USB: Fix NEC OHCI chip silicon bug

This patch fixes a silicon bug in some NEC OHCI chips. The bug appears
at random times and is very, very difficult to reproduce. Without the
following patch, Linux would shut the chip and its associated devices
down. In Apple PowerBooks this leads to an unusable keyboard and mouse
(SSH still working). The idea of restarting the chip is taken from
public Darwin code.

Signed-off-by: Michael Hanselmann <[e-mail]>
Cc: David Brownell <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ohci-hcd.c

···
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
 #include <linux/reboot.h>
+#include <linux/workqueue.h>
 
 #include <asm/io.h>
 #include <asm/irq.h>
···
 static void ohci_dump (struct ohci_hcd *ohci, int verbose);
 static int ohci_init (struct ohci_hcd *ohci);
 static void ohci_stop (struct usb_hcd *hcd);
+static int ohci_restart (struct ohci_hcd *ohci);
+static void ohci_quirk_nec_worker (struct work_struct *work);
 
 #include "ohci-hub.c"
 #include "ohci-dbg.c"
···
 	}
 
 	if (ints & OHCI_INTR_UE) {
-		disable (ohci);
-		ohci_err (ohci, "OHCI Unrecoverable Error, disabled\n");
 		// e.g. due to PCI Master/Target Abort
+		if (ohci->flags & OHCI_QUIRK_NEC) {
+			/* Workaround for a silicon bug in some NEC chips used
+			 * in Apple's PowerBooks. Adapted from Darwin code.
+			 */
+			ohci_err (ohci, "OHCI Unrecoverable Error, scheduling NEC chip restart\n");
+
+			ohci_writel (ohci, OHCI_INTR_UE, &regs->intrdisable);
+
+			schedule_work (&ohci->nec_work);
+		} else {
+			disable (ohci);
+			ohci_err (ohci, "OHCI Unrecoverable Error, disabled\n");
+		}
 
 		ohci_dump (ohci, 1);
 		ohci_usb_reset (ohci);
···
 /*-------------------------------------------------------------------------*/
 
 /* must not be called from interrupt context */
-
-#ifdef	CONFIG_PM
-
 static int ohci_restart (struct ohci_hcd *ohci)
 {
 	int temp;
 	int i;
 	struct urb_priv *priv;
 
-	/* mark any devices gone, so they do nothing till khubd disconnects.
-	 * recycle any "live" eds/tds (and urbs) right away.
-	 * later, khubd disconnect processing will recycle the other state,
-	 * (either as disconnect/reconnect, or maybe someday as a reset).
-	 */
 	spin_lock_irq(&ohci->lock);
 	disable (ohci);
-	usb_root_hub_lost_power(ohci_to_hcd(ohci)->self.root_hub);
+
+	/* Recycle any "live" eds/tds (and urbs). */
 	if (!list_empty (&ohci->pending))
 		ohci_dbg(ohci, "abort schedule...\n");
 	list_for_each_entry (priv, &ohci->pending, pending) {
···
 	ohci_dbg(ohci, "restart complete\n");
 	return 0;
 }
-#endif
+
+/*-------------------------------------------------------------------------*/
+
+/* NEC workaround */
+static void ohci_quirk_nec_worker(struct work_struct *work)
+{
+	struct ohci_hcd *ohci = container_of(work, struct ohci_hcd, nec_work);
+	int status;
+
+	status = ohci_init(ohci);
+	if (status != 0) {
+		ohci_err(ohci, "Restarting NEC controller failed "
+			 "in ohci_init, %d\n", status);
+		return;
+	}
+
+	status = ohci_restart(ohci);
+	if (status != 0)
+		ohci_err(ohci, "Restarting NEC controller failed "
+			 "in ohci_restart, %d\n", status);
+}
 
 /*-------------------------------------------------------------------------*/
 

drivers/usb/host/ohci-hub.c

···
 static void finish_unlinks (struct ohci_hcd *, u16);
 
 #ifdef	CONFIG_PM
-static int ohci_restart(struct ohci_hcd *ohci);
-
 static int ohci_rh_suspend (struct ohci_hcd *ohci, int autostop)
 __releases(ohci->lock)
 __acquires(ohci->lock)
···
 			spin_unlock_irq (&ohci->lock);
 			(void) ohci_init (ohci);
 			status = ohci_restart (ohci);
+
+			usb_root_hub_lost_power(hcd->self.root_hub);
+
 			spin_lock_irq (&ohci->lock);
 		}
 		return status;

drivers/usb/host/ohci-mem.c

···
 	ohci->next_statechange = jiffies;
 	spin_lock_init (&ohci->lock);
 	INIT_LIST_HEAD (&ohci->pending);
+	INIT_WORK (&ohci->nec_work, ohci_quirk_nec_worker);
 }
 
 /*-------------------------------------------------------------------------*/

drivers/usb/host/ohci-pci.c

···
 #endif
 }
 
+/* Check for NEC chip and apply quirk for allegedly lost interrupts.
+ */
+static int ohci_quirk_nec(struct usb_hcd *hcd)
+{
+	struct ohci_hcd	*ohci = hcd_to_ohci (hcd);
+
+	ohci->flags |= OHCI_QUIRK_NEC;
+	ohci_dbg (ohci, "enabled NEC chipset lost interrupt quirk\n");
+
+	return 0;
+}
+
 /* List of quirks for OHCI */
 static const struct pci_device_id ohci_pci_quirks[] = {
 	{
···
 	{
 		PCI_DEVICE(PCI_VENDOR_ID_TOSHIBA_2, 0x01b6),
 		.driver_data = (unsigned long)ohci_quirk_toshiba_scc,
+	},
+	{
+		PCI_DEVICE(PCI_VENDOR_ID_NEC, PCI_DEVICE_ID_NEC_USB),
+		.driver_data = (unsigned long)ohci_quirk_nec,
 	},
 	{
 		/* Toshiba portege 4000 */

drivers/usb/host/ohci.h

···
 #define	OHCI_QUIRK_BE_DESC	0x08			/* BE descriptors */
 #define	OHCI_QUIRK_BE_MMIO	0x10			/* BE registers */
 #define	OHCI_QUIRK_ZFMICRO	0x20			/* Compaq ZFMicro chipset*/
+#define	OHCI_QUIRK_NEC		0x40			/* lost interrupts */
 	// there are also chip quirks/bugs in init logic
 
+	struct work_struct	nec_work;	/* Worker for NEC quirk */
 };
 
 /* convert between an hcd pointer and the corresponding ohci_hcd */