Re: [PATCH v9 5/6] Documentation: DT: Add HiSilicon PCIe host binding

On 09/15/2015 08:14 PM, Zhou Wang wrote:

On 2015/9/16 3:43, Rob Herring wrote:

quoted

On 09/15/2015 07:49 AM, Zhou Wang wrote:

quoted

This patch adds related DTS binding document for HiSilicon PCIe host driver.

Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
---
 .../devicetree/bindings/pci/hisilicon-pcie.txt     | 46 ++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pci/hisilicon-pcie.txt

diff --git a/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt b/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt
new file mode 100644
index 0000000..2afc9d1
--- /dev/null
+++ b/Documentation/devicetree/bindings/pci/hisilicon-pcie.txt

@@ -0,0 +1,46 @@
+HiSilicon PCIe host bridge DT description
+
+HiSilicon PCIe host controller is based on Designware PCI core.
+It shares common functions with PCIe Designware core driver and inherits
+common properties defined in
+Documentation/devicetree/bindings/pci/designware-pci.txt.
+
+Additional properties are described here:
+
+Required properties:
+- compatible: Should contain "hisilicon,hip05-pcie".
+- reg: Should contain rc_dbi, subctrl, config registers location and length.
+- reg-names: Must include the following entries:
+  "rc_dbi": controller configuration registers;
+  "subctrl": whole PCIe hosts configuration registers;
+  "config": PCIe configuration space registers.
+- msi-parent: Should be its_pcie which is an ITS receiving MSI interrupts.
+- port-id: Should be 0, 1, 2 or 3.

What is port-id for? Use of instance indexes need to have good reason.

Rob

There are four PCIe controllers in HiSilicon Hip05 SoC, port-id just indicates
which one we use. And we will use port-id to locate related registers in driver.

Just having multiple instances is not a reason. So looking at the
driver, port-id is used to calculate register addresses for these registers:

#define PCIE_SUBCTRL_MODE_REG                           0x2800
#define PCIE_SUBCTRL_SYS_STATE4_REG                     0x6818

Is the base address of subctrl the same on all 4 ports? If so, you
should not have overlapping resources in the DT. Either split these 2
registers into 2 reg regions (for each register) or use syscon to
provide access to the region.

Rob