ARM/PCI: Save MSI controller in pci_sys_data

Currently ARM associates an MSI controller with a PCI bus by defining
pcibios_add_bus() and using it to call a struct hw_pci.add_bus() method.
That method sets the struct pci_bus "msi" member.  That's unwieldy and
unnecessarily couples MSI with the PCI enumeration code.

On ARM, all devices under the same PCI host bridge share an MSI controller,
so add an msi_controller pointer to the struct pci_sys_data and implement
pcibios_msi_controller() to retrieve it.

This is a step toward moving the msi_controller pointer into the generic
struct pci_host_bridge.

[bhelgaas: changelog, take pci_dev instead of pci_bus]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

arch/arm/include/asm/mach/pci.h

@@ -21,6 +21,9 @@ struct device;
 struct hw_pci {
 #ifdef CONFIG_PCI_DOMAINS
 	int		domain;
+#endif
+#ifdef CONFIG_PCI_MSI
+	struct msi_controller *msi_ctrl;
 #endif
 	struct pci_ops	*ops;
 	int		nr_controllers;
@@ -46,6 +49,9 @@ struct hw_pci {
 struct pci_sys_data {
 #ifdef CONFIG_PCI_DOMAINS
 	int		domain;
+#endif
+#ifdef CONFIG_PCI_MSI
+	struct msi_controller *msi_ctrl;
 #endif
 	struct list_head node;
 	int		busnr;		/* primary bus number			*/

arch/arm/kernel/bios32.c

@@ -18,6 +18,15 @@
 
 static int debug_pci;
 
+#ifdef CONFIG_PCI_MSI
+struct msi_controller *pcibios_msi_controller(struct pci_dev *dev)
+{
+	struct pci_sys_data *sysdata = dev->bus->sysdata;
+
+	return sysdata->msi_ctrl;
+}
+#endif
+
 /*
  * We can't use pci_get_device() here since we are
  * called from interrupt context.
@@ -470,6 +479,9 @@ 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_ctrl = hw->msi_ctrl;
 #endif
 		sys->busnr   = busnr;
 		sys->swizzle = hw->swizzle;