Add pci_save_state() and pci_restore_state() wrappers around

pci_cfg_save() and pci_cfg_restore() for device drivers to use when
saving and restoring state (e.g. to handle device-specific resets).

Reviewed by:	imp
MFC after:	2 weeks

2 files changed, 28 insertions, 0 deletions

diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index af2a216..81063b9 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -980,6 +980,8 @@ MLINKS+=pci.9 pci_disable_busmaster.9 \
 	pci.9 pci_find_device.9 \
 	pci.9 pci_get_powerstate.9 \
 	pci.9 pci_read_config.9 \
+	pci.9 pci_restore_state.9 \
+	pci.9 pci_save_state.9 \
 	pci.9 pci_set_powerstate.9 \
 	pci.9 pci_write_config.9
 MLINKS+=pfil.9 pfil_add_hook.9 \
diff --git a/share/man/man9/pci.9 b/share/man/man9/pci.9
index d8ed624..93ea75e 100644
--- a/share/man/man9/pci.9
+++ b/share/man/man9/pci.9
@@ -38,6 +38,8 @@
 .Nm pci_disable_io ,
 .Nm pci_set_powerstate ,
 .Nm pci_get_powerstate ,
+.Nm pci_save_state ,
+.Nm pci_restore_state ,
 .Nm pci_find_bsf ,
 .Nm pci_find_dbsf ,
 .Nm pci_find_device
@@ -63,6 +65,10 @@
 .Fn pci_get_powerstate "device_t dev"
 .Ft uint32_t
 .Fn pci_read_config "device_t dev" "int reg" "int width"
+.Ft void
+.Fn pci_save_state "device_t dev"
+.Ft void
+.Fn pci_restore_state "device_t dev"
 .Ft device_t
 .Fn pci_find_bsf "uint8_t bus" "uint8_t slot" "uint8_t func"
 .Ft device_t
@@ -188,6 +194,26 @@ of
 is set.
 .Pp
 The
+.Fn pci_save_state
+and
+.Fn pci_restore_state
+functions can be used by a device driver to save and restore standard PCI
+config registers.
+The
+.Fn pci_save_state
+function must be invoked while the device has valid state before
+.Fn pci_restore_state
+can be used.
+If the device is not in the fully-powered state
+.Pq Dv PCI_POWERSTATE_D0
+when
+.Fn pci_restore_state
+is invoked,
+then the device will be transitioned to
+.Dv PCI_POWERSTATE_D0
+before any config registers are restored.
+.Pp
+The
 .Fn pci_find_bsf
 function looks up the
 .Vt device_t