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

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Submitter Thierry Reding
Date March 22, 2013, 8:51 a.m.
Message ID <1363942307-9327-2-git-send-email-thierry.reding@avionic-design.de>
Download mbox | patch
Permalink /patch/229926/
State Not Applicable
Headers show

Comments

Thierry Reding - March 22, 2013, 8:51 a.m.
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>
---
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(-)
Andrew Murray - March 22, 2013, 9:37 a.m.
On Fri, Mar 22, 2013 at 08:51:46AM +0000, Thierry Reding wrote:
> 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);
> +};

Is there a need to add setup_irqs and teardown_irqs functions here? This will
allow your MSI chips to support multiple MSIs per requesting device.

What about restore_msi_irqs? Does this fit in here too?

Andrew Murray
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Thierry Reding - March 22, 2013, 10 a.m.
On Fri, Mar 22, 2013 at 09:37:50AM +0000, Andrew Murray wrote:
> On Fri, Mar 22, 2013 at 08:51:46AM +0000, Thierry Reding wrote:
> > 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);
> > +};
> 
> Is there a need to add setup_irqs and teardown_irqs functions here? This will
> allow your MSI chips to support multiple MSIs per requesting device.
> 
> What about restore_msi_irqs? Does this fit in here too?

I guess those could be added as well. I've concentrated on the most
common use-cases here, which seem to be the three included functions.
Most other implementations use the generic implementations for multiple
MSIs.

Note that the proposed framework is in no way fixed and can be extended
at will. The important step is to get rid of the one implementation for
the whole kernel concept.

Thierry

Patch

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 */