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.red...@avionic-design.de>
---
 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 f42cdc6..7e44085 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -431,6 +431,7 @@ 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 */
 
-- 
1.8.2

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