ohci1394: steps to implement suspend/resume

I did a quick shot on what I described and the appended patch
does the first thing needed for working suspend/resume
in ohci1394 which is HW de- and re-initialisation.

It works with suspend2disk on my Ricoh R5C552 IEEE 1394 Controller
with the 2.6.17 kernel to the extent that if I call dvgrab --interactive
after suspend2disk without unloading ohci1394, it does not lock up
dvgrab with 100% CPU but properly connects to the camera, given
that I first unplug and plug the camera after coming back from
suspend.

I guess that could be fixed by forcing a bus reset in the resume
function.

I cannot test suspend to RAM here at the moment and should
follow the guidelines in Documentation/power/pci.txt also,
so this is rather a quick report than a finished patch and
there are some rough edges:

However, with this patch, I have to unload at least some in-kernel
users of ohci1394 like dv1394 or video1394 before suspending.

Not doing that caused an Oops and a bad tasklet error, probably from
not handling ISO tasklets during suspend/resume properly.

Maybe these can be temporarily cleared or unregistered and
re-registered for suspend/resume with help from the other
layers or from the highlevel 1394 core, but I do not really
know what these do.

But this patch provides a useful base to start from and is
already of much help for people which do not need dv1394
and video1394 or can unload them at least during suspend.

I cannot test function with sbp2 at the moment, but raw1394
seems to work fine.
Signed-off-by: Bernhard Kaindl <bk@fsfe.org>

Update 1: merge with previous two ohci1394 suspend/resume patches
Update 2: version for application on top of Linux 2.6.19-rc4
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/ieee1394/ohci1394.c

@@ -3531,6 +3531,9 @@ static void ohci1394_pci_remove(struct pci_dev *pdev)
 #ifdef CONFIG_PM
 static int ohci1394_pci_resume (struct pci_dev *pdev)
 {
+	int err;
+	struct ti_ohci *ohci;
+
 /* PowerMac resume code comes first */
 #ifdef CONFIG_PPC_PMAC
 	if (machine_is(powermac)) {
@@ -3545,28 +3548,89 @@ static int ohci1394_pci_resume (struct pci_dev *pdev)
 
 	pci_set_power_state(pdev, PCI_D0);
 	pci_restore_state(pdev);
-	return pci_enable_device(pdev);
+	err = pci_enable_device(pdev);
+	if (err)
+		return err;
+
+	ohci = pci_get_drvdata(pdev);
+	if (!ohci)
+		return -1; /* or which exit status to use? */
+
+	PRINT(KERN_DEBUG, "resume called");
+
+	/* The following lines are copied from ohci1394_pci_probe(): */
+
+	/* Start off with a soft reset, to clear everything to a sane
+	 * state. */
+	ohci_soft_reset(ohci);
+
+	/* Now enable LPS, which we need in order to start accessing
+	 * most of the registers.  In fact, on some cards (ALI M5251),
+	 * accessing registers in the SClk domain without LPS enabled
+	 * will lock up the machine.  Wait 50msec to make sure we have
+	 * full link enabled.  */
+	reg_write(ohci, OHCI1394_HCControlSet, OHCI1394_HCControl_LPS);
+
+	/* Disable and clear interrupts */
+	reg_write(ohci, OHCI1394_IntEventClear, 0xffffffff);
+	reg_write(ohci, OHCI1394_IntMaskClear, 0xffffffff);
+
+	mdelay(50);
+
+	ohci_initialize(ohci);
+
+	return 0;
 }
 
 static int ohci1394_pci_suspend (struct pci_dev *pdev, pm_message_t state)
 {
 	int err;
+	struct ti_ohci *ohci;
+
+	ohci = pci_get_drvdata(pdev);
+	if (!ohci)
+		return -1; /* Not sure if this is the correct return code */
+
+	PRINT(KERN_DEBUG, "suspend called");
+
+	/* clear the async DMA contexts and stop using the controller: */
+	hpsb_bus_reset(ohci->host);
+
+	/* The following calls are from ohci1394_pci_remove(): */
 
-	printk(KERN_INFO "%s does not fully support suspend and resume yet\n",
-	       OHCI1394_DRIVER_NAME);
+	/* Clear out BUS Options */
+	reg_write(ohci, OHCI1394_ConfigROMhdr, 0);
+	reg_write(ohci, OHCI1394_BusOptions,
+		  (reg_read(ohci, OHCI1394_BusOptions) & 0x0000f007) |
+		  0x00ff0000);
+
+	/* Clear interrupt registers */
+	reg_write(ohci, OHCI1394_IntMaskClear, 0xffffffff);
+	reg_write(ohci, OHCI1394_IntEventClear, 0xffffffff);
+	reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, 0xffffffff);
+	reg_write(ohci, OHCI1394_IsoXmitIntEventClear, 0xffffffff);
+	reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, 0xffffffff);
+	reg_write(ohci, OHCI1394_IsoRecvIntEventClear, 0xffffffff);
+
+	/* Disable IRM Contender */
+	set_phy_reg(ohci, 4, ~0xc0 & get_phy_reg(ohci, 4));
+
+	/* Clear link control register */
+	reg_write(ohci, OHCI1394_LinkControlClear, 0xffffffff);
+
+	/* Let all other nodes know to ignore us */
+	ohci_devctl(ohci->host, RESET_BUS, LONG_RESET_NO_FORCE_ROOT);
+
+	/* This stops all DMA contexts, disables interrupts,
+	 * and clears linkEnable and LPS: */
+	ohci_soft_reset(ohci);
 
 	err = pci_save_state(pdev);
-	if (err) {
-		printk(KERN_ERR "%s: pci_save_state failed with %d\n",
-		       OHCI1394_DRIVER_NAME, err);
-		return err;
-	}
+	if (err)
+		goto out;
 	err = pci_set_power_state(pdev, pci_choose_state(pdev, state));
-#ifdef OHCI1394_DEBUG
 	if (err)
-		printk(KERN_DEBUG "%s: pci_set_power_state failed with %d\n",
-		       OHCI1394_DRIVER_NAME, err);
-#endif /* OHCI1394_DEBUG */
+		goto out;
 
 /* PowerMac suspend code comes last */
 #ifdef CONFIG_PPC_PMAC
@@ -3579,8 +3643,8 @@ static int ohci1394_pci_suspend (struct pci_dev *pdev, pm_message_t state)
 			pmac_call_feature(PMAC_FTR_1394_ENABLE, of_node, 0, 0);
 	}
 #endif /* CONFIG_PPC_PMAC */
-
-	return 0;
+out:
+	return err;
 }
 #endif /* CONFIG_PM */