[RFC 1/2] PCI: Introduce new MSI chip infrastructure

From: Thierry Reding
Date: Fri Mar 22 2013 - 04:52:53 EST


The new struct msi_chip is used to associated an MSI controller with a
PCI bus. It is automatically handed down from the root to its children
during bus enumeration.

This patch provides default (weak) implementations for the architecture-
specific MSI functions (arch_setup_msi_irq(), arch_teardown_msi_irq()
and arch_msi_check_device()) which check if a PCI device's bus has an
attached MSI chip and forward the call appropriately.

Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>
---
TODO:
- remove arch_msi_check_device (and other arch-specificities)
---
drivers/pci/msi.c | 35 +++++++++++++++++++++++++++++++----
drivers/pci/probe.c | 1 +
include/linux/msi.h | 10 ++++++++++
include/linux/pci.h | 1 +
4 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 00cc78c..fce3549 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -26,14 +26,41 @@

static int pci_msi_enable = 1;

-/* Arch hooks */
+int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
+{
+ struct msi_chip *chip = dev->bus->msi;
+
+ if (chip && chip->setup_irq) {
+ int err;
+
+ err = chip->setup_irq(chip, dev, desc);
+ if (err < 0)
+ return err;
+
+ irq_set_chip_data(desc->irq, chip);
+ return err;
+ }
+
+ return -EINVAL;
+}

-#ifndef arch_msi_check_device
-int arch_msi_check_device(struct pci_dev *dev, int nvec, int type)
+void __weak arch_teardown_msi_irq(unsigned int irq)
{
+ struct msi_chip *chip = irq_get_chip_data(irq);
+
+ if (chip && chip->teardown_irq)
+ chip->teardown_irq(chip, irq);
+}
+
+int __weak arch_msi_check_device(struct pci_dev *dev, int nvec, int type)
+{
+ struct msi_chip *chip = dev->bus->msi;
+
+ if (chip && chip->check_device)
+ return chip->check_device(chip, dev, nvec, type);
+
return 0;
}
-#endif

#ifndef arch_setup_msi_irqs
# define arch_setup_msi_irqs default_setup_msi_irqs
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b494066..9307550 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -634,6 +634,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,

child->parent = parent;
child->ops = parent->ops;
+ child->msi = parent->msi;
child->sysdata = parent->sysdata;
child->bus_flags = parent->bus_flags;

diff --git a/include/linux/msi.h b/include/linux/msi.h
index ce93a34..ea4a5be 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -58,5 +58,15 @@ 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 int arch_msi_check_device(struct pci_dev* dev, int nvec, int type);

+struct msi_chip {
+ struct module *owner;
+ struct device *dev;
+
+ int (*setup_irq)(struct msi_chip *chip, struct pci_dev *dev,
+ struct msi_desc *desc);
+ void (*teardown_irq)(struct msi_chip *chip, unsigned int irq);
+ int (*check_device)(struct msi_chip *chip, struct pci_dev *dev,
+ int nvec, int type);
+};

#endif /* LINUX_MSI_H */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2461033a..6aca43ea 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -416,6 +416,7 @@ struct pci_bus {
struct resource busn_res; /* bus numbers routed to this bus */

struct pci_ops *ops; /* configuration access functions */
+ struct msi_chip *msi; /* MSI controller */
void *sysdata; /* hook for sys-specific extension */
struct proc_dir_entry *procdir; /* directory entry in /proc/bus/pci */

--
1.8.1.5

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