diff options
author | Bjorn Helgaas <bhelgaas@google.com> | 2016-06-13 18:01:51 +0200 |
---|---|---|
committer | Bjorn Helgaas <bhelgaas@google.com> | 2016-08-18 23:04:57 +0200 |
commit | eec097d43100a8195fd4f678671ecd5d986dd675 (patch) | |
tree | ec874686b415958f9123b68f4ba0f85bae6b8c86 /drivers/pci/pcie | |
parent | PCI: Add Precision Time Measurement (PTM) support (diff) | |
download | linux-eec097d43100a8195fd4f678671ecd5d986dd675.tar.xz linux-eec097d43100a8195fd4f678671ecd5d986dd675.zip |
PCI: Add pci_enable_ptm() for drivers to enable PTM on endpoints
Add an pci_enable_ptm() interface so drivers can enable PTM.
The PCI core enables PTM on PTM Roots and switches automatically, but we
don't enable PTM on endpoints unless a driver requests it.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/pci/pcie')
-rw-r--r-- | drivers/pci/pcie/ptm.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index 48eea4e65247..a14ac94b96dc 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -68,3 +68,48 @@ void pci_ptm_init(struct pci_dev *dev) pci_ptm_info(dev); } + +int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) +{ + int pos; + u32 cap, ctrl; + struct pci_dev *ups; + + if (!pci_is_pcie(dev)) + return -EINVAL; + + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); + if (!pos) + return -EINVAL; + + pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap); + if (!(cap & PCI_PTM_CAP_REQ)) + return -EINVAL; + + /* + * For a PCIe Endpoint, PTM is only useful if the endpoint can + * issue PTM requests to upstream devices that have PTM enabled. + * + * For Root Complex Integrated Endpoints, there is no upstream + * device, so there must be some implementation-specific way to + * associate the endpoint with a time source. + */ + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) { + ups = pci_upstream_bridge(dev); + if (!ups || !ups->ptm_enabled) + return -EINVAL; + } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) { + } else + return -EINVAL; + + ctrl = PCI_PTM_CTRL_ENABLE; + pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl); + dev->ptm_enabled = 1; + + pci_ptm_info(dev); + + if (granularity) + *granularity = 0; + return 0; +} +EXPORT_SYMBOL(pci_enable_ptm); |