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Subject[tip: irq/msi] genirq/msi: Provide msi_alloc_msi_desc() and a simple allocator
The following commit has been merged into the irq/msi branch of tip:

Commit-ID: 602905253607ba892336f7bba8bb45b5be819d87
Gitweb: https://git.kernel.org/tip/602905253607ba892336f7bba8bb45b5be819d87
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 06 Dec 2021 23:51:10 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 16 Dec 2021 22:22:17 +01:00

genirq/msi: Provide msi_alloc_msi_desc() and a simple allocator

Provide msi_alloc_msi_desc() which takes a template MSI descriptor for
initializing a newly allocated descriptor. This allows to simplify various
usage sites of alloc_msi_entry() and moves the storage handling into the
core code.

For simple cases where only a linear vector space is required provide
msi_add_simple_msi_descs() which just allocates a linear range of MSI
descriptors and fills msi_desc::msi_index accordingly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211206210747.873833567@linutronix.de

---
include/linux/msi.h | 2 +-
kernel/irq/msi.c | 59 ++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 61 insertions(+)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 703221f..bbb8c1e 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -247,6 +247,8 @@ static inline void pci_write_msi_msg(unsigned int irq, struct msi_msg *msg)
}
#endif /* CONFIG_PCI_MSI */

+int msi_add_msi_desc(struct device *dev, struct msi_desc *init_desc);
+
struct msi_desc *alloc_msi_entry(struct device *dev, int nvec,
const struct irq_affinity_desc *affinity);
void free_msi_entry(struct msi_desc *entry);
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index bc67b2c..6ffe75e 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -60,6 +60,65 @@ void free_msi_entry(struct msi_desc *entry)
kfree(entry);
}

+/**
+ * msi_add_msi_desc - Allocate and initialize a MSI descriptor
+ * @dev: Pointer to the device for which the descriptor is allocated
+ * @init_desc: Pointer to an MSI descriptor to initialize the new descriptor
+ *
+ * Return: 0 on success or an appropriate failure code.
+ */
+int msi_add_msi_desc(struct device *dev, struct msi_desc *init_desc)
+{
+ struct msi_desc *desc;
+
+ lockdep_assert_held(&dev->msi.data->mutex);
+
+ desc = alloc_msi_entry(dev, init_desc->nvec_used, init_desc->affinity);
+ if (!desc)
+ return -ENOMEM;
+
+ /* Copy the MSI index and type specific data to the new descriptor. */
+ desc->msi_index = init_desc->msi_index;
+ desc->pci = init_desc->pci;
+
+ list_add_tail(&desc->list, &dev->msi.data->list);
+ return 0;
+}
+
+/**
+ * msi_add_simple_msi_descs - Allocate and initialize MSI descriptors
+ * @dev: Pointer to the device for which the descriptors are allocated
+ * @index: Index for the first MSI descriptor
+ * @ndesc: Number of descriptors to allocate
+ *
+ * Return: 0 on success or an appropriate failure code.
+ */
+static int msi_add_simple_msi_descs(struct device *dev, unsigned int index, unsigned int ndesc)
+{
+ struct msi_desc *desc, *tmp;
+ LIST_HEAD(list);
+ unsigned int i;
+
+ lockdep_assert_held(&dev->msi.data->mutex);
+
+ for (i = 0; i < ndesc; i++) {
+ desc = alloc_msi_entry(dev, 1, NULL);
+ if (!desc)
+ goto fail;
+ desc->msi_index = index + i;
+ list_add_tail(&desc->list, &list);
+ }
+ list_splice_tail(&list, &dev->msi.data->list);
+ return 0;
+
+fail:
+ list_for_each_entry_safe(desc, tmp, &list, list) {
+ list_del(&desc->list);
+ free_msi_entry(desc);
+ }
+ return -ENOMEM;
+}
+
void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
{
*msg = entry->msg;
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