linux-kernel - Re: [RFC 2/4] PCI: generic: Add support for ARM64 and MSI(x)

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Date:	Tue, 30 Sep 2014 22:01:14 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	Liviu Dudau <Liviu.Dudau@....com>,
	Mark Rutland <Mark.Rutland@....com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	Marc Zyngier <Marc.Zyngier@....com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Will Deacon <Will.Deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>
Subject: Re: [RFC 2/4] PCI: generic: Add support for ARM64 and MSI(x)

On Tuesday 30 September 2014 20:54:41 Arnd Bergmann wrote:
> On Tuesday 30 September 2014 18:48:21 Liviu Dudau wrote:
> > > > > > These are the functions I found that refer to pci_sys_data on arm32:
> > > > > > 
> > > > > > pcibios_add_bus
> > > > > > pcibios_remove_bus
> > 
> > These are only needed if you want to do per HB processing of the bus
> > 
> > > > > > pcibios_align_resource
> > 
> > mvebu is the only user of this function.
> > 
> > > > > > pci_mmap_page_range
> > 
> > This is only needed when mapping a PCI resource to userspace. Is that your case here?
> > 
> > > > > > pci_domain_nr
> > > > > > pci_proc_domain
> > 
> > We have equivalent functionality in the generic patches for those.
> > 
> 
> We clearly don't need those functions for the new drivers, but that's not
> the point. The problem is that when you build a kernel that has both
> a traditional host bridge driver and a new one in it, you always get those
> functions and they get called from the PCI core, with incorrect arguments.

FWIW, the last time we discussed this, I think I had suggested that the
functions that are currently architecture specific and have a generic
__weak fallback could become function pointers in a per-host structure
passed to pci_scan_root_bus, either a new structure or an extended
struct pci_ops. Something along these lines:

diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
index 7fc42784becb..3da32fc631d0 100644
--- a/arch/arm/include/asm/mach/pci.h
+++ b/arch/arm/include/asm/mach/pci.h
@@ -36,7 +36,6 @@ struct hw_pci {
 					  resource_size_t start,
 					  resource_size_t size,
 					  resource_size_t align);
-	void		(*add_bus)(struct pci_bus *bus);
 	void		(*remove_bus)(struct pci_bus *bus);
 };
 
@@ -65,7 +64,6 @@ struct pci_sys_data {
 					  resource_size_t start,
 					  resource_size_t size,
 					  resource_size_t align);
-	void		(*add_bus)(struct pci_bus *bus);
 	void		(*remove_bus)(struct pci_bus *bus);
 	void		*private_data;	/* platform controller private data	*/
 };
diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index 17a26c17f7f5..3cbcf8dc41e4 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -360,13 +360,6 @@ void pcibios_fixup_bus(struct pci_bus *bus)
 }
 EXPORT_SYMBOL(pcibios_fixup_bus);
 
-void pcibios_add_bus(struct pci_bus *bus)
-{
-	struct pci_sys_data *sys = bus->sysdata;
-	if (sys->add_bus)
-		sys->add_bus(bus);
-}
-
 void pcibios_remove_bus(struct pci_bus *bus)
 {
 	struct pci_sys_data *sys = bus->sysdata;
@@ -475,7 +468,6 @@ static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
 		sys->swizzle = hw->swizzle;
 		sys->map_irq = hw->map_irq;
 		sys->align_resource = hw->align_resource;
-		sys->add_bus = hw->add_bus;
 		sys->remove_bus = hw->remove_bus;
 		INIT_LIST_HEAD(&sys->resources);
 
diff --git a/drivers/pci/host/pci-mvebu.c b/drivers/pci/host/pci-mvebu.c
index b1315e197ffb..c9a0ee0429e8 100644
--- a/drivers/pci/host/pci-mvebu.c
+++ b/drivers/pci/host/pci-mvebu.c
@@ -716,6 +716,7 @@ static int mvebu_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where,
 static struct pci_ops mvebu_pcie_ops = {
 	.read = mvebu_pcie_rd_conf,
 	.write = mvebu_pcie_wr_conf,
+	.add_bus = mvebu_pcie_add_bus,
 };
 
 static int mvebu_pcie_setup(int nr, struct pci_sys_data *sys)
@@ -823,7 +824,6 @@ static void mvebu_pcie_enable(struct mvebu_pcie *pcie)
 	hw.map_irq        = of_irq_parse_and_map_pci;
 	hw.ops            = &mvebu_pcie_ops;
 	hw.align_resource = mvebu_pcie_align_resource;
-	hw.add_bus        = mvebu_pcie_add_bus;
 
 	pci_common_init(&hw);
 }
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index a63a47a70846..be6d56358320 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1885,6 +1885,8 @@ int __weak pcibios_root_bridge_prepare(struct pci_host_bridge *bridge)
 
 void __weak pcibios_add_bus(struct pci_bus *bus)
 {
+	if (bus->ops && bus->ops->add_bus)
+		bus->ops->add_bus(bus);		
 }
 
 void __weak pcibios_remove_bus(struct pci_bus *bus)

	Arnd
--
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