msi_shutdown(struct pci_dev* dev)
{
@@ -621,26 +648,30 @@ EXPORT_SYMBOL(pci_disable_msi);

static int msi_free_irqs(struct pci_dev* dev)
{
- struct msi_desc *entry, *tmp;
+ int i, nvec = 1;
+ struct msi_desc *desc, *tmp;

- list_for_each_entry(entry, &dev->msi_list, list) {
- if (entry->irq)
- BUG_ON(irq_has_action(entry->irq));
+ list_for_each_entry(desc, &dev->msi_list, list) {
+ nvec = 1 << desc->msi_attrib.multiple;
+ if (!desc->irq)
+ continue;
+ for (i = 0; i < nvec; i++)
+ BUG_ON(irq_has_action(desc->irq + i));
}

- arch_teardown_msi_irqs(dev);
+ arch_teardown_msi_irqs(dev, nvec);

- list_for_each_entry_safe(entry, tmp, &dev->msi_list, list) {
- if (entry->msi_attrib._type == MSIX_ATTRIB) {
- writel(1, entry->mask_base + entry->msi_attrib.entry_nr
+ list_for_each_entry_safe(desc, tmp, &dev->msi_list, list) {
+ if (desc->msi_attrib._type == MSIX_ATTRIB) {
+ writel(1, desc->mask_base + desc->msi_attrib.entry_nr
* PCI_MSIX_ENTRY_SIZE
+ PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);

- if (list_is_last(&entry->list, &dev->msi_list))
- iounmap(entry->mask_base);
+ if (list_is_last(&desc->list, &dev->msi_list))
+ iounmap(desc->mask_base);
}
- list_del(&entry->list);
- kfree(entry);
+ list_del(&desc->list);
+ kfree(desc);
}

return 0;
diff --git a/include/linux/msi.h b/include/linux/msi.h
index d322148..4731fe7 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -45,9 +45,10 @@ struct msi_desc {
* The arch hook for setup up msi irqs
*/
int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc);
+int arch_setup_msi_block(struct pci_dev *dev, struct msi_desc *desc, int nvec);
void arch_teardown_msi_irq(unsigned int irq);
extern int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type);
-extern void arch_teardown_msi_irqs(struct pci_dev *dev);
+extern void arch_teardown_msi_irqs(struct pci_dev *dev, int nvec);
extern int arch_msi_check_device(struct pci_dev* dev, int nvec, int type);


diff --git a/include/linux/pci.h b/include/linux/pci.h
index d18b1dd..f7ca7f8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -699,7 +699,7 @@ struct msix_entry {


#ifndef CONFIG_PCI_MSI
-static inline int pci_enable_msi(struct pci_dev *dev)
+static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int count)
{
return -1;
}
@@ -726,7 +726,7 @@ static inline void msi_remove_pci_irq_vectors(struct pci_dev *dev)
static inline void pci_restore_msi_state(struct pci_dev *dev)
{ }
#else
-extern int pci_enable_msi(struct pci_dev *dev);
+extern int pci_enable_msi_block(struct pci_dev *dev, unsigned int count);
extern void pci_msi_shutdown(struct pci_dev *dev);
extern void pci_disable_msi(struct pci_dev *dev);
extern int pci_enable_msix(struct pci_dev *dev,
@@ -737,6 +737,8 @@ extern void msi_remove_pci_irq_vectors(struct pci_dev *dev);
extern void pci_restore_msi_state(struct pci_dev *dev);
#endif

+#define pci_enable_msi(pdev) pci_enable_msi_block(pdev, 1)
+
#ifdef CONFIG_HT_IRQ
/* The functions a driver should call */
int ht_create_irq(struct pci_dev *dev, int idx);
--
1.5.5.4


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