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authorMarc Zyngier <marc.zyngier@arm.com>2018-05-08 13:14:30 +0100
committerThomas Gleixner <tglx@linutronix.de>2018-05-13 15:58:59 +0200
commit0be8153cbc2af9a96e9ab8631fc3ba23bb52dbe3 (patch)
tree84328dcb38f9a9d81ce2086419fe40d7b24909dc /kernel/irq
parentb5c5f3959bb3c018a68f5659bcd6adf05e141a03 (diff)
downloadlinux-0be8153cbc2af9a96e9ab8631fc3ba23bb52dbe3.tar.bz2
genirq/msi: Allow level-triggered MSIs to be exposed by MSI providers
So far, MSIs have been used to signal edge-triggered interrupts, as a write is a good model for an edge (you can't "unwrite" something). On the other hand, routing zillions of wires in an SoC because you need level interrupts is a bit extreme. People have come up with a variety of schemes to support this, which involves sending two messages: one to signal the interrupt, and one to clear it. Since the kernel cannot represent this, we've ended up with side-band mechanisms that are pretty awful. Instead, let's acknoledge the requirement, and ensure that, under the right circumstances, the irq_compose_msg and irq_write_msg can take as a parameter an array of two messages instead of a pointer to a single one. We also add some checking that the compose method only clobbers the second message if the MSI domain has been created with the MSI_FLAG_LEVEL_CAPABLE flags. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Rob Herring <robh@kernel.org> Cc: Jason Cooper <jason@lakedaemon.net> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Cc: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://lkml.kernel.org/r/20180508121438.11301-2-marc.zyngier@arm.com
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/msi.c33
1 files changed, 24 insertions, 9 deletions
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 2a8571f72b17..4ca2fd46645d 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -76,6 +76,19 @@ static inline void irq_chip_write_msi_msg(struct irq_data *data,
data->chip->irq_write_msi_msg(data, msg);
}
+static void msi_check_level(struct irq_domain *domain, struct msi_msg *msg)
+{
+ struct msi_domain_info *info = domain->host_data;
+
+ /*
+ * If the MSI provider has messed with the second message and
+ * not advertized that it is level-capable, signal the breakage.
+ */
+ WARN_ON(!((info->flags & MSI_FLAG_LEVEL_CAPABLE) &&
+ (info->chip->flags & IRQCHIP_SUPPORTS_LEVEL_MSI)) &&
+ (msg[1].address_lo || msg[1].address_hi || msg[1].data));
+}
+
/**
* msi_domain_set_affinity - Generic affinity setter function for MSI domains
* @irq_data: The irq data associated to the interrupt
@@ -89,13 +102,14 @@ int msi_domain_set_affinity(struct irq_data *irq_data,
const struct cpumask *mask, bool force)
{
struct irq_data *parent = irq_data->parent_data;
- struct msi_msg msg;
+ struct msi_msg msg[2] = { [1] = { }, };
int ret;
ret = parent->chip->irq_set_affinity(parent, mask, force);
if (ret >= 0 && ret != IRQ_SET_MASK_OK_DONE) {
- BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
- irq_chip_write_msi_msg(irq_data, &msg);
+ BUG_ON(irq_chip_compose_msi_msg(irq_data, msg));
+ msi_check_level(irq_data->domain, msg);
+ irq_chip_write_msi_msg(irq_data, msg);
}
return ret;
@@ -104,20 +118,21 @@ int msi_domain_set_affinity(struct irq_data *irq_data,
static int msi_domain_activate(struct irq_domain *domain,
struct irq_data *irq_data, bool early)
{
- struct msi_msg msg;
+ struct msi_msg msg[2] = { [1] = { }, };
- BUG_ON(irq_chip_compose_msi_msg(irq_data, &msg));
- irq_chip_write_msi_msg(irq_data, &msg);
+ BUG_ON(irq_chip_compose_msi_msg(irq_data, msg));
+ msi_check_level(irq_data->domain, msg);
+ irq_chip_write_msi_msg(irq_data, msg);
return 0;
}
static void msi_domain_deactivate(struct irq_domain *domain,
struct irq_data *irq_data)
{
- struct msi_msg msg;
+ struct msi_msg msg[2];
- memset(&msg, 0, sizeof(msg));
- irq_chip_write_msi_msg(irq_data, &msg);
+ memset(msg, 0, sizeof(msg));
+ irq_chip_write_msi_msg(irq_data, msg);
}
static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,