This commit adds two new functions. pci_enable_device gives drivers
finer control over how the PCI device is initialized and
pci_restore_device is the shutdown path counterpart.
adjust_pci_device is now implemented in terms of pci_enable_device
and its functionality hasn't changed, i.e. it still unconditionally
enables both memory and I/O space access, and makes sure that the PCI
latency timer is set to a minimum value of 32.
Signed-off-by: Ladi Prosek <lpro...@redhat.com>
Suggested-by: Michael S. Tsirkin <m...@redhat.com>
---
src/drivers/bus/pci.c | 58 +++++++++++++++++++++++++++++++++++++++++---------
src/include/ipxe/pci.h | 3 +++
2 files changed, 51 insertions(+), 10 deletions(-)
diff --git a/src/drivers/bus/pci.c b/src/drivers/bus/pci.c
index 6fbedd9..6ccbaf5 100644
--- a/src/drivers/bus/pci.c
+++ b/src/drivers/bus/pci.c
@@ -143,29 +143,67 @@ static void pci_read_bases ( struct pci_device *pci ) {
*
* @v pci PCI device
*
- * Set device to be a busmaster in case BIOS neglected to do so. Also
- * adjust PCI latency timer to a reasonable value, 32.
+ * Set device to be a bus master in case BIOS neglected to do so. Enable
+ * both memory and I/O space access. Also adjust PCI latency timer to a
+ * reasonable value, 32.
*/
void adjust_pci_device ( struct pci_device *pci ) {
+ pci_enable_device ( pci,
+ PCI_COMMAND_MASTER | PCI_COMMAND_MEM |
+ PCI_COMMAND_IO,
+ 32 );
+}
+
+/**
+ * Enable PCI device
+ *
+ * @v pci PCI device
+ * @v flags PCI command flags to enable
+ * @v latency Minimum desired PCI latency timer or 0 to not adjust it
+ * @ret old_flags Original PCI command flags
+ *
+ * Enable device by setting bits in the command register in case BIOS neglected
+ * to do so. Also optionally adjust the PCI latency timer.
+ */
+unsigned pci_enable_device ( struct pci_device *pci, unsigned flags,
+ unsigned char latency ) {
unsigned short new_command, pci_command;
unsigned char pci_latency;
pci_read_config_word ( pci, PCI_COMMAND, &pci_command );
- new_command = ( pci_command | PCI_COMMAND_MASTER |
- PCI_COMMAND_MEM | PCI_COMMAND_IO );
+ new_command = ( pci_command | flags );
if ( pci_command != new_command ) {
- DBGC ( pci, PCI_FMT " device not enabled by BIOS! Updating "
+ DBGC ( pci, PCI_FMT " device not fully enabled by BIOS!
Updating "
"PCI command %04x->%04x\n",
PCI_ARGS ( pci ), pci_command, new_command );
pci_write_config_word ( pci, PCI_COMMAND, new_command );
}
- pci_read_config_byte ( pci, PCI_LATENCY_TIMER, &pci_latency);
- if ( pci_latency < 32 ) {
- DBGC ( pci, PCI_FMT " latency timer is unreasonably low at "
- "%d. Setting to 32.\n", PCI_ARGS ( pci ), pci_latency );
- pci_write_config_byte ( pci, PCI_LATENCY_TIMER, 32);
+ if ( latency ) {
+ pci_read_config_byte ( pci, PCI_LATENCY_TIMER, &pci_latency );
+ if ( pci_latency < latency ) {
+ DBGC ( pci, PCI_FMT " latency timer is unreasonably low
at "
+ "%d. Setting to %d.\n", PCI_ARGS ( pci ),
+ pci_latency, latency );
+ pci_write_config_byte ( pci, PCI_LATENCY_TIMER, latency
);
+ }
}
+ return pci_command;
+}
+
+/**
+ * Restore PCI device
+ *
+ * @v pci PCI device
+ * @v old_flags Flags to restore, returned from
pci_enable_device
+ *
+ * Restore the command register of a PCI device to state it had before we
+ * changed it.
+ */
+void pci_restore_device ( struct pci_device *pci, unsigned old_flags ) {
+ DBGC ( pci, PCI_FMT " restoring PCI command to %04x\n",
+ PCI_ARGS ( pci ), old_flags );
+ pci_write_config_word ( pci, PCI_COMMAND, old_flags );
}
/**
diff --git a/src/include/ipxe/pci.h b/src/include/ipxe/pci.h
index 0c6bc7e..ced6128 100644
--- a/src/include/ipxe/pci.h
+++ b/src/include/ipxe/pci.h
@@ -278,6 +278,9 @@ struct pci_driver {
PCI_FUNC ( (pci)->busdevfn )
extern void adjust_pci_device ( struct pci_device *pci );
+extern unsigned pci_enable_device ( struct pci_device *pci, unsigned flags,
+ unsigned char latency );
+extern void pci_restore_device ( struct pci_device *pci, unsigned old_flags );
extern unsigned long pci_bar_start ( struct pci_device *pci,
unsigned int reg );
extern int pci_read_config ( struct pci_device *pci );
--
2.5.5
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