Re: [PATCH 3/3] PCI: generic: Add support for Cavium ThunderX PCIe root complexes.
From: David Daney
Date: Tue Sep 22 2015 - 12:57:11 EST
On 09/22/2015 09:40 AM, Lorenzo Pieralisi wrote:
On Tue, Sep 22, 2015 at 05:13:45PM +0100, David Daney wrote:
On 09/22/2015 09:05 AM, Lorenzo Pieralisi wrote:
On Thu, Sep 17, 2015 at 11:41:34PM +0100, David Daney wrote:
[...]
Properties of the host controller node:
-- compatible : Must be "pci-host-cam-generic" or "pci-host-ecam-generic"
- depending on the layout of configuration space (CAM vs
- ECAM respectively).
+- compatible : One of the following with bus:devfn:reg mapped to the
+ PCI config space address window in the bit positions shown:
+ "pci-host-cam-generic" -- 'CAM' bits 16:8:0
+ "pci-host-ecam-generic" -- 'ECAM' bits 20:12:0
+ "cavium,pci-host-thunder-pem" -- bits 24:16:0
To me that's ECAM left shifted by 4. Is not it just a matter of defining
config space base address (ie reg property) differently ?
No.
That's like saying ECAM is just CAM shifted by 4, can't we just specify
the "reg" differently.
Ok, sorry I was not clear, apologies. I meant to ask if it is something
that can be configured in your platform and apparently it is not,
No, the hardware cannot be adjusted.
I worded it wrongly.
OK, I guess I also misunderstood what you were suggesting.
The "reg" property describes the base of the config space access window.
CAM/ECAM/cavium,pci-host-thunder-pem describe how to generate offsets
from that base, The offset calculation requires information that is not
present in the "reg" property, it is enumerated in the various
"compatible" values listed above.
Agreed, this also forces you to map in more virtual address space for
a given bus, right ?
Yes. It takes a full 32-bits of address space to have access to all PCI
buses on the root complex.
I am also a bit worried about how we can make this
work with ACPI, where MCFG accessors take the bus and devfn shifts for
granted (ie ECAM specs), so I asked.
If ACPI is not flexible enough to describe actual hardware, it will
either have to be enhanced, or not used.
Thanks,
Lorenzo
David Daney
Lorenzo
- device_type : Must be "pci".
diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
index e364232..e1d8d5b 100644
--- a/drivers/pci/host/pci-host-generic.c
+++ b/drivers/pci/host/pci-host-generic.c
@@ -91,6 +91,32 @@ static struct gen_pci_cfg_bus_ops gen_pci_cfg_ecam_bus_ops = {
}
};
+static void __iomem *gen_pci_map_cfg_bus_thunder_pem(struct pci_bus *bus,
+ unsigned int devfn,
+ int where)
+{
+ struct gen_pci *pci = bus->sysdata;
+ resource_size_t idx = bus->number - pci->cfg.bus_range->start;
+
+ /*
+ * Thunder PEM is a PCIe RC, but without a root bridge. On
+ * the primary bus, ignore accesses for devices other than
+ * the first device.
+ */
+ if (idx == 0 && (devfn & ~7u))
+ return NULL;
+ return pci->cfg.win[idx] + ((devfn << 16) | where);
+}
+
+static struct gen_pci_cfg_bus_ops gen_pci_cfg_thunder_pem_bus_ops = {
+ .bus_shift = 24,
+ .ops = {
+ .map_bus = gen_pci_map_cfg_bus_thunder_pem,
+ .read = pci_generic_config_read,
+ .write = pci_generic_config_write,
+ }
+};
+
static const struct of_device_id gen_pci_of_match[] = {
{ .compatible = "pci-host-cam-generic",
.data = &gen_pci_cfg_cam_bus_ops },
@@ -98,6 +124,9 @@ static const struct of_device_id gen_pci_of_match[] = {
{ .compatible = "pci-host-ecam-generic",
.data = &gen_pci_cfg_ecam_bus_ops },
+ { .compatible = "cavium,pci-host-thunder-pem",
+ .data = &gen_pci_cfg_thunder_pem_bus_ops },
+
{ },
};
MODULE_DEVICE_TABLE(of, gen_pci_of_match);
--
1.9.1
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