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| author | David E. Box <david.e.box@linux.intel.com> | 2020-12-07 23:39:50 +0100 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2020-12-10 21:43:54 +0100 |
| commit | 39850ed51062f89cd46214a16aaafba5ca49fd6c (patch) | |
| tree | b8cb10061b1aecb2eb14001219f1bf8277565354 /drivers/pci/pcie/ptm.c | |
| parent | Linux 5.10-rc3 (diff) | |
| download | linux-39850ed51062f89cd46214a16aaafba5ca49fd6c.tar.xz linux-39850ed51062f89cd46214a16aaafba5ca49fd6c.zip | |
PCI/PTM: Save/restore Precision Time Measurement Capability for suspend/resume
The PCI subsystem does not currently save and restore the configuration
space for the Precision Time Measurement (PTM) Extended Capability leading
to the possibility of the feature returning disabled on S3 resume. This
has been observed on Intel Coffee Lake desktops. Add save/restore of the
PTM control register. This saves the PTM Enable, Root Select, and Effective
Granularity bits.
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20201207223951.19667-1-david.e.box@linux.intel.com
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/pci/pcie/ptm.c')
| -rw-r--r-- | drivers/pci/pcie/ptm.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index 357a454cafa0..6b24a1c9327a 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -29,6 +29,47 @@ static void pci_ptm_info(struct pci_dev *dev) dev->ptm_root ? " (root)" : "", clock_desc); } +void pci_save_ptm_state(struct pci_dev *dev) +{ + int ptm; + struct pci_cap_saved_state *save_state; + u16 *cap; + + if (!pci_is_pcie(dev)) + return; + + ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); + if (!ptm) + return; + + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM); + if (!save_state) { + pci_err(dev, "no suspend buffer for PTM\n"); + return; + } + + cap = (u16 *)&save_state->cap.data[0]; + pci_read_config_word(dev, ptm + PCI_PTM_CTRL, cap); +} + +void pci_restore_ptm_state(struct pci_dev *dev) +{ + struct pci_cap_saved_state *save_state; + int ptm; + u16 *cap; + + if (!pci_is_pcie(dev)) + return; + + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_PTM); + ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); + if (!save_state || !ptm) + return; + + cap = (u16 *)&save_state->cap.data[0]; + pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap); +} + void pci_ptm_init(struct pci_dev *dev) { int pos; @@ -65,6 +106,8 @@ void pci_ptm_init(struct pci_dev *dev) if (!pos) return; + pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u16)); + pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap); local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8; |