USB: EHCI, OHCI: handover changes

This patch (as887) changes the way ehci-hcd and ohci-hcd handle a loss
of VBUS power during suspend. In order for the USB-persist facility
to work correctly, it is necessary for low- and full-speed devices
attached to a high-speed port to be handed back to the companion
controller during resume processing.

This entails three changes: adding code to ehci-hcd to perform the
handover, removing code from ohci-hcd to turn off ports during
root-hub reinit, and adding code to ohci-hcd to turn on ports during
PCI controller resume. (Other bus glue resume methods for platforms
supporting high-speed controllers would need a similar change, if any
existed.)

Signed-off-by: Alan Stern <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ehci-hcd.c

···
 				is_on ? SetPortFeature : ClearPortFeature,
 				USB_PORT_FEAT_POWER,
 				port--, NULL, 0);
+	/* Flush those writes */
+	ehci_readl(ehci, &ehci->regs->command);
 	msleep(20);
 }
 

drivers/usb/host/ehci-hub.c

···
 
 /*-------------------------------------------------------------------------*/
 
+#ifdef	CONFIG_USB_PERSIST
+
+static int ehci_hub_control(
+	struct usb_hcd	*hcd,
+	u16		typeReq,
+	u16		wValue,
+	u16		wIndex,
+	char		*buf,
+	u16		wLength
+);
+
+/* After a power loss, ports that were owned by the companion must be
+ * reset so that the companion can still own them.
+ */
+static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
+{
+	u32 __iomem	*reg;
+	u32		status;
+	int		port;
+	__le32		buf;
+	struct usb_hcd	*hcd = ehci_to_hcd(ehci);
+
+	if (!ehci->owned_ports)
+		return;
+
+	/* Give the connections some time to appear */
+	msleep(20);
+
+	port = HCS_N_PORTS(ehci->hcs_params);
+	while (port--) {
+		if (test_bit(port, &ehci->owned_ports)) {
+			reg = &ehci->regs->port_status[port];
+			status = ehci_readl(ehci, reg);
+
+			/* Port already owned by companion? */
+			if (status & PORT_OWNER)
+				clear_bit(port, &ehci->owned_ports);
+			else
+				ehci_hub_control(hcd, SetPortFeature,
+						USB_PORT_FEAT_RESET, port + 1,
+						NULL, 0);
+		}
+	}
+
+	if (!ehci->owned_ports)
+		return;
+	msleep(90);		/* Wait for resets to complete */
+
+	port = HCS_N_PORTS(ehci->hcs_params);
+	while (port--) {
+		if (test_bit(port, &ehci->owned_ports)) {
+			ehci_hub_control(hcd, GetPortStatus,
+					0, port + 1,
+					(char *) &buf, sizeof(buf));
+
+			/* The companion should now own the port,
+			 * but if something went wrong the port must not
+			 * remain enabled.
+			 */
+			reg = &ehci->regs->port_status[port];
+			status = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;
+			if (status & PORT_OWNER)
+				ehci_writel(ehci, status | PORT_CSC, reg);
+			else {
+				ehci_dbg(ehci, "failed handover port %d: %x\n",
+						port + 1, status);
+				ehci_writel(ehci, status & ~PORT_PE, reg);
+			}
+		}
+	}
+
+	ehci->owned_ports = 0;
+}
+
+#else	/* CONFIG_USB_PERSIST */
+
+static inline void ehci_handover_companion_ports(struct ehci_hcd *ehci)
+{ }
+
+#endif
+
 #ifdef	CONFIG_PM
 
 static int ehci_bus_suspend (struct usb_hcd *hcd)
···
 	 * then manually resume them in the bus_resume() routine.
 	 */
 	ehci->bus_suspended = 0;
+	ehci->owned_ports = 0;
 	while (port--) {
 		u32 __iomem	*reg = &ehci->regs->port_status [port];
 		u32		t1 = ehci_readl(ehci, reg) & ~PORT_RWC_BITS;
 		u32		t2 = t1;
 
 		/* keep track of which ports we suspend */
-		if ((t1 & PORT_PE) && !(t1 & PORT_OWNER) &&
-				!(t1 & PORT_SUSPEND)) {
+		if (t1 & PORT_OWNER)
+			set_bit(port, &ehci->owned_ports);
+		else if ((t1 & PORT_PE) && !(t1 & PORT_SUSPEND)) {
 			t2 |= PORT_SUSPEND;
 			set_bit(port, &ehci->bus_suspended);
 		}
···
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
 	u32			temp;
+	u32			power_okay;
 	int			i;
 
 	if (time_before (jiffies, ehci->next_statechange))
···
 	 * the last user of the controller, not reset/pm hardware keeping
 	 * state we gave to it.
 	 */
-	temp = ehci_readl(ehci, &ehci->regs->intr_enable);
-	ehci_dbg(ehci, "resume root hub%s\n", temp ? "" : " after power loss");
+	power_okay = ehci_readl(ehci, &ehci->regs->intr_enable);
+	ehci_dbg(ehci, "resume root hub%s\n",
+			power_okay ? "" : " after power loss");
 
 	/* at least some APM implementations will try to deliver
 	 * IRQs right away, so delay them until we're ready.
···
 	ehci_writel(ehci, INTR_MASK, &ehci->regs->intr_enable);
 
 	spin_unlock_irq (&ehci->lock);
+
+	if (!power_okay)
+		ehci_handover_companion_ports(ehci);
 	return 0;
 }
 
···
 ) {
 	struct ehci_hcd	*ehci = hcd_to_ehci (hcd);
 	int		ports = HCS_N_PORTS (ehci->hcs_params);
-	u32 __iomem	*status_reg = &ehci->regs->port_status[wIndex - 1];
+	u32 __iomem	*status_reg = &ehci->regs->port_status[
+				(wIndex & 0xff) - 1];
 	u32		temp, status;
 	unsigned long	flags;
 	int		retval = 0;

drivers/usb/host/ehci-pci.c

···
 	ehci_work(ehci);
 	spin_unlock_irq(&ehci->lock);
 
-	/* here we "know" root ports should always stay powered */
-	ehci_port_power(ehci, 1);
-
 	ehci_writel(ehci, ehci->command, &ehci->regs->command);
 	ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag);
 	ehci_readl(ehci, &ehci->regs->command);	/* unblock posted writes */
+
+	/* here we "know" root ports should always stay powered */
+	ehci_port_power(ehci, 1);
+	ehci_handover_companion_ports(ehci);
 
 	hcd->state = HC_STATE_SUSPENDED;
 	return 0;

drivers/usb/host/ehci.h

···
 
 	/* per root hub port */
 	unsigned long		reset_done [EHCI_MAX_ROOT_PORTS];
+
 	/* bit vectors (one bit per port) */
 	unsigned long		bus_suspended;		/* which ports were
 			already suspended at the start of a bus suspend */
 	unsigned long		companion_ports;	/* which ports are
 			dedicated to the companion controller */
+	unsigned long		owned_ports;		/* which ports are
+			owned by the companion during a bus suspend */
 
 	/* per-HC memory pools (could be per-bus, but ...) */
 	struct dma_pool		*qh_pool;	/* qh per active urb */

drivers/usb/host/ohci-hcd.c

···
 	// flush the writes
 	(void) ohci_readl (ohci, &ohci->regs->control);
 	msleep(temp);
-	temp = roothub_a (ohci);
-	if (!(temp & RH_A_NPS)) {
-		/* power down each port */
-		for (temp = 0; temp < ohci->num_ports; temp++)
-			ohci_writel (ohci, RH_PS_LSDA,
-				&ohci->regs->roothub.portstatus [temp]);
-	}
-	// flush those writes
-	(void) ohci_readl (ohci, &ohci->regs->control);
+
 	memset (ohci->hcca, 0, sizeof (struct ohci_hcca));
 
 	/* 2msec timelimit here means no irqs/preempt */
···
 	if ((temp = ohci_run (ohci)) < 0) {
 		ohci_err (ohci, "can't restart, %d\n", temp);
 		return temp;
-	} else {
-		/* here we "know" root ports should always stay powered,
-		 * and that if we try to turn them back on the root hub
-		 * will respond to CSC processing.
-		 */
-		i = ohci->num_ports;
-		while (i--)
-			ohci_writel (ohci, RH_PS_PSS,
-				&ohci->regs->roothub.portstatus [i]);
-		ohci_dbg (ohci, "restart complete\n");
 	}
+	ohci_dbg(ohci, "restart complete\n");
 	return 0;
 }
 #endif

drivers/usb/host/ohci-pci.c

···
 	return ret;
 }
 
+#if	defined(CONFIG_USB_PERSIST) && (defined(CONFIG_USB_EHCI_HCD) || \
+		defined(CONFIG_USB_EHCI_HCD_MODULE))
+
+/* Following a power loss, we must prepare to regain control of the ports
+ * we used to own.  This means turning on the port power before ehci-hcd
+ * tries to switch ownership.
+ *
+ * This isn't a 100% perfect solution.  On most systems the OHCI controllers
+ * lie at lower PCI addresses than the EHCI controller, so they will be
+ * discovered (and hence resumed) first.  But there is no guarantee things
+ * will always work this way.  If the EHCI controller is resumed first and
+ * the OHCI ports are unpowered, then the handover will fail.
+ */
+static void prepare_for_handover(struct usb_hcd *hcd)
+{
+	struct ohci_hcd	*ohci = hcd_to_ohci(hcd);
+	int		port;
+
+	/* Here we "know" root ports should always stay powered */
+	ohci_dbg(ohci, "powerup ports\n");
+	for (port = 0; port < ohci->num_ports; port++)
+		ohci_writel(ohci, RH_PS_PPS,
+				&ohci->regs->roothub.portstatus[port]);
+
+	/* Flush those writes */
+	ohci_readl(ohci, &ohci->regs->control);
+	msleep(20);
+}
+
+#else
+
+static inline void prepare_for_handover(struct usb_hcd *hcd)
+{ }
+
+#endif	/* CONFIG_USB_PERSIST etc. */
+
 #ifdef	CONFIG_PM
 
 static int ohci_pci_suspend (struct usb_hcd *hcd, pm_message_t message)
···
 static int ohci_pci_resume (struct usb_hcd *hcd)
 {
 	set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
-	usb_hcd_resume_root_hub(hcd);
+
+	/* FIXME: we should try to detect loss of VBUS power here */
+	prepare_for_handover(hcd);
+
 	return 0;
 }