PCI/PTM: Use FIELD_GET()

Use FIELD_GET() and FIELD_PREP() to remove dependences on the field
position, i.e., the shift value. No functional change intended.

Link: https://lore.kernel.org/r/20231010204436.1000644-9-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

PCI/PTM: Reorder functions in logical order

pci_enable_ptm() and pci_disable_ptm() were separated.
pci_save_ptm_state() and pci_restore_ptm_state() dangled at the top. Move
them to logical places. No functional change intended.

Link: https://lore.kernel.org/r/20220909202505.314195-8-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Preserve RsvdP bits in PTM Control register

Even though only the low 16 bits of PTM Control are currently defined, the
register is 32 bits wide and the unused bits are RsvdP ("Reserved and
Preserved"), so software must preserve the values of those bits when
writing the register.

Update PTM Control reads and writes to use 32-bit accesses and preserve the
reserved bits on writes.

Link: https://lore.kernel.org/r/20220909202505.314195-7-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Move pci_ptm_info() body into its only caller

pci_ptm_info() is simple and is only called by pci_enable_ptm(). Move the
entire body there. No functional change intended.

Link: https://lore.kernel.org/r/20220909202505.314195-6-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Add pci_suspend_ptm() and pci_resume_ptm()

We disable PTM during suspend because that allows some Root Ports to enter
lower-power PM states, which means we also need to disable PTM for all
downstream devices. Add pci_suspend_ptm() and pci_resume_ptm() for this
purpose.

pci_enable_ptm() and pci_disable_ptm() are for drivers to use to enable or
disable PTM. They use dev->ptm_enabled to keep track of whether PTM should
be enabled.

pci_suspend_ptm() and pci_resume_ptm() are PCI core-internal functions to
temporarily disable PTM during suspend and (depending on dev->ptm_enabled)
re-enable PTM during resume.

Enable/disable/suspend/resume all use internal __pci_enable_ptm() and
__pci_disable_ptm() functions that only update the PTM Control register.
Outline:

pci_enable_ptm(struct pci_dev *dev)
{
__pci_enable_ptm(dev);
dev->ptm_enabled = 1;
pci_ptm_info(dev);
}

pci_disable_ptm(struct pci_dev *dev)
{
if (dev->ptm_enabled) {
__pci_disable_ptm(dev);
dev->ptm_enabled = 0;
}
}

pci_suspend_ptm(struct pci_dev *dev)
{
if (dev->ptm_enabled)
__pci_disable_ptm(dev);
}

pci_resume_ptm(struct pci_dev *dev)
{
if (dev->ptm_enabled)
__pci_enable_ptm(dev);
}

Nothing currently calls pci_resume_ptm(); the suspend path saves the PTM
state before disabling PTM, so the PTM state restore in the resume path
implicitly re-enables it. A future change will use pci_resume_ptm() to fix
some problems with this approach.

Link: https://lore.kernel.org/r/20220909202505.314195-5-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Separate configuration and enable

PTM configuration and enabling were previously mixed together:
pci_ptm_init() collected granularity info and enabled PTM for Root Ports
and Switch Upstream Ports; pci_enable_ptm() did the same for Endpoints.

Move everything related to the PTM Capability register to pci_ptm_init()
for all devices, and everything related to the PTM Control register to
pci_enable_ptm().

Link: https://lore.kernel.org/r/20220909202505.314195-4-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Add pci_upstream_ptm() helper

PTM requires an unbroken path of PTM-supporting devices between the PTM
Root and the ultimate PTM Requester, but if a Switch supports PTM, only the
Upstream Port can have a PTM Capability; the Downstream Ports do not.

Previously we copied the PTM configuration from the Switch Upstream Port to
the Downstream Ports so dev->ptm_enabled for any device implied that all
the upstream devices support PTM.

Instead of making it look like Downstream Ports have their own PTM config,
add pci_upstream_ptm(), which returns the upstream device that has a PTM
Capability (either a Root Port or a Switch Upstream Port).

Link: https://lore.kernel.org/r/20220909202505.314195-3-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Cache PTM Capability offset

Cache the PTM Capability offset instead of searching for it every time we
enable/disable PTM or save/restore PTM state. No functional change
intended.

Link: https://lore.kernel.org/r/20220909202505.314195-2-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

PCI/PTM: Remove error message at boot

Since 39850ed51062 ("PCI/PTM: Save/restore Precision Time Measurement
Capability for suspend/resume"), devices that have PTM capability but
don't enable it see this message on calls to pci_save_state():

no suspend buffer for PTM

Drop the message, it's perfectly fine not to use a capability.

Fixes: 39850ed51062 ("PCI/PTM: Save/restore Precision Time Measurement Capability for suspend/resume")
Link: https://lore.kernel.org/r/20210811185955.3112534-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: David E. Box <david.e.box@linux.intel.com>

PCI: Add pcie_ptm_enabled()

Add a predicate that returns if PCIe PTM (Precision Time Measurement)
is enabled.

It will only return true if it's enabled in all the ports in the path
from the device to the root.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

PCI: Disable PTM during suspend to save power

There are systems (for example, Intel based mobile platforms since Coffee
Lake) where the power drawn while suspended can be significantly reduced by
disabling Precision Time Measurement (PTM) on PCIe root ports as this
allows the port to enter a lower-power PM state and the SoC to reach a
lower-power idle state. To save this power, disable the PTM feature on root
ports during pci_prepare_to_sleep() and pci_finish_runtime_suspend(). The
feature will be returned to its previous state during restore and error
recovery.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=209361
Link: https://lore.kernel.org/r/20201207223951.19667-2-david.e.box@linux.intel.com
Reported-by: Len Brown <len.brown@intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

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>

PCI/PTM: Inherit Switch Downstream Port PTM settings from Upstream Port

Except for Endpoints, we enable PTM at enumeration-time. Previously we did
not account for the fact that Switch Downstream Ports are not permitted to
have a PTM capability; their PTM behavior is controlled by the Upstream
Port (PCIe r5.0, sec 7.9.16). Since Downstream Ports don't have a PTM
capability, we did not mark them as "ptm_enabled", which meant that
pci_enable_ptm() on an Endpoint failed because there was no PTM path to it.

Mark Downstream Ports as "ptm_enabled" if their Upstream Port has PTM
enabled.

Fixes: eec097d43100 ("PCI: Add pci_enable_ptm() for drivers to enable PTM on endpoints")
Reported-by: Aditya Paluri <Venkata.AdityaPaluri@synopsys.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/PTM: Remove spurious "d" from granularity message

The granularity message has an extra "d":

pci 0000:02:00.0: PTM enabled, 4dns granularity

Remove the "d" so the message is simply "PTM enabled, 4ns granularity".

Fixes: 8b2ec318eece ("PCI: Add PTM clock granularity information")
Link: https://lore.kernel.org/r/20191106222420.10216-2-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Cc: Jonathan Yong <jonathan.yong@intel.com>

PCI: Add SPDX GPL-2.0 to replace GPL v2 boilerplate

Add SPDX GPL-2.0 to all PCI files that specified the GPL version 2 license.

Remove the boilerplate GPL version 2 language, relying on the assertion in
b24413180f56 ("License cleanup: add SPDX GPL-2.0 license identifier to
files with no license") that the SPDX identifier may be used instead of the
full boilerplate text.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

PCI: Add wrappers for dev_printk()

Add PCI-specific dev_printk() wrappers and use them to simplify the code
slightly. No functional change intended.

Signed-off-by: Frederick Lawler <fred@fredlawl.com>
[bhelgaas: squash into one patch]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI: Add PTM clock granularity information

The PTM Control register (PCIe r3.1, sec 7.32.3) contains an Effective
Granularity field:

This provides information relating to the expected accuracy of the PTM
clock, but does not otherwise affect the PTM mechanism.

Set the Effective Granularity based on the PTM Root and any intervening PTM
Time Sources.

This does not set Effective Granularity for Root Complex Integrated
Endpoints because I don't know how to figure out clock granularity for
them. The spec says:

... system software must set [Effective Granularity] to the value
reported in the Local Clock Granularity field by the associated PTM
Time Source.

but I don't know how to identify the associated PTM Time Source. Normally
it's the upstream bridge, but an integrated endpoint has no upstream
bridge.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

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>

PCI: Add Precision Time Measurement (PTM) support

Add Precision Time Measurement (PTM) support (see PCIe r3.1, sec 6.22).

Enable PTM on PTM Root devices and switch ports. This does not enable PTM
on endpoints.

There currently are no PTM-capable devices on the market, but it is
expected to be supported by the Intel Apollo Lake platform.

[bhelgaas: complete rework]
Signed-off-by: Jonathan Yong <jonathan.yong@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>