linux-kernel - [PATCH V9 10/11] ARM64/PCI: Implement ACPI low-level calls to access PCI

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Date:	Fri, 10 Jun 2016 21:55:18 +0200
From:	Tomasz Nowicki <tn@...ihalf.com>
To:	helgaas@...nel.org, arnd@...db.de, will.deacon@....com,
	catalin.marinas@....com, rafael@...nel.org, hanjun.guo@...aro.org,
	Lorenzo.Pieralisi@....com, okaya@...eaurora.org,
	jchandra@...adcom.com
Cc:	robert.richter@...iumnetworks.com, mw@...ihalf.com,
	Liviu.Dudau@....com, ddaney@...iumnetworks.com,
	wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
	msalter@...hat.com, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
	jcm@...hat.com, andrea.gallo@...aro.org, dhdang@....com,
	jeremy.linton@....com, liudongdong3@...wei.com, cov@...eaurora.org,
	Tomasz Nowicki <tn@...ihalf.com>
Subject: [PATCH V9 10/11] ARM64/PCI: Implement ACPI low-level calls to access PCI_Config region from AML

ACPI spec6.1 - chapter: 5.5.2.4 defines OperationRegion (Declare Operation
Region). Following the spec: " [...] An Operation Region is a specific
region of operation within an address space that is declared as a subset
of the entire address space using a starting address (offset) and a length.
Control methods must have exclusive access to any address accessed via
fields declared in Operation Regions. [...]".

OperationRegion allows to declare various of operation region address space
identifiers including PCI_Config. PCI_Config is meant to access PCI
configuration space from the ASL. So every time ASL opcode operates
on PCI_Config space region, ASL interpreter dispatches accesses to OS
low-level calls - raw_pci_write() and raw_pci_read() for Linux - so-called
ACPI RAW accessors.

In order to support PCI_Config operation region, implement mentioned
raw_pci_write() and raw_pci_read() calls so they find associated bus
and call read/write ops.

Waiting for clarification in the ACPI specifications in relation
to PCI_Config space handling before PCI bus enumeration is completed,
current code does not support PCI_Config region accesses before PCI bus
enumeration whilst providing full AML PCI_Config access availability
when the PCI bus enumeration is completed by the kernel so that
RAW accessors can look-up PCI operations through the struct pci_bus
associated with a PCI bus.

Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
Signed-off-by: Jayachandran C <jchandra@...adcom.com>
---
 arch/arm64/kernel/pci.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index b3b8a2c..328f857 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -71,13 +71,21 @@ int pcibios_alloc_irq(struct pci_dev *dev)
 int raw_pci_read(unsigned int domain, unsigned int bus,
 		  unsigned int devfn, int reg, int len, u32 *val)
 {
-	return -ENXIO;
+	struct pci_bus *b = pci_find_bus(domain, bus);
+
+	if (!b)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	return b->ops->read(b, devfn, reg, len, val);
 }

 int raw_pci_write(unsigned int domain, unsigned int bus,
 		unsigned int devfn, int reg, int len, u32 val)
 {
-	return -ENXIO;
+	struct pci_bus *b = pci_find_bus(domain, bus);
+
+	if (!b)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+	return b->ops->write(b, devfn, reg, len, val);
 }

 #ifdef CONFIG_NUMA
-- 
1.9.1