diff options
author | Marc Zyngier <marc.zyngier@arm.com> | 2018-05-08 13:14:30 +0100 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2018-05-13 15:58:59 +0200 |
commit | 0be8153cbc2af9a96e9ab8631fc3ba23bb52dbe3 (patch) | |
tree | 84328dcb38f9a9d81ce2086419fe40d7b24909dc | |
parent | b5c5f3959bb3c018a68f5659bcd6adf05e141a03 (diff) |
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
-rw-r--r-- | include/linux/msi.h | 2 | ||||
-rw-r--r-- | kernel/irq/msi.c | 33 |
2 files changed, 26 insertions, 9 deletions
diff --git a/include/linux/msi.h b/include/linux/msi.h index 1f1bbb5b4679..5839d8062dfc 100644 --- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -289,6 +289,8 @@ enum { * MSI_FLAG_ACTIVATE_EARLY has been set. */ MSI_FLAG_MUST_REACTIVATE = (1 << 5), + /* Is level-triggered capable, using two messages */ + MSI_FLAG_LEVEL_CAPABLE = (1 << 6), }; int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask, 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, |