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Subject[RFC PATCH v4 08/13] genirq/msi: Add support for allocating single MSI for a device
Date
Previously all msi for a device are allocated in one go
by calling msi_domain_alloc_irq() from a bus layer. This might
not be the case when a device is trying to allocate interrupts
dynamically based on a request to it.

So introduce msi_domain_alloc/free_irq() apis to allocate a single
msi. prepare and activate operations to be handled by bus layer
calling msi_domain_alloc/free_irq() apis.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
---
include/linux/msi.h | 3 +++
kernel/irq/msi.c | 62 +++++++++++++++++++++++++++++----------------
2 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 784fb52b9900..474490826f8c 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -301,8 +301,11 @@ int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,
struct irq_domain *msi_create_irq_domain(struct fwnode_handle *fwnode,
struct msi_domain_info *info,
struct irq_domain *parent);
+int msi_domain_alloc_irq(struct irq_domain *domain, struct device *dev,
+ struct msi_desc *desc, msi_alloc_info_t *arg);
int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
int nvec);
+void msi_domain_free_irq(struct msi_desc *desc);
void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev);
struct msi_domain_info *msi_get_domain_info(struct irq_domain *domain);

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index ad26fbcfbfc8..eb7459324113 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -387,6 +387,35 @@ static bool msi_check_reservation_mode(struct irq_domain *domain,
return desc->msi_attrib.is_msix || desc->msi_attrib.maskbit;
}

+int msi_domain_alloc_irq(struct irq_domain *domain, struct device *dev,
+ struct msi_desc *desc, msi_alloc_info_t *arg)
+{
+ struct msi_domain_info *info = domain->host_data;
+ struct msi_domain_ops *ops = info->ops;
+ int i, ret, virq;
+
+ ops->set_desc(arg, desc);
+
+ virq = __irq_domain_alloc_irqs(domain, -1, desc->nvec_used,
+ dev_to_node(dev), arg, false,
+ desc->affinity);
+ if (virq < 0) {
+ ret = -ENOSPC;
+ if (ops->handle_error)
+ ret = ops->handle_error(domain, desc, ret);
+ if (ops->msi_finish)
+ ops->msi_finish(arg, ret);
+ return ret;
+ }
+
+ for (i = 0; i < desc->nvec_used; i++) {
+ irq_set_msi_desc_off(virq, i, desc);
+ irq_debugfs_copy_devname(virq + i, dev);
+ }
+
+ return 0;
+}
+
/**
* msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
* @domain: The domain to allocate from
@@ -404,7 +433,7 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
struct irq_data *irq_data;
struct msi_desc *desc;
msi_alloc_info_t arg;
- int i, ret, virq;
+ int ret, virq;
bool can_reserve;

ret = msi_domain_prepare_irqs(domain, dev, nvec, &arg);
@@ -412,24 +441,9 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
return ret;

for_each_msi_entry(desc, dev) {
- ops->set_desc(&arg, desc);
-
- virq = __irq_domain_alloc_irqs(domain, -1, desc->nvec_used,
- dev_to_node(dev), &arg, false,
- desc->affinity);
- if (virq < 0) {
- ret = -ENOSPC;
- if (ops->handle_error)
- ret = ops->handle_error(domain, desc, ret);
- if (ops->msi_finish)
- ops->msi_finish(&arg, ret);
+ ret = msi_domain_alloc_irq(domain, dev, desc, &arg);
+ if (ret)
return ret;
- }
-
- for (i = 0; i < desc->nvec_used; i++) {
- irq_set_msi_desc_off(virq, i, desc);
- irq_debugfs_copy_devname(virq + i, dev);
- }
}

if (ops->msi_finish)
@@ -487,6 +501,12 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
return ret;
}

+void msi_domain_free_irq(struct msi_desc *desc)
+{
+ irq_domain_free_irqs(desc->irq, desc->nvec_used);
+ desc->irq = 0;
+}
+
/**
* msi_domain_free_irqs - Free interrupts from a MSI interrupt @domain associated tp @dev
* @domain: The domain to managing the interrupts
@@ -503,10 +523,8 @@ void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
* enough that there is no IRQ associated to this
* entry. If that's the case, don't do anything.
*/
- if (desc->irq) {
- irq_domain_free_irqs(desc->irq, desc->nvec_used);
- desc->irq = 0;
- }
+ if (desc->irq)
+ msi_domain_free_irq(desc);
}
}

--
2.19.2
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