Saving msi chip in pci_sys_data can make pci bus and
devices don't need to know msi chip detail, it also
make pci enumeration code be decoupled from msi chip.
In fact, all pci devices under the same pci hostbridge
share same msi chip. So msi chip should be seen as one
of resources or attributes to be initialized in pci host
bridge driver. Currently, pci hostbridge drivers create
pci_host_bridge in pci_create_root_bus(), and pass arch
specific pci sysdata to core pci scan functions. So pci
arch sysdata is good place to save msi chip.

Signed-off-by: Yijing Wang <redacted>
---
 arch/arm/include/asm/mach/pci.h |    6 ++++++
 arch/arm/include/asm/pci.h      |    9 +++++++++
 arch/arm/kernel/bios32.c        |    3 +++
 drivers/pci/msi.c               |    6 ++++++
 include/linux/pci.h             |    9 +++++++++
 5 files changed, 33 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
index 7fc4278..59b0d87 100644
--- a/arch/arm/include/asm/mach/pci.h
+++ b/arch/arm/include/asm/mach/pci.h

@@ -22,6 +22,9 @@ struct hw_pci {
 #ifdef CONFIG_PCI_DOMAINS
 	int		domain;
 #endif
+#ifdef CONFIG_PCI_MSI
+	struct msi_chip *msi_chip;
+#endif
 	struct pci_ops	*ops;
 	int		nr_controllers;
 	void		**private_data;

@@ -47,6 +50,9 @@ struct pci_sys_data {
 #ifdef CONFIG_PCI_DOMAINS
 	int		domain;
 #endif
+#ifdef CONFIG_PCI_MSI
+	struct msi_chip *msi_chip;
+#endif
 	struct list_head node;
 	int		busnr;		/* primary bus number			*/
 	u64		mem_offset;	/* bus->cpu memory mapping offset	*/

diff --git a/arch/arm/include/asm/pci.h b/arch/arm/include/asm/pci.h
index 7e95d85..b562c09 100644
--- a/arch/arm/include/asm/pci.h
+++ b/arch/arm/include/asm/pci.h

@@ -31,6 +31,15 @@ static inline int pci_proc_domain(struct pci_bus *bus)
 }
 #endif /* CONFIG_PCI_DOMAINS */
 
+#ifdef CONFIG_PCI_MSI
+static inline struct msi_chip *pci_msi_chip(struct pci_bus *bus)
+{
+	struct pci_sys_data *root = bus->sysdata;
+
+	return root->msi_chip;
+}
+#endif
+
 /*
  * The PCI address space does equal the physical memory address space.
  * The networking and block device layers use this boolean for bounce

diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index 17a26c1..a19038d 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c

@@ -471,6 +471,9 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
 #ifdef CONFIG_PCI_DOMAINS
 		sys->domain  = hw->domain;
 #endif
+#ifdef CONFIG_PCI_MSI
+		sys->msi_chip = hw->msi_chip;
+#endif
 		sys->busnr   = busnr;
 		sys->swizzle = hw->swizzle;
 		sys->map_irq = hw->map_irq;

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 22e413c..f11108c 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c

@@ -35,6 +35,9 @@ int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
 	struct msi_chip *chip = dev->bus->msi;
 	int err;
 
+	if (!chip)
+		chip = pci_msi_chip(dev->bus);
+
 	if (!chip || !chip->setup_irq)
 		return -EINVAL;
 

@@ -50,6 +53,9 @@ void __weak arch_teardown_msi_irq(unsigned int irq)
 	struct msi_desc *entry = irq_get_msi_desc(irq);
 	struct msi_chip *chip = entry->dev->bus->msi;
 
+	if (!chip)
+		chip = pci_msi_chip(entry->dev->bus);
+
 	if (!chip || !chip->teardown_irq)
 		return;
 

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 9cd2721..7a48b40 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h

@@ -1433,6 +1433,15 @@ static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
 
 #include <asm/pci.h>
 
+/* Just avoid compile error, will be clean up later */
+#ifdef CONFIG_PCI_MSI
+
+#ifndef pci_msi_chip
+#define pci_msi_chip(bus)	NULL
+#endif
+#endif