PCI: Introduce new MSI chip infrastructure

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@avionic-design.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Daniel Price <daniel.price@gmail.com>
Tested-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

4 files changed, 38 insertions, 2 deletions

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 823c3861c4d8..2837285c4e83 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -32,16 +32,39 @@ static int pci_msi_enable = 1;
 
 int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 {
-        return -EINVAL;
+        struct msi_chip *chip = dev->bus->msi;
+        int err;
+
+        if (!chip || !chip->setup_irq)
+                return -EINVAL;
+
+        err = chip->setup_irq(chip, dev, desc);
+        if (err < 0)
+                return err;
+
+        irq_set_chip_data(desc->irq, chip);
+
+        return 0;
 }
 
 void __weak arch_teardown_msi_irq(unsigned int irq)
 {
+        struct msi_chip *chip = irq_get_chip_data(irq);
+
+        if (!chip || !chip->teardown_irq)
+                return;
+
+        chip->teardown_irq(chip, irq);
 }
 
 int __weak arch_msi_check_device(struct pci_dev *dev, int nvec, int type)
 {
-        return 0;
+        struct msi_chip *chip = dev->bus->msi;
+
+        if (!chip || !chip->check_device)
+                return 0;
+
+        return chip->check_device(chip, dev, nvec, type);
 }
 
 int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 46ada5c098eb..b8eaa8167849 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -666,6 +666,7 @@ 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 271dfd14a05f..090ddadbc838 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -65,4 +65,15 @@ void arch_restore_msi_irqs(struct pci_dev *dev, int irq);
 void default_teardown_msi_irqs(struct pci_dev *dev);
 void default_restore_msi_irqs(struct pci_dev *dev, int irq);
 
+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 0fd1f1582fa1..4044e3c00609 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -433,6 +433,7 @@ 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 */