--------------
Usage:
- pci_save_state(dev, buffer);
+ pci_save_state(struct pci_dev *dev);
Description:
- Save first 64 bytes of PCI config space. Buffer must be allocated by
- caller.
+ Save first 64 bytes of PCI config space, along with any additional
+ PCI-Express or PCI-X information.
pci_restore_state
-----------------
Usage:
- pci_restore_state(dev, buffer);
+ pci_restore_state(struct pci_dev *dev);
Description:
- Restore previously saved config space. (First 64 bytes only);
-
- If buffer is NULL, then restore what information we know about the
- device from bootup: BARs and interrupt line.
+ Restore previously saved config space.
pci_set_power_state
-------------------
Usage:
- pci_set_power_state(dev, state);
+ pci_set_power_state(struct pci_dev *dev, pci_power_t state);
Description:
Transition device to low power state using PCI PM Capabilities
---------------
Usage:
- pci_enable_wake(dev, state, enable);
+ pci_enable_wake(struct pci_dev *dev, pci_power_t state, int enable);
Description:
Enable device to generate PME# during low power state using PCI PM
events, which is implicit if it doesn't even support it in the first
place).
- Note that the PMC Register in the device's PM Capabilties has a bitmask
+ Note that the PMC Register in the device's PM Capabilities has a bitmask
of the states it supports generating PME# from. D3hot is bit 3 and
D3cold is bit 4. So, while a value of 4 as the state may not seem
semantically correct, it is.
int (*suspend) (struct pci_dev *dev, pm_message_t state);
int (*resume) (struct pci_dev *dev);
- int (*enable_wake) (struct pci_dev *dev, pci_power_t state, int enable);
suspend
Usage:
-if (dev->driver && dev->driver->suspend)
+if (dev->driver && dev->driver->resume)
dev->driver->resume(dev)
The resume callback may be called from any power state, and is always meant to
this function, except for PM-capable devices when pci_set_power_state is used.
-enable_wake
------------
-
-Usage:
-
-if (dev->driver && dev->driver->enable_wake)
- dev->driver->enable_wake(dev,state,enable);
-This callback is generally only relevant for devices that support the PCI PM
-spec and have the ability to generate a PME# (Power Management Event Signal)
-to wake the system up. (However, it is possible that a device may support
-some non-standard way of generating a wake event on sleep.)
+A reference implementation
+-------------------------
+.suspend()
+{
+ /* driver specific operations */
-Bits 15:11 of the PMC (Power Mgmt Capabilities) Register in a device's
-PM Capabilties describe what power states the device supports generating a
-wake event from:
+ /* Disable IRQ */
+ free_irq();
+ /* If using MSI */
+ pci_disable_msi();
-+------------------+
-| Bit | State |
-+------------------+
-| 11 | D0 |
-| 12 | D1 |
-| 13 | D2 |
-| 14 | D3hot |
-| 15 | D3cold |
-+------------------+
+ pci_save_state();
+ pci_enable_wake();
+ /* Disable IO/bus master/irq router */
+ pci_disable_device();
+ pci_set_power_state(pci_choose_state());
+}
-A device can use this to enable wake events:
+.resume()
+{
+ pci_set_power_state(PCI_D0);
+ pci_restore_state();
+ /* device's irq possibly is changed, driver should take care */
+ pci_enable_device();
+ pci_set_master();
- pci_enable_wake(dev,state,enable);
+ /* if using MSI, device's vector possibly is changed */
+ pci_enable_msi();
-Note that to enable PME# from D3cold, a value of 4 should be passed to
-pci_enable_wake (since it uses an index into a bitmask). If a driver gets
-a request to enable wake events from D3, two calls should be made to
-pci_enable_wake (one for both D3hot and D3cold).
+ request_irq();
+ /* driver specific operations; */
+}
+This is a typical implementation. Drivers can slightly change the order
+of the operations in the implementation, ignore some operations or add
+more driver specific operations in it, but drivers should do something like
+this on the whole.
5. Resources
~~~~~~~~~~~~
PCI Local Bus Specification
PCI Bus Power Management Interface Specification
- http://pcisig.org
+ http://www.pcisig.com