[RFT PATCH] ARM: pci: kill pcibios_msi_controller

[Lorenzo Pieralisi]

On ARM PCI systems relying on the pcibios API to initialize PCI host
controllers, the pcibios_msi_controller weak callback is used to look-up
the msi_controller pointer, through pci_sys_data msi_ctrl pointer.

pci_sys_data is an arch specific structure, which prevents using the
same mechanism (so same PCI host controller drivers) on ARM64 systems.

Since the struct pci_bus already contains an msi_controller pointer and
the kernel already uses it to look-up the msi controller,
this patch converts ARM host controller and relate pcibios/host bridges
initialization routines so that the msi_controller pointer look-up can be
carried out by PCI core code through the struct pci_bus msi pointer,
removing the need for arch specific pcibios_msi_controller callback
and the related pci_sys_data msi_ctrl pointer.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Pratyush Anand <pratyush.anand at gmail.com>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Jingoo Han <jingoohan1 at gmail.com>
Cc: Bjorn Helgaas <bhelgaas at google.com>
Cc: Simon Horman <horms at verge.net.au>
Cc: Russell King <linux at arm.linux.org.uk>
Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Cc: Thierry Reding <thierry.reding at gmail.com>
Cc: Michal Simek <michal.simek at xilinx.com>
Cc: Marc Zyngier <marc.zyngier at arm.com>
---
Bjorn, all,

I am posting this patch to sound out if that's a reasonable approach.
xgene implements MSI look-up this way at present and this would represent
another step forward towards having common drivers for ARM/ARM64, comments
and testing welcome.

Thanks,
Lorenzo

 arch/arm/include/asm/mach/pci.h    |  3 ---
 arch/arm/kernel/bios32.c           | 35 +++++++++++++++++------------------
 drivers/pci/host/pcie-designware.c |  9 +++++++--
 drivers/pci/host/pcie-xilinx.c     | 12 ++++++++++--
 4 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
index 28b9bb3..32abc0c 100644
--- a/arch/arm/include/asm/mach/pci.h
+++ b/arch/arm/include/asm/mach/pci.h
@@ -42,9 +42,6 @@ struct hw_pci {
  * Per-controller structure
  */
 struct pci_sys_data {
-#ifdef CONFIG_PCI_MSI
-	struct msi_controller *msi_ctrl;
-#endif
 	struct list_head node;
 	int		busnr;		/* primary bus number			*/
 	u64		mem_offset;	/* bus->cpu memory mapping offset	*/
diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index fcbbbb1..c841b33 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -18,15 +18,6 @@
 
 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.
@@ -462,9 +453,6 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
 		if (!sys)
 			panic("PCI: unable to allocate sys data!");
 
-#ifdef CONFIG_PCI_MSI
-		sys->msi_ctrl = hw->msi_ctrl;
-#endif
 		sys->busnr   = busnr;
 		sys->swizzle = hw->swizzle;
 		sys->map_irq = hw->map_irq;
@@ -483,14 +471,25 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
 				break;
 			}
 
-			if (hw->scan)
+			if (hw->scan) {
 				sys->bus = hw->scan(nr, sys);
-			else
-				sys->bus = pci_scan_root_bus(parent, sys->busnr,
-						hw->ops, sys, &sys->resources);
+				if (!sys->bus)
+					panic("PCI: unable to scan bus!");
+			} else {
+				sys->bus = pci_create_root_bus(parent,
+							       sys->busnr,
+							       hw->ops, sys,
+							       &sys->resources);
+				if (WARN_ON(!sys->bus)) {
+					kfree(sys);
+					break;
+				}
+#ifdef CONFIG_PCI_MSI
+				sys->bus->msi = hw->msi_ctrl;
+#endif
 
-			if (!sys->bus)
-				panic("PCI: unable to scan bus!");
+				pci_scan_child_bus(sys->bus);
+			}
 
 			busnr = sys->bus->busn_res.end + 1;
 
diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index 69486be..e584dfa 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -526,7 +526,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
 
 #ifdef CONFIG_PCI_MSI
 	dw_pcie_msi_chip.dev = pp->dev;
-	dw_pci.msi_ctrl = &dw_pcie_msi_chip;
 #endif
 
 	dw_pci.nr_controllers = 1;
@@ -708,11 +707,17 @@ static struct pci_bus *dw_pcie_scan_bus(int nr, struct pci_sys_data *sys)
 	struct pcie_port *pp = sys_to_pcie(sys);
 
 	pp->root_bus_nr = sys->busnr;
-	bus = pci_scan_root_bus(pp->dev, sys->busnr,
+	bus = pci_create_root_bus(pp->dev, sys->busnr,
 				  &dw_pcie_ops, sys, &sys->resources);
 	if (!bus)
 		return NULL;
 
+#ifdef CONFIG_PCI_MSI
+	bus->msi = &dw_pcie_msi_chip;
+#endif
+
+	pci_scan_child_bus(bus);
+
 	if (bus && pp->ops->scan_bus)
 		pp->ops->scan_bus(pp);
 
diff --git a/drivers/pci/host/pcie-xilinx.c b/drivers/pci/host/pcie-xilinx.c
index f1a06a0..b21eb7d 100644
--- a/drivers/pci/host/pcie-xilinx.c
+++ b/drivers/pci/host/pcie-xilinx.c
@@ -647,9 +647,18 @@ static struct pci_bus *xilinx_pcie_scan_bus(int nr, struct pci_sys_data *sys)
 	struct pci_bus *bus;
 
 	port->root_busno = sys->busnr;
-	bus = pci_scan_root_bus(port->dev, sys->busnr, &xilinx_pcie_ops,
+	bus = pci_create_root_bus(port->dev, sys->busnr, &xilinx_pcie_ops,
 				sys, &sys->resources);
 
+	if (!bus)
+		return NULL;
+
+#ifdef CONFIG_PCI_MSI
+	bus->msi = &xilinx_pcie_msi_chip;
+#endif
+
+	pci_scan_child_bus(bus);
+
 	return bus;
 }
 
@@ -847,7 +856,6 @@ static int xilinx_pcie_probe(struct platform_device *pdev)
 
 #ifdef CONFIG_PCI_MSI
 	xilinx_pcie_msi_chip.dev = port->dev;
-	hw.msi_ctrl = &xilinx_pcie_msi_chip;
 #endif
 	pci_common_init_dev(dev, &hw);
 
-- 
2.2.1